Given that RCT data show that dietary supplements have either no effect on cancer risk or that they can sometimes have adverse effects, why do messages still abound in the popular press about the cancer-fighting properties of these supplements? The “apple-a-day” and “we are what we eat” axioms resonate strongly within us, and they may well be true. However, these fundamentally positive beliefs about the connections between nutrition and health can be exploited by nutritional supplement manufacturers to suggest cancer-fighting effects of supplements that exceed the objective evidence (78
). The basic sales pitch is that if a little of a nutrient is good, then a lot must be better. This is not simply a matter of economic exploitation in the marketplace; the safety of dietary supplements is a valid public health issue.
How can there be such a discrepancy between the scientific evidence and public perceptions about dietary supplements? A review of the regulatory history of supplements provides some perspective (). The US Food and Drug Administration (FDA) was created in 1906 to regulate the production and marketing of foods and drugs, but it was not until the 1960s that FDA began to attempt to regulate dietary supplements. With many different pieces of legislation, the US Congress has limited the authority of FDA to regulate manufacturing and marketing of supplements, leaving them in a gray zone somewhere between foods and drugs (79
). Even health claims for foods were not regulated by the FDA until 1990 when, in response to a growing number of unsubstantiated health claims by food manufacturers (including anticancer advertisements for specific foods), the Congress passed the Nutrition Labeling Education Act (NLEA) (80
). Under the NLEA, the FDA began investigations and rulemaking to apply standards of scientific evidence to health claims for nutritional supplements, but this effort was short-lived. Sensing that supplement marketing might be adversely affected by this scrutiny, the nutritional supplement manufacturers organized mass media campaigns and a write-in campaign to put pressure on the Congress to limit FDA authority over nutritional supplements. As a result, in 1994, Congress passed the Dietary Supplement Health and Education Act, which classified dietary supplements as food and substantially limited the role of the FDA in regulating the manufacture or marketing of dietary supplements (81
Regulatory history of dietary supplements in the United States.
As a result of the Dietary Supplement Health and Education Act, the US nutritional supplement industry has been relatively free from message regulations (82
). In response to several high-profile deaths from ephedra, the Congress passed the Dietary Supplement and Non-prescription Drug Consumer Protection Act in 2006 (83
). Although that act defined new roles for FDA in collecting reports of acute adverse events from supplements, it gave the agency no new powers to regulate dietary supplement health claims or marketing. In 2010, in response to the continued need for better regulation of nutritional supplements, as evidenced by the problem of steroids being included without labeling in some sports supplements, US Senators John McCain and Byron Dorgan sponsored the Dietary Supplement Safety Act (DSSA), designed to give FDA the legal authority to monitor supplement safety and to withdraw from the market any deemed to be potentially hazardous to health (84
). Again, fearing FDA encroachment into marketing, the powerful supplement industry protested; after an entreaty from Senator Orrin Hatch, a known supporter of the dietary supplement industry (85
), Senator McCain, withdrew his support for the DSSA. More recent attempts to set guidelines for assessing supplement safety have also come under attack by the industry, even though some experts argue that those guidelines do not go far enough (9
Some of the marketing by the dietary supplement industry, especially by online retailers, can be deceptive. In 2009, even after publication of the null findings from SELECT, Bayer stopped advertising that its One-A-Day
Men's Health Formula
supplement could prevent prostate cancer because it contained selenium and vitamin E (86
) only after it was threatened by a lawsuit. Perhaps, the most current direct evidence of this practice relates to vitamin D, which is being marketed in the popular media for its benefits in reducing cancers of the colon, breast, pancreas, and prostate. Even without such direct statements, anticancer effects can be implied. For example, even though the manufacturers of Pill X cannot openly advertise that it prevents prostate cancer, they can create an advertisement that states that prostate cancer is a major health problem, that Pill X has a role to “support prostate health,” and that a particular study found that the compounds in Pill X reduced the growth of prostate cells in culture. Their website can then be accompanied by advertisements for Pill X and can contain links to testimonials that are free to expound the benefits of Pill X as experienced by real people. The absence of credible scientific evidence that taking Pill X confers anti-prostate cancer properties in men can be easily obscured by this constellation of claims that collectively suggest anticancer effects. As a result of limited regulatory authority, manufacturers who cannot overtly claim anticancer benefits of supplements without scientific proof are nonetheless free to imply those benefits in ways that make it difficult for the consumer to discern innuendo from scientific fact (82
). As evidence of this practice, a recent investigation by the US Government Accountability Office (GAO) found that certain herbal dietary supplements were deceptively or questionably marketed to consumers, and when GAO investigators posed as consumers, they were given potentially harmful medical advice (78