Wisdom Wednesday: A Soy-based Diet Could Help Strengthen Bones

A new study has investigated the impact of dietary soy on bone strength in postmenopausal women. The authors conclude that eating more soy might in fact strengthen bones in women of all ages.

The reduction in bone density and strength that is common in postmenopausal women is of huge concern. As women age, osteoporosis, reduced activity levels, and weight gain act together to decrease bone health and negatively impact metabolism. Osteoporosis and bone weakness increases the risk of fractures, which then lead to even more inactivity and weight gain, exacerbating the issue further. As the population becomes – on average – older and heavier, bone health is an important area of medical science to study.

To investigate, researchers from the University of Missouri in Columbia utilized so-called low-capacity running rats, which have lower fitness levels.

The researchers surgically removed the ovaries of half of the rats to mimic menopause. The scientists fed half of the rats a soy-based diet and the remaining animals a corn-based diet. Both diets contained the same amount of calories. They weighed the rats every week for the duration of the 30-week trial.

Then, the team took blood samples, tested bone strength, and assessed body composition. The analysis showed that, although turnover markers were not significantly altered, the leg bones of soy-fed rats were stronger than the bones of the rats that were fed a corn-based diets.



The study also showed that the soy-based improvement in bone strength occurred in rats with and without ovaries; the authors write that, in both sets of rats, soy “significantly improved whole-bone strength and stiffness.” In other words, even “postmenopausal” rats’ bones benefited from the change in diet.

As Prof. Pamela Hinton, lead study author concludes, “The findings suggest that all women might see improved bone strength by adding some soy-based whole foods, such as tofu and soy milk, to their diet. We also believe that soy-based diets can improve metabolic function for postmenopausal women.”

My Take:
I would suggest that comparing a protein-based diet (soy) against a carbohydrate-based diet (corn) shows that increased protein helps build and maintain bone. Any protein would show the same benefit.

Soy contains a lot of phytoestrogens than can mimic or inhibit normal estrogen metabolism. Soy has been associated with an increased rate of estrogen dominant breast cancer in women. The exception is naturally fermented soy often consumed in Asia but seldom in the United States.
The theory is that the phytoestrogens in soy will stimulate the osteoblasts to make new bone, much like natural estrogen does prior to menopause. However, the fact that “turnover markers were not significantly altered” indicates no increase in bone metabolism was found in the rats eating soy. Again, it was the increased protein, not the soy itself that improved bone health.

Bottom Line:
Increase your protein intake to support bone health during and after menopause. However, please do not use soy as your protein source, unless it is naturally fermented soy.

Source: August 9, 2018 National Institutes of Health