Bitter Sometimes Better

Your mother was always trying to convince you that what tasted worst was actually best for you. According to new research from scientists at Duke Medical Center, University College London, and the German Institute of Human Nutrition, she was only half wrong.

The researchers examined one gene encoding a bitter-taste receptor in sixty human populations from all over the world and reconstructed the history of that gene. They say bitter-tasting plant toxins in the diets of early humans drove the evolution of a taste receptor better able to detect them. Such ability, they say, likely offered a survival advantage by protecting ancient people from poisonous fare.

The evidence of positive selection is interesting because it has generally been assumed that human behavioral habits that inactivate toxins in foods, such as soaking and cooking foods, would make such selection less essential to humans than other animals, according to senior author David Goldstein, director of the Duke Center for Population Genomics and Pharmacogenetics, a part of the Duke Institute for Genome Sciences & Policy.

While avoidance of bitter foods may have constituted good health policy in the old days, the researchers say, today, the same sensory sensitivity may have adverse consequences for human health by causing an aversion to certain bitter-tasting nutrients, some of which might lower the risk of cancer and heart disease.

"Bitter compounds are a heterogeneous class, some of which are toxic and some of which lower the risk of cancer and heart disease," says lead author Nicole Soranzo of UCL. "Owing to their bitter taste, these compounds are routinely removed by the food industry and represent a key limitation in increasing the nutrient content of plant foods."

The findings were published in the July 26 issue of Current Biology.