Along with the proteins and minerals that build healthy bones,
tofu also contains nutrients that make bones stronger.
One of the diseases that is becoming more prominent as the population ages is osteoporosis. Osteoporosis, a disease that occurs frequently in post-menopausal women, causes bones to lose density and become brittle. When female hormone (estrogen) secretion decreases, the bones’ ability to assimilate calcium deteriorates, and conversely, the calcium in the bones is dissolved. Although the bones’ ability to assimilate calcium also deteriorates in men as they grow older, they do not experience the sudden swing to brittle bones that is experienced by post-menopausal women.
On its own, osteoporosis will not cause bones to break. However, if an individual with osteoporosis falls over, etc, the weakened bones will break as they become unable to absorb sudden strong impacts. Cases of elderly people who have become bedridden through such fractures are common.
The calcium that builds bones can easily become deficient in the diet. According to the “National Nutrition Survey” taken by the Ministry of Health, Labor and Welfare of Japan, the daily intake of calcium is about 10% less than the required. Although meat is rich in calcium, meat also contains large amounts of phosphorus. When there is excess phosphorus in the blood, the body balances this by eluting calcium from the bones. Other than meat, phosphorus is also present in large quantities in processed foods and soft drinks. The pre-existing calcium deficiency coupled with excessive levels of phosphorus means that the Japanese are in a state of chronic calcium deficiency. As far as ingesting calcium is concerned, since tofu contains little phosphorus and is easily digested and absorbed, the calcium content is more easily assimilated.
Not only are soybeans products excellent for replenishing calcium, they also work to strengthen the bones themselves. According to a survey taken by the Ministry of Health, Labor and Welfare of Japan, the proportion of middle-aged and older women suffering fractures is low in eastern Japan and high in western Japan. Since this difference corresponds to the ratio of “Natto” (fermented soybeans) consumption in the two regions, it bears testimony to the effects of the nutritional constituents of natto. Although the proportion of fractures occurring in western Japan is high, there is one exception. In Okinawa prefecture, the incidence of fractures as well as osteoporosis is low. This is not due to natto consumption. The people of Okinawa prefecture eat a considerable amount of tofu, and this underlines the ability of tofu to support strong bones and protect against the onset of osteoporosis.
Calcium absorption increases when calcium is ingested with foods containing proteins that have balanced amino acid content. Tofu has high calcium content and proteins with well balanced amino acid content. This helps to increase calcium absorption and protect against osteoporosis.