Soy and Bones

[Guest guest]

Soy isoflavones (SoyLife) may protect against bone loss in postmenopausal women,

according to the results of a single-blind, randomized trial reported in the

June 8 Online First issue of the European Journal of Nutrition.

http://www.medscape.com/viewarticle/540858?sssdmh=dm1.203054 & src=nldne

" It is imperative to find natural, safe and effective alternatives for women to

help maintain bone health after menopause -- without the risky side effects

associated with long-term hormone replacement therapy use, " Jocelyn Mathern, RD,

technical specialist for Acatris, said in a news release. " This promising

research is another step in advancing soy germ isoflavones as a safe, effective

option. "

This study, led by Y. B. Ye, MPhil, and Y. X. Su, MD, from Sun Yat-sen

University in Guangzhou, China, examined the bone-sparing effect of high-dose

isoflavones in Chinese early postmenopausal women. Previous studies showed that

daily doses of 40 to 99 mg of soy isoflavones had inconsistent effects on

preventing estrogen-related bone loss in postmenopausal women.

In this study, 90 women aged 45 to 60 years were randomized to receive daily

dosages of 0 (placebo), 84, or 126 mg of isoflavones for 6 months. At baseline,

body mass index was less than 30 kg/m2, and Kuppermann Climacteric Scale was

greater than 15. Outcomes included bone mineral density (BMD) of the spine and

hip measured with dual-energy x-ray absorptiometry at 0 and 6 months; and serum

osteocalcin, bone-specific alkaline phosphatase, and urinary deoxypyridinoline

levels at 0, 3, and 6 months.

After adjustment for age, years since menopause, body weight, and height;

dietary intakes of isoflavones, calcium, and protein; physical activities and

baseline BMD and mean percent changes in BMD at the lumbar spine (P = .114) and

femoral neck (P = .053) increased with supplementations of soy isoflavones.

After adjustment, there was a significantly dose-dependent linear relationship

between the supplemental isoflavones and percent changes of BMD at the spine (P

= .042) and femoral neck (P = .016) after treatment, and urinary total

deoxypyridinoline (P = .014) at 12 weeks but not at 24 weeks. Percent changes in

serum osteocalcin and bone-specific alkaline phosphatase levels were not

significantly different among the 3 treatment groups at 12 and 24 weeks after

treatment.

" There is a significantly dose-dependent effect of soy isoflavones on

attenuating bone loss at the spine and femoral neck possibly via the inhibition

of bone resorption in non-obese postmenopausal Chinese women with high

Kuppermann Scale, " the authors write. " The high dose of 126 mg isoflavones/d is

an effective dose for the prevention of postmenopausal bone loss over a short

duration. "

Study limitations include short duration, lack of generalizability to obese

postmenopausal women, and relatively small sample size.

" In addition to this research, more studies are examining the effects of either

soy or isoflavones on bone density in humans, " Dr. Mathern says. " We are

awaiting results of a large study, the Osteoporosis Prevention Using Soy (OPUS)

study, a multi-site, two year research study on the use of soy isoflavones to

prevent bone loss in 400 postmenopausal women. Both this current study and OPUS

used SoyLife, and we're excited to see SoyLife helping lead the way in

determining the required dosage of soy isoflavones for safely decreasing bone

loss and preventing osteoporosis in postmenopausal women. "

Guangzhou Sciences and Technology Bureau and Acatris Holding B.V., the maker of

SoyLife, supported this study. The soy isoflavone extract was donated by

Acatris.

Eur J Nutr. Published online June 8, 2006.

Learning Objectives for This Educational Activity

Upon completion of this activity, participants will be able to:

a.. Describe previous research of soy isoflavones on bone health.

b.. Identify markers of bone loss improved through treatment with soy

isoflavones among postmenopausal women.

Clinical Context

Soy isoflavones may offer some promise in ameliorating the natural decrease in

bone density associated with menopause. These compounds have been demonstrated

to improve reproduction and differentiation of osteoblasts, and previous

research has suggested an improvement in bone density associated with

administration of soy isoflavones to estrogen-deprived animals. In addition,

epidemiologic research has found an inverse relationship between dietary

consumption of soy products and the incidence of osteoporosis.

Clinical trials of soy isoflavones for promoting bone health have been

disappointing, with little to no change associated with active treatment. The

authors of the current research suspect this lack of efficacy may have been due

to using lower dosages of isoflavones, and they compare higher doses with

placebo in their trial.

Study Highlights

a.. Women with a history of menopause between 1 and 5 years in duration were

recruited for study participation in China. Eligible women were between 45 and

60 years old and had a follicle-stimulating hormone level of at least 30 IU/L.

Women with chronic disease or who used medications that could affect bone

density were excluded from study participation, as were those with a body mass

index greater than 30 kg/m2.

b.. Subjects were randomized to receive 80 or 126 mg of soy isoflavones daily

or matching placebo. Subjects were asked to discontinue calcium supplementation

and increase dietary calcium intake during the trial. The authors also tried to

limit dietary consumption of soy isoflavones. The treatment period was 6 months.

c.. The main study outcome was BMD, as determined by dual-energy x-ray

absorptiometry of the lumbar spine and left hip. Serum biomarkers of bone

turnover, including osteocalcin, bone-specific alkaline phosphatase, and urinary

deoxypyridinoline, were also assessed on a pretreatment and posttreatment basis.

Results were adjusted for potential confounders, including diet and exercise

habits.

d.. 90 women underwent randomization, and 78 participants completed all

pretreatment and posttreatment testing. Clinical, dietary, and exercise

variables were similar between treatment groups. The mean age was 52 years, and

the mean number of years since menopause was approximately 2.5.

e.. There was a significant, linear dose-related response for isoflavones vs

placebo in terms of bone density at the lumbar spine and femoral neck, but not

at the trochanter. While the bone density in the placebo group tended to

decrease slightly during the 6-month treatment period, it increased slightly in

the isoflavone cohorts.

f.. Urinary deoxypyridinoline values were lower at 12 weeks in the isoflavone

126-mg group vs the isoflavone 84-mg and placebo groups. However, there was no

significant difference in this outcome between groups at 6 months.

g.. Osteocalcin and bone-specific alkaline phosphatase levels increased to

similar levels in all treatment groups during the intervention period.

Pearls for Practice

a.. While research from in vitro, animal, and epidemiologic studies has

suggested that soy isoflavones can improve bone health, previous clinical trials

of isoflavones have been disappointing.

b.. The current study demonstrates a dose-dependent effect of soy isoflavones

on the BMD of the lumbar spine and femoral neck, although isoflavones had no

significant effect on urinary deoxypyridinoline, serum osteocalcin, and serum

bone-specific alkaline phosphatase levels at 6 months.

Nutrition.teach-nology.com

Ortiz, RD

nrord@...

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