Whey protein and calcium have a positive effect on body weight and composition
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| 31st October 2008
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| Whey proteins and calcium have a beneficial effect on obesity induced problems in the liver and adipose tissue as well as on body composition, states Taru Pilvi, Master of Science (Food Sciences) in her doctoral dissertation. Protein quality may therefore have an important effect on weight management.
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Ms Pilvi studied the effect of dairy protein and calcium on the prevention and treatment of obesity, and on the liver and adipose tissue. The study was conducted in a model of diet induced obesity in mice. Previous studies have observed that people with a high dairy intake have a lower body mass index and a smaller risk of metabolic syndrome and type 2 diabetes compared with those who have a low dairy intake. Dairy proteins and calcium are postulated to affect body weight, yet studies on the effects and effective mechanisms of milk protein are scarce.
Dairy intake inhibited weight gain and had a positive effect on hepatic lipids
The different milk proteins have different effects on body weight and the amount of adipose tissue in the body. A high calcium diet containing whey protein prevented body weight gain and an increase of adipose tissue, and enhanced weight loss and the loss of adipose tissue during energy restriction. α-lactalbumin, one of the major whey proteins, was the most effective protein fraction showing significantly accelerated weight and fat loss during energy restriction, and it reduced the amount of visceral fat gain during ad libitum feeding after weight loss.
The microarray data suggest the sensitisation of insulin signalling in the adipose tissue resulting from a calcium rich whey protein diet. Lipidomic analysis revealed that weight loss on a whey protein based high calcium diet was characterised by significant decreases in harmful lipid compounds in the liver.
Further research needed on the effective mechanisms
The calcium supplementation led to a small but statistically significant decrease in fat absorption independent of the diet’s protein source. This augments but does not fully explain the effects of the studied diets on body weight.
A diet containing whey protein and high in calcium increases e.g. β3 adrenergic receptor expression and leptin expression in adipose tissue, which may contribute to the changes in body weight. The potential sensitisation of insulin signalling in adipose tissue, together with the improved hepatic lipid profile, suggest a novel mechanistic link to explain why increased dairy intake is associated with a lower prevalence of metabolic syndrome and type 2 diabetes in epidemiological studies. These experimental results lay down a good basis for the future study of more precise mechanisms and the clinical effects of milk proteins.
Taru Pilvi, Master of Science (Food Sciences), conducted the public defence of her doctoral thesis "Effects of dairy proteins and calcium on diet-induced obesity in mice" at the University of Helsinki Faculty of Medicine on Friday 31st October 2008 (Biomedicum, Lecture Hall 2, Haartmaninkatu 8, Helsinki). Opponent: Professor Hannu Mykkänen, University of Kuopio; Custos: Valio Vice President, Research, Professor Riitta Korpela of the University of Helsinki Faculty of Medicine.
Further information
Taru Pilvi, Senior Scientist, PhD, Valio Ltd, R&D
Tel. +358 10 381 3021, E-mail: taru.pilvi@valio.fi
The thesis can be read at http://ethesis.helsinki.fi
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Taru Pilvi
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