Does a high soy intake prevent the development of

osteoporosis?Elizabeth Yahn

Soybean or SoyaEstrogen

GenisteinDaidzein

Glycitein

Nutrition of SoyNutrition Facts

Soybean, boiledAmount per 1 cup (172 g)Calories 298Total Fat 15gSat. Fat 2.2 gPolyunsat. 9gMonounsat. 3.4gCholesterol 0mgSodium 2mgPotassium 886mgTotal Carb 17gProtein 29gCalcium 17%

Food Serving Total PEs (mg)Soy protein concentrate, water wash

3.5 oz 102

Soy protein concentrate, alcohol wash 3.5 oz 12Miso 1/2 cup 59Soybeans, cooked 1/2 cup 47Tempeh 3 oz 37Soybeans, dry roasted 1 oz 37Soy milk 1 cup 30Tofu based yogurt 1/2 cup 21Tofu 3 oz 20Soybeans, green, cooked (Edamame) 1/2 cup 12Soy hot dog 1 hot dog 11Soy sausage 3 links 3Soy cheese, mozzarella 1 oz 2

OsteoporosisCalcium is used as a buffer.

Poor absorption in elderly leads to greater resorption from deposits in bones.

Rate of osteoporosis determined by rate of fractures.

Soy proteins and isoflavones affect bone mineral density in older women: a randomized

control trial (Kenny et. al., 2009)1 year, double blind, randomized, placebo controlled prospective, 2x2 factorial97 women aged 60 or older4 intervention groups: soy protein/isoflavone, soy protein/placebo, control protein/isoflavone, control protein/placeboDietary counseling every 3 mo for duration of study

(Kenny et. al., 2009)

Gender-specific Associations Between Soy and Risk of Hip Fracture in the

Singapore Chinese Health Study (Koh et. al. 2009)

Population cohort.Singapore immigrants from Hokkien or Cantonese dialects.Baseline questionnaire and food frequency survey.Record linkage identified 968 subjects with fracture history and 62,186 without.

Women in Quartiles 3 and 4 saw a significant decrease in fracture risk.

Longer followup resulted in greater

significance for women with greater

intakes.

(Koh et. al. 2009)

The Soy Isoflavones for Reducing Bone Loss (SIRBL) Study: a 3-y randomized controlled trial in

postmenopausal women (Alekel et. al. 2010)

Effect of isoflavones on lumbar spine and total proximal femur BMD.Account for lifestyle and biological confounding factors.209 of 216 participants met compliance standards

(Alekel et. al. 2010)

90 eligible subjectsAt baseline and post-treatment: dietary intake and physical activity assessed.BMD of lumbar spine and left hip at baseline and post-treatment.

Soy isoflavones attenuate bone loss inearly postmenopausal Chinese women: A

single-blind randomized, placebo-controlled trial

(Ye et. al. 2006)

High dosage significantly reduced BMD loss of femur neck and reduced bone turnover.

Bone turnover markers returned to normal 24 weeks post-treatment.

All subjects were counseled on diet and activity along standardized guidelines.

(Ye et. al. 2006)

Summary

Two trials in the US found little correlation between soy and fracture risk. In Singapore, soy intake reduced fracture risk for women but not men. An earlier Chinese trial found high doses of isoflavones to have beneficial effects.

In Conclusion...

For women of Asian descent soy has been shown to prevent loss of BMD. Evidence is less clear in studies that do not account for ethnic backgrounds. Further studies are needed to determine the role ethnicity may play in the soy-BMD saga.