Effects of soy on health outcomes.

Authors' conclusions A wide variety of soy products and formulations have been investigated for a large number of conditions. However, a large proportion of the studies suffer from poor reporting or study design, limiting conclusions. Soy products appear to exert a small benefit on LDL and triglycerides; these effects may be of small clinical effect in individuals, although possibly large enough to have a population-wide effect. The inconsistent association between soy protein dose and effect, and the lack of association between soy isoflavone dose and effect, limit possible determination of an appropriate amount of soy product needed for lipid reduction. Soy products may reduce menopausal symptoms in postmenopausal women. The current literature does not support other effects of soy products. However, other than menopausaland menstrual-related symptoms, no clinical outcomes were evaluated. The evidence from human studies does not suggest any worrisome adverse events beyond mild gastrointestinal intolerance. Conclusions were often limited due to small numbers of studies or heterogeneity across studies.