New research confirms that eating soy beans, or taking soybean protein supplements, can help to prevent osteoporosis, or brittle bones.
Worldwide, osteoporosis affects 1 in 3 women and 1 in 5 men over the age of 50, contributing to one bone fracture every 3 seconds. Your risk of developing osteoporosis depends on numerous factors, including the genes you inherit, the amount of exercise you take, how much vitamin D you synthesise on exposure to sunshine and your dietary intake of key micronutrients, including calcium, magnesium and vitamin K as well as vitamin D3. Now, the Society For Endocrinology suggests that eating more soy bean foods may offer significant protection, too.
Why are soy beans so beneficial?
Soy beans are a good source of vegetable protein (which supplies building blocks for laying down new osteocalcin protein in bones). Their main benefit comes from their high concentration of isoflavones, however. Isoflavones are plant hormones whose weak, oestrogen-like action stimulates the formation and activity of osteoblasts (cells that make new bone) as well as suppressing the action of osteoclasts) cells that dissolve old bone. The balance between the activity of these two types of cells is important to ensure that sufficient new bone is made to replace the old bone that is re-absorbed.
In the latest study, researchers from the University of Hull gave 200 women in the early stages of menopause either a daily supplement of 30 grams soy protein (containing 66mg soy isoflavones) or a placebo for six months. They assessed changes in the women’s bone activity and found that those taking soy supplements had significantly lower levels of a bone breakdown protein called beta-CTX. This implies their rate of bone loss was slower than normal, which would reduce their risk of osteoporosis or at least delay its onset.
The researchers suggest that eating more soy bean foods or taking isoflavone supplements could reduce the number of women developing osteoporosis. Beneficial effects of isoflavones on the circulation also lowered their risk of a heart attack or stroke.
What is the best dose?
The dose used in this study was 30 grams soy protein, providing 66mg isoflavones, per day. This was selected as representing intakes in a typical oriental diet where soy is a food staple. In contrast, women following a western-style diet typically only obtain between 2mg and 16mg isoflavones per day.
In Japan, doctors already recommend that women at risk of osteoporosis increase their intake of tofu (fermented soybean curd coagulated with calcium salts, making it a rich source of isoflavones, calcium and vitamin K), natto (fermented soybeans with a high vitamin K content) and increase their intake of vitamin D by eating more fish.
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