When taken appropriately, some dietary supplements have clear benefits. Folic acid lowers the risk of some birth defects. Calcium supplements can strengthen bones and help prevent osteoporosis. But some dietary supplements pose health risks. They may be improperly manufactured or handled, or their ingredients may cause harmful effects on the body.

Under the Dietary Supplement Health and Education Act of 1994 (DSHEA), dietary supplements are regulated like foods. Unlike new drugs, dietary supplements don't generally have to go through review by the Food and Drug Administration for safety and effectiveness or be "approved" before they can be marketed. But manufacturers must provide premarket notice and evidence of safety for any supplements they plan to sell that contain dietary ingredients that were not on the market before DSHEA was passed.

The FDA evaluates the safety of dietary supplements after they are on the market primarily through research and adverse event monitoring. Those who market and make dietary supplements are responsible for ensuring that any claims are substantiated with adequate evidence, and they cannot claim that the dietary supplements will treat or cure any disease.

Monitoring Industry

The dietary supplement industry has changed a lot in the last decade. When DSHEA was passed, there were about 4,000 dietary supplements on the market. Now there are about 29,000 on the market, with another 1,000 new products introduced each year, according to a recent Institute of Medicine report that was sponsored by the FDA. "We have seen a huge growth in the industry over the last 10 years, including the introduction of products that seem far removed from the vitamins and minerals of the pre-DSHEA days," says Dr. Lester M. Crawford, Acting FDA Commissioner. "Unlike most foods, some dietary supplements are pharmacologically active." When a substance is pharmacologically active, it can cause changes in the body. Such a substance could be toxic on its own or cause dangerous interactions with over-the-counter or prescription drugs.

Ephedra, which was often marketed for weight control and improved energy, was linked to cardiovascular problems, such as increased blood pressure and irregular heart rhythm. In the first formal action to stop the sale of a dietary supplement since DSHEA was passed, the FDA banned ephedra last year. "This is an example of how we can get a dietary supplement off the market if we have solid scientific proof that it does more harm than good," Crawford says.

Manufacturers and retailers can make claims about the impact of dietary supplements on the structure or function of the body, but these claims must be truthful. An example of such a claim is "calcium builds strong bones." The FDA plans to issue guidance for what data substantiates these types of claims. The agency has worked closely with the Federal Trade Commission to aggressively enforce the law against dietary supplements that are labeled with fraudulent health claims. In April 2004, the FDA sent warning letters to 16 firms, asking them to stop making false claims for weight loss.

From November 2003 to April 2004, the FDA inspected 180 domestic dietary supplement manufacturers, sent 119 warning letters to dietary supplement distributors, refused entry to 1,171 foreign shipments of dietary supplements, and seized or supervised the voluntary destruction of almost $18 million worth of mislabeled or adulterated dietary supplement products.

In March 2004, the FDA requested that 23 companies stop distributing dietary supplements containing androstenedione, also known as "andro." Widely marketed to athletes and body builders, androstenedione has been touted as a way to increase muscle growth and reduce fat. However, it acts like a steroid in the body and increases the risk of serious diseases. For example, women who use these products may be at increased risk for breast cancer and endometrial cancer. Children who use these products are at risk of early onset of puberty and of premature cessation of bone growth.

Additionally, the FDA is developing regulations for industry on good manufacturing practices (GMPs) for dietary supplements. When finalized, the rule will set standards for the manufacturing and handling of dietary supplements to ensure that consumers are provided with high-quality dietary supplements.

"The GMP regulation is the linchpin for properly regulating dietary supplements," Crawford says. "It gives FDA benchmarks for regulating dietary supplements and it gives clear instructions to the industry on how to manufacture products that meet rigorous quality standards."

Continuing Research

Crawford says that these initiatives are an important part of the agency's science-based approach to regulating dietary supplements. He also notes that the FDA was pleased to welcome Barbara O. Schneeman, Ph.D., as the new director of the Office of Nutritional Products, Labeling, and Dietary Supplements, part of the FDA's Center for Food Safety and Applied Nutrition. Schneeman has an extensive background in nutrition science and has served on the faculty of the University of California , Davis , since 1976.

The FDA continues to collaborate with federal research partners at the National Institutes of Health and other organizations to gather evidence about the safety and effectiveness of dietary supplements. "In evaluating dietary supplements, we look at scientific information from a range of sources," Crawford says, "including published research, evidence-based reports, and data about the pharmacology or toxicology of a compound." Crawford notes that the agency has particular interest in gathering safety data about certain dietary supplements suspected to pose human health risks, including:

• an ephedra substitute called Citrus aurantium, also known as bitter orange, which may present health risks similar to ephedra
• usnic acid, marketed for weight loss and linked to liver damage
• kava, a botanical ingredient that has caused liver failure
• pyrrolizidine alkaloids, which are found in some plants and have been shown to have toxic effects that can cause liver damage.

Tags: Nutrition, Food Safety, Vitamins

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