What Is the Optimal Vitamin C Intake?

What Is the Optimal Vitamin C Intake?
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Experiments showing how much vitamin C our body absorbs and excretes can give us a sense of how many vitamin C rich fruits and vegetables we should be eating each day.


Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

For many years, the RDA (the recommended daily allowance) for vitamins was just based on preventing deficiency with a margin of safety. But, the minuscule amount of vitamin C, for example, needed to avoid scurvy is not necessarily the ideal intake for optimal health. So, what might be the optimal intake of vitamin C? Let’s ask the body. How might we do that? By seeing how much the body absorbs and excretes.

If you swallow 15 milligrams of vitamin C, which is what you would get eating about one-quarter of an orange, your body sucks up nearly 90% of it. But, if you take a supplement containing 1,250 milligrams, your body seems to realize that’s too much—and so, clamps down on absorption at the intestinal lining level, and you end up absorbing less than half.

So, by doing experiments where you slowly ratchet up the level of intake, you can see when the body starts to say, “Okay, that’s enough.”  And, that magic level of intake appears to be about 200 milligrams a day. When you take up to 200 a day, your body sucks it all up. But, above that, the body tries to block further absorption—suggesting our intestinal vitamin C transport mechanisms “have evolved to fully absorb up to about 200 mg of vitamin C” a day.

In addition, vitamin C is reabsorbed in our kidneys, back into our bloodstream, to maintain our vitamin C blood levels up at around 70 or 80 micromoles per liter. That’s the shaded region here, which is what you reach at a vitamin C intake of about 200 milligrams a day. So, even if you take ten times as much in vitamin C supplements—2,000 milligrams a day—your body will just pee and poop it out to keep your blood levels in that narrow range. So, based on these kinds of data, one might propose that 200 milligrams is the optimal daily intake of vitamin C.

You can confirm, using disease data. At what daily intake of vitamin C is there the lowest stroke risk? Apparently, at about 200 milligrams a day. While dietary vitamin C intake was associated with lower stroke risk, vitamin C supplements were not—which is consistent with the overall body of evidence showing that antioxidant supplements in general don’t seem to protect against heart attacks or strokes.

But, wait, can you get up to an intake of 200 milligrams a day without taking supplements? No problem. Single servings of fruits and vegetables may have about 50 milligrams each; so, a measly five servings of fruits and veggies a day could get you to ideal blood levels.

Please consider volunteering to help out on the site.

Image credit: Frank Lindecke via flickr. Image has been modified.

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

For many years, the RDA (the recommended daily allowance) for vitamins was just based on preventing deficiency with a margin of safety. But, the minuscule amount of vitamin C, for example, needed to avoid scurvy is not necessarily the ideal intake for optimal health. So, what might be the optimal intake of vitamin C? Let’s ask the body. How might we do that? By seeing how much the body absorbs and excretes.

If you swallow 15 milligrams of vitamin C, which is what you would get eating about one-quarter of an orange, your body sucks up nearly 90% of it. But, if you take a supplement containing 1,250 milligrams, your body seems to realize that’s too much—and so, clamps down on absorption at the intestinal lining level, and you end up absorbing less than half.

So, by doing experiments where you slowly ratchet up the level of intake, you can see when the body starts to say, “Okay, that’s enough.”  And, that magic level of intake appears to be about 200 milligrams a day. When you take up to 200 a day, your body sucks it all up. But, above that, the body tries to block further absorption—suggesting our intestinal vitamin C transport mechanisms “have evolved to fully absorb up to about 200 mg of vitamin C” a day.

In addition, vitamin C is reabsorbed in our kidneys, back into our bloodstream, to maintain our vitamin C blood levels up at around 70 or 80 micromoles per liter. That’s the shaded region here, which is what you reach at a vitamin C intake of about 200 milligrams a day. So, even if you take ten times as much in vitamin C supplements—2,000 milligrams a day—your body will just pee and poop it out to keep your blood levels in that narrow range. So, based on these kinds of data, one might propose that 200 milligrams is the optimal daily intake of vitamin C.

You can confirm, using disease data. At what daily intake of vitamin C is there the lowest stroke risk? Apparently, at about 200 milligrams a day. While dietary vitamin C intake was associated with lower stroke risk, vitamin C supplements were not—which is consistent with the overall body of evidence showing that antioxidant supplements in general don’t seem to protect against heart attacks or strokes.

But, wait, can you get up to an intake of 200 milligrams a day without taking supplements? No problem. Single servings of fruits and vegetables may have about 50 milligrams each; so, a measly five servings of fruits and veggies a day could get you to ideal blood levels.

Please consider volunteering to help out on the site.

Image credit: Frank Lindecke via flickr. Image has been modified.

Doctor's Note

Doctors can circumvent our body’s natural barriers to vitamin C overload by dripping high levels directly in the bloodstream of cancer patients. Is this a good idea? See:

What about other common supplements? See, for example:

If you haven’t yet, you can subscribe to my videos for free by clicking here.

158 responses to “What Is the Optimal Vitamin C Intake?

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  1. Very interesting, I’ve been wondering about this question for a long time, so it’s good to know.

    By the way, since many plant eaters including myself eat far more than 5 servings of fruits and veggies per day, does it mean we may be getting too much vitamin C for optimal health? 2 servings (170g) of raw kale gives you about 200mg and one large yellow bell pepper alone contains about 340mg… I think I’m getting around 1000mg on some days. I have a feeling that’s not necessarily a bad thing.

    1. Great question, though I suspect the excess, as indicated in the video, just passes through. If there is a negative to the body having to reject the excess, it’s not been mentioned yet.

      1. The body actively excretes levels above (80 μM). There are negatives to the transient peaks induced by high-dose supplementation, including hampering adaptations to and increasing oxidative stress after exercise, and increasing cataract risk. Vitamin C’s primary role in the body remains the one it was discovered for, as a cofactor in collagen synthesis. However, its a “secondary” antioxidant to urate in fluids and to glutathione and enzyme antioxidants in cells, and excess vitamin C both has the potential to catalyze prooxidant reactions with iron and may interfere with normal intracellular signalling. Mother Nature is still wiser than Linus Pauling.

          1. Sorry, no. You can’t really do placebo controlled studies with food, supplements are often in the context of replete diets, and supplement users tend eat healthier diets, so its difficult to directly compare. We just have the prospective epidemiology that consistently reports an advantage for more fruits & vegetables up to about 5 a day, and the placebo-controlled studies with C supplementation which show no benefit. There’s a potential from non-placebo controlled prospective studies that there may be some limited benefits to higher dose supplementation, but as noted above, it also has drawbacks.

            1. Thanks Darryl: I am just curious about the claims of supplement manufacturers that sell very expensive whole-food vitamin supplements, basically dried and ground high-vitamn C fruits.

              1. You’re certainly getting other compounds with, say, rose-hips, some positive and some negative. Some whole-food powder supplements have caused hepatoxicity, either through adulteration or overdose of naturally occurring hormetins.

                As we should be able to get everything we need besides B12,and maybe D & EPA/DHA from a whole foods plant based diet, my reaction is why bother. The only similar supplement I take is kelp tablets for their iodine content, mostly because I use kosher salt in my salt cellar.

                1. I think you’ve posted about other supplements you take, though, or have you changed your opinion? (I remember glycine, there were a few others, but maybe I’m thinking of another person). What’s your opinion on zinc?

                2. Dr, Greger
                  Do you recommend a healthy plant based 69 year old woman take kelp tabs as well!
                  If so could you recommend favorite brand perhaps?

          2. that’s a good question George. I am not a large person, but in eating a wfpb diet I may easily consume 12 or more servings of fruit and veg while grazing through the day. I am wondering if the vit c is a hardship for the body to ‘clear, and if so, what am I going to eat? lol

            1. Is eating too many fruits and veggies a hardship for the body? Well, if it is, then I’m in trouble. HeHe. “I hope I die before I get old”. That one made me laugh Susan.

              1. hahaha funny Blair Rollin.. I just kept thinking about the modest levels quoted in the video, and thinking about stresses on kidneys or if there is a negative impact . Daryl mentioned some negatives in connection to supplements, and that there is a lack of studies. I am in kidney function preserving mindset these days , so thats why I ask.

                1. Take it easy, it down and relax – then think about this. Not even two bell peppers have the same amount of vitamin C, not two apple and so fort… why? Because if a apple is hanging on the south side near the top of the tree, he will store more vitamin C and others then a apple hanging on the same tree but near the earth and on the north side. Are you sure your apple from your favorite store is from the garden next door? Or is he coming from New Zealand waiting in a warehouse for month? What about the bananas which harvested green? Maybe no problem for you in the USA but in German, we have not so much really “fresh harvested”…What does it all mean? You can’t be sure how much vitamin C you get be eating a apple or something other. In addition, it also depends on your lifestyle how much Vitamin C your body “burns”. May you enjoy a run for 1 hour or you drink a beer with friends, stay at outside at the coolness this days or, or, or… So I think the conclusion of this video today should be, that taking supplements its not helpful because the best way to get enough and good available vitamin C is… from fruits and vegetable in the natural form. That’s it… ;-)

                  1. Thank you so much Steffen Jurisch! Makes so much sense , and really makes me so glad I embarked on this wfpb eating style.. its been nothing but good news since. I learn something everyday on here, and you have pointed out useful factors to consider. thanks again, I will happily continue to graze…

                  2. OMG Steffen…you just told a woman to “sit down and relax”….Susan took that really graciously :) Anyway, I concur with your comments….no need to worry, our bodies have it covered.

                2. Check out the “Kidney” videos in the index. http://nutritionfacts.org/topics/kidney-health/ Better yet, read the book. Turns out that the same diet that is good for your cardio system, lungs, brain, digestive tract, cancer preventative, etc, is also good for your kidneys. You guessed it. A WFPB diet. I am a fan of all our WFPB doctors; Greger, Esselstyn, Barnard, McDougall, Campbell, Ornish. They are all in 99% agreement that a WFPB diet is the solution to most health issues. There are some differences on supplements, but I think, with the exception of B12, it’s safe to say that supplements are to be avoided unless proven otherwise with a lot of evidence. At least, that’s my take. One thing I am sure of; you can’t eat too many fruits and vegetables.

                  1. Awesome Blair Rollin! That is all such great news , specially since I’m eating fruits and vegies alllll day long ! Thank you for the link also… I will enjoy reading up. I was looking to preserve (good) kidney function since I understood it can decrease with age, but hey, seems like we’re doing the right thing with wfpb diet. I feel so fortunate to have this information and resources, and I never ate better in my life. thanks again

            2. Susan: I’m not a large person either, so your point is well taken. Just to give you an example, during the cherry season, if I eat a small bowl of cherry a day for a few days consecutively, I feel a little sick. The other problem is where I live it’s not easy to find truly fresh “fresh” fruits during the winter months. Vitamin C is heat sensitive, light sensitive, and air sensitive; I don’t think I get enough vitamin C day after day during the winter.

              1. Exactly George, I can relate to the points you’ve made. I live in canada where some types fruit and some veg can be expensive or not available. (The oranges the stores bring in at this time of year are terrific though.) I garden too, and I can end up eating the same thing for weeks, so its kind of a feast ot famine thing I have going on here.

                Darryl posted links to some interesting studies showing negative effects of vit c supplements (1000 mg in the cataract study). Vit C is not the innocuous substance many of us have been led to believe. I wont be consuming the popular 1000mg fizzy vit c in future, but may at rare times of illness take small amounts if necessary , or if my diet is wanting.
                Blair Rollin and Stephen Jurisch made helpful comments to consider in getting enough or more than enough vit c eating wfpb style.

          3. My book is packed but others here will recall from Campbell’s book “Whole” the research reference of one of Campbell’s PhD students comparing the amount of C in an apple (100 mg?) but the antioxidant effect being as if it were a 1000 plus mg because of being in the Apple.

        1. Mother Nature may be smarter than Linus Pauling, but that doesn’t make him a stupid man. I read that he took over 20 grams of C a day and he lived to be 94. To me that casts some doubt on negative effects of C supplements.

          1. Bill Jenkins: Here’s some perspective on the matter. Suppose I told you that I knew someone who smoked a pack of cigarettes a day and lived to be 100 and never got cancer. Would that tell us anything about whether or not smoking is generally healthy? No, because that’s an anecdote and we don’t have enough information about anecdotes to make a conclusion like that.
            Similarly, whatever happened to Linus Pauling tells us almost nothing about the safety or lack there of any single supplement.

            1. Thanks for your reply. I agree with you that we should not make conclusions too quickly. Some doubt should be kept, so we don’t begin to believe that one person has all the answers. I merely suspect there is more to learn about Vit C.
              I think it would be interesting if we could tell what exactly happens at the cellular level when Vit C drops below the level the body works so hard to keep it at.

        2. There could of course be beneficial compounds in high C-vitamin whole foods that far outweigh the negatives of the high C. Studies on supplements can’t really tell us what we like to know about whole foods.

    2. I agree with you Ishay. Since we have mechanisms to reduce amount of Vit C absorbed by our body if the concentration is too high (above 200 mg as in the video) as well as pee any excess out since it is a water soluble vitamin, high dietary intakes don’t appear to have cause for concern. Also, if you’re cooking some of your veggies, there will be loss of some Vit C through heat (above 70 degrees) and in water (if you are boiling veggies, but who does that these days? Steaming is of course preferable). Hope that helps!

        1. You should strive to get all of your nutrients from whole plant foods since food is a package deal. You are getting thousands of beneficial phytochemicals on top of the vitamin C from plants whereas supplementation can be actively harmful http://nutritionfacts.org/topics/supplements/

          I also suspect that with high dose vitamin C supplementation your body doesn’t have as much time to adjust vitamin C absorption so you would end up with more in your bloodstream. This might cause more stress on your kidneys to excrete the extra compared to whole plant foods where the fiber in the foods slows the absorption of most nutrients. This is entirely conjecture on my part though.

      1. Joanne, longtime fan (indeed, friend of MG since early 90s in Ithaca) despite not being on nf.org often…but one thing I wish he included in this vid (unless I missed it, I watched twice) and I know at least once in the past I had a similar “Request” — he included mg but not percents…I know fresh is best, but I do have things like (looks at kitchen counter) like Farmer’s Market brand Organic Sweet Potatos Puree “BPA Free liner” can…there’s no “mg” just % on the can!

        So, what does “200mg” translate into, in (current) U.S. nutrition facts labels, the 200mg translates into what %? Then I’ll know what to aim for, for this “optimal” level, when my diet includes not only fresh items (where I can google for how many mg of vit C the individual fruit/veg has) but also cans like the above (and frozen!) that only give percents. I searched comments for the word and symbol for percent but it found none so hoping this can be answered…thanks!

        1. Hi Barzilai,
          Thanks for your question. If you only see % DV on a food label for a specific nutrient it is based on a 2000 kcal diet or in the case of vitamins/minerals, those people with highest needs (although there are some exceptions to this). For Vit C the reference standard used to calculate % DV is only 60 mg. Doing the math, 200 mg Vit C would translate to 333% DV if you were aiming to get all from one food item adjusting serving size accordingly. You might be interested to check this out, the reference standards used for all nutrients on food labels can be found here:

          There are change coming to food labels which were approved earlier this year. One area of change includes removing Vit C as a mandatory component. Why? The FDA states “In the early 1990’s, American diets lacked Vitamins A and C, but now Vitamins A and C deficiencies in the general population are rare. Manufacturers are still able to list these vitamins voluntarily.” http://www.fda.gov/Food/GuidanceRegulation/GuidanceDocumentsRegulatoryInformation/LabelingNutrition/ucm385663.htm

          Since food labels do not necessarily reflect optimal intake of a nutrient, looking for the mg on food labels is your best bet when it’s available. Hopefully food manufacturers if they are highlighting this nutrient will continue to include it on food labels. Hope this helps!

    3. I have to post here but it has nothing to do with the video. I just don’t know another way to ask. I want to if there has been a study of collagen powder supplements. I’m a meat eating smoker. I’m still reading how not to die and well I’m ready to quit smoking and eat plant based or really try. But my issue is that I don’t want to stop taking collagen. It has made my bones feel better and skin look better but I don’t know what real damage I’m doing by taking it. Everything I look up it seems like it good to take. But well after reading this book well I’m half way through I trust Dr Michael Gregger
      Reading this book has changed my whole outlook. I’m researching everything I can to prep myself for this change. More so for my so who is 1 this is great to start him early with eating the right way. I know it brings calcium levels up. I have no allergic reactions. All I have felt from taking is benefits. So please if there is info and studies I would like to know

      1. Hi Tracy, thanks so much for your comment and questions. It’s great to hear that you’re educating yourself to improve the health of you and your family.

        Regarding collagen supplements, there isn’t much research done on long-term collagen use. To my knowledge, they have only shown that up to 24 week supplementation is safe. However, I would offer two routes regarding the supplement.

        1.) As you continue to improve your diet and lifestyle, continue taking the supplement. The supplement will probably have a minuscule role in your health one way or the other, in comparison to eating healthy and quitting smoking.

        2.) Or you could stop the supplementation for a couple months while you improve your lifestyle habits. You might find that you don’t need them at all, and you may feel better than ever. At worst, you could always start taking them again after a few months if you feel the need to.

        In either case, focus on improving your diet and other lifestyle habits. Those are going to make the biggest differences for your health! I wish you the best of luck on your journey!

    1. Nice one, Joe.

      Ya, Dr. G seems to change his opinion from one day to the next. Avocado helps proliferate cancer cells – no avocado! Oh, turns out that’s not the case – eat avocado! You can meet your Omega 3 requirements by taking just a tablespoon of flax a day – whole foods for the win! Oh, turns out you need to buy ridiculously expensive algae oil supplements for adequate Omega 3 intake – whole foods just aren’t enough!

      I take two Vitamin C chewables each day, 500mg each. They’re naturally flavoured – I like the blueberry and orange ones. Suck on them like candy, one in the morning, one later in the day, taken to flavour the otherwise flavourless vitamin D supplements I also suck on.

      Good quality fruit is kinda scarce and expensive up here (Canada). A bottle of 120 of these 500mg Vitamin C chewables is like $4-5. Depending on whether you take 1 or 2 a day, you’re good for 2-4 months Vitamin C intake. That same $4-5 might buy you 4-5 large oranges, good for a couple days Vitamin C intake (assuming min 200mg).

      1. Each of us has to assess our individual needs and situation and take these “expert” studies with a grain of salt. Not everyone can afford the quantity/variety of fruits and veges that are supposed to provide all the nutrition we ever need.

        1. HI Jean, I am a volunteer for Dr. Greger. Thank you for your comment. While you are absolutely correct that some people may not be able to afford some of the healthier foods like berries or other organic produce, it is important to know that most of the cheapest foods in the world are actually plant-based–potatoes, beans, lentils, sweet potatoes, brown rice, oats, and other grains. Additionally, there are frozen and canned varieties of fruits and vegetables that can help people save money. Overall, with the alarming rate of chronic disease that continues to persist and even increase in this country and throughout the world, people cannot afford NOT to invest money into their health. We see so many purchases of materialistic things like cars, TVs, entertainment, etc. (which is okay in moderation), but many people fail to invest money into their own bodies. Eating a whole food, plant-based diet (if done properly), can save money in the short-term and especially the long-term, as pricey medications, surgeries, and other treatments can be avoided through the reduced risk of disease development. This doesn’t even include peace of mind– the increased opportunity to be disease-free, happy, and healthy, with more quality years on the earth to enjoy the most valuable things in life.

          1. Its all well and good to say we cant afford not to invest in our health, but frankly, if the money isnt there, it isnt there. It is the single biggest obstacle I hear from people, and I struggle too, even though I am very resourceful, organized and a good cook. Those foods ie peas, beans and lentils take spices etc to make them edible. It can take months to get organized for just kne genre of cuisine. Sweet potatoes are very expensive here.
            I myself can not afford the daily dozen for much of the year, especially organic!
            Its a problem is all I’m saying. Calorie restriction, not a problem

          2. Sticking to the theme of the video – Vitamin C – you just wouldn’t get enough eating any normal amount of the budget friendly foods listed.

            According to the USDA nutrient database, a large baked sweet potato contains a not-so-whopping 35mg of C. A large regular (Russet) potato contains 25mg. Lentils, beans, brown rice, oats and other grains contain negligible amounts of C (lentils 3 mg per cup, brown rice and oats 0 mg each). So unless you plan on eating 8 large potatoes a day, you’ll be C deficient on those budget friendly foods.

            Not sure where the commenter is from, but tinned fruit ain’t cheap, and it ain’t healthy. A whole tin of canned peaches in light syrup (the typical tinned fruit), contains a whopping 6 mg of C per cup. Not surprising since most tinned fruit is processed.

            The main dietary source of C for most people is fresh fruits, predominantly citrus and berrries, which ain’t cheap, orgainic or otherwise. Sure, you could eat half a pound of kale, but most people would rather not. There’s probably no better food when it comes to turning people off veganism than kale.

            So ya, unlike Dr. G’s beloved algae oil, vitamin C supplements are the cheapest supplements around. You could literally buy a tub of the stuff, over a year’s supply, for like $10. And contrary to Dr. G’s assertion, they’re perfectly safe and health-promoting in moderation. You definitely won’t suffer a C deficiency taking them, and you’re wallet won’t suffer either.

            The NIH has a page about Vitamin C.


            Ya, C supplements don’t seem to show any significant positive effect on cancer, but the study notes an important limitation of most of these studies. C supplements had mixed results in terms of heart disease, positive results in terms of stroke and macular degeneration, and were found to shorten the duration and ameliorate symptoms of the common cold.

          3. Great reply Cody and so true! I’d like to add that since my diet changed to a primarily WFPBD, my grocery bills have actually gone DOWN since I no longer buy expensive meat, fish and fowl products! Eating better and spending less, a double win!

          1. “What effect might the economic downturn have on healthy eating, though? Recently, researchers at Harvard compared the cost and healthfulness of various foods across the country, hunting for the best nutritional bargain. They conclude that people should purchase more nuts, soy, and beans, and whole grains—and less meat and dairy.”

            No that is not a very helpful video. We are talking fruits and veges here for vitamin C.

            1. I hear ya, Jean. See my earlier comment, where I started off by saying we should stick to the topic, vitamin C. Not sure why the mods are talking in generalities about how inexpensive being vegan is. Ya, a bag of rice and a bag of beans are ridiculously cheap and will keep your stomach full. But they won’t do you any good when it comes to vitamin C, as well as many other micronutrients. I point out the Vitamin C content (from the USDA nutrient database) of the budget-friendly foods Cody listed — not good.

          2. In addition, one can learn to be a smart shopper. I utilize 6 different stores picking off the ‘loss leaders’ and to find the best values. For example: 8 pounds of navel oranges for $5, strawberries for .97 a container, mangoes 2/$1, etc. I find that a store such as Sam’s or Costco has the best prices on raw nuts: almonds, walnuts, pecans, pine nuts etc. Just takes a little effort.

  2. I would imagine that the optimal amount is not an absolute figure and varies depending on size/bodyweight (and perhaps age). Some studies suggest that the body reaches a steady-state concentration (60 to 80 μmol/L) of plasma vitamin C at doses of 200 to 400 mg/day in healthy young adults. Due to genetic variation some people may also have lower or higher requirements.

    Additionally, I notice that the Linus Pauling Institute at OSU has observed
    “Overall, results of individual and pooled analyses of large prospective studies in conjunction with pharmacokinetic data of vitamin C in humans (see Bioavailability) and RCTs suggest that maximal reduction of CHD risk may require vitamin C intakes of 400 mg/day or more (27).”

  3. Orthomolecular doctors have for years warned that heart disease is low grade scurvy. Vitamin C and Lysine, according to Dr. Pauling, can be used by the body to make new collagen and new vein tissue. I intend to eat more Vitamin C rich foods now.

  4. But how rapidly is the circulating Vitamin C oxidized by free radicals? Perhaps there are advantages to high continuous turnover with fresh Vitamin C to replace the oxidized C. Can anyone cite relevant research on this question?

  5. This is not the full story and is misleading. Blood levels of vitamin C depend on physical requirements. If you are under stress (and who isnt) the adrenals will suck C down. If you are a competition athlete – your antioidant requirements go up and C is one. If are sick – ditto.

    1. You might be interested in this re: athletes and antioxidants:

      They sell good quality loose lemon verbena tea on amazon. I didn’t notice much difference in how I felt when taking it (and it reminds me of the smell of furniture polish). Also, I don’t know if it should be cycled (probably). I have noticed a big difference from consuming pomegranate pith (similar to PQQ); again, should it be cycled? IDK

  6. I’ve been a raw vegan for about 10 years. I’ve become very aware of my body’s need for different types of food. Normally, I have no special draw to citrus fruits. However, I recently had the flu and I had an immense urge for oranges. I would eat 4 or 5 at a time, several times a day, on top of my regular diet. As soon as I recovered, the urge disappeared. I conclude from this that your vitamin C need varies according to your present condition.

    1. That’s pretty interesting. I’ve often thought about whether or not some types of cravings might be a nutrient-induced need by the body (as distinct from food addictions cravings). Here is some interesting info re: VitC in oranges and bell peppers. Per 100 grams (3.5 oz roughly), The Vit C content is the following:
      navel oranges – 59mgs;
      tangerines – 26.7mgs;
      green peppers – 80.4;
      red peppers – 128mgs;
      yellow peppers – 183mgs.
      Kale(raw) – 120mgs.
      In the future, I will be serving my hummous with bell pepper slices for dipping. And I suspect you might be right – that when ill, our nutrient requirements might increase. There is still so much to learn in this field. :-)

      1. Love bell peppers. Broccoli is another surprisingly rich source of C, even when cooked. Another one is kiwis – I like them since they are fairly cheap and conventional is okay according to the Environmental Working Group.

      2. Thanks for sharing, Rachel! Wow, kale and peppers are packed with vitamin C! That’s good to know, though 100 grams is a LOT of kale. But I normally use 5 or 6 large kale leaves in my green smoothie each day.

        1. Hi Brent, . .100 grams of kale is only about 3.5 ounces (28 grams in an ounce). Then, when you cook it down (unless you put it in your salad), its just small plop on your plate.
          But now that you’ve brought it up, I’m going to have to get out my little kitchen scale and take a look at just exactly what 100 grams looks like.
          What I thought was interesting about the bell peppers was the wide difference in VitC content between the three colors. I would have bet that the highest content would have been the red, but was surprised to see that the highest VitC content was in the yellow. Who knew?

  7. All this data and research seems to assume that the body’s requirement for vitamin C is linear, x amount/unit of time. I believe the body’s need varies according to environmental stressors – infection, toxic stress, injury, etc. The standard example given is that a 150 lb. goat will make about 13 grams (13,000 mg) of vitamin C a day normally (remember most animals make their own vitamin C), but that amount will shoot up to 100 grams a day under stress from infection, injury etc. (p. 40 of Dr. Levy’s, “Curing the Incurable” which includes the actual scientific reference which I am too lazy to look up because the book has over 1200 scientific references). Most animals make their own vitamin C, and they make a lot more than 200 mg/day. Oral ingestion is a poor substitute for making your own, but it has been sufficient to keep humans and our ape ancestors on the planet for millions of years. The use of intravenous vitamin C in dealing with infectious diseases has shown to be more effective than oral vitamin C whether from foods or supplements. The rise of liposomal vitamin C to bridge the gap between regular oral vitamin C and intravenous vitamin C looks promising.

  8. Well, this is kind of reductionst view. Applying this methodology to fibre you would conclude that the optimal intake is zero. Maybe all above 200mg remains for our little friends in the colon, the gut flora. They may be happy with it, you never know, untill you test it ;)

      1. The referenced paper says rather that E faecalis can grow on ascorbid acid and that ascorbid acid alters bacterial metabolism. This study – PMID: 27595636 – suggests that vitamin intake is in some way associated with composition of gut microbiota. It is hard to go below 200mg as an adult on a reasonable whole-food plant based diet. The video seems to suggest that going above 200mg is a waste of money while there is insufficient data to support such statement.

  9. Vitamin C is NOT the same thing as ascorbic acid. Ascorbic acid is the antioxidant component of vitamin C complex… REAL vitamin C (as found in nature). As a complex REAL vitamin C is always found with other vitamins/bioflavanoids (vitamin P), enzymes (tyrosinase), trace minerals (copper), etc.

      1. 40 years of daily study. You can find the same information out their as well. Try looking into The Price-Pottinger Foundation, Judy DeCava’s work, etc. basically, calling ascorbic acid “vitamin c” is like calling the shell of an egg “the egg”.

            1. Thanks for the link Kirk but doesn’t that pretty much make the point that I raised previously?

              The people making this factually incorrect claim aren’t credible on the matter. Thiel is a naturopath and Royal Lee was a dentist. Both run or ran companies selling supplements which are promoted using false claims like these. Royal Lee and his company got into hot water with the FDA on multiple occasions for making false claims. Thiel appears to have learnt the lesson. His supplement company is headquartered in the Caribbean and I assume safely beyond the reach of the FDA.

              The article by Thiel you linked is published in a webjournal which he edits and presumably owns. It is used to promote the sales of his products

              Let me remind you again that the definition of vitamin C is L-ascorbic acid. The opinions of a couple of supplement manufacturers don’t affect this fact.

              1. Who care if Royal Lee was a dentist?… Very few minds that have lived before or after him had his understanding of CLINICAL nutrition.

                Thiel also has a PhD. A “degree” doesn’t make a person. What degree did Leonardo DaVinci have?… Royal Lee contributed more to the understanding of REAL nutrition than most any other human. His work is still YEARS ahead of current understanding, although it is being proven on a regular basis by “modern” science.

                Some people choose to live in Ivory Towers and cast dispersions on others while being isolated and insulated from the consequences of their thoughts and actions. I choose to live on the Front Lines of the Real World where CLINICAL nutrition with Real People rules the day. I would put my results next to anyone on planet earth… regardless of their degree… or mine. :-)

                See also: https://www.seleneriverpress.com/srp-historical-archives/all-subjects/

                1. Thanks Kirk.

                  I am not aware of any (bio)chemists or other serious scientists who question the definition of vitamin C as L-ascorbic acid.

                  Your opinions about Royal Lee are not shared by everyone:

                  ” In a speech on the day after the seizure had been made, Kenneth Milstead, Deputy Director of the FDA Bureau of Enforcement, described Lee as “probably the largest publisher of unreliable and false nutritional information in the world.” [5]”

        1. The pure compound, synthetic or isolated from natural sources, that cures scurvy is called L-ascorbic acid. Since humans need it but don’t make it, it’s designated as a vitamin. To distinguish it from other vitamins, it’s called vitamin C.

            1. I too don’t understand your point.

              Your own reference also defines vitamin C as L-ascorbic acid. I thought that we were talking about vitamin C here?

              1. Original statement:

                “Vitamin C is NOT the same thing as ascorbic acid.”

                I added a link with information that verified that statement as correct because it was questioned afterwords.

                1. Your link did not “verify” that incorrect statement. Quite the opposite. This is clear in the VERY FIRST SENTENCE of your link:

                  “Ascorbic acid [vitamin C, L-ascorbic acid (LAA)] participates in many different biological processes and is important in human diet.”

                  The article simply discussed the differences and similarities between vitamin C and d-ascorbic acid.

        1. Vitamin C is defined as L-ascorbic acid. You can Google this or eg

          Kirk’s claim, if I recall correctly, comes from some marketing material relating to supplements sold by chiropractors. It is factually incorrect and the (founder of the) supplement manufacturer concerned has had an incident-filled history of relations with the FDA over false claims. Apparently they now rely on people like Kirk to make such claims to avoid problems with the FDA.

    1. In mainstream science, vitamins are synonymous with individual chemical compounds. Vitamins obtained their names before they were chemically identified. Vitamins A & B were postulated as factors required in rat diets in 1919, and C was suggested in 1920. Ascorbic acid, purified and crystalized out of paprika juice, prevented scurvy in guinea pigs in this Nobel winning research in 1933, and has since been known in the scientific community as identical with Vitamin C.

  10. So the 200mg per day figure comes from the study of 7 healthy men ? Not a very large sample population.

    What was their diet? They were from what regions of the world ?

    What was the form of Ascorbic acid used in this study?

    What happens if the Ascorbic Acid is encapsulated in a liposome ? What is the effect of consuming phospholipids (e.g. lecithin) at the same time as dietary sources of Vitamin C ?

    What happens to blood Vitamin C levels when we consume Camu-Camu fruit, whose flour is up to 9% Vitamin C (PMID: 23561148)

    Goats produce up to 200 mg/kg Vitamin C daily (http://www.ipubli.inserm.fr/bitstream/handle/10608/6436/MS_2008_4_434.pdf?sequence=3).

    What happens to blood Vitamin C levels when we eat goat meat ? Or better yet goat organ meats ?

    When measuring blood ascorbate levels, is the analysis restricted to the reduced form L-Ascorbic Acid, or is L-dehydroascorbic acid (DHA), the oxidized form considered as well ? (https://www.eurekalert.org/pub_releases/2008-03/cp-hhm031408.php)

    1. Hi, Louis. I am Christine, a NF volunteer. No, the 200 mg. per day figure was not derived from a study of 7 healthy men. There were several studies cited in this video. If you want more information about the research cited in the video, I invite you to click the tab above, to the right of the video, labeled “Sources Cited,” and read the studies for yourself. I hope that helps!

  11. This is one of the sources cited under the video. I found it more informative than the video. https://www.ncbi.nlm.nih.gov/pubmed/22698272

    The recommended dietary allowance (RDA) of vitamin C has traditionally been based on the prevention of the vitamin C deficiency disease, scurvy. While higher intakes of vitamin C may exert additional health benefits, the limited Phase III randomized placebo-controlled trials (RCTs) of vitamin C supplementation have not found consistent benefit with respect to chronic disease prevention. To date, this has precluded upward adjustments of the current RDA. Here we argue that Phase III RCTs-designed principally to test the safety and efficacy of pharmaceutical drugs-are ill suited to assess the health benefits of essential nutrients; and the currently available scientific evidence is sufficient to determine the optimum intake of vitamin C in humans. This evidence establishes biological plausibility and mechanisms of action for vitamin C in the primary prevention of coronary heart disease, stroke, and cancer; and is buttressed by consistent data from prospective cohort studies based on blood analysis or dietary intake and well-designed Phase II RCTs. These RCTs show that vitamin C supplementation lowers hypertension, endothelial dysfunction, chronic inflammation, and Helicobacter pylori infection, which are independent risk factors of cardiovascular diseases and certain cancers. Furthermore, vitamin C acts as a biological antioxidant that can lower elevated levels of oxidative stress, which also may contribute to chronic disease prevention. Based on the combined evidence from human metabolic, pharmacokinetic, and observational studies and Phase II RCTs, we conclude that 200 mg per day is the optimum dietary intake of vitamin C for the majority of the adult population to maximize the vitamin’s potential health benefits with the least risk of inadequacy or adverse health effects.

    1. So jj I am wondering why we as WFPB nutritarians are thinking we should supplement. I absolutely agree vit C is very important but it looks like we are getting way more than 200 mg per day.
      Red bell pepper 341 mg
      Kiwi 64 mg
      Broccoli and kale cup 80 mg

      So we are getting way more 200 mg or 400 mg per day. What an important topic though because it beminds us to eat our fruits and veggies! And vit C is so important for CVD, BP, etc. Tom posted a great article from Oregon State university on its importance.

      1. I try to make sure I eat at least one of those vitamin C rich foods each day. If I don’t, I don’t always take in the RDA for vitamin C. You could eat, for example, what is considered to be a typical serving of sweet potato (100g), green beans (85g), tomatoes (148g), romaine lettuce (85g), blueberries (0.5 cup), and apple (1 medium) – that’s 6 servings of fruit and veg – and not quite make the RDA (according to the data in cronometer and nutritiondata).

  12. I am not sure this really answers the question as not enough information is given to evaluate the truth of the claim. Vitamin C is water soluble and clears from the body relatively rapidly so one would have to look at timing of doses in addition to the total amount. Unfortunately, I cannot read the full text article without paying so I can’t really evaluate the protocols fully. However, this also contradicts other work that shows tissue saturation at 400 mg and work on specific health parameters that show, for one instance, that around 1100-1500 is optimal for glycation control. As usual, Dr. Greger is so anti-supplement that once he finds something supporting his position he doesn’t bother to dig deeper. It does appear that there is an optimal dose that is way lower than some previous mega-dose recommendations but there is not enough given here to have any confidence in the conclusion.

    1. I take vitamin C supplements and generally concur with the conclusions of the LPI on this matter. However, your comment appears to say more about your bias than Dr G’s.

      All in all, the evidence in favour of vitamin C supplementation is not particularly strong. This is clear from reading the LPI summary of the evidence – I find it convincing (as does the LPI obviously) but I do not think it is “strong” evidence. It is also worth noting that the advice here is both conservative and almost mainstream. Dr G may not have mentioned some studies apparently favouring increased vitamin C dosing – but then he didn’t mention the studies showing an association between vitamin C supplementation and increased coronary atherosclerosis in some diabetic women or with increased cataract risk either.

      It is important to accept, IMHO, that bite-sized videos like this can only ever present very broad discussions of the issue. They are necessarily incomplete.

      1. Tom that was a good review you posted. So basically we would be getting enough Vit C through the foods we eat-as a WFPB community. The problem I have with that review though is that it is from the LPI who are founded by Bayer. Bayer makes supplements too.

        Great article though because it speaks on the importance of vit C in our bodies and which systems are affected including the various symptoms -it illustrates the importance of fruits and vegetables. Too red peppers takes us over the 400 mg of vit C required.

          1. WFPBRunner: :-) I know you can edit your own posts. There is an edit option under your post when you are logged in disqus as yourself.
            re: typos. Been there, done that! A million times. And I don’t even have a smart phone as an excuse.

        1. Thanks. Yes,the LPI site is useful because it provides a good overview of the evidence base and reports the negatives as well as the positives.

          I have always eaten a lot of fruit but I have found that if I do not supplement with vitamin C, then I get stinkers of colds/flu 3 or 4 times year. With a daily supplement, I have a few mild symptoms for 2 or 3 days and that’s it. I have a mild but chronic form of psoriasis – very well controlled on a WFPB diet – so perhaps I have a higher then usual need for (anti inflammatory) vitamin C.

          1. That is interesting. I have noticed since going WFPB that I rarely get a cold. Maybe one every 2 years if that.

            What can I say? We are perfect!

          2. Tom: Isn’t that the key? Different people have different requirements of nutrients; even the same person may have different requirements depending on circumstances. Pauling talks about this is his book; if I remember right, he calls is biochemical individuality.

            1. George,

              On the mark ! Biochemical individuality is indeed the key factor that now is well understood as being our combination of genetics, epigenetic expression coupled with exposures. Linus understood the individuals chemical complexity and the need to be respond to the observed phenomena.

              As an FYI you might find the Oregon State University site from the Linus Pauling Institute of interest: http://lpi.oregonstate.edu/ Lots of excellent nutritional work and publications.

              Dr. Alan Kadish Moderator for Dr. Greger

            2. Thanks George. It is certainly an important factor. Dr Alan has summed it up wonderfully in just a sentence or two.

              Unfortunately, I am more long-winded so I would point to other differences as well to reinforce the point. For example, sex is important. Women (especially pre-menopausal women) and men have different risk profiles for CVD. Ethnic background may also reflect varying genetic factors eg the rates of lactose and alcohol intolerance tend to be higher in people of Asian origin than in people of European descent. Salt sensitivity may be more common in African Americans than other groups. And age/lifestage can affect the need for nutrients as well as sensitivity to drugs.

              All of these things are important. This is why clinical judgement and individual case management are powerful tools in the armouries of general/medical/family practitioners, It is also why most risk calculators try to encompass at least some of these factors rg

              However, when it comes to population health, the focus has to be on advice which benefits the majority of the population. For example, advice on smoking does not focus on saying, hey, if you are genetically favoured and have a host of offsetting beneficial ;lifestyle factors, then you may be able to smoke and still live to a ripe old age, Population health advice has to take the same approach. Consequently, NF and Dr Greger aren’t focussed on providing on nutritional advice for specific individuals. Nor are World Health Organization, World Cancer Research Fund or various national dietary guidelines. Instead, they look at the total picture and spend less time discussing the “ifs”, “ands” and “buts”..

    2. Steven: Regarding your overall post: It is perfectly fair to say that you put different emphasis on different information and come to a different conclusion than Dr. Greger. On the other hand, the following sentence from your post makes no sense to me: “As usual, Dr. Greger is so anti-supplement that once he finds something supporting his position he doesn’t bother to dig deeper.”
      *Depending* on a person’s situation, Dr. Greger may recommend the following supplements: B12, algae DHA, vitamin D, calcium, iodine, iron, and selenium. http://nutritionfacts.org/2011/09/12/dr-gregers-2011-optimum-nutrition-recommendations/ That does not translate to me to being “anti-supplement” in any way let alone “so anti-supplement” that Dr. Greger cherry picks information / is biased, which what you are saying above.
      It’s funny to me that different people can have such opposite views of the same information. Just two days ago, I was having a discussion with someone who thinks that Dr. Greger recommends way too many supplements / is too pro-supplement.
      I may not agree with all of Dr. Greger’s supplement recommendations, but I don’t think he is biased when it comes to this topic. (Ie, disagreeing with someone doesn’t mean the other person is biased if we want the term to have any meaning beyond “someone’s opinion”.) I love that Dr. Greger is super careful about recommending supplements, keeping in mind that supplements can harm as well as help. As I see it, Dr. Greger only recommends those supplements that he believes has a solid body of evidence to support such recommendations. I appreciate that approach.

  13. Proponents for vitamin C megadoses suggest that your bodies need for vitamin C will vary depending on your disease state. I read one talking about how he increased his dose by 10 times when he had a fever and claimed that his body was using it. Is there any evidence for this?

    1. Hi, Todd. I am Christine, a NF volunteer. The short answer to your question is no. There is no good scientific evidence that megadoses of vitamin C are absorbed or beneficial. As the video states, the body absorbs about 200 mg/day. After that, the excess is excreted in urine and feces. I hope that helps!

  14. FIVE SERVINGS! Whoo Hoo!

    What the Heck IS FIVE servings? How many servings in a banana, orange, apricot, stalk of celery, carrot, tomato, apple, avocado, head of lettuce?

    Seriously, I don’t have a label to look at and tell me how nutritionless my food is. I’m sure there’s a whole fruit/veggie translated to servings chart/graph somewhere. Lil’ help?

    Okay, I was being a bit silly on the help request. I won’t meter my whole fruit and veggie intake on serving sizes, I was just confused instead of informed by the last statement of the video. I might look it up, but I’m sure I get plenty. ;-P

    1. 5 servings is fairly easy to get. 1 serving of fruit (generally) is 1 piece of medium sized fruit, 1 cup cut up fresh fruit, 1/2 cup frozen or canned fruit, 1/4 cup dried fruit. Vegetables (generally) are 1 cup raw or 1/2 cup cooked. There was an educational campaign in the early 90’s by the National Cancer Institute which has been replaced by the current public health initiative Fruits and Veggies: More Matters. http://www.fruitsandveggiesmorematters.org/about-fruits-and-veggies-more-matters. Did you know that September was Fruits and Veggies More Matters Month?… I don’t think I saw 1 public service announcement regarding that in September.

  15. If the label is correct, all that’s needed is one and half frozen amla fruits, about the equivalent of a third of an orange. In nearly all food categories, we are far from eating the best of what exists in nature.

  16. I will reiterate what others are saying about ascorbic acid not being the same as Vitamin C, ascorbic acid is produced by bacteria in a factory while natural Vitamin C is produced by a plant. Ascorbic acid is an organic acid but it doesn’t have the same properties as the Vitamin C found in fruits and vegetables. I prefer to eat natural instead of taking a supplement.

    Here are a few ways to get 200 mg of Vitamin C:
    15 oz of orange juice
    2 cups of broccoli
    5 oranges
    1 papaya
    2 cups brussel sprouts

    1. You can say and think what you want but Vitamin C is defined as L-ascorbic acid.

      Obviously, fruits and vegetables are the best sourec because they come with a whole range of co-factors that have additional benefits of their own

    2. I have absolutely no use for fruit juice.

      I love fruit and eat a lot of it, but give me pulp and fibre and sometimes a twist!

      Of course billions have been spent brainwashing us to believe that orange juice is the best source of Vit C on the planet.

      It’s not. It’s unwhole, and we here know that whole plant food trumps unwhole every single time. Even that some juices may have negative consequences.

      Smoothies on the other hand, are delightful and whole.

      1. Wade,

        Can’t agree with you more. There are some interesting facst for vitamin c content in orange juice….it’s only ~60 mg per serving …..How much vitamin C is in orange juice?

        Type of Orange Juice Mg of vitamin C per 8 fl oz % DV
        Fresh Made 124 208%
        Florida’s Natural – No Pulp 72 120%
        Tropicana 100% – orange juice 48 80%
        Minute Maid – 100% orange juice 72 120%
        Simply Orange – 100% Orange Juice 60 100%

        Eat the whole fruit and get the full benefits of the flavonoids and other components, generally not found in the juice, reduce your blood sugar spikes, get some fiber and save some $’s.

        Dr. Alan Kadish moderator for Dr. Greger

    1. smith: If the oldest living person on earth smoked a pack a day, would you suggest people follow that lead? It’s not wise to emulate a person who plays “Russian Roulette” and happens to be the 1 in a billion who wins.

    2. “eat 3 eggs a day … Vit C … in eggs”

      –Corn Fuschia say ‘Man who eats food with value of statement above, on starvation diet.’–

  17. George: If you had trouble finding this post for a bit, it had been caught by our automated spam filter. I rescued it. Not that I condone sharing information or anything. ;-)

  18. Thanks for the link George.

    However, I still think your criticisms of the NF position on supplements and alleged bias are unbalanced. You almost seem to be implying that you uncritically think that all supplements are beneficial. I don’t think the evidence supports that position.

    There is quite a bit of evidence that some supplements may be harmful and others may be useless. I see no reason why Dr G shouldn’t report that evidence and only support use of those for which there is good evidence or to address identified deficiencies that cannot optimally be addressed by diet.

    Personally I take a multivitamin and supplemental vitamin C but I still think that Dr G’s and NF’s position on supplement use simply reflects the evidence base.

    However, you might find this an interesting read

    1. Yes, I gave you a link from the nation’s #2 public health school (Harvard School of Public Health) and you could only send me a link from the medical research arm of the parent university of nation’s #1 public health school (Johns Hopkins Bloomberg School of Public Health). :)
      And the 2 don’t necessarily disagree, Hopkins says high doses could hurt, normal doses seem useless and you shouldn’t care because a healthy diet will bring you all you need. Harvard recommends a normal dose as a “insurance policy”. Today for instance, because I skipped my morning smoothie, according to cronometer, I have ~5 vitamins at only about ~70%. If I’d have a multivitamin at home now, I’d go with Harvard advice.

      1. Advice isn’t evidence, George, even if that advice is the opinion of someone at Harvard. Where is the evidence that taking a multivitamin – as opposed to a folic acid supplement – delivers a clear benefit?

        As it happens, I do take a daily multivitamin. However, I don’t kid myself that there is good evidence of benefit. I take it because there is no evidence of harm and there are reasons to believe it might be beneficial in my particular circumstances. However, if we go strictly by the evidence, there is no justification for recommending multivitamin use.

  19. I had an abscessed tooth and could not get to the dentist til the next day. I was in so much pain, and the swelling was incredible in the morning, that I did what any other follower of Orthomolecular Medicine would do; I started taking 2000mg of Vitamin C every 10 mins..
    Let me qualify that; I decided on that dose because of my experience in Titrating to Bowel Tolerance, which is the way Therapeutic levels of Vitamin C are achieved.
    When I reached 46,000 mg(46g) I noticed that my pain was diminished and that the swelling had abated. When I reached 52g(52,000mg) the pain was gone and when I looked inside my mouth, the abscess was 1/2 the size that it was in the morning and the Mucas Membrane was loose to the touch. I backed off the Frequency of dosage to 1g every 1/2 hour so I wouldn’t get diarrhea. That is about the worst thing that can happen if one takes too much “C”.
    The next morning I called the Dentist and the receptionist was all frazzled that I hadn’t gone to the Emergency room! I heard the dentist tell her to relax, ” Its George, he knows what hes doing.”
    When I got there the staff was just looking at me in disbelief and then the doc came in and said, ” Good to see you, How much did you take?” My dental hygienist asked me what the dentist had meant by that. I told her to go to doctoryourself.com and see what Andrew Saul PhD. had to say about Vitamin C in High Dosage and what it can do for you.
    The dentist came in and asked me Why I didn’t cut the abscess at home, and i told him that I couldn’t see it well enough to do it by my self. He nodded and cut it open. Mean while, the looks that were going back and forth between the assistant and the dental hygienist were scary.
    My Dentist knows about Orthomolecular Medicine and explained to them, that at high enough doses, Vtiamin C is an antibiotic, antitoxin, anti inflammatory, and it also kills pain better than Ibuprofen
    I’m writing too much, so to close this, I took Vitamin C instead of an antibiotic and I no longer have any issues with tooth except that I will go back and have it removed. God Bless and Gods Speed

  20. To me it sounds like the optimal dose during normal health conditions is 200mg. Not necessarily a 200mg cap per day.

    Also, keep in mind that this is all just the normal intake for optimal health. The high doses(orally or IV) are used when you are sick or in high stress times.


    I will continue to eat as many Vitamin C rich foods as I can in a day to maintain optimal health. When I start to get sick or do get sick, I will supplement with high doses orally spread across the day in MUCH smaller doses. If I get extremely sick then I will go in and get it intravenously in order to bypass the possibility of bowel tolerance(that higher oral doses can cause) and put the C directly into the blood. If for some reason I can not get enough vitamin C from foods in a day, either from laziness or any other reason, then I will supplement. So it is very good to know that if I take a 1,000mg pill I will most likely only be getting half of it, which is still 300mg more than what “most” people under “normal” conditions can absorb at a time.

    I, along with my wife and kids will continue to lean on those smarter than us and aim for our weight in grams a day (up to 10,000). So my 3 year old gets 3,000mg a day spread throughout the day with as much as possible coming from the food we eat. Me and my wife aim for 10,000 daily with as much as possible coming from the food we eat and the rest coming from supplementation.

    I am thinking that what I might test out is only taking the C supplements in between meals or with meals that are low in C. In the past we were taking the C supplements with every meal. But now, seeing that if we eat a meal with a lot of C in it and take the supplements at the same time, it would just be a waste.

    That is unless we were sick, then our bodies can absorb more at a time.

    Our family has successfully treated (meaning we didn’t use pharmaceuticals and got through the sickness much faster than if we had used them instead of vitamin C): the common cold, the flu, bacterial infections, pink eye, viral infections, kidney stones, bladder infections, urinary tract infections, and I am sure there are some more. My point is I would much rather put 10,000mg of vitamin C into myself and kids than an antibiotic any day!!!!

  21. Regarding the optimum amount of vitamin C being about 200 mg, This does not make a lot of sense from an orthomolecular point of view. In Dr. Greger’s video, he indicates that at the 1250 mg level the body only absorbs 49%, however that means that the body absorbs 575 mg as compared to 13 mg when taking 15 mg. of vitamin C. So as long as the body absorbs more vitamin C it is better to take a higher amount, if it can be established that more vitamin C can be advantageous for health.

  22. 200 milligrams per day vitamin C is only adequate for young healthy adults who have no toxic load no viruses or bacteria lurking around in the system. Vitamin C is an absolute virucide and gets used up as it kills a virus so the need for vitamin C goes up enormously when you have a viral infection. If you get a tetanus infection high dose vitamin C will save your life. Vitamin C also neutralizes toxins so as you get older and you accumulate more heavy metals pcb’s and other toxins your need for vitamin C goes up enormously. Most animals make their own vitamin C a level of at least 20 milligram per kg body weight. Apes don’t make their own vitamin C consume enormous amount of vitamin C in their diet which adds up to about 30 milligram per kg. In zoos they supplement primates around about 70 milligram per kg to keep them healthy. Vitamin C is required in different concentrations in different parts of the body so just looking at the blood levels is extremely naive. Vitamin C is also used in the process of making neurotransmitters. Some cases of depression can be cured by taking a vitamin C supplement of 1 to 2 grams per day. Vitamin C helps to recycle glutathione the body’s major antioxidant. Instead of just looking at a few articles and thinking you know all about vitamin C you should study the scientist’s who research vitamin C and debunk them if you can. In this way you might actually learn something. One such researcher is Suzanne Humphries who has some excellent videos on the subject.

  23. I respectivly disagree. I wish you would address linus pauling research on vitamin c and it is based on how much c animals produce in their own bodys. It is a ratio based on weight and doctor linus pauling had humans at about 20 grams a day of vitamin c for optimum health.

  24. I’m a new member here. 3/9/17
    I suffered a mild heart attack at 45. I’m 65 today, so it was 20 years ago when I had my quadruple bypass.
    Way back then I did a little reading on Vitamin C and upped my intake via powdered C supplements to 20 GRAMS a day. Everyday. Yes, for the past 20 years. No kidney stones. I do minimal exercise (that IS something I’m working on). I maintain a vegetable heavy diet and avoid red meat but occasionally eat chicken and fish. It seems the only problem I had with my cardio vascular system was when I went through a period of eating lots of wild caught Steelhead. Steelhead is a very fatty fish. This negatively affected my blood pressure (unless there was some coincidently problem which ended when I stopped eating Steelhead).
    However, I’m not convinced that my vitamin C intake is risky. You’d think that after 20 years of my evidently extreme intake of vitamin C that I’d notice some ill effects. I am inspired by the information on this site to read the latest research on Vitamin C as well as any other health matters as they relate to my health.
    In fact I only learned about this site through the purchase of How Not to Die, which I find to be an amazingly practical book which I can now HIGHLY recommend!!!

    1. ThomasManning: Welcome to the site!

      One thing I try to keep in mind when learning about this type of information is that we are dealing in risks, not absolutes. For example, I could smoke every day for all of my adult life and never get lung cancer. What the science says is that smoking increases the risks of getting lung cancer. No one says that I *will* get it. We can certainly find examples of people who heavily smoked and never suffered an ill effect. Their personal experience doesn’t mean that smoking isn’t risky after all…

      With that in mind, it doesn’t surprise me that someone (you) has taken a lot of vitamin C every day and not had a problem (so far?). That’s good news for you. For all I know, you will never have a problem. (And more power to you!) However, your personal experience doesn’t necessarily mean that the science is wrong about the risks of taking vitamin C for the general population.

      This site does not try to tell anyone what to do. This site is about laying out the science (at least as Dr. Greger sees it). Once educated, people can decide a) which risks seem credible and b) which risks are not worth taking. On the more fun side, we also learn here about a) which benefits (which whole plant foods) seem credible and b) which benefits are worth pursuing.

      I too highly recommend How Not To Die. I’ve given copies to all my friends and family and always have a copy waiting to give out in case someone else just *must* have it. ;-)

  25. 2 months ago, i got a flu with high temperature
    i cured it with 2gr vitamin C every 30 minutes
    3 hours later, i was cured without temperature

  26. Im not sure ᴡhy but thіs web site iss loading incгediblly ѕlow for me.
    Is anyone else haνing this problem or is it a problem
    on my end? Ill cheсk back lateг aand see іf the pгoblem still exists.

  27. Hi,
    I’ve noticed that you have shown favor to the view that 200mg a day supports a “normal” level of 70 microM/L of C in the blood. Hickey and Roberts et al. have shown research that shows much higher levels can be achieved by frequent dosing with Liposomal and oral ascorbic acid – 400microM/L and as high as 2000 microM/L. https://firstlaw.wordpress.com/2012/12/12/oops-they-got-it-wrong/ . also https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1236801/ . You are neglecting to study all the research and are mentioning easily debunked information. Also high dose IV vitamin C has recently been mentioned as an adjunt treatment for cancer – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2516281/ where its ability to create H2O2 has been found to attack cancer cells and trigger apoptosis.

    1. Rest assure that Dr. Greger does review all the relevant literature. There are thousands of studies that are published every month. Much more goes into reviewing a study than simply accepting the conclusion that is promulgated by the authors. Careful statistical analysis verification, conflict of interest review, etc. In addition, the vast body of peer-reviewed literature is going to hold more weight than a one-off study that finds +2 sigma data. These are just general tenets involved in literature reviews. Specific to the point that you raise, the fact that serum vitamin C level CAN be increased, doesn’t mean it SHOULD be increased and/or that this is optimum for the lowest morbidity and mortality rates. We have evolved to eat WFPB diet which supplies all the vitamin C that is needed. Going above and beyond this might help in cancer treatment, but this cannot be extrapolated to conclude that these high levels must be the “new optimum.” Also, one cannot extrapolate laboratory findings such as increased H202 levels as this may not occur in vivo and/or may not result in clinical benefit if it does occur. Don’t forget that H202 is a known carcinogen that your cells go to great length to create enzymes to inactivate it. So if we’re doing “thought experiments” we could mentally conclude that excess vitamin C levels could cause cancer. For all we know, and until its been fully investigated, its possible. Therefore, we must follow the vast body of clinical literature that demonstrates safety and efficacy for the vitamin C levels that Dr. Greger outlines.

  28. Higher than usual (supplement) intake of vitamin C to combat nitrite content of urine.
    I understand that oral supplementation does not have the positive effects of dietary sources of vitamin C (up to 200mg a day as optimal quantity); however, here’s a question for you clever foodies out there:
    If, as Dr G says, excess (above 200mg) doses of vitamin C are “peed and pooped out”, then isn’t this a good thing to combat the nitrite-producing bacteria in the urinary tract? I mean, yes, the blood vitamin C level will not be affected (since the small intestine walls will not absorb any more vitamin C than the body requires); but, if the urine is full of the excess amounts of unwanted vitamin C, won’t this clobber the nitrite-producing bacteria in the bladder, etc, which are (in certain cases of, say, high nitrites but low leukocytes in urine test samples) causing the unpleasant urinary tract infections? That is, if I am correct in my belief that high levels of vitamin C can inhibit and erradicate the UTI-causing bacteria?
    I would be really grateful for an informed response to this, since my wife is still suffering from a UTI (indications of nitrites but no indications of leukocytes in urine home-test kit) and would prefer not to use antibiotics as a treatment.

    1. Foggy,

      your reasoning is correct. Large doses of vitamin C will cause your urine to acidify and thus inhibit growth of bacteria. It is also important to: eat cranberries, drink a lot, pee when you need it (don’t hold urine), take probiotics, eat garlic and you (she) can also try apple cider vinegar (orally – but only short term, mechanism of action is similar to vitamin C, but it is so highly acidic that it can damage the tooth enamel). You can also try D-Mannose. For some people it work wonders, see this: https://www.stoputiforever.com/prevention/d-mannose/

      If you have any more questions, don’t hesitate to ask me. Good luck!

      Moderator Adam P.

      1. Brilliant response. Thanks Adam. She’s on board for all of that D-mannose is new to us (and we will get some), but the cider vinegar and vit C have combined with lots of fluid intake to clobber the UTI – just as well, since it has now been two weeks after asking, and she still has not received a doctor’s appointment from the surgery!

    1. Hi Mathieu

      There is no doubt that optimal levels of vit C are easily achievable by eating a (healthy and balanced) veggie diet. I average around 300mg/day on a WFPB diet.

      The research, Vitamin C For Preventing and Treating the Common Cold states “Five trials involving a total of 598 marathon runners, skiers and soldiers on subarctic exercises yielded a pooled RR of 0.48 (95% CI 0.35 to 0.64).” I cannot see any other data about their lifestyles or diets. It may well be that your suggestion is correct that the vit C may have boosted what was already a low dietary vit C level. I suspect that there may be two other possible interferences with the results: firstly, high metabolic/physical health levels might ‘utilise’ vit C better; and, secondly, high protein intake from animal foods (especially if at the expense of plant foods) might weaken the immune system sufficiently in the 598 subjects to cause a sudden rush of vit C to have a more dramatic effect than it would on, say, a person with low animal/high plant food intake.

      It is also not clear to me what type of study the 598 involved. Was there a control group? Was there a placebo? Was it double blind? How reliable was the data in any event?

      Perhaps someone who has access to the full research on this study could elucidate.

      In any event, I wonder if part of the reason why vit C works for the common cold (IF it really does) is linked to the same process involved in its use for UTI infections – viz. creating an environment where ‘bad’ bacteria cannot survive so well and are more speedily flushed out of the body?


      Consumption of veggies is enough to reach the optimal level of 200mg/day.
      But supplementation of vitamine C allow athlete to recover 50%faster form a cold.
      https://nutritionfacts.org/video/do-vitamin-c-supplements-prevent-colds-but-cause-kidney-stones/ Is it because those athletes tested were not eating enough veggies?

    2. Mathieu,

      It may indeed be the athletes intake or………. they have a significant difference in their production of free radicals from the exercise. I think you might find this article of interest to get a sense of how significant exercise makes an impact on our bodies at: https://www.hindawi.com/journals/omcl/2015/295497/ and also an older piece 2003 talking about the transient nature of vitamin c and exercise at: http://journals.humankinetics.com/doi/abs/10.1123/ijsnem.13.2.125 which as part of their findings included , “Exercise generally causes a transient increase in circulating ascorbic acid in the hours following exercise, but a decline below pre-exercise levels occurs in the days after prolonged exercise. These changes could be associated with increased exercise-induced oxidative stress”.

      As another consideration you might have heard of vitamin C loading tests which essentially bring you to saturation levels an loose bowels. The extreme variance in amounts and individuals is so broad that making claims for a certain level being adequate is almost laughable from a statistical point of view. In practice I have seen even small intakes at the 50-250 mg make an impact in some and others needed macro doses in the grams level to move their responses.

      And another consideration is the variance based on multiple doses, as the vitamin is water soluble and does not maintain a concentration, without multiple daily intakes.

      Remember that eating the WFPB diet is literally going to supply you with one of the highest intakes of all populations sans those using supplements. Also keep the perspective that it’s about the whole exposure and synergy of foods that ultimately determines the outcome not a single dose of a single vitamin.

      Trust this address some of the considerations.

      Dr. Alan Kadish moderator for Dr. Greger http://www.CenterofHealth.com

  29. I haven’t looked too much into ascorbic acid since for a while I’ve considered amla fruit sufficient; plus it’s the only truly decent source I can find. Estimates range from 200-1800+ mg per 100 g, I’d assume varying with conditions such as soil, climate, etc. I recall from some work an Australian relative reaches levels of 2000-5000 mg. As far as amla, one ayurvedic doctor has mentioned a rasayana (rejvenative) of 3, 6, or 9 fruits daily, I assume varying with activity level and digestive strength. I’ve tried 6 and it’s quite heavy; 2-3 seems like a good amount.

    Looking at a bit at food science works, I’ve found:

    urtica dioica (nettle) – 238-333 mg
    various plants in the ~130-200+ range
    chenopodium album (lamb’s quarters) – 131-171
    capsella bursa-pastoris (shepherd’s purse) 169

    I think those are the main plants that one might have a chance of finding at farmers markets. Shepherd’s purse I’ve seen frozen at Asian markets and fresh in a local Chinatown. Indeed it looks like wild greens are a good source though far from fruits. I’m curous about other fruits within the ericaceae family (blueberry, cranberry), though examples such as whortleberry don’t do well. black current ranges from 150-215 and that’s not bad, though far from the higher ranking members of phyllanthus (amla, p. emblica).

    If one is curious about other possible natively eaten plant sources, the best work is possibly Edible Medicinal and Non-Medicinal Plants (T.K. Lim), 12-volumes covering 1000+ plants. Info is scattered among individual entries and it’d be some work to search through.

  30. I would like to hear Dr. Greger’s take on the info in this article regarding the lack of scurvy on the carnivore diet. It seems to work, but will it function long term?

  31. If you want to know the optimal levels of vitamin C….. go to a verified source.

    Ask 112 year old Richard Arvin Overton, but please stay slim and active for life.

    And always enjoy some soup, it’s good for you.

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