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  • What about Vitamin A? I quote:

    “Researchers at Newcastle University in England, led by Dr. Georg Lietz, found 47 percent of volunteer group of 62 women carried a genetic variation that prevented their bodies from effectively converting beta-carotene into vitamin A.”

    If this is the case, it implies nearly half of vegan women do not have the enzymes that convert carotenes to vitamin A – should we be concerned? Do some people simply require this vitamin preformed (or by supplement)?

    • Michael Greger M.D.

      I assume you’re talking about this study? That was over ten years ago. According to a review published last year, “Methods to assess the bioavailability and bioconversion of provitamin A carotenoids have advanced significantly in the past 10 y….” Though the conversion is not as efficient as we used to think, there is no need to consume preformed vitamin A according to the Institute of Medicine. But that doesn’t mean we don’t have to beta-carotene containing foods! That’s one of the reasons I recommend we eat dark green leafy vegetables every day.

      • Mary MacDonald

        I would love to hear an update on this topic.

  • jen.ferdinand

    Hi Dr. Greger. Thank you so much for creating this site. It is very much appreciated.

    I noticed the bottle of Vitamin D in this video was Vitamin D2. I have read that D3 is the better source for us(colecalciferol). Can you please clarify?

    Many thanks,

    • Michael Greger M.D.

      Such a good question. Taken daily in doses under 2000IU, vitamin D2 (ergocalciferol) and D3 (cholecalciferol) appear bioequivalent (meaning they both work just as well in your body). However if your physician suggests you take large intermittent doses (such as 50,000IU weekly, then D3 is probably superior).

      • Khari

        Vitamin D2 is Vegan….Vitamin D3 is not Vegan….am I correct?

        • Lindsey

          Correct, but there is a new vegan D3 on the market derived from mushrooms!

          • Actually,it’s from lichen not mushrooms.

          • Israel Navas Duran

            Actually, a lichen is part fungus and the other part either algae or cyanobacteria.

      • RobiDon

        My understanding is that currently vitamin D2 is the only FDA approved version available by prescription in the 50,000IU doses. I was diagnosed as being deficient in vitamin D and have been taking this form for awhile. Now I take one every two weeks, except when I harvest D from the sun. I don’t know if you can get this amount in non-prescription versions. I am successfully maintaining my D levels using D2, and because I’m a wfpg vegan I am happy to have a non-animal source.

  • jen.ferdinand

    Thank you so much for clarifying this, as I often see D2 in supplement powders and have not understood why it is used.

  • DanM15

    What would you recommend as a minimum dose of B6, B12 and Vitamin D for someone following a plant based diet?

    • Toxins

      Hello Dan!
      I have studied nutrition extensively and can answer your question.
      Firstly, a variety of plant foods have significant sources of b6 and therefore is unnecessary to supplement.
      Regarding b12, you can find rather high doses in supplements, some containing %5,000 to %16,000 of your daily value. Its of no concern though to worry about getting too much. If you take one of these supplements once a week it will suffice since what you cant use is simply peed out. Also note that vitamin b12 is used every day in extremely low amounts so once a week will replenish your supply.
      Regarding vitamin d, you should take 2,000 – 4,000 IUs of Vitamin D2 or D3. I take a deva 2,400 IU vitamin d2 supplement. In experiments, these two types of vitamin d proved to be nearly equivalent so do not concern yourself with what type of vitamin d as long as you get it. Just note that vitamin d2 is vegan but there is a new vitamin d3 derived from mushrooms that is also vegan.

      • Erin

        how often do you take the said vitamin d dose?!

  • Khari

    What vegan options are there for vegans to get Vitamin D from besides supplements and the sun?

    • Alexandra Georgiadis

      There are some vegan-friendly foods that are fortified with Vitamin D such as breakfast cereals and soy milk. Make sure to check the nutrition facts on the food label. But remember if you live in an area where you may not be getting enough sunlight, or if you don’t get enough sun exposure, fortified foods may not be an adequate source of vitamin D. As the video mentions supplementing with vitamin D might be a good idea. You might also be interested in this video,, comparing two Vitamin D sources. More information is also available on regarding vitamin supplemention which you may want to check out (since not all vitamin supplements are beneficial) such as this short one ,which mentions vitamin D along with E, A and C. Hope this helps. Good luck!

  • If vitamin B12 is stored in the liver, then why do we get it from eating meat (rather than eating actual liver)?

    • Anya

      After being absorbed in the small intestine & circulated by the blood, Vitamin B12 is stored throughout the tissue of animals – including the liver. Luckily as we have seen by this video, we don’t need to depend on animal products for our Vitamin B12!

    • Israel Navas Duran

      Liver has higher concentration of vitamin B12 than other organs. This is also the case about vitamin D, A and E, up to that point that eating liver of certain animals can be toxic or even lethal (e.g., seal, polar bear).

  • vegantruth

    How much Vitamin D is too much? Whats the recommended supplementation? Is there any science to Vitamin D as a cure for the common cold?

    • SArmstrong

      You can get too much vitamin D; since it is a fat soluble vitamin it can accumulate in the body to toxic levels. If you take significantly more than the RDA (which most agree is too low at 400 IUs daily) it may be wise to get your blood levels checked after supplementing for a few months. At doses more than 10,000 IUs daily there may be an increased risk of kidney stones. In the Nutrition Facts video 4,000 IUs daily in winter is mentioned; I think the chance of toxicity is unlikely at this dose. There are anecdotal reports of vitamin D supplementation preventing or reducing colds in winter. I know of two randomized studies that did NOT show vitamin D reducing upper respiratory infections ( Epidemiol Infect. 2009;137(10):1396 and J Infec Dis. 2010;202(5)809 ).

      • I would look into that some more, what exactly constitutes a toxic dose of vitamin D has yet to be
        determined. Though it is possible this amount may vary with the
        individual. In fact latest studies show the toxic levels to be actually much higher.Published cases of toxicity involve intake of ≥ 40000 IU (1000 mcg) per day. In two cases an intake of over 2,000,000 IU per day. This over-dramatization of the toxic effects of vitamin D can only do harm scaring people away.

      • RobiDon

        Michael F. Holick, Ph.D., M.D. says in his book, The Vitamin D Solution, that while we can get sunburned from too much exposure to the sun, we cannot get too much vitamin D from the sun.

  • Lisa21012

    It was recommended to get cyanocobalamin but those are supplemented with folic acid which we shouldn’t be taking. I like taking it daily so I’m looking for 250 mcg. Is there a brand of B-12 that anyone likes?

  • PeterGerry

    How much of the body needs to be exposed to get “15-30 min mid-day sun”?

    • Toxins

      Hello PeterGerry!

      This is an excellent question! Please see my response to GregV at the bottom of this page describing many aspects of vitamin d including how much you need to get on your body for it to be effective.

      Let me know if you have further questions!

  • evanbrand

    What foods/protocol can reverse gray hair (or revert gray hair to original color); what foods/protocol can revert hair thinning/balding? ( I saw 4:13 in this video, and was curious if there are other suggestions).

  • Stacia

    Hi Dr. Greger,

    I just watched your newest video and it was fantastic as usual. The segment about the adult requirement of 2000 units/day for Vitamin D was interesting and helpful. Can you please tell me what a child’s requirement is likely to be? We have a three year old.

    Thank you,

    Stacia Mesleh

    • Michael Greger M.D.

      I’m so glad you’re finding the videos useful. The official (Institute of Medicine) recommendation for those over 1 year of age is 600 IU a day of vitamin D. In two weeks I’m going to be rolling out a series of vitamin D videos from my volume 6 DVD–stay tuned! (if you can’t wait, I have a special holiday sale on my Latest in Nutrition DVDs–all proceeds to charity, of course).

  • tduke

    would eating mushrooms daily be just as good as supplementation or better since they are so high in vit D?

  • Michael Greger M.D.

    For some context, please check out my associated blog post Multivitamins and Mortality!

  • Phil

    Does suntanning und a suntan bench promote the body’s production of D2? (1-2 times suntanning, approx. 5-10 mins per go)

  • Karen

    Hi Dr. Greger, 
    I really enjoy your videos and have learned so much. As a result I am following a vegan diet. I eat beans, tofu, and vegetables regularly, but my soy milk doesn’t say if it is fortified or not. I am trying to figure out all the vitamins like D and B12 that I may need to supplement with but find it confusing and hard to bring everything together. From what I read it seems iron and zinc supplements are necessary too. Should I talked a multivitamin that has all of these, or get separate supplements, and what brand?

    Thanks for your assistance,

  • Hello Dr, Thanks for the Video. I live in SF Bay Area and I am a native from India so should I take 4000 IU of Vitamin D2 or more?

    Also for B12 There are some articles about Methylcobalamin being better but than cyanocobalamin

    Can you please recommend? Also if you think cyanocobalamin is bad can you please update your site to have B12 recommendations for Methylcobalamin just for the benefit of community.

  • Fortified foods like cereal and almond milk use unmethylated forms of b-12 which contributes to b-12 deficiency in folks like me with an mthfr defect. It is supposed that 40% of the population has this defect, so fortifying cannot be the answer for us.

  • Stephen Lucker Kelly

    Upside down mushrooms soak up Vitamin D too! :-) So if you do this then you will also get lots of vitamin D too! :-)

    • Arjan den Hollander.

      You really think turning bacteria upside down makes them produce vitamin D?

      I think a few biology classes on your part are in order here.

      • Thea

        Arjan: Mushrooms are a fungus. And yes, turning them upside down helps them to make the vitamin D. Check out the following link and notice the paragraph that I highlight below.
        “Here is a simple experiment we did one summer afternoon in Kamilche Point, Washington. We compared several forms of organically grown shiitake mushrooms, which had starting level of 100 IU/100 grams. We compared the vitamin D levels of three sets of mushrooms, all from the same crop. The first was grown and dried indoors. The second set was dried outdoors in the sunlight with their gills facing down. The third set of mushrooms was dried outdoors in the sunlight with their gills facing upwards for full sun exposure. The most vitamin D was found in shiitake dried with gills up that were exposed to sunlight for two days, six hours per day. The vitamin D levels in these mushrooms soared from 100 IU/100 grams to nearly 46,000 IU/100 grams (see chart). Their stems, though, produced very little vitamin D, only about 900 IU. Notably, vitamin D levels dropped on the third day, probably due to over-exposure to UV.”

        Hope that helps.

        • Arjan den Hollander.

          Very thorough answer, thank you for taking the effort of writing it. Informative.

          This explanation actually makes a lot of sense thrue the action of exposing a vastly larger surface area to uv radiation.

          This is off course something else completely to just simply turning mushrooms on their hoods and expect vitamin D to appear as if by magic. What I took from reading the OP.

          But tnx Thea, good stuff!!

  • Mark Hazell

    What about DHA? Since DHA only comes from fish (and some sea vegetables) shouldn’t we vegans be concerned with getting enough? Another thing is that I think I’m not getting enough calcium, what sources do you recommend for those? I’ve been taking a supplement for that as well and would like to cut down on those supplements.

    • Israel Navas Duran

      Sea vegetables? I think you have the wrong idea of what dinoflagellates actually are.

  • lovestobevegan

    Hi Dr. Greger,
    The link to your blog “Multivitamins and Mortality” seems to be broken.
    Take care,

    • Ariel Levitsky

      Hey Michelle,

      The defective link has been replaced with Are Multivitamins Good For You?

      Thanks for letting us know!

  • Brian Bohmueller

    Sounds like a well researched video. Glad to see the (verily unregulated) multivitamin craze (funded by big pharma) isn’t being embraced by sensible Vism. As a new vegetarian mindfully moving toward veganism, i still eat vegetarian dairy products and local, “free range” eggs, so I don’t think I need to be concerned about B12 supplements yet. I’m due for a physical soon…are there tests I can request to confirm I have ample, complete nutrition?

    • Tommasina

      Hi Brian, Dr. Greger has a great video on testing for B12– . Hope that helps! Best of luck with your transition :)

    • Susan

      I supplement for vitamin B-12 because I do not want to increase my blood cholesterol by regularly adding animal proteins to my diet. That is part of the reason I eat vegan. The other reason is that eating animal protein increases pain and inflammation in my body, which is even more noticeable since fracturing my lumbar spine.

  • Arun Mukherjee

    Dr. Greger, the video does not tell me what would be a safe daily dosage of Vitamin B12. I recently heard a radio show which suggested to me that I might be taking too much (1000mcg). Would appreciate clarity on this important matter.

  • tony

    I would rather eat savoury nutritional yeast (tastes good) as a whole food rather than a supplement and the brand I have is lotus and one teaspoon is 500% of your daily b12 plus heaps of other b group nutrients as well.

    • Susan

      I give my kitten nutritional yeast to coat her certified organic kibble every day as a way to reduce fleas. She loves it and has zero fleas.

      The container I use is 10 years old and has spent most of its life in the freezer. Does anyone know if Kal brand is genetically engineered to resist Roundup?

    • mbglife

      But you don’t mean to suggest that nutritional yeast naturally contains B12, right? It only contains what is added to it, since nutritional yeast otherwise contains none.

  • Manm

    Hello Dr. Michael Greger! Are the B12 supplementation and B12 fortified foods really the only safe vegan ways to get that vitamin? Isn’t yeast a good source of B12? Much people who thinks they are omnivore says the only way to get it is by eating animals… some admits we can take it by fortified foods (sometimes forgetting about supplementation too but, anyway…) and a few people talks about yeast, spirulina…
    Well, my doubt is: if yeast is a good (and natural) source of B12, since they and bacteria are the only ones who truly produce it, it is our natural way to get B12, isn’t? It makes me confused because supplementation and fortified foods actually are not natural sources, if we look closer, up because:
    1) Men has to produce it (it isn’t naturally present in nature);
    2) Their production is not sustainable because of the plastic/glass bottles and all the artificial things used to its production and transport, so it has an impact in nature (significant or not) ;
    3) The reason of the cheap production of cyanocobalamin is its (little) content of cyanide.
    I am on the 10th grade, and, my school’s biology manual says yeast are present in places rich in sugars and on the peels of juicy fruits such as red grapes, what lets me pre-conclude that eating those fruits is the natural way to us to get B12.
    Can clarify my doubt?

  • steven bucelato

    thank you for all your info!! my question is, if i cant find b12 in pill form but i have found it injectable,- bottles of 1000mg,is that ok?¿ thank you

  • Grace

    Are there any other supplements that you recommend for vegans or any lab tests that should be done to check for deficiencies ? In the past (in your video about a 40 year old vegan dying from a heart attack), you also recommended DHA for pregnant breastfeeding women and recommendations for vegans including calcium, iodine, iron, selenium, zinc, and omega 3s (from flax seeds). The flax seed supplementation seems rather easy, but the other minerals may be more difficult to regulate. What do you think of the over the counter vegan vitamin supplements such as “Deva”?

  • Sarah V Lucas

    Supplementing all bread (in Australia, don’t know about the US) with folate dramatically reduced incidence of birth defects in children. I think mandatory grain supplementation with B12 would be a good idea considering that it is getting harder and harder for anyone on any diet to meet their requirements.

  • PeggyH1951

    Loving all your videos. This one came just in time for me, as I’ve recently been diagnosed as D deficient (21.5 on my blood work, with a bare minimum of 25 recommended, and 50 even better). I’m a no-oil vegan and already take B12. Recently I read that we should always take D3 with K2. Leafy greens aren’t enough, as the K1 in them doesn’t easily convert to K2 in the body. I have found a supplement that provides d3, k2, calcium and magnesium. But the calcium makes me nervous, given recent studies. Any ideas?

  • Please give me a tremendous help!

    I have 60 years and I need to try to have a reasonable life.

    My question is about supplements that I take, everyday:

    – Astaxanthin 5mg,

    – Pine Bark Extract (Pycnogenol) 100mg

    – Gingko Biloba – standardized extract (24mg Gingkoflavona glycosides and terpenes lactones 6mg), and

    – Coenzyme Q10 100mg.

    Is correct consuming these supplements? Or am I just spoiling the money and health?

    I also use other substances which are foods, not supplements, like Tumeric Curcumin, currently in capsule, 50mg (95% curcuminoids), but I will go to consume it in biological powder.

    I am thinking consume Peruvian Maca powder, bio, because, also, I suffer from erectile dysfunction after I get widowed, in August 2013.

    I appreciate with all my heart your possible help.

    I have published your work on social networks and will continue to do so, with all my enthusiasm.

    My thanks for the good you do to all people who have a little common sense in his head.

    Thank you so much.

  • I have 60 years and I need to try to have a reasonable life.

    My question is about supplements that I take, everyday:

    – Astaxanthin 5mg,

    – Pine Bark Extract (Pycnogenol) 100mg

    – Gingko Biloba – standardized extract (24mg Gingkoflavona glycosides and terpenes lactones 6mg), and

    – Coenzyme Q10 100mg.

    Is correct consuming these supplements? Or am I just spoiling the money and health?

    I also use other substances which are foods, not supplements, like Tumeric Curcumin, currently in capsule, 50mg (95% curcuminoids), but I will go to consume it in biological powder.

    I am thinking consume Peruvian Maca powder, bio.

    I appreciate with all my heart your possible help.

    I have published your work on social networks and will continue to do so, with all my enthusiasm.

    My thanks for the good you do to all people who have a little common sense in his head.

    Thank you so much.

  • Danie

    Hi Dr. Greger,

    I am eating a whole-foods plant-based diet but am unsure whether it is balanced and sufficient enough to get all nutrients and vitamins. Would you recommend taking a multivitamin? Also, would you recommend taking a prenatal vitamin before and during pregnancy? If not, what supplements do you recommend during pregnancy and how much of each? Would you recommend the same while breastfeeding?

    I have been looking everywhere for an answer but cannot find a satisfying one that answers all aspects. Since your videos are always spot on, I thought you would be the one to ask.

    Thank you so much!

  • Jim Fitzpatrick

    Dr. Greger, My thumb nail grows with a split and the corners of my mouth are raw. Am I deficient in B12, D or what? Thank you for your wonderful videos and articles and hopefully the answer to my lack.

  • Gene Auger

    So other than B12 and Vitamin D all other vitamins are useless does this include Co enzyme Q!0? With depleted soils and chemicals how can we get the nutrition needed as organic is not always avaiable?

  • Jordan
    • Joseph Gonzales R.D.

      I would say we need clinical data on them and even then I am not sure “whole-food” supplements can trump real, whole, plant foods. Just my take. Thanks for asking, Jordan.

  • Wade Patton

    Can my well water be lab or otherwise tested for B12? In this part of the country, a large part of the rural population drinks from their own wells. We also often drink from springs-I know where all the good springs are for my extended rides.

  • Lynn Perkins

    Lynn Perkins

    Apr 15, 10:35 AM

    Since I’ve been eating the plant-based, whole food, Forks Over Knives way, I believe my hair has gotten curlier! It has always been thick and healthy but has now developed a lot more curl. I’m 67 years old and don’t know what changes may be natural with age and what may be nutrition related. More natural curl?

    • Joseph Gonzales R.D.

      Healthy diet with the right amount of protein and minerals have been known to promote skin, hair and nail growth so you may be onto something!

  • Evelyn

    I’m wondering if there is a specific food or vitamins that help nails. I’m 67 and female. The past two years my nails have become a mess. They break easily and have changed in appearance. They have long lines.

    • Joseph Gonzales R.D.

      Dr. Greger has a page on skin health. Typical nutrients that aid nail growth are protein, B vitamins, and other minerals. I do not think supplements are needed, but a healthful diet chalk-full of fiber, adequate protein, and vitamins/minerals is suggested. I can add a list of foods high in these nutrients if that is helpful? Thanks for your post, Evelyn.

  • Hello

    Hi Everyone, I would much appreciate your help with a hair loss issue. Young woman in 20’s, at least half of my hair fell out and keeps falling out since going vegan several years ago; it’s so much thinner, dull, crazy split ends and breaks easily; my nails became brittle and have ridges. No weight loss, actually some weight gain, regularly active, supplement with D3, B12, and Iodine. I’ve been coming across a lot of testimonials of people losing hair after going vegan and regaining hair health after including meat again. I’m worried. I don’t want to start eating animals, but I’m at a loss how I can help it. Appreciate your suggestions, thank you!

  • Steven

    In your book, you are against most supplements such as Vitamin C, because they do not contain the other substances that your body needs to process Vitamin C. However, you advocate for B12; what makes B12 different?

  • james wilkinson

    I am thinking about taking ginkgo biloba to help with tinnitus. Though I am not aware of any scientific studies that support its use. A number of people report improvement in their condition after taking ginkgo biloba for 8 weeks. Do you know anything about this or can you suggest diet changes other than lose weight and stop consuming caffeine that might help. Thanks

  • JanineD

    Dr Greger, I take a biotin supplement to make my hair and nails grow. Is this a harmful, harmless or helpful supplement?

  • Bud Kelly

    Love you, Dr. Greger, and I watch all your vids. Very factual. But… I just realized who you remind me of when you speak- Steve Guttenberg from the movies. Hey, it worked for him too! Thanks.

  • JonatanOlsen

    What are you guys thoughts on Andrew Sauls research and results with high dosage of vitamin supplements like Niacin, E and C?

  • Federico Benincasa

    What about some studies that seem to prove that integration might not be effective, because vitamines should not be separated by the original compounds (I recall some statements about fat, for instance). Thank you.

  • BB2

    Dr. Greger, what do you make of the new review published in the Journal of General Internal Medicine that criticizes the vitamin D studies? Thanks. Here’s a link to it:

    • Thea

      BB2: Dr. Greger has another series on vitamin D coming up in about 5 videos. And it looks to be a nice long series with 5 or 6 videos judging by the titles. Maybe your question will be answered soon I the daily videos.

      • BB2

        Thanks Thea. Will stay tuned.

  • Andrea

    Just curious what type of vitamin I should be giving my 17 month old since we have just started eating plant based vegan?

    • Thanks for your question Andrea.

      Glad to hear you are making the right choice but I think this transaction should be done with all the appropriate support for a successful journey. Hence, I’d really recommend you read the Physicians Committee for Responsible Medicine “Vegetarian Starter Kit“. There is a specific chapter for children, please find all the information on the document as it’s very well presented too.

      Hope this answer helps.

      • Andrea

        Thanks! Appreciate the info! Looking into it now :)

    • Thea

      Andrea: I think you already got one reply to your post. I can’t remember what it said, but I wanted to share one of my favorite sources for information about feeding vegan children. The Vegetarian Resource Group is highly respected and researched and has even been spoken of highly by Dr. Greger. They have a whole section on vegan kids:
      The article I recommend starting with is:
      Have fun!