Dietary Supplements: Time to Consider What You're Really Taking

With Madhur Kumar, MS, PhD, Pieter Cohen, MD, and Mitchell Katz, MD

If you are among half of the adults in the United States, you no doubt take a daily nutritional supplement, or two, or three. You may be hoping to boost your overall health, get help losing weight, want to build muscle, perform better in bed, or maybe you’re hoping to improve your memory.

Buyer beware—You may be getting more than you bargained for, according to investigators reporting on two different studies.1,2 Not only are you getting less of the substances you paid for, but you are likely to be getting unexpected ingredients that may be harmful.

Dietary supplements may contain ingredients NOT listed on the label.Choose dietary supplements that been approved by independent labs to assure that what you see (on the label) is what you are really getting. Photo: 123RF

Bottom line: that so-called natural nutritional supplement may not be so natural or healthful, after all. In fact, many popular dietary supplements actually contain pharmaceutical drugs, even substances banned by the Food and Drug Administration (FDA) due to serious health risks. 1,2

Unapproved Substances Found Added to Common Dietary Supplements

In the first study,1 Pieter Cohen, MD, associate professor of medicine at Harvard Medical School and a general internist at Cambridge Health Alliance, in Boston Massachusetts, led a study that uncovered the presence of prohibited stimulants in the 12 supplements his team bought and analyzed in 2014 and again in 2017.

During that time period, the FDA issued notices about four prohibited stimulants, including those known as DMAA, DMBA, BMPEA, methylsynephrine, and oxilofrine. None of these ingredients are approved for use or available in the US, yet they were regularly found in popular dietary supplements.1

These researchers focused on 12 brands of supplements marketed for weight loss, sports performance or cognitive functioning, finding that four banned ingredients found in the supplements in 2014 were often still present in the same supplements in 2017, despite warnings about the ingredients from the FDA.1 This analysis is published in JAMA Internal Medicine.1

Of the 12 supplements bought in 2017,1 75% of these products had at least one of the four unapproved stimulants carrying an FDA warning, and six fo the products had two or more unapproved ingredients. One ingredient, in particular, DMBA, while not detected in any supplements bought in 2014, was found in four of the supplements purchased and analyzed in 2017—even though the FDA had issued an ingredient warning in 2015.

"It's not just pharmacological drugs'' found in common over-the-counter supplements, Dr. Cohen tells EndocrineWeb, it's also experimental drugs or drugs that have been tested only in animals but not people.

Hidden Prescription Drugs Found in Dietary Supplements

In the second study,2 researchers from the California Department of Public Health found more than 700 supplements contained unapproved ingredients

The researcher team analyzed a database maintained by the Food and Drug Administration to capture trends on adulterated dietary supplements that received FDA warning notices during the years 2007-2016,2 says Madhur Kumar, MS, PhD, who led the study, which was published in JAMA Network Open.

"Overall, we found active pharmaceutical ingredients continue to be detected in dietary supplements, especially those marketed for sexual enhancement or weight loss, even after public FDA warnings were issued," Dr. Kumar tells EndocrineWeb.

"The drug ingredients have the potential to cause serious adverse health effects," she says. This could be due to misuse, overuse, or their interaction with other medicines the person is taking. Interactions are also likely to occur in response to underlying medical conditions or to the presence of other pharmaceutical drugs in the supplement, Dr. Kumar says.

Unapproved Ingredients Pose Harm to Unsuspecting Consumers

Dr. Kumar and her team evaluated the FDA's Tainted Products Marketed as Dietary Supplements database.2 The analysis was done independent of the FDA, according to the researchers, and the findings are limited to drugs that the FDA tests for, which means there may be more unknown ingredients in the many over-the-counter dietary products.

Over the time period studied, ''unapproved pharmaceutical ingredients were identified in 776 dietary supplements," Dr. Kumar says. In particular: One in five of the products had more than one unapproved ingredient, and 28 supplements had received two or three FDA warnings, which indicates that the FDA had found the supplements to be tainted more than once.2

Which supplements are most likely to be contaminated with pharmaceutical grade drugs? The researchers broke their findings down by their intended treatment:

  • Sexual enhancement: 353 nutritional supplements, or about 45% of this category
  • Weight loss: 317 dietary supplements, or nearly 41% of these products
  • Muscle building: 92 products, or nearly 12% of the pills and powders marketed for bulking up.

Typically, one tainted ingredient was found in these wide-ranging nutritional supplements, but in two products, six different unapproved prescription drugs were identified.

As for government actions taken, the manufacturer voluntarily recalled nearly half the products, following public notifications issued by the FDA with regard to 342 tainted products. In other instances, a news release was sent out, or a warning letter was directed to the offending company. 

What were the ''hidden'' ingredients? It depended on the type of supplement:2

  • Sexual enhancement: Many of these products contained drugs intended for erectile dysfunction (ED) such as sildenafil (Viagra).
  • Weight loss. These supplements often contained sibutramine, which was taken off the U.S. market in 2010 due to a risk of heart attacks and strokes.
  • Muscle-building.  Nutritional supplements in this category were found to contain steroids and steroid-like substances.
  • Other claims: Tainted supplements commonly were marketed to relieve joint or muscle pain, to improve sleep issues, to treat gout, protect against osteoporosis, among other health concerns.

When Natural Turns Toxic, Good Intentions May Jeopardize Health

The tainted supplement issue ''is a very serious problem that isn't going to go away soon," Dr. Cohen says, a concern he raises in a commentary to accompany the findings of the second study looking at the FDA database.3

He cites a ''fundamental flaw in the law" regulating dietary supplements as one driving force behind the problem.3 Under the Dietary Supplement Health and Education Act (DSHEA) of 1994, the FDA regulates dietary supplements under a different set of regulations than those covering foods and drug products.4

The manufacturers are responsible for evaluating the safety of their own products and for assuring that the product labeling is accurate. Once the product goes on the market, the FDA is responsible for taking action against any tainted or misbranded supplement.4

Legislative Changes Are Needed To Protect Consumers  

"We have a law that is too permissive," Dr. Cohen says. "More than FDA action (after an approved ingredient is found in the supplement) will be required to ensure that all adulterated supplements are effectively and swiftly removed from the market." And, more importantly, it will take action from Congress to reform DSHEA before we can expect to see any substantial improvement.

One way to protect consumers would be to require any manufacturer who produces and markets nutritional supplements to register their products with the FDA before being able to sell them; that way, if a product were adulterated with unapproved substances or contained ingredients not listed on the label, then their registration would be revoked,3 suggests Dr. Cohen.

The FDA, meanwhile, could be more aggressive, he says, even within the limitations of the existing law. "They could issue a mandatory recall, which they did for none of these [cases in the Kumar study]."

Even after the voluntary recalls, as the analysis showed and his own research suggests, the adulterated products still show up again, and these adulterations are not accidental, Dr. Cohen tells EndocrineWeb.

Mitchell Katz, MD, editor of Jama Internal Medicine, and President/CEO of the New York City Health  & Hospital System, wrote an editorial to accompany Dr. Cohen's study about prescription grade stimulants found in dietary supplements. Dr. Katz points out that the lack of evidence regarding any real need for supplements, with exceptions for pregnant women or those with true nutritional deficiencies, raises concerns about these products more generally.5

Consumers should be aware that supplements may not contain what the label promises and that an estimated 23,000 emergency room visits each year are linked to dietary supplements, 5 Dr. Katz writes.

Five Tips for Safer Selection of Nutritional Supplements

Given the risk that dietary supplements will contain ingredients you aren’t aware of and that may cause more harm than help what ails you, here are five tips Dr. Cohen shares with EndocrineWeb to help you protect yourself better in the future:

  • Talking to your doctor first is best, Dr. Cohen says since he or she is familiar with your medical history and is aware of the prescriptions you are taking.
  • Should you choose to use botanical supplements, whether with your doctor's blessing or not, ''stick to single ingredient supplements," Dr. Cohen says. That will reduce the possibility that it is tainted with a pharmaceutical grade drug or other unsuspecting substances but will not eliminate the risks.  
  • If you notice side effects—physical changes or unusual symptoms—after starting a supplement, you should stop taking the supplement immediately and call to your healthcare provider.
  • Steer clear of nutritional supplements that make ''drug-like'' claims, or promise unrealistic results, such as quick and easy weight loss.
  • Best rule: stick with brands that carry a seal of approval from one of three independent testing labs that check that the ingredients listed on the product and promised on the label are present in the bottle, no more and no less. Read more here: What You Need to Know about Supplements

Neither Dr. Kumar nor Dr. Katz has any financial disclosures. Dr. Cohen received research funding from Consumers Union, and was the subject of a civil suit brought by Hi-Tech Pharmaceuticals, a supplement company, regarding BMPEA; the jury found in Dr. Cohen's favor.

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