Fibre was once considered little more than roughage for the gastrointestinal tract. However, advances in nutritional science has shown fibre to be a complex and heterogeneous group of compounds with diverse effects. Many studies have investigated the effects of various fibres and found protective effects from a number of diseases, particularly Western lifestyle disease. This protective effect may be due to the low fibre content of the Western diet. The diverse effects of fibre are dependent on the diverse chemical structure of the particular fibres. Aside from the main categories of soluble and insoluble fibres, there exists a large number of smaller classifications for dietary fibres. Oats possess mainly soluble fibre and part of this comprises of a compound called oat β-glucan (OBG). Oat β-glucan is thought to be responsible for the potent cholesterol lowering effects of oats. It has been suggested that β-glucan is also responsible in part for the cardio protection that is seen in those who regularly consume oats.
A number of studies have been performed on the cholesterol lowering effects of oats. Included in this list of studies are a large number of clinical trials that have administered either oats or isolated β-glucan to human subjects in order to investigate the lipid altering properties of the oat fibre. These studies have subsequently been analysed using a meta-analysis1. The results of this analysis showed that doses of over 3 grams of β-glucan reduced low density lipoprotein (LDL) cholesterol and total cholesterol by around 0.25 mmol/L and 0.30 mmol/L, respectively, relative to the control. The results also showed that there was considerable variation seen in the response of subjects to β-glucan consumption. In addition, the researchers noted there was no observable effect of oat β-glucan on high density lipoprotein (HDL) cholesterol or triglyceride levels. This suggest that part of the beneficial lipid lowering effects of regular oat consumption may come though the β-glucan content of oats.
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