The effect of high intakes of casein and casein phosphopeptide on calcium absorption in the rat

Abstract

The effect of the level or source of dietary protein or protein-derived peptides on Ca absorption is not well understood. We determined, therefore, the influence of habitual dietary casein level, meal casein and meal casein phosphopeptide (CPP) on Ca absorption in the rat. True fractional Ca absorption was investigated in male 7-week-old rats, Wistar strain, in three separate studies using a faecal 47Sc : 47Ca ratio method. In studies A and C, rats (n 8 per group) were fed on a purified diet containing 200 g casein/kg for 2 weeks. Rats were then given a 47Ca-labelled meal (10 g) containing (per kg) either 0, 100, 200, or 300 g casein (study A) or 0, 100, 200, 350 or 500 g CPP (study C). In study B, rats (n 24 per group) were fed on a purified diet containing (per kg) either 200, 350 or 500 g casein for 2 weeks. Each group was then further randomized into three groups (n 8 per group) and given a 47Ca-labelled meal (10 g of the same diet) containing (per kg) either 200, 350 or 500 g casein. Ca absorption from a meal was unaffected by increasing meal casein concentration from 0 to 300 g/kg (study A), but was increased with a meal casein content of 500 g/kg (study B). Fractional Ca absorption decreased with increasing usual dietary casein intake in the range 200–500 g/kg (study B), suggesting intestinal adaptation. Ca absorption was unaffected by inclusion of 100 g CPP/kg in a single meal but was significantly (P < 0·001) reduced by 200, 350 and 500 g CPP/kg meal, with no evident dose-relationship. Thus, while Ca absorption was enhanced by high-casein meals, the mechanism remains unclear.

Dietary Calcium Intake and Risks of Stroke, Its Subtypes, and Coronary Heart Disease in Japanese

“…Calcium in milk and dairy products can be absorbed more efficiently than that in other foods, probably because casein, abundant in milk and dairy products, enhances calcium absorption. 18 In addition to its hypotensive effect, calcium reduces platelet aggregation 19 and lowers plasma total cholesterol levels by forming insoluble complexes with fatty acids and reducing the absorption of fatty acids. 20 The hypotensive effect of dietary calcium helps to explain a protective effect against total stroke, especially hemorrhagic stroke.…”

Evaluation of processed cheese fortified with fish oil emulsion

“…Singh et al (2006) stated that a fish oil emulsion made with casein/whey protein complexes not only provides a thick, interfacial coating on the droplet but also induces a strong antioxidative effect in the emulsion. This is achieved through the metal-chelating capacity of phosphoseryl groups in casein (Bennett et al, 2000;Gaucheron, Famelart, & LeGraet, 1996) and through free radical scavenging by the sulfhydryl groups of whey protein (Faraji et al, 2004;Hu et al, 2003;Kiolias, Dimakou, & Oreopoulou, 2007;McClements & Decker, 2000).…”

Effect of high vegetable protein diets on urinary calcium loss in middle-aged men and women

“…An alternative explanation is that high protein intakes may promote mineral absorption by a direct effect in the gastrointestinal tract (Kerstetter et al, 1998;Bennett et al, 2000). Although this effect has been contested (Heaney, 2000), increased calcium absorption would result in a corresponding increase in urinary calcium output to maintain calcium balance.…”