Improvement of Bone-Sparing Effect of Soy Isoflavones by Pre- and Probiotics in Postmenopausal women

Abstract

Background Phytoestrogens consumption is targeted as a possible way to achieve hormonal permeation in postmenopausal women. However, their health effect could depend on their bioavailability. Objectives As phytoestrogens bioavailability could be improved by modulating intestinal microflora, the present study was undertaken to investigate whether isoflavones and pre-or probiotics may improve bone markers. Design An intervention trial (2 months) was carried out on 39 postmenopausal women receiving 100 mg of IF aglycon equivalents daily, incorporated in two jelly milk and two cereal bars. After the first month, the participants were randomised into three treatment groups: soy (control group), soy + fructooligosaccharides (prebiotics group) and soy + yoghurt cultures (probiotics group). Results Level of isoflavone intake was associated with a significant increase in plasma isoflavone levels from baseline to day 15 which was maintained until day 60. Probiotics consumption was associated with increased plasma equol levels at day 60. A 5% increase of bone alkaline phosphatase was elicited on day 30, compared to initial values. Pre- or probiotics did not modulate this parameter. Urinary deoxypyridinoline excretion was slightly increased at day 60. Prebiotics and probiotics consumption improved this parameter. The effect of prebiotics was exacerbated in early compared to late postmenopausal women. Conclusion Addition of prebiotics or probiotics to a diet providing isoflavones is able to improve parameters of bone turnover in early menopause.