Hypocholesterolaemic effects of soya proteins : results of recent studies are predictable from the Anderson meta-analysis data

In 1995, Anderson et al. published a meta-analysis, derived from most of the clinical studies on soya proteins given to individuals with varying levels of cholesterolaemia that had been reported up to that time. The meta-analysis clearly indicated that cholesterolaemias were generally reduced by diets with soya given as a partial or total substitution of animal proteins, with final mean total and LDL-cholesterol reductions of 23.2 mg/dl and 21.7 mg/dl, respectively. These findings were recently strongly criticised, based on the evaluation of later studies, frequently involving individuals with normal or moderately elevated cholesterolaemias. In the present paper, these more recent studies were re-evaluated using a 'nomogram' prepared on the basis of the quartiles of initial cholesterol concentrations in the Anderson meta-analysis and their corresponding CI for net cholesterol change. The five studies belonging to the first quartile and thirteen out of the fourteen belonging to the second quartile gave results perfectly in line with the nomogram. Out of the fourteen studies belonging to the third quartile, ten agreed with the nomogram and two gave lower cholesterol reductions, whereas two gave higher reductions. Unfortunately, none of the recent studies belonged to the fourth quartile as treatment with statins or other lipid-lowering drugs is now mandatory in the presence of very high cholesterol levels. The re-evaluation thus shows that the thirty-three studies published in the past 10 years are in agreement with the Anderson meta-analysis and confirm its validity.