The ingredient that will make you eat less (but tastes foul)

'We know that adults gain between 0.3kg and 0.8kg a year on average.' - expert. Photo / 123RF

A food ingredient has been found to suppress appetite and prevent weight gain in overweight people, raising the prospect of tackling the national obesity crisis through harmless dietary additives.

Scientists have shown that the ingredient - made of natural substances found in food - makes a person feel fuller than they otherwise would feel during meals, which makes them eat significantly less over a period of time.

Preliminary tests show that overweight people who regularly ate the ingredient with their meals for six months put on significantly less weight and had reduced abdominal fat compared to people who did not have the food additive.

The ingredient is a small fatty-acid molecule called propionate, which researchers attached to a form of dietary fibre found in chicory known as inulin to make it more palatable, said Professor Gary Frost of Imperial College London, who led the study.

"Propionate on its own tastes absolutely foul, really horrible. The closest you get is acetic acid, which is vinegar, and propionate tastes even worse. But this is mostly lost when you stick it to inulin, although it can still taste a little bitter," Professor Frost said.

Propionate is produced naturally in the human colon when undigested dietary fibre is fermented by gut bacteria. The propionate produced in this way has been shown to stimulate the release of appetite-suppressing hormones from the gut wall which send signals to the brain and make a person feel full.

However, the amount of dietary fibre needed to produce this effect on the brain's appetite control is about 10 times higher than the typical 10 grams a day of dietary fibre that people in Britain consume on average, Professor Frost said.

Initial tests on 20 volunteers given the propionate-inulin additive found that they ate about 14 per cent less than people who were given inulin only.

Longer tests over 24 weeks on 60 overweight volunteers showed those given the propionate-inulin additive gained less weight than the group given inulin only as a food additive.

Only one of the 25 volunteers given the propionate-inulin additive gained more than 3 per cent of their body weight, compared with six out of 24 who were given inulin. None of the former group gained more than 5 per cent, while four did so in the latter group. Professor Frost said that conventional "diet pills" concentrate on weight loss, whereas this approach tackles the natural tendency of people to put on weight over time, especially in middle age.

"We know that adults gain between 0.3kg and 0.8kg a year on average, and there's a real need for new strategies that can prevent this," Professor Frost said.

"We were not looking at weight loss, but at preventing people from gaining weight and becoming fat. In the long term this particular food ingredient may well prevent weight gain and so has the potential to be an important public-health tool," he said.

"The aim is to get it developed as a food ingredient, not as a medicine... something that can be added to a staple food such as bread."

Further tests will show whether it helps to prevent people putting weight back on after a diet, Professor Frost said. His findings are published in the BMJ.