• Bioactivity in Whey Proteins Influencing Energy Balance

      McAllan, Liam; Cotter, Paul D.; Roche, Helen M.; Korpela, Riitta; Nilaweera, Kanishka (OMICS Publishing Group, 30/03/2012)
      Obesity develops due to energy (food) intake exceeding energy expenditure. Nutrients that reduce the positive energy balance are thus being considered as therapies to combat obesity. Here, we review the literature related to the physiological, cellular and endocrine effects of intake of whey proteins, namely α-lactalbumin, β-lactoglobulin, glycomacropeptide and lactoferrin. Moreover, we discuss how dietary composition and obesity may influence whey protein effects on the above parameters. Evidence suggests that intake of whey proteins causes a decrease in energy intake, increase in energy expenditure, influence insulin sensitivity and glucose homeostasis and alter lipid metabolism in the adipose, liver and muscle. These physiological changes are accompanied by alterations in the plasma levels of energy balance related hormones (cholecystokinin, ghrelin, insulin and glucagon-like peptide-1) and the expression of catabolic and anabolic genes in the above tissue in the direction to cause a negative energy balance.
    • Protein Quality and the Protein to Carbohydrate Ratio within a High Fat Diet Influences Energy Balance and the Gut Microbiota In C57BL/6J Mice

      McAllan, Liam; Skuse, Peter; Cotter, Paul D.; O'Connor, Paula M.; Cryan, John F.; Ross, R Paul; Fitzgerald, Gerald F; Roche, Helen M.; Nilaweera, Kanishka; Teagasc Vision Programme on Obesity; et al. (PLOS, 10/02/2014)
      Macronutrient quality and composition are important determinants of energy balance and the gut microbiota. Here, we investigated how changes to protein quality (casein versus whey protein isolate; WPI) and the protein to carbohydrate (P/C) ratio within a high fat diet (HFD) impacts on these parameters. Mice were fed a low fat diet (10% kJ) or a high fat diet (HFD; 45% kJ) for 21 weeks with either casein (20% kJ, HFD) or WPI at 20%, 30% or 40% kJ. In comparison to casein, WPI at a similar energy content normalised energy intake, increased lean mass and caused a trend towards a reduction in fat mass (P = 0.08), but the protein challenge did not alter oxygen consumption or locomotor activity. WPI reduced HFD-induced plasma leptin and liver triacylglycerol, and partially attenuated the reduction in adipose FASN mRNA in HFD-fed mice. High throughput sequence-based analysis of faecal microbial populations revealed microbiota in the HFD-20% WPI group clustering closely with HFD controls, although WPI specifically increased Lactobacillaceae/Lactobacillus and decreased Clostridiaceae/Clostridium in HFD-fed mice. There was no effect of increasing the P/C ratio on energy intake, but the highest ratio reduced HFD-induced weight gain, fat mass and plasma triacylglycerol, non-esterified fatty acids, glucose and leptin levels, while it increased lean mass and oxygen consumption. Similar effects were observed on adipose mRNA expression, where the highest ratio reduced HFD-associated expression of UCP-2, TNFa and CD68 and increased the diet-associated expression of b3-AR, LPL, IR, IRS-1 and GLUT4. The P/C ratio also impacted on gut microbiota, with populations in the 30/ 40% WPI groups clustering together and away from the 20% WPI group. Taken together, our data show that increasing the P/C ratio has a dramatic effect on energy balance and the composition of gut microbiota, which is distinct from that caused by changes to protein quality.