Both the lifestyle and nutrient intake have been improving in Japan; however, it is recognized that a high energy and high fat intake can lead to possible health problems. Furthermore, the intake of vitamins and minerals still tends to be low, this having resulted in a considerable number of vitamin and mineral supplements appearing on the market and being claimed to be functional nutrients. Although the physiological functions of vitamins and minerals have been primarily established by evidence-based nutrition, the interactions of minerals and vitamins with other food factors remain unclear. This present study examines the effects of several food factors on mineral bioavailability by using animal models.In order to determine the effect of dietary egg on iron deficiency, weanling male rats were fed on a normal diet, an iron-deficient diet, and an iron-deficient diet supplemented with 5% egg powder. The hemoglobin (Hb) level was decreased, and the heart weight, hepatic copper concentration, and the activities of metallo-enzymes were increased by iron deficiency. However, the supplementation of 5% egg powder improved the effects caused by this iron deficiency. In another experiment, egg iron also improved the decrease in Fib level due to iron deficiency, this observation being similar to that with rats fed on a meat diet which contained heme iron.The level of phytate in tempeh, a fermented soy product, is reduced during the fermentation process, so the iron bioavailability of tempeh was compared with that of unfermented soybean by using iron-deficient weanling male rats. The antioxidative efficacy of tempeh was also examined. The results of this study confirmed that, compared with unfermented soybean, the fermented soybean tempeh increased the level of hepatic iron, an indicator of iron storage, without promoting lipid peroxidation in the iron-deficient rats.The level of phosphatidylcholine hydroperoxide (PCOOH) is increased in the liver of iron-deficient rats. In order to determine the antioxidative effects of dietary β-carotene and α-tocopherol, and their metabolism, weanling male rats were fed iron-deficient diets containing four different levels of β-carotene and three different levels of α-tocopherol. The increased PCOOH level due to iron deficiency was suppressed by the supplementation of β-carotene, although no dose-dependence was apparent. In contrast, the antioxidative efficacy of α-tocopherol was reduced in the liver and plasma of the iron-deficient rats. The metabolism of both β-carotene and α-tocopherol was inhibited by this iron deficiency.Fructooligosaccharides (FOS), indigestible sugars, are well known enhancers of mineral absorption by the large intestine. It was found that FOS increased the bioavailability of daidzein, a major isoflavone found in soybean, and enhanced the transformation of daidzein to equol, a more biologically active metabolite than daidzein, by stimulating the intestinal microflora in rodents. Equol may have a beneficial effect on bone loss in rodents from osteoporosis and osteonenia models.Magnesium (Mg) deficiency induces kidney calcification, bone loss and hyperlipidemia in rodents. On the other hand, hesperidin, a citrus flavonoid, regulates hepatic cholesterol synthesis by inhibiting the activity of 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase. It has been reported that statins, cholesterol-lowering agents, induce bone formation and inhibit bone resorption in vitro and in vivo. Thus, the effects of hesperidin and α-glucosyl (αG) -hesperidin, which is 10, 000 times more soluble in water than hesperidin, on bone and lipid metabolism was examined in Mg-deficient rats. Hesperidin administration not only reduced the cholesterol level in the serum and liver, but also inhibited bone loss.
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Dec 1, 2008
Aline S Demaman + 2
Open Access