Effect of Soy Isoflavones on Bone Mineral Density and Physical Performance Indices

The Effect of Increased Soy Protein Intake on Bone Metabolism

The aim of the present study was to investigate the effects of soy and soy plus isoflavones on bone mineral Density and physical performance in post menopausal women.

Post menopausal estrogen deficiency causes physiologic changes in body composition including decreased lean body weight and bone mass. A decrease in muscle strength along with osteoporosis puts post menopausal women at a high risk of hip fractures causing considerable mortality and morbidity. Estrogen use has been shown to reduce bone density loss and increase muscle strength but given the concerns regarding its use, patients are looking for alternatives such as Soy isoflavones. Most human studies on the effect of Soy on bone mineral density (BMD) in post menopausal women have been short term i.e. 3-6 months and failed to provide conclusive evidence. There is no evidence of its effects on physical performance.

The aim of the present study is to investigate the effects of 25g of soy protein alone or with 90mg of isoflavones on bone mineral Density and physical performance indices in post menopausal women over a duration of 2 years.

Inclusion Criteria:

• at least 55-75 years of age
• at least 7 years post menopausal either spontaneous or surgical

Exclusion Criteria:

• must not have used estrogen for atleast 2 months prior to entering study
• must be on no bone active drugs such as bisphosphonates, anti convulsants, calcitonin and long term steroids
• osteoporosis (T-score<-2.5)
• BMI <18 or >34