Wednesday, August 5, 2009
What is it? Glycomacropeptide (GMP) is a protein sub fraction found in some whey protein supplements. Whey proteins are derived from cow's milk and contain many sub fraction proteins and peptides, including GMP. When we talk about whey we are actually referring to a complex protein made up of many smaller protein sub fractions (peptides) such as: Beta#lactoglobulin, alpha#lactalbumin, immunoglobulins (IgGs), glycomacropeptides, bovine serum albumin (BSA),
and minor peptides such as lactoperoxidases, lysozyme, and lactoferrin. Each of the sub fractions found in whey has its own unique biological properties. Whey protein appears to be a powerful natural food with a host of positive effects on human health, such as improved immunity. What is it supposed to do? GMP may be able to help people trying to lose weight by stimulating the release of a hormone called Cholecystokinin (CCK). CCK has many functions in the human body. CCK plays an essential role relating to gastrointestinal function, including the regulation of food intake in animals and (hopefully) humans. In addition to being a regulator of food intake, CCK stimulates gallbladder contraction, stimulates bowel motility, regulates gastric emptying, and stimulates the release of enzymes from the pancreas. CCK also has effects on the central nervous system In particular, CCK is often referred to as a "satiety hormone," meaning it is a hormone that tells the brain when a person has has eaten enough food. This means that CCK is considered to function as an important regulator of satiety and food intake. What does the research have to say? In animals, CCK is directly related to food intake. Increases in CCK will cause reductions in food intake and consequently weight loss in many animals studied, such as mice, rats, and dogs. Interestingly, new born infants who are breast-fed have much higher levels of CCK and take in less food than formula fed infants. Another interesting tid bit is that one of the ways nicotine may exert its anorectic (appetite suppressing) effects is by raising CCK. In rats exposed to nicotine, CCK levels are much higher and food intake much lower, resulting in weight loss. In humans, the exact relationship of CCK to food intake and weight loss is not as clear (so what else is new?) though CCK is clearly related on some level to food consumption. In the past few decades, the mechanisms of what signal tells people to stop eating (i.e., the satiating effect of food that terminates a meal) have been clinically investigated in animals and humans. The research has revealed that peptides such as cholecystokinin (CCK), pancreatic glucagon, and bombesin are released by ingested food in the gastrointestinal tract and are related to food intake. The release of these gut based peptides appears to decrease meal size in a dose#related manner without toxicity. Perhaps more importantly to people, the stimulation of these peptides appears to decrease meal size without decreasing the reported pleasure or satisfaction of the meal. Research into the the use of these peptides may find them to be a new class of appetite suppressing agents, though more human research is needed but progressing rapidly. There is limited, though interesting, research showing GMP from whey increases CCK. A clinical study done by a Dr. Maubois from France found that the ingestion of whey by healthy volunteers resulted in a substantial elevation in CCK being released. What he did not check, however, was if this large increase in CCK resulted in less food being consumed or if any weight loss occurred.