By Peter Jaret, November/December 2008
As if gene-diet interactions aren’t complicated enough, researchers have uncovered a third crucial player in the mix: physical activity. New studies suggest that exercise can override the harmful effects of some "bad genes" and boost the beneficial effects of others.
In one example, scientists at the University of Kuopio, in Finland, found that people with particular variants of three different genes (dubbed GLUT2, ABCC8 and PPARG) stand a greater risk of developing type 2 diabetes. But when people with these variants exercise regularly, they lessen the danger. Although the studies didn’t look at why, scientists have shown that exercise helps improve insulin sensitivity and blood-sugar levels.
Exercise can also amplify the effects of "good genes." For example, people with one variant of a gene called LIPC, which controls cholesterol metabolism, typically have elevated levels of good HDL cholesterol. When those with this lucky gene variation exercise, as researchers at the Steno Diabetes Center in Gentofte, Denmark, reported recently, they get an even bigger boost in HDL levels.
Sedentary lifestyles, on the other hand, may make bad genetic interactions even worse. Growing evidence shows that certain variations of a gene called FTO are associated with being overweight or obese, for example. Research reported in the journal Diabetes earlier this year suggests that when people with these "fat" forms of the gene skimp on physical activity they are even more likely to accumulate fat. Fortunately, exercise can overpower the effects of this fat-accumulating gene variant, according to a study of 704 adults published in the Archives of Internal Medicine in September.
Findings like these aren’t surprising. A wealth of epidemiological studies already show that physical activity reduces the risk of heart disease and diabetes. The good news: even if you inherit an unlucky roll of the genetic dice, there’s plenty you can do to improve the odds.