The researchers from Lunds University have identified tylakoids, tiny membranes in the choloroplasts and are source of minerals, proteins and fats, which appear to inhibit the digestion of fat. This means the fat stays in the intestinal tract for longer and sets off satiety signals.
The discovery could eventually lead to tylakoid-containing cookies or pies being classed as slimming products. The world market for such products was worth €6.0bn at retail in 2005, of which the US made up €$3.1bn and Western Europe €0.73bn, according to Euromonitor International.
Doctoral candidate Rickard Köhnke told NutraIngredients.com that the idea of tylakoids came from a collaboration between Charlotte Erlanson-Albertsson, who researches obesity and appetite control, and her husband Per-åke Albertsson, a professor of biochemistry, with a specific interest in photosynthesis in plants.
The husband and wife team used spinach as the source of the tylakoids.
The researchers started off with in vitro experiments that showed that fat digestion was inhibited in the presence of both tylakoids and pancreatic lipase, a digestive enzyme.
They then progressed on to in vivo studies in rats and mice, the latter are said to be on going.
For the rat studies, Prof Erlanson-Albertsson and her fellow researchers fed the animals a high fat diet (40 per cent fat) and added tylakoids to the diet of some of the rats. Initial tests with 0.1 per cent tylakoids showed that, as the scientists had predicted, the rats ate less, lost weight, and blood lipid levels decreased.
Increasing the tylakoid content of the diet to 0.6 per cent yielded even better results, said Köhnke.
Human studies in a clinical trial setting are eventually planned.
Köhnke stressed that for maximum benefits the tylakoids should be consumed with a meal, because the green leaf extracts have to be present with lipids.
"But if you were to use raw spinach as a source of tylakoids, you would have to eat about half a kilo of spinach a day," said Köhnke.
"When we isolate and purify the substance, we only need a few grams. The idea is that it should be possible to add the substance to fat-rich products such as pies or cookies," he said.
Köhnke also said that it may be possible to produce supplements that contain tylakoids, but stressed that these would have to be taken at meal times to coincide with fat ingestion.
The mechanism behind how the tylakoids work is not fully elucidated, but the Lunds University researchers theorise that the tylakoids contain substances that inhibit the action of pancreatic lipase by forming a coating around the fat molecules and blocking access of the digestive enzymes.
A patent application has been made, and publication of research results is also expected in peer-review journals. NutraIngredients.com has not seen the data relating to these studies.
It is also said that there has been some preliminary interest from potential industrial partners.
Obesity in Europe is a serious problem, with up to 27 percent of men, 38 percent of women, and 3m children clinically obese in some parts of the bloc.