8, March 2010
Discovery Of 6th Taste Explains Why Some Can’t Resist Fatty Foods; Those Sensitive To Fat Should Consume Less
“We know that the human tongue can detect five tastes – sweet, salty, sour, bitter and umami (a savoury, protein–rich taste contained in foods such as soy sauce and chicken stock),” Russell Keast, from Deakin University, said on Monday. “Through our study we can conclude that humans have a sixth taste – fat.”
Researchers tested the ability of 30 people to taste a range of fatty acids in otherwise plain solutions and found that all were able to determine the taste – though some required higher concentrations than others.
They then developed a screening test to see how sensitive people were to the taste and found that, of the 50 people tested, their ability to detect fat was linked to their weight – a finding which could help counter obesity.
“We found that the people who were sensitive to fat, who could taste very low concentrations, actually consumed less fat than the people who were insensitive,” Keast said. “We also found that they had lower BMIs (Body Mass Indexes).”
The reverse was happening in people who were not sensitive to the taste. “They are over–consuming and this is creating an energy imbalance, which is leading to higher BMI or development of overweight or obesity”, he added. Keast said the research, conducted in collaboration with the University of Adelaide, New Zealand’s Massey University and Australian science body CSIRO, suggested that the taste of fat could trigger a mechanism in the body.
“We all like eating fatty foods. What we speculate is (that) the mechanism is to do with stopping eating. Your body is able to tell you you’ve had enough and stop,” he explained. “And if you are insensitive to it, you’re not getting that feedback.”
With fats easily accessible and commonly consumed, it was possible that people may become desensitised to the taste of fat, leaving some more prone to overindulging in calorie–rich foods, he added.
The results, published in the British Journal of Nutrition, have not definitively classified fat as a taste but Keast says the evidence is strong and mounting.
For something to be classified as a taste there needed to be proven receptor mechanisms on taste cells in the mouth, he said. “We have what... we will call possible candidate receptors for fat on taste receptor cells,” he said.
He says low–fat foods can be ineffective because the body becomes convinced it is not getting what it needs and then people revert to the full–fat version.
He says the research may lead to the development of better low–fat foods people will be less likely to abandon. “Celery will always taste like celery. Brie will always taste like brie. This is not perceivable,” he said.
“(But) what this (research) would do in theory is ensure that the body... actually would recognise there was fat without there being those excessive levels of fat in the food. You can’t replace fat entirely and it would be wrong to think so. Fat is good. It is just that we eat too much of it.”