Isoflavones are a category of phytoestrogens and daidzein is one type of isoflavone.
Intestinal bacteria metabolise daidzein into the active equol. It has been suggested that the health benefits of dietary isoflavones depend on individual differences in the ability to produce equol in the intestines — an ability that is generally greater in Asians and in vegetarians.
In addition, direct supplementation with equol (10mg/d) has demonstrated benefit for menopausal symptoms in previous clinical trials.
Resveratrol is another polyphenolic phytoestrogen, known also for its anti-inflammatory, immunomodulatory and antioxidant properties. Resveratrol has never been evaluated in the context of symptoms associated with menopause.
A randomised, placebo-controlled trial, published by Davinelli, et al., in Maturitas (2017) evaluated the effects of combined supplementation for 12 weeks with equol and resveratrol in recently menopausal women (aged 50-55 years) with hot flushes, anxiety and depressive symptoms.
The product (Equopausa D) provided 200mg of fermented soy (including 80mg of isoflavones and 10mg of equol) and 25mg of resveratrol (from Vitus vinifera).
All symptoms on the Menopause Rating Scale improved in the active treatment group. When compared with the placebo, equol and resveratrol supplementation produced significant improvements in vaginal dryness, heart discomfort, sexual problems, depression and sleep.
One concern related to phytoestrogen supplementation in menopausal women is their potential to stimulate estrogen receptors on breast or endometrial tissue.
Nonetheless, recent clinical trials of equol supplementation in menopausal women have failed to demonstrate an increase in breast cancer risk or endometrial hyperplasia.
Studies of resveratrol suggest that has favorable effects on estrogen metabolism and circulating sex steroid hormones, offering some protection against breast cancer.
The authors of the current study conclude that the synergistic combination of equol and resveratrol may offer a natural option for managing symptoms associated with menopause.
