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UC Davis Health System

UC Davis Health System

Supplements don't improve athletic performance

Photo of joggers No scientific evidence supports the claims of products that purport to increase muscle size, strength, speed and energy.

Athletes today have an ever-expanding assortment of pills, powders, drinks, snacks and other merchandise promising to make them faster, stronger and bigger. Sales figures indicate that many people have bought that promise, but it's an empty one, according to Marlia Braun, a dietitian with the UC Davis Sports Medicine Program.

Balanced diet

Braun says that a well-balanced diet provides most athletes with more than enough of the nutrients they need. “As long as athletes eat a well-balanced diet and drink plenty of water, that should be all they need,” Braun says. “A lot of people are using products that aren't necessary, not scientifically sound, nor are they regulated by the Food and Drug Administration. They certainly can stress the pocketbook.”

Athletes whose nutritional needs exceed normal requirements are those who participate in events of long duration, such as triathlons, marathons or stage races. Even those athletes, Braun says, simply need to include more food and liquid in their diets. During competition, these athletes need to consume fluids to replace losses and would benefit from the ingestion of carbohydrates and electrolytes.

There is no scientific evidence to support the claims of products that purport to increase muscle size, strength, speed and energy, or otherwise enhance athletic performance. But many athletes look for any way to gain an edge or shortcut to success, Braun says.

Marketing techniques

People often are swayed by clever marketing techniques and “experts” with dubious credentials who endorse the use of nutritional supplements, such as employees at health food stores and health clubs, as well as professional athletes.

"As long as athletes eat a well-balanced diet and drink plenty of water, that should be all they need."
— Marlia Braun, UC Davis Sports Medicine dietician

“People who aren't qualified or don't have a background in nutrition are making inaccurate claims about these products,” Braun says.

Because there is no standardization for many of these supplements, it is not uncommon to find several different chemical formulations, depending upon the manufacturer, all claiming to be the same vital compound.

For example, supplements for amino acids, the building blocks for protein, are promoted as helping to build muscle, but the average American diet already has two-to-three times more protein than is needed, Braun says. High levels of a specific amino acid can potentially produce a toxic effect and place an extra burden on the kidneys contributing to kidney failure in the long-term.

Supplementing with Individual vitamins and minerals can also create imbalances within the body, which can lead to acute changes as well as long term negative health consequences such as reduced bioavailability of other nutrients and toxicity.

Sports drinks are popular, but they should be used appropriately, Braun says. The purpose of these beverages is to provide fluid, carbohydrate and electrolytes during long endurance events, where energy stores are depleted and water and electrolytes are lost in sweat. Their contents support athletic performance and can be used to help with recovery, Braun says.

“Sports drinks are not meant to be the sole source of fluid in the diet. They contribute added calories, which can hinder weight loss and weight maintenance goals, and extra sodium, which in excess is associate with high blood pressure,” Braun says. Exercise lasting less than an hour in a temperate environment should only necessitate water, Braun says.