Soymilk Prevents Osteoporosis
Drinking two glasses of soymilk each day may protect postmenopausal women against bone loss that can lead to osteoporosis, reports the European Journal of Nutrition (2004;43:246–57).
Osteoporosis is a disease of the skeleton characterized by thinning, fragile bones that commonly results in fractures of the hip, spine, and wrist. Risk factors include white or Asian race; advancing age, being female, thin, or underweight; family history of osteoporosis; early menopause (younger than age 45); smoking; alcohol abuse; low calcium or vitamin D intake sedentary lifestyle; and use of certain medications.
Osteoporosis is easier to prevent than it is to treat. Weight-bearing exercise and proper nutrition are necessary to ensure healthy bones form early in life. For women who have established osteoporosis, treatment options include hormone replacement therapy (HRT); calcitonin (Miacalcin™); bisphosphonates, such as alendronate (Fosamax™); and selective estrogen receptor modulators (SERMS), such as raloxifene (Evista™). Many of these treatments carry the risk of serious side effects. In particular, HRT may increase the risk of breast cancer and heart disease. While SERMS probably do not increase cancer risk, pulmonary embolism (a blood clot in the lungs) is a possible side effect of these medications. Alendronate can cause allergic reactions and irritation of the esophagus. Because of these potential side effects, alternatives to drug treatments for osteoporosis are being sought.
Several preliminary studies indicate that isoflavones derived from soy have bone-protecting effects. Progesterone, a hormone manufactured by the ovaries, is also considered to have bone-building properties. The new study compared the effects of soymilk with that of a progesterone skin cream on bone density measurements in 107 postmenopausal women whose average age was 58 years. The women had either established osteoporosis or three or more risk factors for the disease.
The participants were assigned to one of the following groups for two years: soymilk, progesterone skin cream, combined soymilk and progesterone, or placebo. The soymilk provided 76 mg of isoflavones per day. The progesterone cream was applied daily for three weeks each month, supplying about 26 mg of progesterone per day. Natural “micronized” progesterone was used in the study; this form of progesterone is thought to carry less risk of causing breast cancer than synthetic progestins such as medroxyprogesterone acetate (Provera).
Participants in each group were also given a dietary supplement containing 680 mg calcium, 300 mg magnesium, 20 mg silica, 15 mg zinc, 6 mg manganese, 3 mg boron, 2 mg copper, 200 mg vitamin C, 40 mg vitamin B6, 200 IU vitamin D, and 1 mg vitamin K, to be taken each day. Total daily calcium intake from diet and supplements was about 1,500 mg in all groups.
Bone densities were measured in the lower spine and hip before and after the study to assess response to treatment. Women in the soymilk and progesterone groups did not lose bone mass in the spine during the study, whereas women in the placebo and combined soymilk and progesterone groups had significant bone loss. None of the groups had changes in bone density in the hips.
Without treatment, postmenopausal women may lose up to 3% of their bone mass per year. The results of this study suggest that isoflavone-rich soymilk can prevent bone loss in the lower spine, protecting against osteoporosis development or halting disease progression in people who already have it. Progesterone also slows bone loss; however, when taken together, progesterone and soymilk seem to have a negative interaction that reduces the beneficial effect of each individual treatment.
Kimberly Beauchamp, ND, received her bachelor’s degree from the University of Rhode Island and her Doctorate of Naturopathic Medicine from Bastyr University in Kenmore, WA. She is a co-founder and practicing physician at South County Naturopaths, Inc., in Wakefield, RI. Dr. Beauchamp teaches holistic medicine classes and provides consultations focusing on detoxification and whole-foods nutrition.
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