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It is hard to stay current with the different supplements that your patients may be taking for weight loss and health. One resource is Red Flag: Bogus Weight Loss Claims, developed by the Federal Trade Commission (FTC). While it is a reference guide for the media, I think it is also a good one for your patients, your staff, and you. The bottom line is, "If a claim is too good to be true, it probably is."1 The claim was put to the test earlier this year when the FTC announced million-dollar fines against makers of four supplement brands. FTC officials stated that any money derived from the fines would be forwarded to affected consumers.
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We have done some research on chitosan, a dietary supplement claimed to "block fat absorption and lead to substantial weight loss." Chitosan is the processed, more water-soluble form of chitin. Chitin is a substance contained in the exoskeletons of arthropods and crustaceans and the walls of many molds, yeasts, and fungi. Chitosan is made by grinding the shells from shellfish such as shrimp, lobster, and crab into a powder that is demethylated, or stripped of certain chemicals. This process allows the chitosan to soak up fats, according to the claims of its manufacturers. It has been used to absorb grease, oil, dangerous heavy metals, and other toxins from water.
I consider the evidence provided by companies that sell chitosan supplements to be not only false, but also misleading. One of the demonstrations on the QVC television channel to substantiate the "fat-blocking" claim shows a man adding a powdered chitosan supplement to a beaker with oil and a water-based fluid to simulate what happens in your gastrointestinal tract. The chitosan clumps. This is supposed to be proof that chitosan prevents fat from being absorbed. There are studies where laboratory rats were fed very large amounts of chitosan in their diet. The rats did not absorb significant amounts of fat. As a result their stools were smelly, yellowish in color, and very loose. That is just what you would expect if your patient was not absorbing more than 100 g of fat.
In a series of three studies using three different brands of chitosan, we measured the amount of fat in the feces of about 40 people taking chitosan.2–4 The claims made by the manufacturer of the product tested included, "Block the absorption of up to 120 grams of fat per day and lose substantial weight." We studied fat absorption by measuring fat in the feces of volunteers before taking chitosan and while they were taking chitosan. In two of our three published studies, chitosan did not block the absorption of any fat.2,3 In a third study, in women, chitosan did not block any fat from being absorbed. In contrast, in men, the absorption of 1.8 g of fat, or 16 kcal, was blocked.4 We calculated that it would take 7 months for men to lose 0.45 kg (1 lb) of fat using chitosan. Finally, in all of our studies, while stools were a little softer, our subjects did not have yellowish, runny, and foul-smelling stools. Research for our first study was sponsored, in part, by the Consumer Affairs Division of the Napa County, California, District Attorney's Office.
To my knowledge, there are not any supplements that cause substantial weight loss. There are not any supplements that result in weight maintenance. Yet according to the Council for Responsible Nutrition, supplements are a billion-dollar industry in the U.S. Consumers are looking for a "magic bullet" to help them lose weight. They rely on testimonials, and they erroneously assume that supplements are safe because they believe the federal government would not allow unsafe products on the market.
In April 2004, the Food and Drug Administration (FDA) made an effort in ensuring public safety by sending warning letters to 16 dietary supplement distributors for making false and misleading claims for weight-loss products promoted over the Internet. "We will not tolerate companies making false claims promising easy fixes," then-Secretary of Health and Human Services Tommy G. Thompson stated in an FDA press release.5
According to the release, many of the products claimed to block starch, carbohydrates, and fat calories, while allowing consumers to lose weight without any changes in lifestyle. These claims are simply not true. Some of the claims on product labels included:
The FDA noted that dietary supplement labeling may include claims about the supplement's effect on the structure or function of the human body. The law requires that "structure/function" claims have substantiation and be truthful and not misleading. Companies should have the data prior to marketing the dietary supplements. The FDA concluded the claims for many products were not supported by reliable scientific evidence.
Unfortunately, the federal government has limited power and money to stop the marketing of such supplements. According to the Dietary Supplement Act (DSHEA) of 1994, supplement manufacturers are not required to perform premarketing safety evaluations of their products (see "FYI"). DSHEA leaves it to the federal government to prove that a specific supplement is not safe. The FDA and FTC simply do not have the budget to do that job.
While your patient has the ultimate responsibility with respect to supplements, you can serve as a resource. Clinicians and staff have to be informed about these different supplements. When you see your patients, ask them to bring in all the containers/labels of pills they are taking, including vitamins, minerals, supplements, and even teas. The FTC and FDA are excellent sources of information. I highly recommend the FDA's "Tips for the Savvy Supplement User: Making Informed Decisions" and FTC's Red Flag campaign.1,5
You and your patients should be aware that certain supplements can interfere with prescription drugs and over-the-counter medications. Did you know, for example, that "coumadin, ginkgo biloba, aspirin, and vitamin E can individually increase the clotting time of blood"? According to the FDA, "if your patient is taking these products together, they can be at risk for internal bleeding."5
My philosophy is that I am always suspicious of claims and testimonials by
weight-loss supplement manufacturers, but I find it hard to stay current with
all the different supplements appearing on the shelves each month. 
Footnotes
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For the Federal Trade Commission's guide for rules governing Internet commerce, visit www.ftc.gov/bcp/conline/pubs/buspubs/ruleroad.htm.
For more information on the Red Flag tips, go to www.ftc.gov/redflag.
References
2. Gades MD, Stern JS: Chitosan supplementation and fecal fat excretion in men. Obes Res 11:683–688, 2003.[Medline]
3. Gades MD, Stern JS: Chitosan supplementation does not affect fat absorption in healthy males fed a high-fat diet, a pilot study. Int J Obes Relat Metab Disord 26:119–122, 2002.[Medline]
4. Gades MD, Stern JS: Chitosan supplementation and fat absorption in men and women. J Am Diet Assoc 105: 72–77, 2005.[Medline]
5. U.S. Food and Drug Administration: FDA warns distributors of dietary supplements promoted online for weight loss (Press Release P04-39). April 1, 2004. Available online at www.fda.gov/bbs/topics/news/2004/NEW01045.html. Accessed November 2006.
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