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Vitamyth, ctd.

October 25, 2012 Leave a comment

Last October I wrote a post cautioning readers about the risks of vitamin supplementation. Mega-dosing vitamins pose health problems such as a higher risk of cancer. Based on oncologist Dr. Larry Norton’s advice I argued that daily multivitamins pose similar risks.

Looks like I need to take that last part back. A large well-done study has recently come out that found a statistically significant reduction in the number of participants developing cancer if they took a daily multivitamin.

Conclusion  In this large prevention trial of male physicians, daily multivitamin supplementation modestly but significantly reduced the risk of total cancer.

I asked health policy blogger and medical doctor Aaron Carroll (who I heard about this study from) what he made of the apparent discrepancy from past research on this topic:

That was also a cohort study. All kinds of biases, and there’s no way that it can test for causation.

Now I’m not dismissing cohort studies out of hand. But the results of the study you link to should make one pause and say, “There appears to be an association between MVI use and mortality. Maybe we should test that with an RCT.”

They did one. It’s the study I talked about. It showed that MVIs reduce mortality. This was huge RCT with years-long follow-up.

Just so everyone knows, an “RCT” is a “randomized controlled trial,” and, as Wikipedia notes, have “a superior methodology in the hierarchy of evidence in therapy.”

I also emailed the Memorial Sloan-Kettering Cancer Center where Dr. Larry Norton works to see if he had a reaction. Unfortunately, when they found out I didn’t work for a well-known publication they, apparently, didn’t feel the need to comment.

Dan,

What publication are you writing for and what is your deadline?

Thanks,

Andrea

I told her and she wrote back:

Hi Dan,

I’m sorry but Dr. Norton is unavailable to weigh in.

Best,

Andrea

I wrote back asking if anyone at the MSKCC “has a position generally on whether it is a good idea to take a multivitamin daily?” I haven’t received a response.

Well, until we learn anything new it looks like taking a daily multivitamin is a good idea, but mega-dosing specific vitamins or supplements is still inadvisable.

Vitamyth

October 14, 2011 Leave a comment

The average healthy person acquires all the nutrients the body needs in a well balanced diet. Numerous studies and meta-analysis research continues to suggest that taking vitamins is unnecessary and potentially harmful. Ronald Bailey of Reason magazine reports on two new studies that show high doses of vitamins may increase certain cancer and early death risks. Without strong evidence that vitamins help and more research that demonstrates they might hurt, Bailey labels taking megadoses a “superstition:”

A good definition of a superstition is “a belief or practice resulting from ignorance, fear of the unknown, trust in magic or chance, or a false conception of causation.” As data accumulate, taking megadoses of vitamins looks more and more like a superstition.

Back in 2007, Dr. Larry Norton, a leading oncology researcher, gave a talk at the Aspen Ideas Festival that described vitamins’ cancer link. Listen to it all, but the relevant bit starts at 12:20 in the audio.

If you look at the entire world’s picture of published literature, vitamin supplementation shortens your life. Unless you’re vitamin deficient – in which case you should replace the specific vitamin you’re deficient in. It’s pretty hard to get vitamin deficient unless you have a malabsorption situation.

To answer Andrew Sullivan’s question, “But a multivitamin a day?”

Eating a good healthy diet and also taking a multivitamin is at the very very least doubling the vitamin level in your body… Imagine you doubled the water you drink, you’d be pretty bloated all the time… In some cases some of these super-vitamins that are out there are increasing levels 10, 20-fold of what’s considered an optimal amount in a diet at the present time.

Cancer cells are your own cells. They’re just more metabolically active and can use those megadoses of vitamins to reproduce. As with many other myths, believing them can lead to dangerous consequences.

(photo by Garry McLeod)

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