The statins are a group of drugs that inhibit the rate limiting enzyme (HMG-CoA reductase) in the cholesterol synthesis pathway in humans. The medical establishment claims that statins are effective at lowering elevated plasma lipoprotein levels, particularly low density lipoprotein, and the results from many clinical trails are cited as evidence for the efficacy of the drugs. However, there are a number of problems associated with statin use that suggest their benefits have been exaggerated. Side effects are common with the drugs, and in particular they appear to deplete the body of coenzyme Q-10, which can result in severe skeletal muscle pain. Some statins are now packaged with coenzyme Q-10 because of this problem. Also, statins use does not confer survival advantages for those who use them because although cardiovascular mortality decreases through treatment, mortality from other causes increases, such that total mortality is not significantly different.
The fact that beans and oats are as effective at lowering elevated plasma lipoprotein levels when compared to statins is however, the single most important factor that argues against statin use. Supplementing hypercholesterolaemic individuals with soluble fibre derived from certain types of beans or oats has been shown to be as effective as statins at lowering plasma lipoproteins in clinical trials. While the effects of statins in studies looks impressive, the results of trials are often reported by using relative risk, which is a ratio of the absolute risk in the treatment and control groups. Comparison of the data showing actual reductions in plasma cholesterol and the absolute risk of cardiovascular events between statin and fibre shows little difference in their effects. When the cheap cost and lack of side effects are considered, dietary fibre therefore compares very favourably to statin treatment for its lipoprotein lowering effects.
The research regarding the use of fibre to lower plasma lipoprotein levels has been extensively reiewed1. Studies suggest that lowering cholesterol by 1 % is associated with a 2 % reduction in cardiovascular disease. High fibre diets including bean and oat soluble fibre may be able to lower plasma cholesterol levels by 11 to 32 % as shown by long term studies. Adding bean or oat fibre to a diet with no other changes can lower plasma cholesterol by 12 to 26 %. These effects can be seen as quickly as 3 weeks after dietary changes are implemented. Chick peas have been shown to lower plasma cholesterol by 23 %, whereas guar gum from Indian cluster beans lowered plasma cholesterol by 0.85 mmol/L compared to wheat bran. In oats, β-glucan is thought to be the main fibre component responsible for its plasma lipoprotein effects.
Soluble fibre probably lowers cholesterol by binding to bile acids, preventing re-absorption through enterohepatic recirculation. In response, the liver increases the cholesterol available to synthesise bile acids and this decreases the cholesterol available for lipoprotein synthesis. This explains the reduction in all lipoprotein sub-classes with soluble fibre supplementation. Additionally, soluble fibre is metabolised by colonic microflora to short chain fatty acids (SCFA) such as propionate, butyrate and acetate. These are absorbed into the portal circulation and can inhibit cholesterol synthesis directly. The SCFA produced in the colon may also inhibit cholesterol synthesis in peripheral tissues, which causes increased LDL receptor upregulation and increased cholesterol clearance from plasma. The exact mechanisms of action may depend largely on the type of fibre and its digestive fate. The benefits of datary fibres are magnified when considering they can also cause weight loss, improve glycaemic control, reduce fasting triglycerides and lower blood pressure.
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