New research shows that there may be a good reason why you should chew your food thoroughly. According Masaaki Eto, M.D., a professor of clinical pharmacology and medicine with Ohu University in Koriyama, Japan, thoroughly chewing food stimulates the release of two intestinal peptides that serve a function in lowering appetite and reducing food intake in obese individuals. Dr. Eto presented the findings of the research at the 47th annual meeting of the European Association for the Study of Diabetes (EASD).
The study, performed on non-diabetic, obese individuals, demonstrated that when participants chewed their food thoroughly, they experienced postprandial increases in plasma glucagon-like peptide, known as GLP-1, as well as in peptide YY, known as PYY. Both peptides are released by L cells in the intestines.
According to Dr. Eto, the study was the first to analyze this occurrence in obese individuals. Dr. Eto presented a similar study at last year’s meeting of the EASD; however, that study was performed on normal-weight individuals.
GLP-1 stimulates the glucose-dependent secretion of insulin and encourages reduced food intake. GLP-1 and PYY are thought to be associated with regulation of triglyceride levels and plasma glucose as well as body weight. Plasma insulin and plasma levels of both peptides rise after a meal in normal-weight individuals, while plasma glucose stays about the same.
The newer study analyzed data from nine subjects (five male, four female); the mean age was 41 years. The mean body mass index (BMI) across the participants was 27.2 ± 0.4 kg/m2, which is considered obese in Japan: a BMI of 25 or over falls into “obese” territory in that country, while 25 would be considered “overweight” in the United States. The mean fasting plasma glucose level of the participants was 99 ± 2 mg/dL while mean blood pressure was 124/77 mm Hg.
The study required the participants to fast for 12 hours, after which they ate an early-morning breakfast consisting of steamed vegetables, a boiled egg, bread, margarine, a banana, and milk. The participants were instructed to stretch the meal out to 20 minutes by chewing each mouthful of food five times. Another test on a different day required them to chew each mouthful 30 times. The researchers measured plasma levels of GLP-1 and PYY before the meal and then one hour after.
According to Dr. Eto, the results showed that postprandial plasma levels of the two peptides were significantly higher when the participants chewed 30 times instead of five. He suggested that the thorough chewing of food could be an effective obesity control measure in overweight individuals.
Dr. Eto based his study on old advice from the Japanese government about chewing food thoroughly.
“In [Japan], 30 times chewing is recommended by the government to prevent obesity,” said Dr. Eto. “Increased incidence of obesity is a very, very [big] problem, so since the old days in my country, 30 times chewing was recommended.” He believes that well-chewed food acts on the intestine to encourage the release of the hormones, rather than the peptides being released by the mechanical action of chewing, as some suggested.
Session moderator Leszek Czupryniak, M.D., Ph.D., of the Medical University of Lodz in Poland, said that “what is interesting here is that if you eat something slowly and chew it slowly, the rate of absorption is much slower, and actually, the meal becomes longer. That probably changes the way any hormones are secreted.” Dr. Czupryniak continued on to say that the study’s results were useful in that the technique could be used in everyday life to help control weight in obese individuals.