March 20, 2010

Exercise Improves Bone Density, Herbs Do Not

A new study suggests that exercise may help older women maintain their bone density, but adding herbs to the routine does not bring any extra benefits.

Researchers studied 128 postmenopausal women for a year and found that those who were randomly assigned to regular exercise generally maintained their bone density.  However, the women that were assigned to a "wellness" group that only received light exercise showed a decline in their bone density.

A Black cohosh supplement is marketed as a "natural" form of hormone replacement therapy and is most commonly used to treat hot flashes and other symptoms of menopause.  Some lab research suggests that the herb may have estrogen-like activity in the body.

However, the women that were randomly selected to add the herb to their diet showed no signs of added effects to their bone density after a year.

According to lead researcher Michael Bebenek of the University of Erlangen, in Germany, the new study appears to be the first to take a look at the effects of black cohosh on bone density.

Bebenek told Reuters Health that although the theory of a substance with estrogen-like effects that can protect women's bone density, the benefits of black cohosh for bone health is "still doubtful."

Their study, which was published in the medical journal Menopause, randomly assigned women to an exercise program that interspersed six weeks of higher-intensity activities designed to protect bone mass with 10 weeks of more-moderate exercise designed to improve heart health.  These activities included brisk walking and step aerobics.

Half of the women that took the exercise route also took a 40-milligram black cohosh supplement each day.

The remaining 42 women of the 128 were assigned to a "wellness" group that performed low-intensity activities like light walking, stretching and balancing exercises for an hour per week.

After a year, women in both exercise groups showed no significant change in bone density at the spine, while those in the wellness group showed a 2 percent decline on average.  The heavy exercisers showed a slight increased in bone mass at the hip at about 0.5 percent, while the women in the wellness group showed an average dip of about 0.6 percent. 

The researchers did not find significant bone-mass differences between exercisers on black cohosh and those who did not take the supplement.

The team also looked for changes in the participants' Framingham risk scores, which is an estimate of a person's odds of suffering from a heart attack or dying from heart disease in the next 10 years.  The score is based on age, smoking history, blood pressure and cholesterol levels and whether a person has diabetes.

The researchers did not find that adding exercise black cohosh to their diet had any effect on the women's risk scores.

Women in the exercise-group at the end of the study were estimated to have a 6 percent chance of suffering a heart attack or dying from heart disease in the next 10 years.  The difference was 7.8 percent in the black cohosh and wellness groups.  However, the differences in the groups' score changes over time were not significant to statistical terms.

According to the researchers, the bottom line is that the study "again clearly demonstrated" the positive effects of exercise on postmenopausal women's bones.  The question still remains whether black cohosh has any bone-health related benefits.


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