FOS - Prebiotic fibres
Fructo-oligosaccharides (FOS ) increase the number of Bifidobacteria and Lactobacilli, which are beneficial bacteria for health, and reduce the number of Clostridia, which are of little use and sometimes harmful.
An in vitro study showed that fructooligosaccharides increase the growth and promote the production of lactic and acetic acids of the following Bifidobacteria strains B. longum, B. adolescentis, B. bifidum, B, infantis e B. breve.
A study in the rabbit evaluated the effects of FOS on the gastrointestinal system. They received a diet supplemented with either 0 or 25 or 50 g/kg FOS for 1 month. It was seen that FOS at the highest dose lowered the ileal pH and promoted hydration of the food bolus (p<0.05). FOS at both dosages reduced bacterial populations of anaerobes and instead favoured those of Lactobacilli and Bifidobacteria, increasing levels of short-chain free fatty acids in the colon. The higher dose of FOS also reduced plasma levels of total cholesterol and triglycerides and increased those of HDL cholesterol. The study indicates that FOS have several positive effects on the rabbit Gut.
Numerous clinical studies have demonstrated the usefulness of FOS as prebiotics also in humans. In fact they promote the development of bacterial flora positive at the expense of the negative in children and adults. They can also be used in pregnant and lactating women.
In summary, the data in the literature indicate that prebiotics do not undergo enzymatic digestion in the upper gastrointestinal tract and arrive at the cecum with their structure unmodified. However, they are not found as such in faeces, indicating that they are degraded by the intestinal flora to a mixture of short-chain fatty acids (acetic, propionic and butyric), L-lactate, carbon dioxide and hydrogen. They greatly stimulate the proliferation of Bifidobacteria and inhibit that of anaerobes, particularly Clostridium perfringens, and other pathogenic bacteria such as Escherichia coli, Salmonella species, Listeria and Shigella. They tend to improve lipid and glucose metabolism. They reduce the risk of colorectal cancer and nitrogen absorption, thus reducing the nitrogenous waste load in the kidney. They also have little cariogenic effect on the teeth.
Recent research indicates that FOS increases butyric acid levels in the large Gut, and this substance is known to have protective action against inflammatory and neoplastic diseases of the colon.