The most recent findings on soy and isoflavones were presented in Washington DC on the occasion of the 9th International Symposium on the Role of Soy in Health Promotion and Chronic Disease Prevention and Treatment (October 16-19, 2010). A major part of the topics was dedicated to safety and health benefits in menopausal women, and to the issue of soy and breast cancer.
Dr. Janice Harland (HarlandHall Associates, UK) reported on the most recent experience with the European Food Safety Authority (EFSA) in the rejection of a health claim application for soy protein and cardiovascular disease (Harland 2010). A meta-analysis of corresponding clinical trials had previously been published (Harland et al. 2008).
According to the EU rules, all health claims are forbidden if not explicitly allowed by a positive opinion of the EFSA. The health claim application had only considered trials in healthy adults with normal to mildly elevated blood lipids, consuming 12 to 25 g of soy protein. The original threshold of < 40 g had to be reduced as required by EFSA, as the target was an intake of 25 g. In addition, no studies with isolated isoflavones were considered for the application. Isoflavone-depleted soy protein was excluded by the applicant as such preparations are not regular food constituents, and as the procedure of alcohol-washing would also remove other potentially relevant constituents than just isoflavones. However, EFSA required that studies with isoflavone-depleted protein should be included.
Of originally 180 studies (including 10 observational trials) 23 studies were selected according to the criteria. The analysis of these studies resulted in an LDL reduction by 0.22 mmol/l, equivalent to a 5.5 % reduction, with no clear difference between study outcomes in the range of 12-25 g of soy protein daily. Isoflavone contents were not significantly associated with LDL reduction (average content 1-2 mg/g protein). The observed reduction would translate into a 25 % lower risk of cardiac death for consumers of soy protein.
However, of these 23 analyzed studies the EFSA considered only four studies as pertinent to the health claim, and only two as relevant – both performed with isoflavone-depleted soy protein, and both with unconvincing results. As a consequence, EFSA considered the cause-effect-relationship as not established and has rejected the claim. The discussion is still ongoing, and many associations have filed their protest to the EU commission.
References
Harland J (2010). Systematic review and meta analyses to support a cholesterol-lowering claim for soy protein in the European Union. 9th International Symposium on the Role of Soy in Health Promotion and Chronic Disease Prevention and Treatment, Washington DC, 16-19 October.
Clinical effects 