Over the past 25 years, the dietary supplement market has ballooned, taking in an estimated $42 billion in revenue last year, up from $4 billion in 1994. This growth can be traced back in part to a federal bill passed that year that loosened industry regulations.
Known as the Dietary Supplement Health Education Act, the law clears supplements—vitamins, minerals, herbs, and more—for supermarket shelves without prior approval from the US Food and Drug Administration. The FDA may take action by issuing public warning letters to manufacturers or recalling items if they determine through product sampling that a supplement has been adulterated. But the agency only steps in after the product has made its way to market and after consumers report adverse events. A 2015 study estimates that supplements were responsible for about 23,000 emergency room trips every year (N. Engl. J. Med. 2015, DOI: 10.1056/nejmsa1504267). According to a FDA spokesperson, “manufacturers and distributors of dietary supplements are responsible for ensuring that their products are safe and lawful.”
Now, for the first time, the retailer CVS is subjecting supplements to independent evaluation. Their program, called “Tested to be Trusted,” requires dietary supplement makers and distributers to submit their products to third-party testing before the company will offer the supplements in their stores or online. CVS first announced the program in 2017 and has since completed the testing of 1,400 supplements from more than 150 suppliers. The retailer plans to test new products as they appear.
The tests do not evaluate any product health claims. Instead, the tests confirm the identity and amounts of the active ingredients in the supplemental label panel. Products are also screened for contaminants such as heavy metals, yeast, mold, pesticides, biological pathogens, and industrial compounds like polychlorinated biphenyls.
Of the initial group of products tested, 7% failed and were either removed from CVS stores or had their labels updated, according to a CVS press release. While supplements failed for a number of reasons including contamination, most cases involved amounts of active ingredients that were below the levels indicated on the label, says Mike Harvey of NSF International, a third-party lab that CVS has enlisted to carry out the tests along with the company Eurofins.
Harvey, who leads NSF’s high performance liquid chromatography (HPLC) group, says that once a product arrives from a supplement manufacturer, it takes 3–4 weeks to go through their testing process.
All products undergo a standard battery of tests to ensure specific contaminants don’t exceed acceptable levels. Then the team evaluates the product against pure standards to confirm whether the active ingredient is present and at what concentration. The lab reviews the products’ labels to figure out what types of analytical tests make the most sense for the supplement’s ingredients, Harvey says. Although HPLC is their most common tool, he says, another method like gas chromatography with flame ionization detection may be used for products containing fatty acids. Meanwhile, for botanicals, the lab must determine if the indicated plant parts—stem, leaf, or root—is actually in the product. They use thin layer chromatography to distinguish between plant parts.
The lab also checks for adulterants that have previously shown up in certain types of products. Adulteration generally falls under two categories, one of which is the addition of cheap compounds to fill in for more expensive ingredients. For example, supplement makers sometimes spike Ginkgo biloba with common flavonoids such as quercetin or rutin, which are found in the plant but only at low concentrations. Harvey says in this case, the team would perform HPLC analysis on a sample before and after hydrolysis extraction. “Samples that have large amounts of flavonoids in the pre-hydrolyzed form are not naturally occurring and therefore are evidence of adulteration,” he explains. According to the American Botanical Council, adding these compounds to a supplement is a cheap way for contract manufacturers to meet flavonoid concentrations that companies are looking for.
The other kind of adulteration involves the addition of pharmaceutical compounds such as sildenafil, sold as Viagra, in sexual enhancement supplements. Harvey says these types of products, along with weight loss supplements, are subject to additional tests that screen for about 270 common pharmaceuticals that could appear in supplements.
“Given the current regulatory situation that we have, the only way a consumer can be confident that a supplement is accurately labeled is if a store is doing what CVS is doing,” says Pieter Cohen, a physician at Harvard Medical School who also conducts dietary supplement research.
Cohen stresses that testing is only helpful if it continues on a given product to ensure that its listed ingredients remain accurate over time. He adds, “If this is a one-time process it’s going to help for maybe a few months, maybe this year, and then we’ll slip back into exactly what was happening before.”
A disclaimer at the bottom of the CVS supplement testing program’s webpage reads, “Tests performed on a single lot of the vitamin or supplement. Third-party testing for subsequent lots is not required. As a result, we cannot confirm that all lots would pass these tests.”
In response to C&EN’s questions regarding single-lot testing, a company representative says, “CVS plans to do follow-up testing to ensure the products we sell continue to meet or exceed our standards.” CVS declined to clarify the timeline for follow-up tests.