Cancer risk linked to tastebuds

Supertasters - people with an unusually large number of tastebuds in the mouth - tend to avoid sweet, high-fat foods. But even though they are often thinner and healthier than most people, they are at higher risk of certain cancers, Linda Bartoshuk of Yale University told the American Association for the Advancement of Science meeting in Denver.

About half of all people are "medium tasters". The other 50% are divided into supertasters and nontasters. To supertasters, vegetables often seem unpleasantly bitter.

Prof Bartoshuk and her colleagues studied colonoscopies of a group of older men, and discovered a match between the number of polyps they found and the subjects' ability to taste bitterness.

The men with more polyps reported eating the fewest vegetables. The finding threw light on the evolution of taste, Prof Bartoshuk said.

"The ability to taste bitter substances has always been associated with poison detection," she said. "We have to avoid poisons and we have to eat a healthy diet. One of the factors is how foods taste, because the way they taste affects whether you like them or not, which affects your diet, which affects all kinds of health risks."

Supertasters - mostly women - lived in a "neon taste world" three times as intense as the "pastel" world of nontasters. "A supertaster is a superperceiver of both burning things in food like chillis and fat in foods, and this has a big impact on their food preferences," Prof Bartoshuk said.

"Female supertasters don't really like high fat, they eat less of it and their cardiovascular profiles are superior to nontasting females.

"Some males show the same pattern, but many males do not - they show the opposite pattern. This means many males who taste fat more intensely also like it more, and gain weight."

Taste may also have played a powerful role in human evolution, according to Timothy Johns of McGill University in Montreal. Humans, unlike any other species, selected spices, made sauces and infused teas. They also tended to eat fat, and anthropologists have proposed a link between high calorie intake and brain size.

This raised a puzzle. Although there were links between fat intake and ill health in the western world, some cultures - such as the Masai of East Africa and the Tibetan highlanders - had diets very high in fats and very low in fruit and vegetables, without high rates of heart disease.

How did indigenous populations develop these dietary practices? "That is the million dollar question," Dr Johns said. "There is no obvious answer, but ultimately there must be a strong evolutionary basis for this."