Calcium-enriched bread supports skeletal growth of young rats

Calcium (Ca) malabsorption is believed to aggravate negative calcium balanc e and contribute importantly to age-related bone loss. Although dairy produ cts are considered a rich and bioavailable source of calcium, there are peo ple who either avoid these products or do not consume them in adequate amou nts. Therefore, there is a need for alternative food choices that can provi de individuals with adequate calcium without a need for supplementation. Th e current study was undertaken to examine whether calcium bioavailability o f a bread-based diet is comparable with that of a milk-based diet. Addition ally, the calcium bioavailability of these two diets were compared with sem i-purified diets with varying amounts of fat and protein. Forty, 28 day old , male Sprague-Dawley rats were divided into four treatment groups and fed for 8 weeks. Treatments were as follows: control, received a semi-synthetic diet; bread, received a bread-based diet in which bread provided 100% of t he CHO, 79% of the protein and 16% of the fat; milk, received a diet compos ed of 49.4% (w/w) non-fat dried milk; and HFHP, received a semi-synthetic d iet with higher fat and protein contents than all the other groups. All the diets, except HFHP, were formulated to be isocaloric and isonitrogenous. A bsorption of Ca was assessed 8 days before the end of the study for a five- day period using the balance technique. Calcium absorption was significantl y lower in the milk and HFHP groups in comparison to the bread and control groups. However, skeletal growth was not jeopardized in any of the treatmen t groups as judged by femoral density and mineral content and tibial protei n content. Despite similar energy intakes, the final mean body weight of an imals fed the milk-based diet was significantly lower than the other groups . These results indicate that enriched bread can serve as a good source of bioavailable calcium. Additionally, our data suggest that diets with higher fat content may interfere with calcium absorption. (C) 1999 Elsevier Scien ce Inc.