Other studies have shown a link between soy products and bone mineral density but the new research is the first large study to investigate the association between soy consumption and the risk of fracture, write Dr Xiao-Ou Shu and colleagues in yesterday's issue of the Archives of Internal Medicine (vol 165, pp1890-1895).
The researchers selected data on around 24,000 postmenopausal women participating in the Shanghai Women's Health Study.
The subjects completed a food frequency questionnaire and at follow-up 4.5 years later, they were asked if they had suffered any fractures.
Higher soy protein consumption was significantly associated with lower risk of fracture, found the researchers, even after accounting for age, calorie intake, socioeconomic status, other nutrients, and osteoporosis risk factors.
The inverse association was more pronounced among women in early menopause, they add. For those within ten years of menopause onset the risk of fracture was reduced by 48 per cent among those with the highest intake of soy protein intake compared to those in the lowest consumption.
For women who had been menopausal for more than ten years, the risk reduction was 29 per cent.
Similar results were also found for intake of isoflavones, said the researchers.