The Supplement Debate

Multivitamins2There have been a rash of articles advising against the use of supplements. I noticed it first with Paul Offit’s* opinion piece on why we should …

Skip the Supplements, New York Times, 15 December 2013

He says that dietary supplements – vitamins, minerals, amino acids, protein powders, herbs, and other botanicals – aren’t well regulated. Sometimes they contain less or more of an ingredient than what the label says. Sometimes they’re contaminated (animal excrement, lead, mercury, arsenic have all been found). Sometimes they contain different herbs altogether; he cites cases involving St. John’s wort and ginko biloba.

He also says most supplements have not been shown to produce the results consumers expect. If a person can point to an effect, it could be their belief that brings it about, not an action caused by the supplement.

He’s right in his first point. Supplement makers should be held to a universal standard in labeling and cleanliness. Right now, they’re not. (That started with the Dietary Supplement Health And Education Act of 1994.)

His second point, about effectiveness, is a big, grey, poorly studied area. Which brings me to another recent article, an editorial published in a peer-reviewed journal 2 days after Offit’s piece:

Enough is Enough: Stop Wasting Money on Vitamin and Mineral Supplements, Annals of Internal Medicine, 17 December 2013

The 5 authors wrote:

“The message is simple: Most supplements do not prevent chronic disease or death, their use is not justified, and they should be avoided. This message is especially true for the general population with no clear evidence of micronutrient deficiencies, who represent most supplement users in the United States and in other countries.”

The journal simultaneously published three related studies:

1. Vitamin And Mineral Supplements In The Primary Prevention Of Cardiovascular Disease And Cancer: An Updated Systematic Evidence Review For The U.S. Preventive Services Task Force, Annals of Internal Medicine, 17 December 2013

The authors reviewed 26 studies (24 randomized, controlled trials and 2 cohort studies):

“We found no consistent evidence that the included supplements affected [heart disease], cancer, or all-cause mortality in healthy individuals without known nutritional deficiencies.”

2. Long-term Multivitamin Supplementation And Cognitive Function In Men. A Randomized Trial, Annals of Internal Medicine, 17 December 2013

The authors gave either a multivitamin or placebo to a group of 5947 men who were part of the Physicians’ Health Study II.  They were looking for cognitive benefit. After 12 years, they found no difference between the two groups:

“In male physicians aged 65 years or older, long-term use of a daily multivitamin did not provide cognitive benefits.”

3. Oral High-dose Multivitamins And Minerals After Myocardial Infarction, Annals of Internal Medicine, 17 December 2013

The authors gave either a high-dose multivitamin supplement or a placebo to a group of 1708 men and women with a history of heart attack.  After 4.6 years, there was no difference between the groups in risk for subsequent heart problems:

“High-dose oral multivitamins and multiminerals did not statistically significantly reduce cardiovascular events in patients after MI who received standard medications.”

This particular study had a problem with compliance.  Close to 400 people in both the vitamin and placebo groups stopped taking their pills.  That makes it harder to draw conclusions.

It’s not helpful to make blanket statements like “skip the supplements” or “stop wasting money.” There are times when taking a supplement is justified … to correct deficiencies or to improve quality of life. (The Institute of Medicine recommends that all adults over 50 years, vegan or not, “obtain most of their vitamin B12 from vitamin supplements or fortified foods.”)

The risk of blanket statements goes the other way too.  Taking supplements as an “insurance policy”, to “top off” a questionable diet, or to “make sure” you’re “getting enough” is not supported by science, and, as has been shown by science, can cause harm.

Studying supplements is difficult. In a drug study, you can prevent the control group from exposure to the drug; it’s a clean comparison.  Not so in a vitamin study.  The control group is getting the test vitamin anyway … in fortified and enriched foods and, of course, in natural foods. It’s not impossible, it’s just more challenging.

What would be helpful is to improve regulation of the supplement industry, so consumers can be assured that what a label says is in the bottle actually is in the bottle, no more and no less.  It would also be helpful to conduct more and better studies (not to consider it a done deal), so consumers can be made aware of what a supplement can and cannot do.

* Dr. Offit has published a number of medical article and books. His most recent book is Do You Believe in Magic?: The Sense and Nonsense of Alternative Medicine

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