We watched in awe as the Olympic athletes set new records running, swimming and cycling faster, jumping higher and further, and performing ever more amazing routines on the rings and parallel bars.
Such levels of skill, strength and stamina were achieved with strict training and body maintenance routines. These super-athletes also pursued diets with the right amount of carbohydrates, protein and fat to build and strengthen muscles; the calories required for energy; and the fluids needed to make everything work properly.
These are the basic building blocks for healthy bodies, even for us ordinary mortals who seek improved skills or better-looking muscles. Some contestants in virtually every modern Olympic contest, however, like many amateurs, supplement their meals with strength and muscle "boosters."
The use of supplements to improve athletic performance is not new. Ancient Greeks ate certain species of mushrooms before the Olympic Games, and the Aztecs consumed human hearts before their athletic competitions. In the 1800s, amphetamines, ether-soaked sugar and even heroin and cocaine were swallowed in efforts to increase Olympians' chances of bringing home the gold. In the 1960 Olympics and at the 1967 Tour de France, a top cyclist died after taking amphetamines.
In 1998, the International Olympic Committee created the World Anti-Doping Agency to police the use of illegal agents such as growth hormone, diuretics, steroids, stimulants and all other performance-enhancing products. That agency expelled Bulgarian and Romanian weight lifters from the Sydney Olympics for drug misuse.
No agency oversees public availability of performance-enhancing products in the U.S. They are widely available through health food stores and other retail and Internet outlets, and the selection is almost limitless. One national chain's catalog devotes seven full pages to products said to help build bodies, boost metabolism or enhance performance.
For the general public, the issues are whether the products work, and whether they work safely. Clinical trials of nutritional aids to enhance athletic ability, conducted between 1966 and 1992, were reviewed in 1993 by the University of Colorado Health Sciences Center. Manufacturers' claims were documented in only 21% of products studied.
Here's a rundown on a few of today's most popular over-the-counter items sold to build muscles, strength and stamina, no prescription required. Perhaps because Americans are so intent on achieving defined musculature, we are supplementing workouts and buying these products in droves. Aside from being illegal in many competitions, some are unsafe.
* Creatine, a compound of three amino acids, is a manufactured version of chemicals produced by the body and stored in muscles. It is said to be the most commonly used nutritional supplement today, popular among professional and college athletes as well as the general public. According to commercial claims, creatine increases muscle mass and releases energy to the muscles, enabling longer and harder workouts. Research indicates that it may enhance performance of high-intensity, brief exercise, but that it is not useful in endurance sports. It may decrease kidney function. Despite many clinical trials, high-quality research is lacking and long-term effects are not well documented.
* DHEA is a steroid hormone manufactured in the adrenal glands. It was banned by the FDA in 1996 and is now marketed as an unregulated nutritional supplement. DHEA is said to increase the production of testosterone and provide a steroid boost effect (users risk disqualification from amateur athletic events internationally). It is also said to burn fat and create weight loss, invigorate sex life, improve mood and extend life; to prevent heart disease, cancer and osteoporosis; and to treat Alzheimer's disease.
There is little scientific evidence that DHEA can accomplish any of these goals. What's more, the supplement has been associated with increased risk of prostate and endometrial cancers.
* L-tryptophan, an amino acid found in many combination supplements, is said to delay fatigue by reducing the discomfort of prolonged muscular effort. According to the American Dietetic Assn., L-tryptophan supplements were associated with 38 deaths in 1989 and 1990. These deaths probably were caused by product contamination, but they represent a tragic consequence of taking supplements not soundly backed by scientific justification of benefit.
There are dozens of additional popular products, such as chromium picolinate, whose sellers have been fined 32 times by the U.S. Federal Trade Commission for false claims.
In addition to chemicals, ginseng and other botanicals are promoted as wonder drugs to enhance physical prowess. Scientific research does not support their safety or value. Nor is there backing for the non-supplement enhancers, such as hyperbaric oxygen chambers and magnet therapy.
Watch out for false claims, poor quality control, and a lot of money down the drain, as these products and methods typically are very costly. Most important, consider long-term safety before swallowing.
Barrie Cassileth is chief of integrative medicine at Memorial Sloan-Kettering Cancer Center in New York and the author of "The Alternative Medicine Handbook" (Norton, 1998). Her column appears the first Monday of the month.