Pectin is a fibre found mainly in the cell walls of fruits. Pectin is a soluble form of fibre, which means that in the aqueous environment of the gut, it absorbs water and forms a viscous gel-like substance. This transformation of the physical form of the pectin gives it some interesting physiological properties such as an ability to inhibit starch and sugar digestion rates and the ability to inhibit glucose absorption across the enterocyte surface. Both of these effects produce a significantly favourable effect on postprandial glycaemia, and this may have insulin sensitising effects. However, the digestive effects of pectin are not limited to its effects on glucose absorption rates. Pectin may also be able to increase the excretion of bile acids and steroids, which may explain its efficous activity at lowering plasma cholesterol levels. As cholesterol is a precursor to bile acid formation, increases in the excretion rates of the latter may divert cholesterol to the synthesis of replacement steroids at the expense of transport in the blood.
The ability of pectin to influence cholesterol metabolism has been demonstrated in the nutritional literature. For example, in one study1, nine healthy subjects were fed a diet containing 15 grams of pectin per day for 3 weeks. The rest of the diet was controlled between the treatment and no treatment period so that only the fibre content of the diet was different. After three weeks on the diet the subject experienced a 13 % decrease in cholesterol levels, a 44 % increase in faecal fat excretion, a 17% decrease in neutral steroid excretion, and a 33 % decrease in faecal bile acid excretion. Bile acids measured were lithocholic acid and deoxycholic acid, whereas neutral steroids were cholesterol and coprostanol. These results support other studies that show that modest additions of pectin fibre to the diet of healthy individuals are able to modify cholesterol metabolism favourably and provide significant health effects. The provision of pectin from dietary fruits may explain some of their health benefits.
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