American and Chinese scientists have found that consumption of soybeans and other foods rich in isoflavones is associated with reduced risk of coronary heart disease. To do this, they examined data from three independent long-term studies of the effects of diet on health over 200 million Americans. The effect, however, was not the highest: when consuming tofu more than once a week, the risk was lower by 18 percent. Article published in the journal Circulation.
Some isoflavones (a type of flavonoids — hydroxypropane isoflavone) attributed to phytoestrogens, substances of plant origin that is structurally very similar to estradiol, the main female sex hormone of estrogens group. A large amount of isoflavones contained in soybeans and some other legumes, and these are often sold in the form of food supplements.
In medicine, the isoflavones are often seen in the context of prevention of cardiovascular disease: for example, one study claimsthat these substances can reduce arterial stiffness and, as a consequence, the development of atherosclerosis. The majority of studies focused on the effect of isoflavones on heart health, have some limitations, particularly small sample.
Sun qi (Qi Sun) from Harvard University and his colleagues have compiled data from three independent long-term studies, the total sample of participants was 210,7 thousand people. On it, scientists estimate how connected the consumption of foods rich in isoflavones, with the development of coronary (ischaemic) heart disease — a violation of myocardial perfusion due to coronary lesions.
None of the participants at the beginning of the relevant studies had neither heart disease nor cancer. In addition to demographic data, information about health, daily activity and habits, the scientists analyzed information on the nutrition of participants depending on the research, it was updated every two to four years. For each participant, the scientists calculated the average daily consumption of isoflavones, focusing in particular on the tofu is the main source.
For all the time of all three studies were registered 8359 cases of coronary heart disease. Consumption of food with high content of isoflavones was associated with a reduced risk of developing the disease by 13 percent. If you look at the consumption of products separately, then when consumed tofu once per week the risk was lower by 18 percent, but less than once per month — 13 per cent. However, such effect was not observed with the consumption of soy milk, and the most significant (p = 0.002) effect was for young women before menopause and during menopause provided that they do not pass any hormone therapy.
Of course, scientists do not claim the work of cause-and-effect relationship. The mechanism by which isoflavones may favorably affect heart and blood vessels, may be imprisoned in the beta estrogen receptor which they bind: involvement of female sex hormones may also explain why the effect was more prominent in women.
Tofu and other soy products — some of the main constituents of some Asian diets, particularly the Japanese. Japanese dietary recommendations, in turn, according to some studies, lower mortality.