Written by Jessica Patella, ND. Study shows that although mixed soy isoflavones may not be as potent as bisphosphonates in preventing loss of bone calcium in post-menopausal women they are effective in protecting bone health.
Estrogen depletion in women after menopause is a major factor in osteoporosis (1,2). Osteoporosis can result in decreased quality of life and even premature death following a hip fracture (1, 2). Current treatment for osteoporosis includes hormone replacement therapy and bisphosphonate pharmaceutical drugs (1, 3), although these include side effects such as heart disease, pulmonary embolism, atypical fractures and bone decay in the jaw (4, 5). For these reasons, more people are turning to alternative treatment options. Recent research has found that soy is effective in preserving bone health (1).
The research included 24 post-menopausal women, who underwent a baseline washout period during which there was no intervention. In Phase 1 of the trial, all the women received the soy-low intervention. This was followed by another washout period (50 days). For Phase II of the trial, 14 women received varying amounts of soy and 10 women received a bisphosphonate drug (risedronate) for 50 days. This was followed by an additional washout period (50 days), after which the participants finished the study by taking the bisphosphonate drug (risedronate, n=19).
The most abundant soy isoflavones, derived from the soy bean, include genistean, diadzein and glycitein. To test the various types of soy isoflavones on preserving bone health, the following combinations were given via 5 tablets per day during Phase II of the trial:
| Intervention | Genistein equivalent mg/d (% total isoflavone) | Diadzein equivalent mg/d (% total isoflavone) | Glycitein equivalent mg/d (% total isoflavone) | Total |
|---|---|---|---|---|
| Gen-low | 44.06 (83.4) | 8.25 (15.6) | 0.54 (1.0) | 52.85 |
| Gen-high | 93.75 (82.6) | 18.22 (16.1) | 1.55 (1.4) | 113.52 |
| Soy-low | 42.20 (43.9) | 44.27 (42.1) | 14.76 (14.0) | 105.23 |
| Soy-high | 95.66 (43.5) | 92.99 (42.3) | 31.02 (14.1) | 219.67 |
| Soy-gen | 91.02 (56.5) | 54.53 (33.9) | 15.52 (9.6) | 161.07 |
Overall, the following results were observed:
- The bisphosphonate drug increased bone calcium retention by 15.3% (P=0.0014)
- Of the soy interventions, soy-low had the greatest effect, with a 7.6% increase in bone calcium retention (P<0.0001).
- All isoflavone interventions (except for Gen-high) significantly increased bone calcium retention. Gen-low increased bone calcium retention by 3.4% (P=0.0263), Soy-high by 5.5% (P=0.0232) and soy-gen by 5.8% (P=0.0096).
In conclusion, a moderate dose of mixed soy isoflavones (soy-low) was the most effective soy supplement in improving bone calcium retention in post-menopausal women. Overall soy isoflavones, although not as potent as bisphosphonate drugs, are an effective therapy for post-menopausal women to protect against bone loss (1). Future research with more participants should be considered.
Source: Pawlowski, Jessica W., et al. “Impact of equol-producing capacity and soy-isoflavone profiles of supplements on bone calcium retention in postmenopausal women: a randomized crossover trial.” The American journal of clinical nutrition 102.3 (2015): 695-703.
© 2015 American Society for Nutrition
Posted October 27th, 2015.
Jessica Patella, ND, is a naturopathic physician specializing in nutrition and homeopathic medicine and offers a holistic approach to health. She earned her ND from Southwest College of Naturopathic Medicine in Tempe, AZ, and is a member of the North Carolina Association of Naturopathic Physicians. Visit her website at www.awarenesswellness.com.
References:
- Powlowski J, et al. Impact of equol-producing capacity and soy-isoflavone profiles of supplements on bone calcium retention in postmenopausal women: a randomized crossover trial. 2015 Am J Clin Nutr 102:695-703.
- Leboime A, et al. Osteoporosis and mortality. Joint Bone Spine 2010;77:S107-12.
- Lydeking-Olsen, et al. Soymilk or progesterone for prevention of bone loss. Eur J Nutr 2004;43:246-57.
- Rossouw JE, et al. Risks and benefits of estrogen plus progestin in healthy post-menopausal women: principal results from the women’s health initiative randomized controlled trial. JAMA 2002;288:321-33.
- Arrain Y, Masud T. Recent recommendations on bisphophonate-associated osteonecrosis of the jaw. Dent Update 2008;35:238-40,242.
