Are Megadoses of Vitamins Healthy and Safe?

Photo by Ragesos

Megavitamin therapy is the use of very large doses of vitamins to prevent or treat illness or some symptom thereof. While not the first major proponent of megavitamin therapy, Linus Pauling is perhaps the best known; he advocated using huge doses of vitamin C (many grams per day) to treat and prevent disease. As a chemist, I have enormous respect for Pauling. His publication record is impressive, and his work in quantum chemistry helped lay the foundation of that field. Oh, and he was part of the team that helped discover the structure of DNA, which was kind of the Holy Grail of chemistry. As much as I hold him in esteem as a chemist, however, I have to wonder what business he thought he had dabbling in nutrition and medicine; he had training in neither of those fields. In any case, there was and is no evidence to support any of Pauling’s theories regarding megadoses of vitamin C. Neither is there evidence to support use of other vitamins in megadoses. The popularity of megavitamins is a “more is better” fallacy. Here’s the science bottom line: we need vitamins in small amounts. They serve a variety of critical roles in the body, and we experience illness, disease, and loss of function in the case of deficiency. More of a vitamin than the body needs, however, does it no good. Depending upon the vitamin, it’s either excreted or builds up and becomes toxic. Let’s stick with vitamin C as an example. Among its functions, vitamin C helps maintain the immune system; you’ll become more susceptible to disease (among other symptoms) if you’re vitamin C deficient. However, taking more vitamin C than recommended (the USDA currently recommends 90 mg/day for adult men, and 75 mg/day for non-pregnant, non-lactating adult women) doesn’t “supercharge” the immune system or help it function any better than it otherwise would. Think about it like this: if you’re trying to wash your hair in the shower, you need shampoo. If you use none, your hair doesn’t get clean. If you use a teeny, tiny amount, your hair gets a little cleaner. Use more, and your hair gets cleaner…up to a point. Once you’re using sufficient shampoo (usually anywhere from a dime-size to a quarter-size dollop, depending upon how much hair you have and how dirty it was), using more won’t get your hair any cleaner. It won’t do anything at all…except go down the shower drain. The same is true of vitamin C. Consume none, and you have problems. Consume some (but less than you need), and you have less severe symptoms of deficiency. Get what you need, and you achieve normal function (where it relates to vitamin C). If you take more vitamin C than your body needs to maintain function, however, the excess is excreted and goes down the toilet (or the shower drain, I suppose, depending upon your habits). Some vitamins aren’t as forgiving. For instance, vitamin A is quite toxic in megadoses. In any case, while there’s all sorts of scientific evidence to support getting your recommended daily dose of each vitamin, there’s just no evidence for — and in many cases, there’s evidence against — using megavitamins.


What’s your vitamin strategy?



USDA Dietary Guidelines. Accessed 11 Nov 2011.



6 Comments (+add yours?)

  1. Megyn @Minimalist Mommi
    Nov 17, 2011 @ 05:28:48

    I’m definitely deficient in some vitamins. But wondering if you have heard of Gerson therapy? Basically, Gerson used food (vegan diet) with high doses of micronutrients to rid the body of cancer. I’m highly skeptical, but would love to hear if you know anything about this.


    • SquintMom
      Nov 17, 2011 @ 16:24:48

      Haven’t ever heard of it, but am highly, HIGHLY skeptical. Simply from a chemical perspective, this doesn’t make sense.


      • Megyn @Minimalist Mommi
        Nov 17, 2011 @ 17:09:28

        Here’s just a quick article I found on Google Scholar:

      • SquintMom
        Nov 17, 2011 @ 17:50:02

        Ok, I took a look at the article. It *looks* official, and the “journal” in which it’s published (“Physiological Chemistry and Physics”) sounds legitimate and sciency, but if you look at the journal’s website, it’s not peer-reviewed. This discredits it. Further, the chief editor is a guy named Ling, whose theories are “proven” by this paper (so it’s dangerously close to self-publication). Even homeopathy, arguably one of the alternative medical practices of which scientists and physicians are MOST skeptical, has at least SOME support in the peer-reviewed literature. That this article is neither published in a peer-reviewed journal nor cited/supported by even ONE peer-reviewed article is a bad sign. I was going to read the paper and pick it apart, but Steven Barrett of Quackwatch (love his site!) has already done it: I’ve said it before and I’ll say it again; there is no secret cure for cancer that the medical establishment is trying to keep us from hearing about!!

      • Megyn @Minimalist Mommi
        Nov 17, 2011 @ 19:26:31

        Thanks so much for your analysis! I have to resort to Google Scholar as I’m no longer a student, so can’t access real databases. I’ve seen a lot of documentaries about Gerson therapy, and they verbally site research…but I have yet to find this research they speak of. Maybe I need to head to the university library!!

        And I agree–if there were a cure, we’d know about it (even though I am a bit skeptical due to the ties between the government & big pharma)

      • SquintMom
        Nov 17, 2011 @ 20:45:58

        I think those ties aren’t as strong as we sometimes like to imagine they are. I deal with this a little bit in

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

%d bloggers like this: