Soy isoflavones for the relief of climacteric symptoms in women with breast cancer or in whom estrogen replacement therapy is not recommended

By Giorgio Secreto et al, Maturitas 47 (2004): 11-20

HRT may be contraindicated or not advisable in postmenopausal women who have or had breast cancer, women with a family history for breast cancer, or women who stopped HRT after 5 years of treatment. Soy isoflavones may be a natural alternative for them. Verifying the efficacy of soy isoflavones for the relief of menopausal symptoms in these women, also means a safety assessment with regards to potential adverse effects.

Study design

In a randomized, multicenter, double blind, placebocontrolled study, 232 postmenopausal women participated and completed the study. Their last menses had been at least 6 months before the start of the study. They had not undergone chemo or hormone therapy for at least 3 months. The participants were randomized in 4 groups: the first group using 2 x 40 mg isoflavones (as glucosides) from the soy germ extract SoyLife EXTRA, the second group using 3 mg of melatonin, the third group receiving a combination of both treatments, and a placebo group. Blood samples were taken before and after the study period of 3 months. The severity of menopausal symptoms was recorded using the Greene Climacteric Scale (GSC) in week 0 and after 3 months. The GCS includes a validated questionnaire listing 21 symptoms in the following categories: 11 psychological symptoms (anxiety and depression), 7 somatic, 2 vasomotor symptoms and 1 sexual dysfunction parameter.


The isoflavone groups showed significant reductions in Greene climacteric scores, both as a total score and per subgroup of symptoms. Their reduction in symptoms was slightly larger than the placebo group. Isoflavone supplementation could especially be related to improvement of vasomotor symptoms.

Blood analysis showed no indication of increased risk factors associated with breast cancer. This is measured by analyzing if isoflavones exerted an estrogenic effect, which is undesired in women with breast cancer risk.

In conclusion

SoyLife EXTRA was shown to improve some menopausal symptoms without altering the risk for breast cancer in high-risk women. Although this does not automatically imply that high-risk women should be advised to use isoflavones, this suggests that SoyLife may be a safe natural alternative for women who are not advised to take HRT.