Food and Drug Administration (FDA - USA)
The Food and Drug Administration (US) have approved a health claim (1) on the association between soya protein and reduced risk of coronary heart disease (CHD). The FDA concluded that there is enough evidence to demonstate that soya protein included in a diet low in saturated fat and cholesterol may reduce the risk on CHD by lowering the cholesterol blood levels. Coronary heart disease is the most common form of cardiovascular disease. Hypercholesterolemia is considered as an important risk factor. Epidemiological and clinical studies show that high blood levels of total cholesterol and LDL-cholesterol are important elements in the process of atherosclerosis and can lead to CHD.
Factors that decrease LDL-cholesterol and total cholesterol levels, will decrease the risk of CHD. An adequate diet and changes in food patterns can help.
In 1998 a petition was submitted to the FDA to approve a health claim on the relationship of soya protein and reduced risk of CHD.
The FDA considered the relevant scientific trials. The FDA concluded that there was a clinically significant decrease in total and LDL-cholesterol in the controlled trials that used at least 25g of soya protein per day (2). The hypocholesterolemic effect of soya protein was seen in addition to the effects of a low saturated fat and low cholesterol diet.
The degree of lowering of blood total cholesterol and LDL-cholesterol seems dependent on the initial levels. Persons having higher initial blood lipid level show the greatest effect. Concerning the role for soya isoflavones in the cholesterol-lowering effect of soya, the FDA was not convinced that the isoflavone content is a relevant factor. The FDA found the available evidence inconclusive. A clear relation was found between soya protein itself and the lowering of the cholesterol-level.
The authorisation by the FDA allows a soya protein containing product in the USA, which contains at least 6.25 g soya protein per serving (ie 25 g divided over 4 intakes) to label the health claim. The claim also mentions that the soya protein should be included in a diet low in saturated fat and cholesterol.
Joint Health Claim Initiative (JHCI – UK)
The JHCI was the official body that helped to ensure that health claims on food are scientifically accurate, legally acceptable and are not likely to mislead or confuse customers.
In July 2002 the JHCI (Joint Health Claims Initiative) in UK has approved a cholesterol lowering health claim for soya “the inclusion of at least 25g of soya protein per day, as part of a diet low in saturated fat, can help reduce blood cholesterol levels”. (See www.jhci.co.uk )
Evidence for the Claims
A systematic review undertaken in 1995 by Anderson et al (3) identified 38 studies published between 1977 and 1994, which investigated the effect of soya protein on serum cholesterol levels : 34 of the trials demonstrated that soya protein consumption resulted in a significant reduction in total and LDL cholesterol beyond that seen from a low fat diet. Using regression analysis Anderson estimated that 25 grams per day of soya protein would result in a decrease in total cholesterol of 0.23mmol/l (8.8 mg/dl). Melanie Ruffell, from the JHCI reports that in a more recent meta-analysis submitted to the JHCI, the average soya protein intake was 22.5g per day and the average reduction in total serum cholesterol was 0.22mmol/l (8 mg/dl). This is consistent with Anderson’s 1995 meta-analysis findings of a 0.23mmol/l (8.8 mg/dl) total cholesterol reduction at 25g soya protein ingestion.
In 1994, Law et al (4) concluded that on average each 1% reduction in cholesterol levels equates to a 2% reduction in CHD risk. Using the estimates from Law et al (4), lowering blood cholesterol by 0.22mmol/l (8 mg/dl) could result in a 10% CHD risk reduction. Interestingly, whilst soya protein significantly reduces total and LDL Cholesterol, HDL cholesterol has been shown to be maintained and in some trials to rise slightly.
- Federal Register Vol 64 no 206 Tuesday oct 26 1999 Rules and Regulation An important study in the evaluation by the FDA was the meta-analysis of Anderson; Anderson J.W., Johnstone BM, Cook-Newell MEl. Meta-analysis of effects of soy protein intake on serum
- FDA. Food labelling, Health Claims; Soy Protein and Coronary Heart Disease – Final rule. Federal Register 1999; 64: 57699-57733.
- Anderson JW, Johnstone BM & Cook-Newall ME. Meta-analysis of the effects of soy protein intake on serum lipids. New England Journal of Medicine 1995; 333: 276-282.
- Law MR, Wald NJ &Thompson SG. By how much and how quickly does reduction in serum cholesterol concentration lower risk of ischaemic hearty disease? British Medical Journal 1994; 308: 367-372.