Diet Advice From DNA

Internet marketers claim that a genetic test can give you a personalized diet. Are they advertising cutting-edge science or a high-tech horoscope?By Laura Hercher   When President Bill Clinton stood in the East Room of the White House on June 26, 2000, and hailed the completion of the Human Genome Project, calling its results “the most important, most wondrous map ever produced by humankind,” he was not looking to inaugurate an era of high-tech snake oil sales. Yet less than a decade later Web-based purveyors of genetic tests and dietary supplements are hawking nutritional genetics, or nutrigenetics, with claims that it can look at an individual’s genetic information to figure out what that person should eat to promote stronger bones, shinier hair and other trappings of good health. So far, though, hyperbole has outpaced promise. This nascent field provides a cautionary tale of how commerce often races ahead of science: the commercialization of gene detection technology has occurred before scientists have developed an adequate understanding of how particular genes contribute to health and disease.Information derived from sequencing the DNA code in every human chromosome is gradually enabling scientists to create tests and treatments that have the potential to prevent, diagnose, ameliorate and perhaps even cure disease. It is also paving the way for “personalized medicine,” which is based on the recognition that genetic differences among individuals can explain why one person’s body reacts differently than another’s to food, drugs, sun, exercise, allergens or other stimuli. In an ideal world, a genetic test would reveal which medication or other therapy would work best and produce the fewest side effects in a given individual. And investigators are now beginning to create such tests. One milestone occurred this past summer, when the Food and Drug Administration approved the first genetic test to help a patient gauge the best dosage for a blood-thinning drug called warfarin. The test is certain to be followed by scores of others that attempt to better match drug to patient.