Soluble fiber extracted from potato pulp is highly fermentable but has no effect on risk markers of diabetes and cardiovascular disease in Goto-Kakizaki rats

The cholesterol-lowering and hypoglycemic effect of dietary fiber are commonly attributed to soluble fiber fractions. By enzymatic treatment of potato pulp, which is rich in cellulose and pectin, we prepared 3 fractions with different chemical composition and solubility, and compared their effects with commercially available crystalline cellulose (negative control) on central parameters related to risk factors of diabetes mellitus and cardiovascular disease in diabetic prone Goto-Kakizaki rats. Forty male rats were fed a semisynthetic Western-type diet containing 5% dietary fiber in the form of concentrated potato fiber (CF), insoluble potato fiber (IF), soluble fiber (SF), or cellulose (CEL) ad libitum for 4.5 weeks to study weight change and induce diabetic conditions. This was followed by 16 days of slightly restricted feeding, for the measurement of fecal organic matter digestibility, fecal dry matter, urinary glucose excretion, and fasting blood glucose. Finally, the rats were euthanized 2 hours postprandial for measurement of postprandial glucose, triacylglycerol and cholesterol levels, and cecal fermentation pattern to assess any relation between digestion processes and hematological risk markers. Diet SF had higher fecal organic matter digestibility and led to a significantly larger pool of organic acids with a higher proportion of propionate than the other diets. There was no difference in hematological parameters except for a small but significant reduction in postprandial plasma triacylglycerol concentration of rats fed diet SF compared to diet CEL and diet CF. In conclusion, increased fermentation and production of propionate with diet SF did not reduce plasma cholesterol or glycemic response.