During a large-scale epidemiological studies, the object of which was 90 thousand Japanese middle-aged and elderly, it was found that the risk of death associated with the consumption of fermented soybeans, particularly natto.
Does the amount of natto in the risk of death?
In studies conducted earlier, it was noted that people who eat more foods from fermented soybeans, the risk of high blood pressure is lower, and that the consumption of natto reduces the risk of death from such cardiovascular diseases as myocardial infarction and stroke (for reference the article is “One package of natto per week, and the risk of death from diseases of the circulatory system down?”).
However, the relationship to the ingestion of food of fermented soy beans and death from diseases that are not associated with the circulatory system were not discussed.
So the team Ryoko Katagiri (Katagiri Ryoko) from the National center for cancer research decided to study the connection of death with the culinary customs of the Japanese 92 915 (42750 5165 men and women) aged 45 to 74 years who participated in a large epidemiological study. The aim was to clarify the relationship of the conditions and lifestyles of Japanese with various diseases.
The research team based on data about the frequency of eating all of the research participants evaluated the consumption of products from soybeans (tofu, Yusi-dofu freeze-dried Koya-dofu, tofu in oil, soy milk and miso), foods from fermented soybeans (natto and miso) and unfermented products from soybeans (tofu, Yusi-dofu freeze-dried Koya-dofu, tofu, deep-fried and soy milk). She also identified the amount of consumption of natto, miso and tofu (tofu, Yusi-DOPA and freeze-dried Koya-dofu) separately.
People were divided into five equal groups according to the volume of consumption of these products: from the smallest number to largest. At the same as for natto, more than 12 thousand people said they do not eat this dish, so they were identified to the lowest group, and the rest of the objects of study were divided into four groups in ascending order: second, third, fourth and maximum.
Looked into the Association of consumption of products from soybeans with mortality on the General causes and deaths from cancer, cardiovascular diseases, heart diseases, cerebrovascular disorders, respiratory diseases and injuries.
People who eat more foods from fermented soybeans, the risk of death is reduced
In the observation period, which lasted 14.8 years, died 13 303 people. Looked into the Association of death and consumption of soybeans subject to certain factors. These include: the body mass index, duration of Smoking, amount of alcohol consumed, the duration of charge in his spare time, diabetes and hypertension, consumption of coffee and green tea, history of medical examinations, the premenopausal or postmenopausal, history of hormone replacement therapy in women, energy intake, consumption of vegetables / fruit / fish / meat.
In the result, it became known that the consumption of soy products and unfermented soy beans is not related to risk of death (table 1 — shown in the original article — ed. ed.). At the same as for fermented soybeans, it was revealed an inverse relationship for both men and women: the more consumption, the less the risk of death. The analysis by products showed that the relationship between consumption of miso and natto with mortality was statistically significant only in women.
Then was analyzed the relationship between consumption of soy products and mortality in the General reasons. Men and women apparent relationship with mortality from different diseases were observed only in the case of natto.
In comparison with the first group who do not eat natto, at maximum, the fifth group that daily consumed more than 26.2 grams, showed reduced risk of death from cardiovascular disease. The weight of the natto sold in Japan in a square packaging is 40 — 50 grams, in the round — 30 — 40 grams.
These results were obtained on the basis of observational studies. At the moment the causal link is not established, but the likelihood reduce the risk of death due to greater consumption of fermented soybeans, particularly natto, is.
It is worth noting that men and women is very different mortality from respiratory diseases and its relationship with the use of soy products, however, the authors are not told the reasons for such results. Usually in comparison with women, men have a higher percentage of mortality and respiratory diseases caused by Smoking. Also, the study involved many men and women about the experience of Smoking which has failed to obtain reliable information. While deaths due to respiratory diseases was lower than from other diseases. It can be assumed that the result of the statistical analysis indicators declined. You need to carefully interpret the results.
Junko Onishi — medical journalist. Graduated from Tsukuba University (major: classification of species and Biomedicine). He graduated from the graduate school of this University (Department of biological studies, majoring in biophysical chemistry). He received the degree of doctor of science. Worked as a researcher at the Japanese Association of prevention of AIDS. Now works as an independent journalist. As writes highly technical articles for scientists and physicians, and non-fiction texts about science and health for a wide range of people.
