Genistein and vitamin K can both help preserve postmenopausal bone health, new research suggests. Lower estrogen levels after menopause can set the stage for osteoporosis.
Italian scientists at the University of Messina assessed the effects of genistein, an estrogen-like substance found in soy, on bone metabolism in about 400 postmenopausal women. The women were all "osteopenic," meaning they had decreased bone mineral density (BMD) but not as severe as in osteoporosis.
They were randomly assigned to receive either a placebo or 54 mg of genistein daily for two years. Both the genistein and placebo tablets contained calcium and vitamin D. At two years, "BMD had increased in genistein recipients and decreased in placebo recipients" at the primary measuring points, located at the small of the back and the upper part of the thigh (femur) bone close to the hip joint.
Genistein supplementation for two years "has positive effects on BMD in osteopenic postmenopausal women," the researchers concluded.
Similarly, Dutch researchers found that vitamin K supplementation improves hipbone geometry and bone strength in postmenopausal women. In this study, 325 postmenopausal women received either a placebo or a very high-dose of vitamin K2 (MK-4, menatetrenone) for three years. Bone mineral content and femoral neck width increased in the vitamin K group compared to the placebo group. As well, hipbone strength remained unchanged in the former group but significantly decreased in the latter. The researchers said a comparable effect may be achieved using a standard dose of the MK-7 form of vitamin K, found in natto supplements.
Sources: Ann Intern Med. 2007 Jun 19;146(12):839-47; Osteoporosis Int. 2007 Jul;18(7):963-72. Epub 2007 Feb 8