YOU EAT A BALANCED DIET and train like a madman. You've even given up beer. But no matter how hard you try, you can't keep up with the hammerheads on bike rides or the LeBron wannabes on the basketball court. What's a genetically challenged striver to do? One option may be nutrigenomics—a fast-emerging (and controversial) nutritional science that can help you overcome your genetic limitations with a diet tailored to your DNA.

Nutrigenomics spun out of the Human Genome Project, the effort begun in 1990 by the U.S. Department of Energy and the National Institutes of Health to identify the nearly 25,000 genes that make us who we are. With the job complete, scientists have started using this knowledge to uncover revelations in fields like evolution, anthropology, molecular medicine, and forensics and to research cutting-edge cures for dozens of genetic disorders like diabetes.

Over the past ten years, countless studies have looked at nutrigenomics and the correlation between diet and genes. A 2002 study published in BMJ (British Medical Journal) stated that specific nutritional advice based on patients' DNA can help them avoid diseases. But it's only recently that this technology has been connected to sports performance.

"It stands to reason that this knowledge would positively affect athletic results," says Mark Troxler, a team physician for USA Track & Field. "Right now athletes take supplements they don't need, and need supplements they don't take, but they don't know it. Nutrigenomics can eliminate a lot of that misunderstanding."

While scientists are still deciphering the effectiveness of manipulating genes through diet, the private sector has already jumped on what it sees as the next big thing. Among the first consumer products to come out of the Genome Project were individual DNA tests designed to help patients deal with predispositions to diseases. "We identified 19 genes that give us an idea of a client's future overall health," says Keith Grimaldi, 45, a molecular biologist and a director of research for Sciona, a Boulder, Colorado–based biotech lab that developed one of the first nutritional DNA tests, in 2000. "We also found that four of those genes were directly relevant to athletes."

For example, the MnSOD gene concerns an individual's ability to produce and regulate the protein MnSOD, an antioxidant formed in cells that squashes muscle-damaging free radicals and aids endurance and recovery. To compensate for a weak MnSOD protein, the natural-foods solution calls for a glass of pomegranate juice or a handful of blueberries (both high in antioxidants) after a workout. Two other genes, IL-6 and TNFa, correspond to the production of cytokines, proteins that repair the type of muscle damage caused by exercise. Some people, however, overproduce these helpers, resulting in excessive muscle and joint swelling. The antidote diet includes wild salmon and broccoli, which both contain anti-inflammatory nutrients. The fourth gene identified is ACE, which is connected to muscle endurance. Your ACE makeup can tell you whether or not you need to fatten up the fish and flaxseed-oil portions of your diet to help create more long-running power.