The degree of polymerization of inulin-like fructans affects cecal mucin and immunoglobulin A in rats.

Cecal amounts of mucin and immunoglobulin A (IgA) were examined through the cecal fermentation pattern in Wistar (WS) or Sprague-Dawley (SD) rats fed inulin-type fructans differing in their degree of polymerization (DP). The animals were fed a control diet or a diet containing one of the fructans with an average DP of 4, 8, 16, or 23, at 60 g/kg diet for 10 d. Cecal fermentation products substantially differed between WS and SD rats fed DP8 fructan, with short-chain fatty acids (SCFAs) as the major organic acids in the former but lactate predominating in the latter. Cecal fermentability of fructans in both strains generally decreased with increasing DP of fructans, and this was especially manifest in reduction of the amounts of lactate in DP16 and 23. In WS rats, cecal mucin and IgA were greater in all fructan groups than in the control group. In SD rats, cecal mucin was greater only in the DP8, 16, and 23 groups as compared to the control group, while IgA was greater in the DP4 and 8 groups. In both strains, cecal mucin correlated with the sum of cecal SCFAs, but not with lactate, succinate, or total organic acids. In contrast, only cecal lactate correlated with cecal IgA in both strains. The present study shows that the different fermentation patterns of fructans affect cecal mucin and IgA; mucin is likely to respond to cecal SCFA production, whereas IgA increases when fermentation occurs rapidly and lactate is a major fermentation product.