Doctor's Note

For more on the correlation between dietary supplements and cancer, check out:
Risk Associated With Iron Supplements
Food Antioxidants and Cancer

Be sure to check out my other videos on breast cancer

For more context, also see my associated blog posts: Are Multivitamins Just a Waste of Money? and Breast Cancer and Diet.

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  • Michael Greger M.D.

    Please feel free to post any ask-the-doctor type questions here in the comments section and I’d be happy to try to answer them. Be sure to check out the other videos on breast cancer. Also, there are 1,449 subjects covered in my other videos–please feel free to explore them!

  • jmerrikin

    Interesting information here Dr. Greger, but now I am a bit confused.

    While research suggests that healthy people should not take a “multivitamin”, what about individual vitamin supplements? I know it would be difficult to answer this because each one would have to be addressed separately however, what about the years of research done by the likes of Dr. Abram Hoffer and Andrew Saul, PhD. on vitamin C supplements?

  • KatTastic

    Having just watched Food Matters, I’m also confused and would like to hear a response regarding Dr. Saul’s work. Also, does the study take into account any of the additives in multivitamins, such as the dyes?

    • Toxins

      KatTastic, I watched food matters too. I thought it was great…except they advocated alot of super foods which proved to be VERY HARMFUL like spirulina, blue-green algae, noni, kombu and kelp. They also advocate other “super” foods with VERY limited research on them, like bee products such as royal jelly, propolsis and bee pollen. After discovering this, the movie to me lost alot of credibility. They obviously didn’t do enough research.

      • Where can I find more information on support of this claim “which proved to be VERY HARMFUL like spirulina, blue-green algae, noni, kombu and kelp.” specifically with regards to the movie?

  • LouiseF

    So, vegetarians should just take a B12 and a DHA suupplement only?
    Thank you!

  • organicsauce

    Not all multi vitamins are equal. Synthetic “typical” (cheap) vitamins versus whole food-based natural vitamins. I think multi vitamin is too vague a term, don’t you think?

  • Louis

    I’m bit disappointed with your presentation, and I’m wondering why you exactly choose this multi vitamin study to underpin your conclusion in this video. The Swedish cohort was from 2010 and in April of this year a meta-analysis (1), which is scientifically stronger in terms of proof, concluded : “Multivitamin use is likely not associated with a significant increased or decreased risk of breast cancer, but these results highlight the need for more case-control studies or randomized controlled clinical trials to further examine this relationship.”
    Furthermore the same study says : “Eight of 27 studies that included 355,080 subjects were available for analysis … Only 1 recent Swedish cohort study (the study you refer to) concluded that multivitamin use is associated with an increased risk of breast cancer.” It is my opinion, backed by science, that there is no need to scare people or make them stop taking their multivitamins. May I refer to a 2009 study (2) stating : “Most people do not consume an optimal amount of all vitamins by diet alone. Pending strong evidence of effectiveness from randomized trials, it appears prudent for all adults to take vitamin supplements.” However, many more studies suggest the positive impact on general health of multi-vitamin use. I can imagine breast cancer prevention isn’t the only health goal. I only hope that especially pregants women don’t stop taking their prenatal vitamins. Maternal consumption of folic acid-containing prenatal multivitamins is associated with decreased risk for several congenital anomalies, not only neural tube defects (3).


    • Michael Greger M.D.

      Thank you so much Louis for taking the time to contribute! It is such a relief to see that meta-analysis come out. This video was queued up from my volume 5 DVD, reviewing the peer-reviewed nutritional science published between Spring 2010 to Spring 2011, and so I must have just missed it (wasn’t indexed by the National Library of Medicine until August 19!). I’ll have to re-record the video now that there’s a systematic review published on the subject.

      Of course negative findings don’t automatically “cancel” out positive findings. As one of my research preceptors once quipped: “if two people drill for oil in Texas and one finds oil and the other does not, one can’t conclude that the question of whether or not there is oil in Texas remains undetermined.” Similarly, the conclusion from the 2010 study profiled in the video is not necessarily invalidated: “These results suggest that multivitamin use is associated with an increased risk of breast cancer. This observed association is of concern and merits further investigation.” But it’s nice to know that if there is an effect it’s it’s not one that has been replicated!

      The critical question remains: should women take multivitamins or not? That depends on the risks versus benefits like any other life decision. Since both the risks and the benefits appear equivocal (see for example the National Institutes of Health State-of-the-Science Conference Statement on multivitamins (PDF here) I agree with the Cleveland Clinic Journal article I featured and would recommend women take the money the would have spent on the pills and instead buy some produce with more proven benefits (see my Breast Cancer and Diet post). A similar recommendation can be made for men (as a similar meta-analysis likewise thankfully casts doubt on the multivitamin link there as well).

      Until we know more, I agree with the conclusion from the meta-analysis you cite: “Until further studies assist in clarifying the association between multivitamin use and increased or decreased risk of breast cancer, health-care professionals should open discussions with their patients regarding multivitamin use and risk of breast cancer.”

      Again, I can’t thank you enough–I hope you will continue to check back and ensure this is the latest info out there!

  • dan9486

    I see an oncologist for breast cancer prevention, and she recommended folic acid as a separate supplement. She also recommended Tamoxifen rather than a plants-based diet. Thank you for providing information to me that my oncologist either ignores or doesn’t even know about!

  • DrSteve

    This video is quite misleading. Reading the study itself (Swedish Mammography Cohort, 1998-2007) and the references we find that risks are very small or inverse. While three studies showed this risk, four showed lowered risk, and seven showed no relationship at all.

    This Swedish study:
    1.19 adjusted for risk factors (1.3 without necessary adjustments)
    1.11 Multivitamins ½ glass red wine
    0.97 Multivitamins > 2/3 glass red wine
    Two other studies showed increased risk of breast cancer with multivitamins:
    Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial
    1.18 Multivitamins

    American Cancer Society Cancer Prevention Study II Nutrition Cohort
    >1 only if < 1/2 cup wine daily

    However, the following FOUR studies referred to in the Swedish study showed a LOWERED risk for breast cancer with multivitamins:

    Nurses’ Health Study
    Maruti, Am J Clin Nutr 2009;89:624–33.
    Ishitani, Am J Epidemiol 2008;167:1197–206.
    Zhang, JAMA 1999;281:1632–7.

    In Addition, there were SEVEN studies referred to in this Swedish study showing NO correlation between breast cancer and multivitamins, including the Women’s Health Study, a French randomized trial
    of antioxidants (Neuhouser, Arch Intern Med 2009;169:294–304), and Feigelson, Cancer Epidemiol Biomarkers Prev 2003;12:161–4.
    Let's be fair and say that no extra risks for breast cancer can now be attributed to multivitamins.

    • jmerrikin

      Dr. Steve, I appreciate your counterpoint on this topic and thank you for pointing out the additional information. As a person who takes in a LOT of information on health and nutrition each and every da, I always try and determine the source of motivation for such information.

      When information is published for or against something, I try and assess why this would be published in the first place. I believe that the main motivation for a lot of these studies is that someone stands to profit from such acts, directly or indirectly. Why would anyone publish an opinion, scientific findings, or research results? In my mind the people who have seen both side and have the least to gain and the most to lose are the ones I place the most credibility in.

      Reading your response I had to ask myself if you are in any way tied to any financial interests in vitamin supplements, or are you just being a good guy helping your fellow human to consider all sides. With the utmost respect, I wonder if your motivation is driven by an attempt to prevent people from getting healthy and keeping them in the doctors office and at hospitals taking prescription medications. Please do not take this as an accusal, it is merely a set of questions in my own head. For all I know, you may be doing this out of the kindness of your own heart with only a desire to give back to humanity during your lifetime. If so, I applaud you!

      What I do know is that billions of dollars are spent every year to keep people in the dark regarding nutrition and it’s impact on personal health. Billions of dollars are spent every year on protecting the financial interests of drug companies and westernized food products. Billions of dollars in revenues are made by pharmaceutical companies and health care practitioners.

      • DrSteve

        I have no financial interest in any supplements. I left my comment because the video seemed to unfairly represent the study cited and the facts. Multivitamin formulas vary and so the studies are inconclusive.

    • Michael Greger M.D.

      Thank you DrSteve! Please see my reply to Louis above.

  • becochic

    Could it be that women more likely to take multi-vitamins used them as a replacement for eating well?

    Also, I agree with the above poster. If other studies came to different conclusions, then I want to know about that. What about prenatal vitamins? I am breastfeeding right now and I take a multi because I don’t always have time to cook and eat like I should.

    It is a crappy excuse, but if I eat bad for even a day or two and don’t take a multi, I am getting sores in my mouth. I’m deficient in something.

  • Eric Needs

    The fact that multivitamin use is even controversial should be enough to put a yellow light on. Seriously. 4 billion dollars a year for inconclusive data??? This is ridiculous and is further indicative to the propoganding media we slurp up everyday. Let’s all just turn off the tv and have a handful of walnuts shall we?

    • barbarabrussels

      Well spoken :-)

  • Mitzi

    I take a multi because we eat a low sodium diet, and the soils in our area are depleted of iodine. I had ancestors with goiter issues. The only local store selling seaweeds is an asian one, and they are all labeled in Chinese. We also need B12 and D, so it is less expensive to just take a multi. We eat a plant-based diet, so we get most of our nutrients form food,and I do not expect any pill to protect us from heart disease or cancer. I just know what is short in our local soil and want to make sure we get the nutrients we need. I’ll be watching for further evidence otherwise.

  • rhelune

    I take half a multivitamin a day (+ additional choline and vitamins B12 and D) because I don’t get the RDA of all vitamins from food only every day. It’s easier and cheaper to buy Deva One Daily multivitamins (without iron, I get more than menstruating woman RDA from food only) than to buy panthotenic acid, niacin, vitamin E, B6 separately and take them only when my intake from food is less than RDA. I do get some minerals from it, too, but sometimes also take calcium (+ vitamin C), depending on my intake from food. Half a tablet contains 200 ug RDA. What worries me is that I sometimes get even 1500 ug folate from food. Is folate from food dangerous, too? I really can’t understand why would a vegan supplement which is not prenatal contain folic acid.

    • Toxins

      Hey there rhelune!

      Firstly, folate from foods is not at all harmful! Folic acid is the synthetic, man made version of folate. Check out Dr. Greger’s video on folic acid!
      Also note that although your taking alot of vitamins and minerals, that is only a tiny segment of health. What really defines healthy eating is your intake of phytochemicals. While a vitamin supplement may have 12 different minerals, broccoli has over a thousand phytochemicals along with all your minerals and vitamins. The bio-availability of calcium from plants is much greater than the calcium from milk, meaning your body can take it in much easier If you eat a varied whole foods plant based diet diet you really dont have to worry at all about vitmains and minerals except vitamin b12, vitamin d and in some cases, iodine.
      Hope this helped!

  • Louis

    Don’t thank me, thank science, good science that is … I wouldn’t define the Swedish cohort, together with other “multivitamin” studies as well-defined. What would you think about a study done to investigate painkillers, where people just took “painkillers” and researchers found inconsistent results, with sometimes dangerous adverse reactions ? That’s because the “painkillers” are ill-defined and therefore, the study is a waste of money and time. What are “painkillers” in this study ? An aspirin, advil caplets, COX2 inhibitors, morphine ? And what were the doses ? The same goes with these “multivitamin studies”, they are mostly plain stupid, because the researched object is not defined well enough and taken at haphazard doses. In some cases, assesments are made with food questionaires going back 20 years; what/how did you eat 20 years ago and which supplements did you use ? This is just asking for skewed results and you’re bound to find strange and conflicting results. The simple fact that some people take multivitamins to compensate for a bad diet most possibly accounts for the higher cancer risk finding. (1) However, if you lift one nutrient out of a multi and look at the research, then all becomes more clear. Let’s take vitamin D. 400 IU vitamin D doesn’t protect against breast cancer (2), however 2000 IU slashed the risk by 50 % (3). Now, if the subjects of the multivitamin study take one Centrum a day (400IU vitamin D) (4), or a multi from Walmart at $7.97 for one month’s supply (5), what would you think the results would be in terms of breast cancer prevention/vitamin D ? No effect ! The doses/exposures aren’t adequate to elicit the hypothesized contrast of effects and intakes of other nutrients or foods, on which the tested nutrients are dependent, weren’t optimized. On top of that, consider the health consciousness (= diet) of someone who chooses to take “a multi” that’s as cheap as chips and hey presto, you have your additional increased cancer risk. Are those multi’s a waste of money, maybe or maybe not, but $7.97/month will not buy you much cancer protection from food either will it ?

    Furthermore, IMHO, the references you stand by aren’t based on real sound science. It would take me too long to discuss every study, but in the Cleveland Clinic reference they argue that a multi is bad and then refer to a meta-analysis of vitamin E, showing that doses up to 2000 IU give evidence of possible adverse effect, this is not entirely correct. The effect of an isolated synthetic nutrient in relative high doses can’t be extrapolated to a multi. The health effects of high dose dl-tocoferol are well-understood and aren’t applicable to multi vitamins. This is just one example.

    I’m pro food, there is nothing better than a really healthy diet, but if you study ALL the literature about vitamins, you see more evidence the study designs are flawed instead of the effect of vitamins/minerals.

    I like your website, and I can only hope you take the responability to use sound science and correct interpretations of it. And for that matter, if new views are published, you should adjust previous articles/videos with correct information.

    Respectfully yours,

    “More VMS-users were categorised as having an unhealthy diet (31.4%) than having a healthy diet (20.6%). ”

    • Michael Greger M.D.

      Just wanted to add an addendum to my comments above. Did you see the Archives today? A report from Iowa Women’s Health Study suggests that multivitamin use may actually shorten women’s lives. To quote the editor of the Archives of internal Medicine: “Because commonly used vitamin and mineral supplements have no known benefit on mortality rate and have been shown to confer risk….A better investment in health would be eating more fruits and vegetables…”

  • weaverinva

    Hello Dr Greger,

    You suggest in this clip that Zinc could be a factor in prostate cancer. Yet it is found that many vegans are zinc deficient. I find that if I take 15mg of zinc per say that I sleep much better and dream more–seems to have helped my skin as well.

    How does one balance risk with real needs? What comments or recommendations do you have on low supplemental zinc?

    Thank you,

    Michael Weaver

  • Michael Greger M.D.

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

  • Lauren Bateman

    Hi!  Is taking a B-100 complex supplement harmful since it has folic acid in it?  What should pre-pregnancy women take to prevent neural tube defects in their unborn?

    Lauren Bateman MS,RN,CNS

    • Toxins

       Lets examine the statistic of neural tube defects with and without folic acid supplementation. The relative data shows a 50% reduction in risk with folic acid supplementation. But looking at the absolute data itself, the 50% reduction is actually as follows: 1 in a 1000 chance of a child developing neural tube defects with folic acid. As opposed to a 2 in a 1000 chance of a child developing neural tube defects without folic acid supplementation. This 2 to 1 reduction is the 50% decrease and considering that the risk of a woman developing breast cancer is 3 times more common in those that do supplement with synthetic folic acid I do not see the end benefit. Remember that folic acid is synthetic and folate, the naturally occurring “folic acid” is the kind we want to consume from plants. Eating lots of greens and beans will give you plenty of folate.

      Check out Dr. Greger’s video on folic acid for additional information.

  • New Subscriber

    I just looked at your video concerning Breast Cancer and Multiple Vitamins. The conclusion was that multivitamins may increase the
    risk of breast cancer. I take Vitamin Code which advertises it is made from raw whole foods and contained live probiotics and enzymes. Are Vitamin Code products safer than other multivitamins?

    • Toxins

      Why take a multivitamin to begin with when we can get all we need (except b12 and vitamin D) from whole plant foods?

  • Julie Martinez

    What are your thoughts on taking individual vitamins rather than a Multi?

  • Ry176

    At 2:10 into the video, the narrator says that zinc is thought to double the chance of prostrate cancer. Does Dr. Greger think that Zinc increases the chance of prostrate cancer? I’m vegan, and I take a Calciusm/Magnesium/Zinc vitamin with Vitamin D. The link to Multivitamins and Mortality didn’t work. This link (from a Dr. Greger comment) doesn’t work either:

    I’m curious what Dr. Greger recommends vegans do in terms of vitamins. Should they take any supplements?

  • Omar Guerrero

    This kind of studies are not very reliable they are just questionaries…
    You cant verify the quality of the supplements they were taking or if they started taking the multivitamin because they had cancer already.
    I think there are a lot of brand some of them are really low quality packed with heavy metals and other stuff.
    Your best source of vitamins and minerals should be your food but I also think that for some vitamins a pill is a good option.

  • dietician afriyie

    how can multivitamin increase the risk of prostate cancer?

  • 4Baccurate

    Could it be possible that too many people rely on vitamin supplements to take the place of a healthful diet, and for many years leading up to the study?