A diet rich in the types of protein and isoflavones found in soybeans may protect women undergoing menopause against bone loss and osteoporosis.
This was the preliminary finding of a study, by researchers from the University of Hull in the UK, presented at the Society for Endocrinology annual conference, which is being held this week in Edinburgh.
Osteoporosis is responsible for some 9 million fractures a year worldwide - or one every 3 seconds. The disease is more common in women. Bone loss occurs more rapidly in women after menopause because they produce less estrogen, a sex hormone that also protects against bone loss.
Soybeans contain isoflavones, compounds that have a chemical structure that is similar to estrogen. This has led scientists to speculate that they may therefore have a similar effect on bones.
The study recruited 200 women in early menopause and randomized them to two groups. In one group, the women took a daily supplement of 30 g soy protein with 66 mg isoflavones, and in the other group, the women also took a daily supplement of the same amount of soy protein but without the isoflavones.
Soy protein with isoflavones linked to lower bone loss
Over the 6 months that the women took the supplements, they gave blood samples from which the researchers could measure markers of bone turnover.
- Worldwide, osteoporosis affects 1 in 3 women, and 1 in 5 men aged over 50
- A 10% loss of bone mass in the hip can result in a 2.5 times greater risk of hip fracture
- Most fractures occur in postmenopausal women and elderly men at moderate risk.
One of these is the protein βCTX, a marker of bone resorption, the process that breaks bone down and releases its minerals into the bloodstream.
The results showed that the women whose daily supplement contained soy protein and isoflavones had significantly lower levels of βCTX than the women whose daily supplement only contained soy protein, suggesting they had a lower rate of bone loss and thus a lower risk of developing osteoporosis.
The women who took soy protein and isoflavones supplements also showed an improvement of cardiovascular risk markers, note the researchers.
Lead author Dr. Thozhukat Sathyapalan, of Hull's department of academic cardiology, says:
"We found that soy protein and isoflavones are a safe and effective option for improving bone health in women during early menopause. The actions of soy appear to mimic that of conventional osteoporosis drugs."
He explains that the 66 mg of isoflavone in the daily supplements that the women took is about the same as that consumed in an oriental diet, which is rich is soybean foods. The average Western diet, on the other hand, only contains around 2-16 mg of isoflavone.
Dr. Sathyapalan suggests supplementing a Western diet with isoflavones could be a way to significantly lower the rate of women being diagnosed with osteoporosis.
He and his colleagues now plan to study the longer-term effects of soy protein and isoflavones supplements, and whether they bring other health benefits.
Earlier this year, Medical News Today learned of a JAMA Internal Medicine study that suggests postmenopausal women who take high-dose vitamin D might not experience the benefits they expect, such as improvements in bone mineral density, muscle mass or muscle function.