Content area
Full text
(ProQuest: ... denotes non-US-ASCII text omitted.)
Diets that are high in protein at the expense of carbohydrate have been shown to be beneficial in weight and body fat loss in human subjects(1,2). Human studies have shown that on an energy basis protein is more satiating than other macronutrients(3). The nature of the protein source may also be relevant, although this has not been well studied. Research has shown in laboratory rats fed a high-protein diet (300 g/kg) that whey protein concentrate was significantly more effective than red meat in reducing body-weight gain and body fat content, when energy intakes were comparable(4). In human short-term studies whey protein has been shown to enhance satiety and decrease food intake relative to casein(5).
Glycomacropeptide (GMP), the glycosylated fraction of caseinomacropeptide is a C-terminal fragment of κ casein released by endopeptidase chymosin (rennin) and is present in whey from cheese manufacture(6) at concentrations in the order of 600 mg/l and this may have been responsible for the whey protein concentrate effect reported in rats by Belobrajdic et al.(7). GMP has been shown to stimulate cholecystokinin (CCK) release(8), thereby potentially having an influence on satiety and food intake(9,10). GMP has been detected in the plasma of volunteers after milk or yoghurt ingestion(11), suggesting that GMP may be produced in the gut before being absorbed into the circulation via intestinal cells.
The aim of the present study was to determine if a GMP-enriched whey protein isolate (WPI) has a significant effect on weight gain, growth rate and body composition, when compared with WPI without GMP, casein and barbequed (BBQ) beef. It was hypothesised that feeding NatraPep(TM), a commercial source of GMP-rich WPI, would decrease both food intake and gain of abdominal and subcutaneous fat.
Experimental methods adopted
Animals
Fifty male Wistar rats, age 12 weeks, were obtained from the Animal Resource Centre (Murdoch University, Western Australia, Australia).
Upon arrival the animals were housed in wire cages to minimse coprophagy and were maintained in an air-conditioned environment of 23 ± 2°C with a...