I was surprised to get this e-mail from a reader:
Surely, Dr. Hall, the public mania for nutritional supplements is baseless. All the alleged nutrients in supplements are contained in the food we eat. And what governmental agency has oversight responsibility regarding the production of these so-call nutritional supplements? Even if one believes that such pills have value, how can the consumer be assured that the product actually contains what the label signifies? I have yet to find a comment on this subject on your otherwise informative website.
My co-bloggers and I have addressed these issues repeatedly. Peter Lipson covered DSHEA (The Diet Supplement Health and Education Act) nicely. It’s all been said before, but perhaps it needs to be said again; and maybe by writing this post I can make it easier for new readers to find the information.
Food, medicine, or something in between?
The FDA regulates foods and has been instrumental in improving the safety of our food supply. It regulates prescription and over-the-counter medications, requiring evidence of effectiveness and safety before marketing. Surveys have shown that most people falsely assume these protections extend to everything on the shelves including diet supplements, but they don’t.
Under the 1994 Diet Supplement Health and Education Act (DSHEA), a variety of products such as vitamins, minerals, herbs and botanicals, amino acids, enzymes, organ tissues, and hormones can evade the usual controls if they are sold as diet supplements. Under the DSHEA, the manufacturer doesn’t have to prove to the FDA that a product is safe and effective; it is up to the FDA to prove that it isn’t safe, and until recently there was no systematic method of reporting adverse effects (required reporting is still limited to serious effects like death).
So far the FDA has only managed to ban one substance, ephedra, and it took the death of a prominent sports figure and considerable skirmishing with the courts to accomplish that. Independent lab tests of diet supplements have found a high rate of contamination (with things like heavy metals and prescription drugs) and dosages wildly varying from the label. A striking example was Gary Null’s recent poisoning with vitamin D from one of his own products which contained 1000 times the intended amount.
The FDA has issued rules on good manufacturing practices, but standardization is not required and it remains to be seen whether the new rules will effectively improve product quality.
It makes sense to supplement the diet with essential nutrients if the food in the diet is deficient in those nutrients or if the patient is not able to absorb nutrients normally. There are specific situations where that applies, such as providing folic acid to women to prevent birth defects or providing vitamins and minerals to bariatric surgery patients whose digestive functions are compromised. There are FDA-approved sources of nutrients for indications like these.
It is commonly claimed that “food is medicine” but there are very few situations where the evidence shows that specific nutrients are useful as medicine. Niacin for treatment of hyperlipidemia comes to mind.
The following (taken from a supplement website) are not rational reasons for supplements and are not supported by evidence:
- We can’t get all the nutrients we need from food.
- Supplements boost the immune system.
- Supplements help get rid of toxins.
- Even if you feel well, your health will only be optimal if you take supplements.
The Big Lie
DSHEA is based on a fiction. It prohibits claims that diet supplements prevent or treat any disease and only allows structure/function claims alleging that they “support” health in various ways. DSHEA is a stealth weapon that allows the sale of unproven medicines just as long as you pretend they are not medicines. It allows the sale of products that are not intended to prevent or treat disease so people can buy them with the intent of preventing or treating diseases. People don’t buy St. John’s wort to correct a deficiency of SJW in their diet or in their bloodstream; they don’t buy it to “support” brain function; they buy it to treat depression. People don’t buy glucosamine to “support joint health” but to treat their arthritis pain. People don’t buy saw palmetto to “support prostate health” or correct a saw palmetto deficiency, but to relieve symptoms of benign prostatic hyperplasia or to prevent prostate cancer. The FDA’s “Quack Miranda warnings” are routinely ignored even by those few who actually read the fine print.
DHEA (dehydroepiandrosterone) is a hormone that was once approved by the FDA as a prescription drug; then it was taken off the market because the FDA decided it was unsafe. Now it’s available as a diet supplement without a prescription. When the FDA later saw evidence that DHEA was effective for a rare adrenal condition, they re-approved it with orphan drug status. Now the people with that rare disease, and only those with that disease, can get a prescription for the drug, while their perfect healthy neighbor can buy it at any health food store. Does that make any sense at all?
Advocates of CAM complain about “Big Pharma.” What about “Big Supplement” (“Big Suppla”?)? The diet supplement industry is a very profitable multibillion dollar industry that was able to lobby effectively to get the DSHEA passed. BP generates huge profits but it also saves lives. BS (double entendre intentional) has generated huge profits for its investors but hasn’t produced any measurable health benefits to those who use its products.
Yes, some of them work
Some of them do work, but do they work better than prescription alternatives or FDA-approved over-the-counter products with more trustworthy, regulated sources? Are they as safe? They are admittedly cheaper and more convenient than prescription drugs, but is there any other reason to prefer them? One argument is that they are safer, but it isn’t safe to assume that—not until proper large-scale studies are done. Just think of all the prescription drugs that appeared to be safe until careful post-marketing surveillance revealed unexpected problems.
What are the chances that a diet supplement picked at random will turn out to be safe and effective when proper studies are done? Not high. Promising drugs that pharmaceutical companies submit to clinical trials only have about a 5% chance of making it to the market. A few years ago, I went through all the entries in the Natural Medicines Comprehensive Database and tabulated their effectiveness ratings. Only 5% were rated “effective” and almost all of those were vitamins, minerals, and medicines that are also available as prescription or over-the-counter products approved by the FDA.
There are many products on the diet supplement market that combine multiple ingredients in a kitchen-sink mixture that has no rationale and has not undergone any testing. Maybe the ingredients act synergistically; maybe they interfere with each other. How would we know? Taking such products is a crap-shoot and is like being a guinea pig in an uncontrolled experiment. Many supplement mixtures are sold by multilevel marketing programs and improve health only to the extent that they improve the health of the promoters’ wallets.
Supplements can also harm. Kava has been associated with fatal liver damage. An herbal weight-loss remedy caused kidney failure in dozens of women in Belgium. One fifth of Ayurvedic remedies have unacceptable levels of arsenic, lead and mercury. Most trials of antioxidant vitamin supplements have shown that patients taking them either do no better or do worse than those taking placebos. Vitamin A supplementation increases the risk of fractures in post-menopausal women.
Conclusions: Nutritional supplements are not a panacea, perhaps not even safe
- As my correspondent put it, “the public mania for nutritional supplements is baseless.”
- In general, all our nutritional needs can be supplied by an adequate diet.
- Supplements are beneficial for a few specific evidence-based indications; otherwise, they offer no benefits and may even be risky.
- Diet supplements are not medicines, but are being used as medicines.
- DSHEA should be repealed.
This article was originally published in the Science-Based Medicine Blog