At least half of Americans (maybe as many as 2/3) take dietary supplements. They assume the government will guarantee safety, efficacy, and truthful advertising. They couldn’t be more wrong. The very term dietary supplement is based on a fiction.
Dietary supplements are regulated by the FDA but the regulations are very different from the regulations governing approval of prescription and over-the-counter medicines. Under the ill-conceived Dietary Supplement Health and Education Act of 1994, dietary supplements are considered to be food, not medicine. They are not intended to diagnose, mitigate, prevent, or cure diseases. But the reality is that they are being used as medicines.
How did this happen?
In the late 1980s and early 1990s, Congress was considering legislation that would have increased the powers of the FDA. A proposed amendment to the Federal Food, Drug, and Cosmetic Act would have authorized any U.S. district court to “order the recall of a food, drug, device, or cosmetic which is in violation of the FDCA if the violation involves fraud or presents a significant risk to human or animal health.”
The Nutrition Advertising Coordination Act was introduced in the House in 1991 to tighten the regulations governing labeling of supplements. Marketers of supplements erupted in protest, claiming that the FDA was trying to ban dietary supplements, which it clearly wasn’t. What the proposed legislation actually said was that it
“Amends the Federal Trade Commission Act to deem a food advertisement misleading if it expressly or by implication characterizes the level of any nutrient, the relationship of any nutrient to a disease or a health-related condition, or the amount of any nutrient in a serving or portion of the food, unless the characterization is in accordance with specified provisions of the Federal Food, Drug, and Cosmetic Act.
Deems a food advertisement misleading if it contains a claim that fails to: (1) disclose the level of fat or saturated fat when a claim characterizes the level of cholesterol; (2) disclose the level of cholesterol when a claim characterizes the level of saturated fat; (3) disclose the level of total fat when a claim is made that the food is high in dietary fiber; or (4) include clearly and conspicuously the statement, ‘See product label for complete nutrition information.’”
The dietary supplement industry lied about the provisions and intent of the proposed legislation. They lobbied the government and put out alarmist ads. One deceptive ad featured Mel Gibson being arrested by FDA agents because he had been taking vitamin C supplements. (Absurd! The FDA does not have the power to arrest anyone.) Viewers were led to believe the lie that the government was about to take their vitamins away.
The DSHEA was introduced in 1994 by two senators: Orrin Hatch (R-Utah) and Tom Harkin (D-Iowa). It had bipartisan support in Congress. It passed and was signed into law by President Clinton in October 1994.
Criticism of the DSHEA
DSHEA has been widely criticized and critics have long been calling for its repeal. In an article in Skeptical Inquirer, Steven Novella called it “a gift to the supplement industry.” He said, “The result has been an explosion of the supplement industry flooding the marketplace with useless products and false claims.” On Quackwatch, Stephen Barrett commented, “Most people think that dietary supplements and herbs are closely regulated to ensure that they are safe, effective, and truthfully advertised. Nothing could be further from the truth.”
Even David Kessler, head of the FDA when the bill was passed, complained that
“The 1994 Dietary Supplement Act does not require that dietary supplements (defined broadly to include many substances, such as herbs and amino acids, that have no nutritive value) be shown to be safe or effective before they are marketed. The FDA does not scrutinize a dietary supplement before it enters the marketplace. The agency is permitted to restrict a substance if it poses a ‘significant and unreasonable risk’ under the conditions of use on the label or as commonly consumed … Congress has shown little interest in protecting consumers from the hazards of dietary supplements, let alone from the fraudulent claims that are made, since its members apparently believe that few of these products place people in real danger. Nor does the public understand how potentially dangerous these products can be.”
Steven Novella pointed out that the pharmaceutical industry spends over 18% of its revenue on research and development. A typical dietary supplement spends 0%. Why would they spend money on research if they can simply “mix blueberries and kale and claim it protects against cancer – all cancer?” Or they can “put some vitamin D into a capsule and make all kinds of specious claims. They’re safe, and they don’t have to show a word of evidence in support of their claims.”
Supplements are not required to show evidence of efficacy and safety before marketing. They are allowed to make structure and function claims like “calcium builds strong bones” or “fiber maintains bowel regularity.” They are required to state in a “disclaimer” that FDA has not evaluated the claim. The disclaimer must also state that the dietary supplement product is not intended to “diagnose, treat, cure or prevent any disease,” because only a drug can legally make such a claim. The required disclaimer usually appears in very small print at the bottom of the page and is easily ignored or dismissed by consumers.
Supplement manufacturers are supposed to report side effects to the FDA, but often they do not, and they don’t keep accurate records. If a product is found to be harmful, it is left up to the FDA to show the evidence and call for the product to be taken off the market. That rarely happens. When ephedra was found to have caused serious side effects and even deaths of prominent athletes, the FDA banned the sale of supplements containing ephedrine alkaloids in 2004. The ban was challenged in court but upheld in 2006 by a U.S. Court of Appeals. Today the sale of ephedra alkaloid-containing products is illegal, but it is still legal to sell products containing ephedra extract if they don’t contain ephedrine.
Supplement manufacturers are supposed to follow good manufacturing practices, but they don’t always comply, and products are often found to contain more or less active ingredient than stated on the label (sometimes none at all), or to be contaminated with bacteria or heavy metals, or even adulterated with undisclosed prescription drugs. A recent study used DNA barcoding to test herbal supplements; 59% of the products they tested had DNA from plant species not listed on the labels. Toxic levels of lead and other heavy metals have been found in a large percentage of Ayurvedic products. In 1993 in Belgium, aristolochia was substituted for the intended Chinese herb in a weight loss product; 105 patients developed kidney damage, sometimes requiring dialysis or kidney transplants. There have been increasing numbers of ER visits and calls to poison control centers about dietary supplements; serious harms have been reported, sometimes resulting in hospitalizations and even deaths.
When are supplements indicated?
Is the diet deficient in some nutrient? The deficiency should be verified; most deficiencies are easily diagnosed by a doctor through lab tests. The first, most obvious remedy would be to improve the diet, but sometimes supplement pills are needed. Some examples: iron supplements for iron deficiency anemia, folate supplements to prevent neural tube birth defects in pregnancies, B12 supplements for pernicious anemia, etc. Such uses are supported by good evidence from scientific studies.
Evidence lacking, regulation ineffective
Most of the dietary supplements on the market are untested or inadequately tested. More worrisome, some have been tested and found to be ineffective or unsafe, but they are still being sold. Recently, public concern about Covid-19 has been exploited by unscrupulous marketers to sell useless or even harmful products with claims that they are effective for the pandemic coronavirus.
The FTC is charged with regulating advertising; the FDA with regulating labeling. They can issue warning letters, but they lack teeth. The agencies lack adequate personnel and funding, and they can’t possibly respond to all the many violations.
The DSHEA requires a disclaimer that the product is not intended to “diagnose, treat, cure or prevent any disease.” But this requirement is often ignored; bogus claims abound. Actually, the sellers don’t have to make claims for their products. Others do that for them. Testimonials report miraculous improvements in all kinds of symptoms. Naturopaths and integrative medicine specialists promote the products. Many dietary supplements are sold through multilevel marketing schemes where distributors are free to say anything to their customers in private interactions: word-of-mouth marketing. And of course, the FDA and FTC can’t control what people say on social media.
Many supplements claim to have evidence of effectiveness from clinical trials. Remember, if a supplement was supported by acceptable evidence, it would qualify for FDA approval and could be classified as a medicine rather than a dietary supplement. Classification as a dietary supplement means it is not supported by good evidence. The studies they cite are often laughable: low quality, poorly designed studies, junk science, studies with equivocal results, studies with no control group, etc. For some products, “clinically proven” seems to mean “we gave free samples to several friends and relatives and got them to agree that it worked.” Strong suggestion and placebo responses are responsible for the positive results of many studies. That’s not enough; to call a medicine effective, we need to show that it can outperform placebos.
Dietary supplements and deception are constant companions. Taking a supplement is a gamble. Skepticism and vigilance are advised. Caveat emptor.
This article was originally published as a SkepDoc column in Skeptic magazine.