INFLUENCE OF REFINED KONJAC MEAL ON THE ABSORPTION OF DIETARY ZINC, IRON AND CALCIUM / 营养学报

ABSTRACT

The influence of refined konjac meal(RKM) on the absorption of dietary zinc, iron, and calcium in rats and human subjects was studied. RKM containing 75-80% glucomannan was prepared and refined from tubers of Amor-phophallus konjac K. KochMale and female SD rats aged 6 weeks were equally divided by randomized blocking into 5 groups of 10 (5M, 5F). The control group was fed on a basai diet, and the other four test groups were also fed on a basal diet but substituting 0.5%, 1%, 5%, or 10% of the RKM respectively for corn-starch. The feeding experiment lasted six weeks during which balance studies of the tested minerals were carried out at the end of every two weeks. At the end of the second week the absorption of zinc was significantly lower in the 5% and 10% RKM groups than that of the control group, but from the week on, the digestibility lowering effect of RKM disappered, perhaps on account of adaptation. As for iron or calcium, no digestibility lowering effect of RKM was observed during the whole experimental period. No reduction in serum levels of these three minerals was observed.Twelve young adult subjects (6M, 6F) participated in a 9-day feeding trial. For the first three days (control period), they were taken ordinary meals without RKM, but during the subsequent 6 days (test period), RKM was added to the ordinary meals in 3-gram increments every two days (i.e beginning with 3g per day for two days, then 6g per day for the consecutive two days and finally 9g per day for the last two days). Mineral analyses were conducted on the subjects' food and stool samples which were collected and weighed separately on the third and ninth day. Results obtaiud indicated that consuming a therapeutic dosage of RKM in association with meals did not influence the absorption of dietary zinc, iron or calcium.