Pectin with low molecular weight and high degree of esterification increases absorption of 58Fe in growing rats

Effects of pectins with different degrees of esterification (DE) and molecular weights (MW) on iron bioavailability were investigated in healthy growing rats by following erythrocyte incorporation of a dose of 58Fe. Rats were fed a control diet for 8 d and then deprived of food for 16 h. Two hours after the start of feeding iron-deficient diets, with or without pectin (80 g/kg diet), a dose of FeSO4 rich in 58Fe (60.28%) was intubated into the stomach; rats were then allowed to feed for an additional 4 h before withdrawal of food for 10 h. Rats were then fed iron-adequate diets for 9 d. The pectins differed in DE and MW, respectively, as follows: P-A (73%, 860,000), P-B (75%, 89,000), P-C (22%, 1,260,000) and P-D (24%, 114,000). Rats fed pectin-free diet with free access to food or restricted to the same quantity consumed by a respective pectin group served as controls. Iron absorption was 48% in the control group and 57% in rats fed P-B. Rats fed P-B had higher (P 2 < or = 0.05) serum iron, transferrin saturation, hematocrit and liver and spleen iron than the control group or the group fed P-C. These indices, except for transferrin saturation, were also higher In rats fed P-A and P-D compared with those fed P-C and controls, but to a lesser extent than in rats fed P-B. The data indicate that bioavailability of dietary non-heme iron was enhanced when pectin of low MW and high DE was added to the diet. This improvement was not evident with pectins having high MW and/or low DE.