Do Vitamin D Supplements Help with Diabetes, Weight Loss, & Blood Pressure?

Do Vitamin D Supplements Help with Diabetes, Weight Loss, & Blood Pressure?
4.52 (90.48%) 21 votes

Those with higher vitamin D levels tend to have lower rates of obesity, diabetes, and hypertension, but is it cause and effect? Interventional trials finally put vitamin D to the test.

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My last in-depth video series on vitamin D was done more than four years ago—as in 15,950 papers ago. I had a lot of catching up to do.

Review articles like this continue to be published, touting vitamin D as a veritable cure-all. The vitamin D receptor is found in most tissues in the body, including the brain. Upwards of 2,000 genes may be regulated by vitamin D. Within 24 hours of vitamin D exposure, you can change the expression of hundreds of genes.

The term vitamin is actually a misnomer. Vitamins, by definition, cannot be synthesized within our body. But we can make all the D we need with sufficient sun exposure. D is not a vitamin, but a hormone, produced by our skin in response to sunlight exposure. And it’s not just a hormone of calcium regulation and bone health, but a hormone of fertility and immunity and brain function. But is it a panacea, or a false prophet?

Remember when vitamin E was the vitamin du jour, touted as curative for many clinical disorders. “Vitamin E: the radical protector,” with supplement sales in general forming a billion-dollar business to capitalize on the public’s fears. After all, those with low levels of vitamin E in their blood had 50% higher cancer risk. Hey, and what about vitamin A or beta carotene? After all, people who eat lots of greens and sweet potatoes and other beta carotene-rich foods have lower risk of cancer; so, we should give people beta carotene pills. But when they were put to the test, beta carotene pills increased cancer rates. Beta carotene, vitamin A, and vitamin E supplements may increase mortality, in effect potentially paying to shorten our lifespan. So, you can understand the skepticism in the medical community regarding claims about vitamin D, which is now enjoying its moment in the sun.

Having a half-billion dollar vitamin D supplement industry doesn’t help matters, not to mention the highly lucrative vitamin D-testing industry that loves to talk about the studies suggesting having higher vitamin D levels may reduce the risk of heart disease, and cancer, and diabetes, autoimmune diseases, and infections.

But most of this research stems from observational studies—meaning studies that correlate higher D levels in the blood with lower disease risk. It doesn’t mean vitamin D is the cause. It’s like the early beta carotene data. Higher levels in the blood may have just been a marker of healthy eating, just like vitamin D levels may just be a marker of healthy behaviors. Who has high D levels? Those that run around outside. And those that run around outside, run around outside. Higher vitamin D levels may just be a sign of higher physical activity, for example.

So, when you see studies like this, showing significantly lower diabetes rates among those with higher vitamin D levels, it doesn’t mean giving people vitamin D will necessarily help. You have to put it to the test. And when you do, vitamin D supplements fall flat on their face. No benefit for preventing or treating type 2 diabetes.

So, when supplement companies wave around studies like this, suggesting vitamin D deficiency plays a role in obesity, because most population studies show lower vitamin D levels in the blood of those who are obese, is that because they’re exercising less, or, simply because it’s a fat-soluble vitamin, and so is just lodged in all the fat? One might expect obese sunbathers would make more vitamin D since they have more skin surface area. But the same exposure leads to less than half the D, because it gets socked away in the fat. That’s why obese persons may require two to three times the dose of vitamin D—though they may get it back when they lose weight, and release it back into the circulation. So, that would explain the population data. And indeed, when you put vitamin D to the test, try vitamin D as a treatment for obesity, it doesn’t work at all.

Similar story with artery health. Those with low vitamin D levels have worse coronary blood flow, more atherosclerosis, and worse artery function. But if you actually put it to the test in randomized controlled trials, the results are disappointing. Also ineffective in bringing down blood pressures.

This all just adds to the growing body of science casting doubt on the ability of vitamin D supplementation to improve anything beyond just falls, fractures, the common cold, and all-cause mortality.

Wait—what?! Vitamin D supplements can make you live longer? That’s kind of important. I’ll explore that next.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.

Please consider volunteering to help out on the site.

Image thanks to mojzagrebinfo via Pixabay.

My last in-depth video series on vitamin D was done more than four years ago—as in 15,950 papers ago. I had a lot of catching up to do.

Review articles like this continue to be published, touting vitamin D as a veritable cure-all. The vitamin D receptor is found in most tissues in the body, including the brain. Upwards of 2,000 genes may be regulated by vitamin D. Within 24 hours of vitamin D exposure, you can change the expression of hundreds of genes.

The term vitamin is actually a misnomer. Vitamins, by definition, cannot be synthesized within our body. But we can make all the D we need with sufficient sun exposure. D is not a vitamin, but a hormone, produced by our skin in response to sunlight exposure. And it’s not just a hormone of calcium regulation and bone health, but a hormone of fertility and immunity and brain function. But is it a panacea, or a false prophet?

Remember when vitamin E was the vitamin du jour, touted as curative for many clinical disorders. “Vitamin E: the radical protector,” with supplement sales in general forming a billion-dollar business to capitalize on the public’s fears. After all, those with low levels of vitamin E in their blood had 50% higher cancer risk. Hey, and what about vitamin A or beta carotene? After all, people who eat lots of greens and sweet potatoes and other beta carotene-rich foods have lower risk of cancer; so, we should give people beta carotene pills. But when they were put to the test, beta carotene pills increased cancer rates. Beta carotene, vitamin A, and vitamin E supplements may increase mortality, in effect potentially paying to shorten our lifespan. So, you can understand the skepticism in the medical community regarding claims about vitamin D, which is now enjoying its moment in the sun.

Having a half-billion dollar vitamin D supplement industry doesn’t help matters, not to mention the highly lucrative vitamin D-testing industry that loves to talk about the studies suggesting having higher vitamin D levels may reduce the risk of heart disease, and cancer, and diabetes, autoimmune diseases, and infections.

But most of this research stems from observational studies—meaning studies that correlate higher D levels in the blood with lower disease risk. It doesn’t mean vitamin D is the cause. It’s like the early beta carotene data. Higher levels in the blood may have just been a marker of healthy eating, just like vitamin D levels may just be a marker of healthy behaviors. Who has high D levels? Those that run around outside. And those that run around outside, run around outside. Higher vitamin D levels may just be a sign of higher physical activity, for example.

So, when you see studies like this, showing significantly lower diabetes rates among those with higher vitamin D levels, it doesn’t mean giving people vitamin D will necessarily help. You have to put it to the test. And when you do, vitamin D supplements fall flat on their face. No benefit for preventing or treating type 2 diabetes.

So, when supplement companies wave around studies like this, suggesting vitamin D deficiency plays a role in obesity, because most population studies show lower vitamin D levels in the blood of those who are obese, is that because they’re exercising less, or, simply because it’s a fat-soluble vitamin, and so is just lodged in all the fat? One might expect obese sunbathers would make more vitamin D since they have more skin surface area. But the same exposure leads to less than half the D, because it gets socked away in the fat. That’s why obese persons may require two to three times the dose of vitamin D—though they may get it back when they lose weight, and release it back into the circulation. So, that would explain the population data. And indeed, when you put vitamin D to the test, try vitamin D as a treatment for obesity, it doesn’t work at all.

Similar story with artery health. Those with low vitamin D levels have worse coronary blood flow, more atherosclerosis, and worse artery function. But if you actually put it to the test in randomized controlled trials, the results are disappointing. Also ineffective in bringing down blood pressures.

This all just adds to the growing body of science casting doubt on the ability of vitamin D supplementation to improve anything beyond just falls, fractures, the common cold, and all-cause mortality.

Wait—what?! Vitamin D supplements can make you live longer? That’s kind of important. I’ll explore that next.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.

Please consider volunteering to help out on the site.

Image thanks to mojzagrebinfo via Pixabay.

117 responses to “Do Vitamin D Supplements Help with Diabetes, Weight Loss, & Blood Pressure?

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  1. Dr. McDougall talks about a study out of England that looked at supplementation vs no supplementation of D for elderly women and found the supplementation increased falls and fractures. I was hoping Dr. Greger would have comments on that paper.




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    1. Journal of Gerontology 55 (2000) M585-M592 Frasetto et. al. “A high ratio of vegetable to animal protein consumption was found to be impressively associated with a virtual disappearance of bone fractures (in elderly women)”. Look at NutritionFacts.org recommended diet. “Magic pills” don’t work.

      A more convenient summary and chart is on pages 206-208 of “The China Study” (2006) by Cornell nutritional biochemist prof. T. Colin Campbell. This is a very effective way to really reduce osteoporosis risk. I’m 81, we ski, I fall hard, no breaks. My wife’s recent pelvis and lateral hip X-rays show satisfactory bony mineralization.




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  2. Yep, Dr. Pam has been going on and on about how Vitamin D supplements don’t work for some time now.

    No substitute for sunshine.




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      1. She’s found on YouTube and at her clinic in Ohio. Pamela Popper. Her videos are simpler but are her commentaries on published articles from the field of nutrition and such.




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    1. WELL crap, what do those of us who live in places like Oregon do? I’m always low on D, I have to supplement and it still doesn’t get me up to where I want.




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      1. Maybe try other supps? I wouldn’t get too hung up on “where I want” but simply be CERTAIN to not succumb to deficiency symptoms. Your personal level for such may not be accurately determined by the available research.




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  3. Dammit. That’s disappointing. :(
    On the other hand, we’ll have to look more closely into these quoted studies. I have looked into a lot of studies failing to show a positive effect of VD3 supplementation myself, and the difference between those and the ones which actually showed positive effects, where that the supplementation wasn’t given daily or in short term intervals. So it appeared to me that one has to supplement at least every 2 or three days or better daily to gain a positive effect.
    Also if the actual presence of VD3 does shows a changed expression in over 200 genes and almost every tissue in our bodies has a VD3 receptor, then it is clearly needed!




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    1. Note: Dr. G. is NOT saying that you don’t need any Vitamin D. As you say, it affects expression of over 200 genes. He is simply looking at randomized trials where you take a group of people with a certain condition (e.g. diabetes) and give half of them (at random) Vitamin D3 supplements and the other half get a placebo; they follow them forward and see if taking Vitamin D improved their diabetes. The placebo group also gets Vitamin D — via sunshine, dairy products, etc.

      Clear deficiency of Vitamin D certainly has deleterious consequences. But that doesn’t mean we all need to be taking Vitamin D supplements. In my practice, I don’t screen healthy patients for Vitamin D levels; however, I do screen certain populations — e.g. people with depression, people who almost never get outside, people with unexplained severe fatigue, etc.




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      1. Fair point! Maybe I got it all wrong, or not listening thoroughly enough. Before your comment I was under the impression that Dr. Greger claimed that oral Vitamin D supplementation had no effect whatsoever. Yet, there are a lot of people, which actually don’t have any other option, as sunlight is not available to them in sufficient amounts. Either because they live way up north/south, or because of their jobs they cannot leave their houses/bureaus/working places around noon or simply are immobile.
        I hope there will be also some trials on these kinds of people particularly, who without any supplementation suffer from severe deficiency. In order to see if removing it by means of supplementation improves there general health?
        Or is this already proven? I mean, like Vitamin C and scurvy back in the day?




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      2. My 88 year old mother takes two hour long outdoor walks daily but like many people who get sun exposure, she wears long pants and long sleeved shirts; she slathers sunscreen on exposed body parts. When tested, her vitamin D levels were under 20. I’ve known many other people (myself included) who weren’t depressed or fatigued and got outside some and were deficient. I was able to reverse my osteopenia with dedicated sun exposure and supplementation. You might want to consider broadening your screening parameters.




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        1. Hi. Actually, I didn’t list all the groups of people I screen for Vitamin D; I also screen most post-menopausal women, and anyone with a family history of osteoporosis or osteopenia. One problem for us physicians is that several health insurance companies — including Medicare — will not pay for Vitamin D levels, unless the patient already has a diagnosis of low Vitamin D. Which is to say, they do not pay for ANY screening. Vitamin D deficiency is so common, though, that in the high risk groups I’ve mentioned, I am pretty safe in giving them a diagnosis of “Vitamin D deficiency” even before I order the test. My other strategy is to be sure to order a Vitamin D level before the patient reaches age 65 and gets on Medicare!

          This first Vitamin D video by Dr. G was a little confusing. It sounded like he was saying Vitamin D is not very helpful. Then in his next several videos he makes a strong case that most of us need to be taking Vitamin D — since it is linked with longer life.




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          1. Thanks so much for this post–I learned a lot about what you’re up against with Medicare. Sounds like one of those areas where advocacy with Medicare is sorely needed. Great that you’ve figured out a strategy for getting the coverage.

            I’m curious about what percentage of your screened patients are deficient.

            I agree about Dr. G’s first video. I was worried he had taken a sweeping anti-supplement stance (with the exception of B12) and was glad to see that he had either shifted gears or was sending out a clearer message.




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    1. I have learned from a friend who has done a ton of research on this
      topic that the old-style “low-pressure” tanning beds are relatively
      safe, much more similar to actual sunshine, than the newer, quicker,
      HIGHLY carcinogenic high-pressure tanning beds popular nowadays. You
      want about 95% UVA and 5% UVB. More than 5% gets dangerous. Call around
      if you live in a metropolitan area and ask if they still have any
      low-pressure (20-minute) beds. If they do, ask for the make and model
      and look up the specs yourself. Then make sure that the bed is actually
      used in the lowest-pressure mode when you’re in it (some have different
      settings). There are some variables in how they are rated … it’s a bit
      of a research project. If you find one, start at 6 minutes every other
      day. Don’t increase if there is ANY pink to your skin at all. Dark
      people need this as much as lighter-skinned people, but few know this.




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  4. The first link in the “Doctor’s Note” leads to the same video (though with a mistake in the url), it should lead to the next video “Will You Live Longer if You Take Vitamin D Supplements?”.




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  5. My understanding is that we need to supplement Vit D because most of us us use sunscreen. Also, no matter how much we get outside, those of us living in northern latitudes will not have enough exposure during the winter months. I was taking 2000i iu’s daily last winter and had my levels tested in the spring. The results showed a level of 31 nm which is on the low side of normal but not high enough to prevent disease. I have been following the work of Dr Rhonda Patrick who has some excellent videos on YouTube. I believe she is doing some research on the link between autism and Vit D levels. Get out in the early morning sun folks – enjoy.




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        1. I’ve even heard Mercola say that sunlight that is nit mid day, early or late day sunlight, actually LOWERS your vitamin D levels. I don’t know if it’s true, Mercola is not a trusted source for me, but I am at least considering that it could be true.




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    1. Several years ago I was talking 2000 units of D3/day. I went to the doctor’s because I felt horrible and bad no energy. I was very low. That same week I heard a report on tv that the fda found that half of all vitamins and supplements had little or nice if the listed ingredients. I went on Amazon and noted those posts where users said their blood levels were low and then then went up after taking whatever brand and then got retested. I settled on BlueBonnet band single drops. One drop equals 2000 units (they also have other units/drop). It didn’t have all the junk other brands have in it. I’ve been using it for 2.5 years now. One bottle lasts well over a year. And my levels are always at ~40 where my doctor wants them.

      The other thing I found was a study that noticed since people responded to D3 and dine didn’t. They researched it and concluded that the people whose levels did not go up with supplementation were not taking it with enough food. You must take it with a little fat and a full meal. So I take it while eating a walnut or two at breakfast and then I eat my regular breakfast of oatmeal and fruit.

      I hope that info is helpful to you.
      Mark G




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      1. Thanks for the info. I’ll see if I can get BlueBonnet. I’ll get re tested in the fall, hopefully they will be in the optimal range.




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        1. I just reordered from Amazon. I think it was about $15 for a very tiny bottle. But it lasts a long time. It says it has 970 servings, which I don’t think is true. I’m still working on my last bottle which I’ve had for a year and a half. And given that I’ve done extra drops some days, I’m sure I’ve gotten about 600 to 700 drops out of it already. So don’t let the tiny size fool you. Oh, and keep it in the fridge. It doesn’t need to be, but it helps make the drop come out perfect and easy to control every time.




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          1. What is the source of the medium chain triglycerides?
            Supplement Facts
            Serving Size: 1 Drop
            Servings per Container: 900
            Amount Per Serving % Daily Value
            Vitamin D3 (cholecalciferol from natural lanolin) 2000 IU 500%
            Other Ingredients: Medium chain triglycerides, orange and lemon essential oils.




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            1. Have no idea. It might be the lemon or orange oil. But it’s only one drop. And the lemon taste is so faint that if you drop it straight on your tongue and forget to pay attention you likely won’t remember what it tasted like.




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              1. Don’t think it is the essential oils as they are listed separately. Probably this…
                As the name implies, Fractionated coconut oil is a fraction of the coconut oil from which almost all the long chain triglycerides are removed, thus leaving mainly the medium-chain triglycerides and making it an absolutely saturated oil.
                Which tastes a lot better than in olive oil.




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                  1. I’d go for the fractionated coconut oil any day. Gel caps have too much junk just in them and they burp awful. If I’m going to take lanolin derived D3 a little coconut oil isn’t going to bother me.




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                    1. Lol. That’s kind of what I was thinking. Thanks for your thoughts. I think I’ll stick with it. Especially since my blood tests are always so good on it.




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        2. I also started taking the Bluebonnet per Mbglife’s recommendation, and it worked, it raised my D levels to the normal range confirmed by blood tests.




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          1. That’s awesome! I’m glad it helped you. I don’t really notice the taste even though it’s supposed to be Lemmon flavored. Does it seem faint to you too? And if you missed my note above, keep it in the fridge because it makes it drop from the bottle slower so you only get one drop, not two.




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  6. Now don’t get disappointed people. We have another cliffhanger coming. And don’t forget the conclusion…

    “This all just adds to the growing body of science casting doubt on the ability of vitamin D supplementation to improve anything beyond just falls, fractures, the common cold, and all-cause mortality.” What!

    But on a personal side note. I run so you would think I get all the D I need. But no I was below 20. I use sunscreen, I wear a hat and I like to wear leggings so I am pretty covered up. I also seem to have developed this bad habit of waking up around 2 AM and staying awake for a couple of hours. I started supplementing with some liquid drops of Vit D about 3 weeks ago. And I have been sleeping like a baby! Is it coincidental? I looked up any research I could find on this and the only paper was from a practitioner who noticed if her patients D levels were kept between 60-80 their sleeping issues were better. 1500 patients but no control group. So many people have sleeping issues. We need that study!




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    1. ” D levels were kept between 60-80 ” — that’s quite high. I have no references handy but recall that some studies have indicated that there’s a “backward J curve”, meaning it’s worse to be deficient than have high levels, but still levels higher than ~ 50ng/dL are associated with more “adverse events”. Around 80 seems to me to be getting well into a possibly undesirable range.




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      1. Right. The author was saying the same. Would you like me to try and find it for you? Mainly a theory she would like to see researched.




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      2. 10,000 mgs of VD3 DAILY is an Anti Cancer remedy. As a holistic vet. told us to give it to our 7tr old Rottie with an Osteocarsonoma, and we gained ‘8’ months more of life with him when other vets said he would be gone in ‘2’ months! Although we did give him ‘other’ supplements too, i.e.; Mushrooms, IP3, Brocolli Sprouts, Oregano Oil, Echinacea and more on a daily basis. The tumor actually STOPPED growing for 5 months! I myself take 10,000 VD3 too as to my levels being low from Bariatric Surgery and now are fine. I only take it when I remember.(daily or every 2-3 days).




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        1. That’s interesting about your dog, I wonder if dogs make vitamin D from sunshine? Or any animal as far as that goes. I know in most formulated animal feeds they have supplemental added vit D .
          As a kid I lived in extreme north , and we had to take cod liver oil, yuck.




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        2. Thanks for the information. You got me interested in the topic and searching, the following discussion popped up, which I post for those interested in more information:

          https://www.vitamindcouncil.org/vitamin-d-news/researchers-suggest-vitamin-d-sufficiency-range-and-its-relation-to-risk-of-cancer-in-dogs/

          It seems to me, though, that we should keep in mind what’s helpful for special needs vs. the general case (normal levels, no known disease, etc.). In my case, 2000 IU per day, puts my level just over 50 ng/dL (I’m thin). That’s around the upper limit currently recommended by e.g. Dr. Fuhrman (45 ng/dL), based on the “reverse J curve” studies, I’m not sure what upper range Dr. Greger recommends.

          Older people should also be aware that they do not produce vitamin D from sunshine as readily as younger people. Perhaps the same is true for dogs and cats. Now I am wondering what my dog’s level is!




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  7. Can’t wait for the next installment. There seems to be a lot of buzz about vitamin D and autoimmune diseases, particularly MS. Hope the link is explored.




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  8. It’s not even worthwhile to consider whether supplementation had an effect without looking at study participants’ blood levels of Vitamin D. A lot of studies on it supposedly showing no benefit supplement with a very small amount (400 IUs, for instance) for everyone, regardless of their initial blood levels. And then if there’s no effect shown, they conclude that Vitamin D supplementation doesn’t work. But the research on its relationship to different health conditions is about where those blood levels are — there are protective effects at certain levels. Just throwing supplements at people and not even bothering to test the blood levels is worthless and doesn’t prove anything useful at all. Similarly, people taking supplements without knowing their blood levels can have no idea whether the supplements are needed or if they’re taking enough to get to the optimal levels. This is the same with any kind of research on nutritional supplements. There are target levels of these things (sometimes best studied in blood and sometimes in some tissue). If people are already within that, then supplementing either won’t help or it will harm. If the supplement isn’t the right amount to get a given person into that optimal range (either too high or too low), it won’t show effect and there’ll be another headline out there saying VITAMIN X SUPPLEMENTATION HAS NO BENEFIT. Always be skeptical of studies on supplements that don’t test levels in people’s bodies before and after and compare results to those.




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    1. Sometimes they use manufactured forms of the vitamin, too, which doesn’t work the way the food form does. This was true in some of the vitamin E studies which showed no effect or harm. It could also be true with using vitamin D2 instead of D3.

      I know Dr McDougall is totally opposed to supplementing D, but he lives in a warm, sunny (most of the year) climate. Does he really, really understand what it’s like up here in the Northwest for months on end with mostly cloudy, short days and the sun at such a low angle? Add to that the fact that it’s too dang cold to be outdoors uncovered during those months and anybody’s vitamin D would fall. This is true for much of the country, not just here, of course.

      On the other hand, my husband doesn’t supplement and he tests well into the healthy range. He spends many hours daily outside in the warmer months and even quite a bit in winter. But he does eat fish, especially salmon, and other animal proteins.




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        1. About a year ago, I think. But he did not say why he fell, although he mentioned he blacked out for a short time. He did not go to a hospital and had no x-rays so the extent of any bone fractures is unknown, although he said he assumed he had some. I got this info from some video or other of his.




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          1. So sitting in the doctors office ,I notice he has a chart on how to assess the mobility of a person by how they get out of a chair , do they use their arms to push themselves up etc. Each method of sitting down or getting up gets you certain points . We are being assessed all the time . This is why I think it’s fair to be a little critical of Dr McDougall , like if I went to my doc and told him I blacked out and fell and broke three bones , which Dr McDougall assumes he did , my doctor would be very concerned doing that much damage from such a small fall. Lets not forget McDougall has had spectacular success with his starch diet , a diet devoid of toxic foods like meat , milk etc. It does not mean it’s the ultimate diet , just that it’s a whole lot better than a standard diet.




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            1. Yes, it is worrisome and can make one wonder, but since he could have fallen for many reasons, some not relevant to his diet/lifestyle, I don’t think it productive to draw general conclusions from his fall / blacking out, or be critical of him for that reason. This is not to say that I subscribe to his diet or all of his views; I don’t.




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              1. if you look on wikipedia and use their search, look for “Mantle Site, Wendat (Huron) Ancestral village”
                Is totally amazing and certainly backs up Dr. McDougall and what some of the native ancestors ate. Researchers were simply floored at how much corn was consumed by natives in this area, there is a documentry on it too, very interesting stuff




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          1. WFPBRunner: re: “People of all ages fall…” That is so true. Freak falls happen all the time. I have a friend whose young and fit husband fell and just happened to land wrong in his own home–and ended up being killed. [It] happens.

            I really like your last point too. I remember that a couple of years ago a forum poster was saying how her diet helped her bones to heal fast enough that it surprised/impressed her doctor, and she attributed that quick healing to her whole plant food diet.




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        2. I hadn’t heard that. You would think he would do a vitamin D test on himself to be certain of his status, since he takes such a strong stance against supplementing D.




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      1. I think I read if a plant gets enough sun to photosynthesize, than people can get enough to make vitamin D, they just have to actually get outside sometimes and expose some skin!




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        1. Yes, but there are people who live in Hawaii and are outside a lot who still have very low serum levels, for reasons we don’t know. What about those of us who live in places too cold for months of the year to have exposed skin, or people who are inside in their office for most of the day? It’s good to get tested.




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  9. I think one the important questions that needs to be asked in the controlled studies is the dosage amounts of vitamin d and more specifically the level of 25 hydroxyvitamin d in the blood serum. If studies are using low doses (RDA) and or low blood serum levels, then the results of vitamin d may be ineffectual on various chronic diseases.




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    1. K2, D3, and calcium are all parts of a complicated, living, interactive system. Our reductionist approach, as Dr. G points out, often leads us to an understanding of our bodies that is overly simplistic. Nature is also very parsimonious with its use of chemical substances: the same substance may have multiple uses in the body, sometimes seemingly contradictory. Think of neurotransmitters mediating all different kinds of nerve pathways. What happens when we up the availability of a neurotransmitter system-wide is anyone’s guess, but this is the approach of Big Pharma. The same substance may also have a completely different function in another organism. This is the case with vitamin K2 in the natto bacterium. I’m glad that users of this site are smarter about health matters, and more inclined to think twice before throwing a pill at the problem.




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  10. Isn’t vitamin D oil basically fish oil that is concentrated to some degree? And, those companies that make vitamin D capsules, are they not reductionist in their approach? How do Siberians in Northern Russia near the arctic manage to live long lives with very little sun exposure, and I am sure they do not have any “health food” stores in their primitive villages to run to in order to get their daily dose of vitamin D?




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    1. I think the answer to Siberian and others living in the extreme north is that they eat livers from fish and other animals. I remember reading somewhere that polar bear liver is so high in vitamin D that it would actually be toxic to eat it, but other kinds of liver would probably have plenty of vitamin D.




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    2. Gelcap D3 is from tuna and salmon skins, powdered D3 (as used in multis) is extracted from sheep lanolin (a wool byproduct). Vegan D is D2, which is produced by fungi exposed to UV.




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      1. Darryl: I have seen vitamin D products containing D3 but claimed to be for vegans because the source is a lichen. I haven’t seen any published research confirming this though. (Haven’t seriously looked.)




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  11. The skin makes Vitamin D3. “Vitamin D” without qualifiers ordinalrily means Vitamin D2 which the body can convert a small amount slowly into D3. We take D3 since NH is pretty far north and cloudy.




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  12. I live in Florida and get outside everyday for at least an hour and my doc says my vitamin D is low and I should supplement. I was very surprised when she told me.




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    1. Linda: The darker the skin, the harder for it to make vitamin D. To get the skin to make vitamin D, it needs to be exposed to the sun roughly between 10 AM to 3 PM. And the older one gets, the harder for the skin to make vitamin D. Those who take cholesterol-lowering drugs may have a hard time making vitamin D because cholesterol is the precursor to vitamin D in humans.




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      1. Do you think its possible that a person with really low cholesterol, i’m under 100 total cholesterol, would have trouble making enough D from sunlight? Is there a way to raise cholesterol without consuming animal products?




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        1. Ben: I used the word “may” because it’s not proven that statins lower vitamin D levels. It’s just a hypothesis. (It would be difficult to prove that because the confounding factor, amount of sunlight test subjects receive, is hard to control.) And I’ve seen a paper reporting that one statin, namely Crestor, increases vitamin D levels, not just slightly but dramatically, although subsequent attempts to reproduce the result under real-life conditions have failed. As for you case, I haven’t seen any study that showed naturally low cholesterol levels lower vitamin D synthesis in the body. But it’d be easy to find out, just for your own benefit. I’d have a vitamin D test done.




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        2. Ben: I don’t have a clinical answer for you, but I do have a thought. Here http://nutritionfacts.org/video/can-cholesterol-be-too-low/, Dr. Greger addresses the question: Can cholesterol be too low from a cancer perspective? The answer was: No. It can’t be too low for cancer, heart disease, etc.
          .
          Dr. Greger did not specifically mention the cholesterol/vit D connection, but I would be really surprised if there was evidence out there on this particular topic that Dr. Greger has not seen. I think he pays a lot of attention to cholesterol related studies. So, I can’t say for sure, but my guess is that if there was any evidence that cholesterol could be too low in such a way that it impacted our health, I think Dr. Greger would have found and reported on it.
          .
          Rami, an old-time moderator here on NutritionFacts, has this to say a long time ago to someone who asked about whether cholesterol levels could be too low or not:
          “Cholesterol can be as low as the 10 range and you will still live a perfectly healthy life. This is evident in those who have genetic disorders resulting in extremely low cholesterol, thus, the argument that below 150 is too low is simply untrue. I would see this video for the evidence.
          http://plantpositive.com/22-cholesterol-confusion-5-cho/
          .
          I would think that problems synthesizing vit D would show up in individuals with ultra-low cholesterol if it were going to be a problem.

          .
          None of that is direct evidence for your question. But I hope you find it helpful.




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    2. Linda, Many, many years ago I remember reading Adelle Davis (my first exposure to nutrition information, much of which I now discount or qualify), and she talked about two little neighbor girls who played out in the sun on the beach a lot in LA. But she said they looked deficient in D to her because of the shapes of their sternums. She also said they were kept scrupulously clean, which she thought kept them from having the oil in their skin that would allow vitamin D to be made by cholesterol. Now, I may be saying this all wrong, but her point was that we can’t wash all the oils off our skin and still make vitamin D. This was decades before sunscreen was invented. If her premise was correct, perhaps simply having dry skin without much oil at all (like I do) would prevent us from making sufficient vitamin D even if we sunbathed every day at noon.




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        1. David, thank you. Now I would love to know the answer to Ben’s question: would rubbing coconut oil on the skin help? Does anybody know?




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  13. Why do we always assume we can pop a pill as a workaround for intricate natural systems that have evolved over millennia, and get the desired result? Our reductionist thinking has us slathering copious amounts of dubious chemicals onto even our vulnerable children’s skin, instead of using traditional methods of limiting sun exposure, and then dosing them with a slew of fake vitamins to compensate? This modern insanity is at the root of the rampant ill health in our society… everyone wants an easy fix to “inconvenient” reality. Or maybe I’m just old! lol




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    1. Vege-tater: My reality is that I work all day in a windowless room and live in a location which does not get enough natural sunlight a good portion of the year. I follow your general sentiment, but I think you go too far by not qualifying your points. We don’t all live in natural situations and thus sometimes an unnatural solution may be needed. As an example, think of our needs for B12 and why popping the pill is the best/safest option in our modern times. Just pointing out that a little perspective and gentleness may be needed for the vitamin D discussion.




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      1. I get that Thea, that was my reality too, and I lived in New England which isn’t exactly the tropics, but I managed if I cared to because I didn’t believe supplements were equivalent, even though they are easier. My point is we NEED to make some room for nature and real life in what is unfortunately becoming a unnatural construct all around, because “progress” isn’t always all it’s cracked up to be. Man is always being proved wrong, nature, not.




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        1. I agree with you that if we’re able to get our vitamin D from natural sources (i.e. the sun), it’s ideal. But it’s important to acknowledge that many people, like Thea, are working all day in windowless rooms. And on weekends, people are running around doing chores, most of which keep them indoors. Many folks do not have yards or neighborhood parks. I happen to believe that many of us, especially vegans/vegetarians, can’t get enough D from sun and food exposure and thus need to supplement. But I do agree that whenever we are able, we need to get outside and connect with the natural world and soak up the rays!




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    1. Thanks for your comment.

      It is & according to the National Institute of Health “Two forms of vitamin A are available in the human diet: preformed vitamin A (retinol and its esterified form, retinyl ester) and provitamin A carotenoids. Preformed vitamin A is found in foods from animal sources, including dairy products, fish, and meat (especially liver). By far the most important provitamin A carotenoid is beta-carotene; other provitamin A carotenoids are alpha-carotene and beta-cryptoxanthin. The body converts these plant pigments into vitamin A. Both provitamin A and preformed vitamin A must be metabolized intracellularly to retinal and retinoic acid, the active forms of vitamin A, to support the vitamin’s important biological functions. Other carotenoids found in food, such as lycopene, lutein, and zeaxanthin, are not converted into vitamin A.”

      Hope this answer helps!




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  14. Reviews on Vit D such as this one are so rare. Thank you Dr. Greger for shedding some light on Vit D. There is a well described theory on Vit D and disease that says that “low levels of Vit D do not cause disease, but disease causes low levels of Vit. D. Remember Vit D is actually a hormone, therefore it is highly regulated by the body. Not very long ago it was also thought that Vit D receptors were only found in few tissues; now we know that is not the case.




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  15. Vitamin D deficiency is related to almost every disease mankind commonly has. There are many thousands of vitamin D studies launched with respect to cancer which are reporting large reductions in tumor size, 50 percent or so. Vitamin D is essential in disease prevention.




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  16. S o o, if you DO take a VD3 supplement and your levels DO go up to where they should be you are saying there is NO benefit? Why would it matter how or where it’s coming from as long as it gets into your blood? I take 10,000 VD3. (10,000 is an Anti Cancer,- see my reason below in reply).




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    1. Same question – can somebody address this? If somebody has low D, takes a supplement, and gets it’s up to better levels, there’s no benefit?




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  17. So you have felt benefits from going vegan?
    Your a guy that can take a fall that’s for sure , so you feel you fall a lot from the vertigo?
    Hope things will start going your way as time goes by.
    Cheers!




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  18. Still some intriguing studies out there! For example: Just 13 patients, none of whom could control their seizures with drugs,
    but upon “normalization” of D in blood with D3, they saw 40% reduction in number
    of seizures in a 90-day study. 40% is BIG if nothing else has worked!

    Hollo A et al. 2011. Correction of Vitamin D deficiency improves seizure control in epilepsy: a pilot study. Epilepsy Behav. 2012 May;24(1):131-3. doi:
    10.1016/j.yebeh.2012.03.011. Epub 2012 Apr 11. http://www.ncbi.nlm.nih.gov/pubmed/22503468

    (Isn’t there also some association of deficiency with MS?)

    (Doesn’t one also need K2 with D3 for Ca to be deposited in bones rather than in soft tissue?)




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  19. Most studies on vitamin D may not be all that useful, the body likely did not evolve to use vitamin D to help prevent diseases that we’re interested in. The whole point of using vitamin D to regulate all sorts of processes in the body has likely little to do with preventing cancer or heart disease, as cancer and heart disease were not a major driving force in our evolution. We have to consider first what is most likely the role of vitamin D and then consider what the most likely health benefits could be and then consider how to best test such ideas. It seems to me that the whole point of making gene expression depending on the amount of Sun exposure, has likely to do with fine tuning the body to the available food resources.

    An animal whose calcidiol levels are dropping may have to survive a harsh winter a few months later. But at the time the calcidiol levels are dropping it may still be autumn the temperature may be high and there may still be plenty of food around. But the calcidiol levels tell the animal that harsh conditions are ahead, so it may be a good idea to save energy, invest a little less in maintaining optimal physical fitness and divert energy to build up some fat reserves. In the tropics where there s no winter, there may be prolonged drought periods; many animals burrow underground and then their calcidiol levels will also go down.

    So, this suggests that high vitamin D levels will make it easier to maintain optimal physical fitness. There are some research results that are consistent with this idea, e.g.:

    http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0101659

    “Vitamin D and Exercise Performance in Professional Soccer Players”

    “Our findings suggest that vitamin D levels are associated with the ergometric evaluation of muscle strength, as expressed by SJ and CMJ, sprinting capacity, and VO2max in professional soccer players, irrespective the levels of performance. Furthermore, our data reaffirm the importance of UVB on serum vitamin D levels. Moreover, reductions in exercise training stress may also have beneficial effects on vitamin D levels, suggesting a possible association of its levels and the training-induced stress. Our results indicate a possibly bidirectional interaction between soccer performance indices and vitamin D levels.”

    The drop in calcidiol levels due to heavy exercise suggests that the body is using calcidiol to ration the amount of physical activity it will easily tolerate.

    Suppose then that vitamin D actually does nothing more than to make exercise a bit easier, and that without vitamin D with greater effort you could actually get to the same fitness levels. After all, if an animal survives the harsh winter and there is now plenty of food available, its vitamin D level will be a lot lower than it was in autumn. Evolution will also have had to deal with that, so likely the pathways inhibited by low vitamin D can be overridden by other processes.

    So, a minimal hypothesis that one could consider is that vitamin D has no role other than to let hard exercise be subjectively perceived as being harsher the lower the vitamin D levels are. The research article I quoted suggests more, that vitamin D helps with building muscle. But even this minimal hypothesis would have big consequences if it were correct. Most people who don’t get adequate amounts of exercise will have made their lifestyle decisions based on subjective experiences, they may have stopped exercising due to lack of energy. It costs time and the time left after exercising is of less quality if you feel tired. If people with higher vitamin D levels simply tolerate exercise better without vitamin D having any effect on the their bodies other than feeling less tired, more of them would have been able to stick to an exercise routine.

    So, vitamin D would then still be useful as a means to be able to exercise harder. We can even consider hypotheses where vitamin D does have a direct positive health effect, e.g. helping to build muscle if you you exercise hard enough, but that it will have negative health effects if you are a couch potato. The way health effects such as all cause mortality depends on lifestyle may be modulated by vitamin D levels, such that a healthy lifestyle with plenty of exercise leads to a better result, but if all cause mortality goes down steeper as a function of vitamin D levels, it will also go up faster in the opposite direction of where you decrease exercise levels.

    So, that’s why I don’t really take the research results on vitamin D supplementation of elderly people living in elderly care facilities all that seriously. They may well be worse off taking high dose supplements as some results suggests. I just make sure I get plenty of exercise and I take high dose vitamin D supplements (I take about 7000 IU/day). The vitamin D dose I take is what I would get were I be exposed to tropical sunlight all day long. The exercise I do, running for an hour per day is what is typical for indigenous people living in the bush. Mye diet is low fat, I eat huge amounts of carbs and huge amounts of vegetables. Because in Nature you would not be be able to get the low carb high fat meals that most of us are used to. So, the carb loading that athletes do is an entirely normal process that our bodies have evolved to do. High vitamin D levels will probably help to fine tune the whole body with all of this.




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  20. It may not prevent disease, but supplements are important to avoid deficiency for those who live in regions where they’re not getting enough sunlight during periods of the year, so whole foods supplements can be extremely important in avoiding deficiency. Plus more and more people are avoiding the sun due to the sun scare which makes you wonder about the ties with the sunscreen and cosmetic industries and supplement industries. I would never turn to a supplement for preventing disease, just avoiding deficiency and I’d always choose a whole foods version. I wish there were more studies on whole food supplementation. This could be helpful for people unable to get sufficient nutrition from food, e.g. people in the military, people on calorie restriction, etc.

    Looking forward to seeing the next video on this!




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  21. Ask the Dr. Q: Is Nutrient Data Software -like Cronometer- useful? For a while I entered everything I ate into a computer to determine if I was getting the Recommended Daily Intake of the vitamins and minerals that it was able to track, checking methionine and leucine, where my Omega ratios were, etc . This was educational on many levels -but after a while I started to wonder how accurate all this data could actually be. As research suggested more of one vitamin, less of some mineral, I customized my targets accordingly. Still, there is much the software can’t take into account: antioxidants, phytonutrients, how fresh my produce is, the soil it was grown in, various cooking methods, the fact that I’m shorter than the average human, my personal genetic mutations… How big of a grain of salt should these numbers be taken with? Is it worth doing at all? How accurate do you think the RDI targets are?




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  22. This randomized double-blind controled trial has just been published proving vitamin D provides real substantial benefits for autism!
    https://www.ncbi.nlm.nih.gov/pubmed/27868194

    Also, my daughter MS has been completely inactive since she started to keep her Vit.D levels 4 years ago!
    About those cases were Vit.D were put to the test and showed no benefits, I would like to check them, is it possible to share those links? I like to check what are the Vit.D levels used on these research, if they were applied as dry capsules or dissolved in oil, etc.




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    1. Are you referring to Vit D articles Dr. Greger has referred to in this series of videos? All articles cited in the videos are listed in the tab “Sources cited” over on the right side of the video.




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  23. Dr Gregor,Why every time i try to take d3 even a small dose like 1000u after a day or 2 i fell very bad…diziness and other things..
    Please help




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  24. Pedro,

    I would encourage you to check you levels before taking any vitamin D supplement.

    I have seen side effects in those who take excessive doses, not typical of the 1000iu, per your experience. Not knowing your ethnicity you might see in the literature that there are some groups who typically should be taking a lower limit of vitamin d. Could this be a genetic issue, probably.

    Anytime that you react to a vitamin or for that matter any food, consider a trial without the product in question and then reintroduce. Chart the responses and most of the time the results are obvious.

    I firmly believe that we should test PRIOR to the use of any supplement as each of us has such a different chemical profile that “typical” levels don’t really apply. Dr. Alan Kadish moderator for Dr. Greger




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  25. I’ve never seen any evidence of this at typical recommended supplementation doses in study subjects that are otherwise healthy. There is evidence of disease reduction in those deficient in vitamin D that take supplements.

    Dr. Ben




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  26. I am confused about how much vitamin D to take. I watched all the Vit D videos a while back and started taking 2500iu 3 times a week but I can’t find the video that recommended that amount. I live in Southern California and I supplement only during the winter months ie November to about March. Is this enough? I work in an office but I go out at lunch for at least 15 minutes of sun a day.




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