Intestinal absorption of zinc is promoted by low-level intake but inhibited by high-level intake of corn husk fiber in rats
2001
Hara, Hiroshi | Hayashi, K. | Aoyama, Y.
We examined the effects of feeding several types of insoluble dietary fiber (100 g/kg diet), including cellulose (control), wheat bran (demineralized), sugar-beet fiber and corn husk fiber, on zinc absorption in rats. Zinc absorption was higher after intake of a zinc-deficient diet (0.229 mmol/kg diet) containing corn husk fiber than that after intake of a cellulose-containing diet for 3 wk. Ingestion of wheat bran or sugar-beet fiber did not influence zinc absorption. We compared the effects of cellulose and demineralized- and washed-corn husk fiber at graded levels in the diets (1, 2 and 3 parts to 10 basal diet). Zinc absorption in rats fed the diet with the lowest level of corn fiber was higher than that in rats fed a diet with the same level of cellulose or a fiber-free diet (control). In rats fed the diets with higher levels of corn fiber, the zinc absorption was lower than that in rats fed either the diet with the lowest level of cellulose or the fiber-free diet in the period day 9-12, however, reduced absorption that occurred upon intake of the high-fiber diet recovered in the period day 18-21. Cecal fermentation and the bulking action of corn husk fiber may not be responsible for the zinc absorption-promoting effect of the dietary fiber. In conclusion, corn husk fiber is effective in increasing zinc absorption when ingested at low levels, but absorption is inhibited upon intake at higher levels in rats.
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