Calcium-fortified foods, especially milk and dairy products are recommended to be consumed daily for groups in risk of nutritional deficiency, including children, young adults, menopausal women, pregnant women and the elderly, however Ca-supplementation promotes gallstone formation because Ca is a nucleating factor. The objective of the current study was to assess the influence of cow or goat milk-based diets, either normal or Ca-supplemented, on bile composition, biochemical parameters and hepatic antioxidant status. Weanling male rats were randomly divided into six groups, fed standard, goat or cow milk-based diets, either with normal Ca content (5·0 g/kg), or Ca-supplemented (10·0 g/kg), for 2 weeks. Bile cholesterol concentration and output was higher in rats fed goat milk in comparison with those fed with standard and cow-milk-based diet. Ca-supplementation increased lithogenic index with the standard and cow-milk based diets, this change was not observed with the goat milk diet. Activities of plasma transaminases were also lower in the animals fed Ca-supplemented goat milk, in comparison with the other diets assayed. In general, Ca-supplement in the diet led to an increase in the hepatic oxidative damage, with an increase in the activities of all the antioxidant enzymes studied in the standard and cow milk diet, but not with goat milk. The habitual consumption of goat milk has positive effects on the plasma lipid profile, biliary composition and hepatic antioxidant defence. In addition, under our experimental conditions, Ca-supplementation of this type of milk does not increase the lithogenic index, or hepatic oxidative damage.

The effects of adaptation to dietary fat of different degrees of unsaturation (olive oil and sunflower oil) on bile secretion were studied in dogs at rest and after food intake. The animals were prepared with a bidirectional biliary cannula and a duodenal cannula to provide bile return. The two experimental groups were fed on diets containing 150 g fat/kg in the form of either olive oil (O) or sunflower-seed oil (S). The flow-rate under resting conditions and the patterns of response to food were similar in both experimental groups, although postprandial hypersection were significantly greater in volume and more prolonged in group O. No appreciable differences in concentration and output of biliary cholesterol or phospholipids were noted between the two groups. In contrast, the concentration and output of bile acids differed significantly both at rest and after food: concentration and output of bile acids were greater at rest in group S. However, after food intake, these responses were increased only in group O. The results suggest that the type of dietary fat affects biliary response to food, probably through differences in the contribution of the gall bladder in the two experimental groups.