Effects of dietary calcium and fiber on digestibility of fat and energy and on health indices of cardiovascular disease

Scope and method of study. This study investigated the effects of calcium and fiber on the digestibility and caloric contribution of fat as well as the association of these nutrients with cardiovascular disease risk. Fat digestibility was measured in mice and pigs during four weeks of feeding isocaloric diets rich in either beef tallow or corn oil with or without added calcium. Mice were fed beef tallow with 5 levels of calcium (0.6, 1.0, 1.5, 2.0, and 2.5% of the diet) or with one of four sources of added dietary fiber. Additionally, the dietary intake of 49 middle-aged men and women was analyzed. Relationships of fat fiber, and calcium intake to various indices of cardiovascular disease risk assessment were examined.;Findings and conclusions. In mice, fecal excretion of fat and soap was greater for animals fed tallow than for those fed corn oil. Digestible and retained energy was greater from corn oil than from tallow. Added calcium depressed dry matter and energy digestibility with both sources of fat, but the effect was greater with tallow than with corn oil. For mice fed beef tallow, metabolizable energy of fat decreased by 2% for every 1% increase in dietary calcium. Dietary fiber also increased fecal excretion of fat and soap and depressed the digestibility of dry matter and energy. For pigs, diets containing tallow resulted in greater fecal energy concentrations than diets containing corn oil. Added calcium depressed digestibility of dry matter and energy. Pigs fed calcium with corn oil had greater average daily gain than pigs fed calcium with tallow. Results indicated that the caloric value of fat varies with fat source, calcium level, and dietary fiber content of the diet. Based on dietary records of human subjects, cardiovascular disease risk factors were more favorable with greater calcium intakes but unfavorable with greater fat intakes.