Effect of dietary fiber on mineral absorption in growing rats.

The effect of "indigestible" polysaccharides fed at the 10% level in a semi-synthetic diet on absorption of Ca, Fe, Zn, Cu, Cr and Co, on weight gain and on fecal dry matter excretion was studied over a period of 8 days in five groups of 12 weanling male rats each and compared to a control group. Carrageenan (C) and agar-agar (AA) reduced absorption of all minerals tested, Na-alginate (NA-A) decreased Fe-, Cr- and Co-absorption, carob bean gum (CBG) and gum guar (GG) interfered with the absorption of Zn, Cr, Cu and Co. In a second study the long-term effect of GG and AA-ingestion at the 10% dietary level on mineral absorption was investigated during three 4-day balance periods of a 21-week feeding trial in 24 young rats. Mineral content of rat carcasses, assayed at the termination of the experimental period, did not reveal any significant differences between controls and animals fed AA or GG, suggesting that the rat is able to compensate for the increased fecal losses, presumably by reduced urinary losses. Ingestion of AA, C or Na-A resulted in a marked increase of fecal dry matter, indicating that hardly any of these substances were degraded, whereas a considerable portion of GG and CBG was metabolized, presumably due to the action of intestinal bacteria.