HIGHLY ESTERIFIED PECTIN WITH LOW-MOLECULAR-WEIGHT ENHANCES INTESTINAL SOLUBILITY AND ABSORPTION OF FERRIC IRON IN RATS

The effects of the degree of esterfication (DE) and the molecular weig ht (MW) of pectins on intestinal solubility and absorption of ferric i ron were investigated in vivo and in vitro. The pectins prepared diffe red 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). All the rats were fed a basal diet containing ferric sulfate as an iron source for 7 d. Rats were deprived of feed for about 19 h and then fed 68 (based on the preliminary experiment) of the basal diet or basal diet contai ning one of pectins (80 g/kg diet) for 2 h. One hour later, soluble, i nsoluble and tissue iron concentrations in both stomach and intestinal segments and serum iron concentration in portal blood were determined and the amounts of absorbed iron were calculated. Addition of pectin B to the diet resulted in significantly greater intestinal iron absorp tion and postprandial iron concentration in portal blood compared to t he other groups. There were no significant differences in calculated a bsorbed iron and serum iron concentration in portal blood between cont rol and other pectin groups except those fed pectin B. When ferric sul fate was added to the pectin solutions and pectin diets in vitro under simulated gastrointestinal condition, more iron was found in the solu ble fraction compared to control containing no pectin (P < 0.05). Solu bility of ferric sulfate in vitro was also significantly greater in bo th the solution and diet containing pectin B than in those containing no pectin (P < 0.05). The present findings clearly indicate that iron solubility was influenced by pectin's DE and MW. The pectin with the h igh DE and low MW enhanced ferric iron solubility and absorption of so lubilized iron. (C) 1998 Elsevier Science Inc.