In any given pharmacy or grocery aisle, in any given American city, you will find shelves lined with dietary supplements claiming to support your immune system, prevent diseases such as heart disease and cancer, and boost your energy and even your sex drive. Almost half of all American adults take at least one supplement a day at a collective price of over $36 billion a year — a clear sign that we have a legitimate desire for good health. Their popularity, presence and packaging all seem to suggest that dietary supplements are regulated for our safety and scientifically proven to keep us healthy — but are they?

Before they can be sold in the United States, all prescription and over-the-counter medications must be approved by the Food and Drug Administration — the manufacturers must provide data that supports its safety and efficacy, and even after approval, the FDA continues to monitor adverse reactions. The same requirements do not apply to products marketed as ‘dietary supplements’ — manufacturers of these products are not required to submit any evidence of their purity, potency, safety or efficacy. A supplement can be marketed using seductive claims such as being ‘all-natural’ and ‘clinically proven’ without having anything to substantiate it. As a matter of fact, the FDA can only step in after a supplement has been marketed and an adverse reaction has been reported.

If we can’t trust the claims made on a supplement’s label, how do we know if they are safe and effective? We have to look at the scientific evidence — but even here, we have to be careful. Most studies around dietary supplements have been observational — unlike a clinical study, they do not test a particular supplement against a placebo in a controlled environment. In observational studies, the health of a group of people taking a supplement is compared to a group that is not, but they do not control for dietary factors, exercise habits and other important variables.

Several randomized clinical studies have been conducted into dietary supplements, and more often than not, their findings have been at odds with the observational studies. Currently, a few supplements have been shown to be helpful, others have been shown to be potentially harmful, and the vast majority are little more than very expensive disappointments.

Perhaps instead of being focused on supplements, we should be focused on ensuring that our diets are balanced and rich in the nutrients we need to be healthy — after all our bodies metabolize vitamins and minerals much more effectively when they are in the form of food. For those nutrients that are difficult to get at the levels we need from a healthy diet, some supplements can help — but make sure you know exactly what you are getting and how much you need. Without the protection of FDA oversight, choose a product that has been verified by private organizations like the United States Pharmacopeia (USP) and consult with your doctor before you begin taking them.

Dr. Ann Lebeck is a physician and the owner of Kynetic Health — a clinic in Sierra Vista that specializes in Sports and Regenerative Medicine.