Effects of Feeding Potato Pulp on Cholesterol Metabolism and Its Association with Cecal Conditions in Rats

Abstract

To clarify the functional properties of potato pulp (PP), a waste product resulting from extraction of starch from potatoes, we examined the effects of PP on cholesterol metabolism and cecal conditions in rats. Plasma total cholesterol (T-Chol) levels were lower in rats fed a PP-supplemented diet for four weeks than in those fed a control diet. Cecal pH was lowered due to an increase in the levels of cecal total short-chain fatty acids, especially butyrate, in the PP group compared to the control group. Furthermore, animals fed with the PP-supplemented diet showed increased cecal ratios of Lactobacillus and Clostridia and decreased cecal ratios of Bacteroides and Gammaproteobacteria with slightly negative and positive correlations with plasma T-Chol levels, respectively. In conclusion, ingestion of PP for four weeks is likely to improve both cecal conditions and cholesterol metabolism, suggesting that PP has prebiotic effects.

Effect of Potato Ethanol Residue on Rat Plasma Cholesterol Levels

“…Plasma cholesterol levels and fecal cholesterol and total bile acid levels were measured as reported previously. 4) Real-time polymerase chain reaction (PCR) was conducted to determine the abundances of mRNAs:…”

“…Conceivably, cecal fermentation of DFs and/or intestinal bacteria also improve cholesterol metabolism. 3,4,13,14) The DF fraction of PER or PP, more than induction of hepatic mRNAs, might have promoted the excretion of cholesterol directly or via fermentation in the cecum. The hepatic mRNA levels of low-density lipoprotein receptor (Ldlr), hydroxymethylglutarylcoenzyme A reductase (Hmgcr), sterol regulatory element binding proteins (Srebf1 and Srebf2), and apolipoproteins (Apoa1 and Apob) were not changed by the present diets (data not shown).…”

“…4) The present PP diet contained half of the amount of PP used in the previous study, 4) to mimic a regular diet. 7) Thus, high-level administration of PP might improve the plasma cholesterol level via higher expression of hepatic Cyp7a1 mRNA, whereas an increase in fecal steroids may require the administration of PP for more than 4 weeks.…”

“…Byproducts derived from crops often contain dietary fiber (DF), which has been reported to have physiological functions. [2][3][4] Blood cholesterol is known to be a risk factor for atherosclerosis and cardiovascular disease, 5) and lowering its level is desirable. In Japan, potatoes are sometimes used in producing alcoholic beverages such as shochu.…”

“…Potato pulp (PP), a by-product of potato starch processing, contains an abundance of DF and has similar effects in rat. 4) By-products of potato ethanol production might also have a cholesterol-lowering effect although their effects on cholesterol metabolism have never been demonstrated. In this study, we investigated the effect of a potato ethanol residue (PER) on cholesterol metabolism in rats.…”