The effect of formulated goats' milk on calcium bioavailability in male growing rats.
BACKGROUND
There are two main proteins in milk; whey and casein. Casein contains casein phosphopeptides (CPP), which are released on digestion of the milk. These may increase calcium solubility by binding calcium in the small intestine. Thus increasing casein in the diet may help to stimulate bioavailability of calcium and increase bone density. The present study tested this hypothesis in growing male rats fed diets containing three different concentrations of casein from goat milk.


RESULTS
Rats fed the diet containing no casein had significantly lower calcium absorption when compared to rats fed the diets that contained 80% and 57% of goat milk protein as casein; however, no significant difference was observed between rats fed diets with 80% and 57% casein. The varying amounts of casein had no effect on mineral uptake or retention in the femur. Biomechanical testing and mineral analysis of the femurs showed no differences between diet groups. The mechanism to explain this lack of retention remains unclear.


CONCLUSIONS
The diets containing 80% and 57% of goat milk protein as casein delivered increased calcium absorption compared to the diet containing no casein, suggesting a minimum level of casein is needed to optimize calcium absorption from goat milk.
McKinnon
Hilary
H
Institute of Food, Nutrition and Human Health, Massey University, Private Bag 11222, Palmerston North, New Zealand.
Kruger
Marlena
M
Prosser
Colin
C
Lowry
Dianne
D
D000818:Animals; D001682:Biological Availability; D001823:Body Composition; D015519:Bone Density; D001842:Bone and Bones / Q000187:drug effects* / Q000378:metabolism; D002136:Calcium, Dietary / Q000008:administration & dosage / Q000493:pharmacokinetics*; D002364:Caseins / Q000494:pharmacology*; D004044:Dietary Proteins / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D005526:Food, Formulated; D006041:Goats; D006128:Growth; D007408:Intestinal Absorption; D008297:Male; D008892:Milk / Q000737:chemistry*; D008894:Milk Proteins / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012995:Solubility
D002136:Calcium, Dietary; D002364:Caseins; D004044:Dietary Proteins; D008894:Milk Proteins