Apparent absorption of copper and zinc from composite vegetarian diets in young Indian men

In order to identify the factors affecting apparent absorption of copper and zinc in vegetarian subjects, percent absorption of copper and zinc was estimated during 6 metabolic experiments, each of 2 weeks duration, carried out on 6 healthy young men. They were observed at 3 levels of energy, i.e. 9.2, 10.5 and 12.1 MJ/day. Intakes of zinc were in the range of 20.6-27.1 mg/day and the observed values of apparent absorption (intake-fecal output) were 11.2-20.3%. In case of copper, intakes were 2.7-5.2 mg/day while the apparent absorption was to the tune of 10.6-21.7%. These values of absorption were lower than those of the non-vegetarian diets. Multiple regression analysis of 17 dietary factors suggested that hemicellulose, milk protein, niacin and cereal protein act as significant enhancers in zinc absorption while thiamine, phytate, oxalates, ascorbic acid and phosphorus acted as inhibitors. Copper absorption was enhanced by the dietary levels of riboflavine, cellulose, milk proteins, oxalates and zinc, while phosphorus, niacin, calcium and pulse protein inhibited the absorption of copper.