Appetite-controlling brain cells activated by amino acids
You've likely heard that eating protein can fill you up faster than eating simple carbs like bread and pasta. Now, researchers at the University of Warwick (UW) in England have figured out just why that is, and they've identified the specific foods that satisfy hunger the quickest. Their findings could put a serious dent in the obesity epidemic and may even lead to treatments that make us feel fuller without having to eat a lot of food to get there.
The researchers pinpointed brain cells called tanycytes. These cells are located in the wall that lines the third ventricle of the brain. They are thought to transfer information between the brain and the cerebrospinal fluid (CSF), and are known to sense glucose in CSF. The new research indicates that they're also quite adept at sensing amino acids as well.
After exposing tanycytes from the brain tissue of mice to the amino acids lysine and arginine they discovered that these cells released signals to the brain indicating satiety within 30 seconds. What's more, they determined that the tanycytes were activated when taste receptors in the mouth detected certain umami foods. Along with sweet, sour, bitter and salty, umami is one of the five basic taste receptors and is often described as an earthy or meaty flavor.
According to UW, foods that are high in the two key amino acids involved in the study include pork shoulder, beef sirloin steak, chicken, mackerel, plums, apricots, avocados, lentils and almonds. Eating such foods, the research suggests, could help you become fuller faster and causing you to consume fewer calories and contributing to weight loss. The same holds true for another umami food – walnuts – as shown in a different study earlier this year.
"Amino acid levels in blood and brain following a meal are a very important signal that imparts the sensation of feeling full," said Nicholas Dale, professor of neuroscience at the University of Warwick. "Finding that tanycytes, located at the centre of the brain region that controls body weight, directly sense amino acids has very significant implications for coming up with new ways to help people to control their body weight within healthy bounds."
The researchers say that the finding could help doctors and nutritionists develop more effective diets for overweight patients or possibly lead to drugs that could stimulate our tanycytes directly, bypassing the digestive system entirely.
The UW finding adds to a growing body of research regarding ways in which we might be able to keep our weight in check – outside of the tried and true methods of diet and exercise.
A study from the Columbia University Medical Center earlier this year uncovered a protein formed in bones that suppresses appetite, while researchers at the Mayo Clinic found that two chemotherapy drugs blasted fat off obese mice. Other recent weight-loss breakthroughs include the biological alchemy of turning calorie-storing white fat into calorie-burning beige fat by blocking a certain protein, as well as the development of skin patches that accomplish the same goal. According to the World Health Organization, such intervention by science seems to be sorely needed, as the worldwide obesity has more than doubled since 1980.
The results of the research have been published in the journal Molecular Metabolism.
Source: University of Warwick