Blood cholesterol reduction Foods that are high in viscous fibres have been found to lower
blood cholesterol by binding with
bile acids. In order to compensate for this,
cholesterol from the liver may be used to make more bile acids. The products of bacterial fermentation in the colon may also decrease the rate of cholesterol synthesis in the liver. However, research has produced mixed results with respect to whether fibre supplements are as effective as
dietary fibre in reducing
blood cholesterol. Two recent studies show nearly opposing results, using fibre-supplemented apple juice containing both the soluble pectin from apples and gum arabic. In the first study, the supplement-enriched juice had no discernible effect on the blood cholesterol levels of 110
hypercholesterolaemic men and women. In the second study, the total and
LDL-cholesterol levels of mildly hypercholesterolaemic men were lowered. In another study, a dietary supplement consisting of both
soluble fibre (guar gum, pectin) and insoluble fibre (soy fibre, pea fibre, corn bran) was found to reduce
LDL-cholesterol for individuals that have mild to moderate hypercholesterolaemia without reducing
HDL-cholesterol or increasing
triglycerides. Supplements containing extracted
insoluble fibre may have an effect on
blood lipids that most resembles the effects of dietary fibre. In a more recent randomized, double blind clinical study of 58 hypercholesterolaemic volunteers, an extruded
carob pulp preparation added to daily diet reduced total and
LDL-cholesterol and improved the ratio of
HDL:LDL cholesterol in all participants, and also showed a marked reduction in
serum cholesterol in the women of the study.
Gastrointestinal health Colorectal cancer The protective properties of
dietary fibre against
colorectal cancer are undisputed. However, not all fibre supplements seem to provide the same defensive effect. A study of 1429 men and women over six months showed that a high-fibre cereal (
wheat bran) supplement had no protective effect on recurring colorectal
adenomas. In addition, no significant improvement in the proportion or features of existing colorectal adenomas was observed.
Diverticular disease Diverticulitis is mainly attributed to the low fibre intake commonly found in the Western diet for which a gradual increase in dietary fibre over several weeks is a commonly prescribed clinical solution. Fibre supplementation has been found to be less effective than dietary fibre in this regard. One study of 58 men and women with uncomplicated diverticulitis in a double-blind controlled trial concluded that common doses of wheat bran and a
psyllium-derived supplement provided relief of constipation only, with no other observable effects.
Irritable bowel syndrome Irritable bowel syndrome (IBS) is a common gastrointestinal ailment for which dietary soluble fibre is often prescribed as part of a therapeutic solution. As a supplement, partially hydrolysed
guar gum (PHGG - completely soluble, fully fermentable) has been shown to be quite effective in clinical trials for decreasing IBS symptoms such as abdominal pain and generally improving quality of life for sufferers well beyond treatment. In addition, PHGG has been shown to have prebiotic properties by acidifying bowel contents and increasing
gut microflora. Acacia senegal fiber (
gum arabic - completely soluble, fully fermentable) has also been shown to have a prebiotic effect in the gut, significantly increasing Bifidobacteria and Lactobacilli after 4 weeks of consumption. Acacia ferments very slowly in the gut, and due to its polymeric nature does not disturb osmotic pressure, so it has a good gastrointestinal tolerance (it has no sudden and painful release of gas, and the total gas production is much lower than with
fructooligosaccharide, for instance) and does not present any side effects at dosages up to 50 grams per day. Particularly helpful for IBS is that Acacia senegal behaves as a regulator; it is able to reduce diarrhea and reduce constipation.
Weight management It has been suggested that the refining of fibre-rich grains has contributed to the
obesity epidemic of
Western countries. Whole,
dietary forms of fibre are more difficult to ingest and absorb than milled and refined food products. This is because dietary fibre may be able to displace available
calories and
nutrients, requires more time for chewing (thereby slowing intake rate and inducing
satiety), and reduces the efficiency of absorption in the
small intestine. Supplemental forms of fibre have been shown to potentially assist
weight management by increasing
satiety, decreasing the absorption rate of starches and sugars, and binding to lipids in the small intestine thereby reducing serum
triglycerides and
chylomicron. Powdered
guar gum, a
soluble fibre, was shown to be associated with a significantly lower energy intake in
obese subjects who ingested a non-restricted diet over one week, when the same participants did not consume the fibre supplement. Fibre supplementation has also been indicated to assist compliance to low-calorie diets, as indicated through decreased feelings of
hunger and increased ratings of
satiety. ==Side effects==