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Long-term intake of traditionally made Doenjang, particularly high in certain species, may improve symptoms of estrogen deficiency more effectively than unfermented soybeans.
2023 Foods Improvement of Estrogen Deficiency Symptoms by the Intake of Long-Term Fermented Soybeans (Doenjang) Rich in Bacillus Species through Modulating Gut Microbiota in Estrogen-Deficient Rats Zhang T, Yue Y, Jeong SJ, Ryu MS, Wu X, Yang HJ, et al.
Animal Study Bacillus Gut Microbiota Menopause
The study involved using four different types of traditionally made Doenjang (TMD), distinguished based on the quantities of certain species and biogenic amines they contained. These were used to observe possible alterations in energy, glucose, and lipid metabolism in estrogen-deficient female rats via potential modification of the gut microbiota. This involved comparing a control group of rats that underwent ovary removal with five other groups that were supplemented with different types of TMD and cooked soybeans.
The outcomes revealed that weight gain and visceral fat mass were lower and lean body mass was higher in the TMD and cooked soybean intake groups compared to the control group, however, these figures were not as good as those in the normal control group. Additionally, the hepatic triglyceride content was lower with TMD intake. It was further observed that the intestinal health significantly improved in the TMD groups, and some groups revealed more improvements than others. Concerning gut microbiota, certain groups showed an increase in certain types of organisms, suggesting a benefit from high amounts of the specific species in TMD. The study inferred that TMD rich in certain species correlates positively with the regulation of estrogen-related markers.
Natto and Miso, Japanese fermented soy foods, contain health-promoting bioactive components, including nattokinase, bacillopeptidase F, vitamin K2, dipicolinic acid, γ-polyglutamic acid, isoflavones, and phenolic acids.
2021 Food Research Natto and miso: an overview on their preparation, bioactive components and health-promoting effects Chan EWC, Wong SK, Kezuka M, Oshiro N, Chan HT
Review Article Isoflavone Miso Natto
The process of preparing natto involves fermenting cooked soybeans with Bacillus subtilis natto. This gives the soybeans a sticky appearance, a slippery texture, a sour aroma and a nutty flavour, and results in the production of bioactive components such as nattokinase, bacillopeptidase F, vitamin K2, dipicolinic acid, and γ-polyglutamic acid. Miso, on the other hand, refers to a paste produced by fermenting cooked soybeans with koji, which is steamed rice inoculated with Aspergillus oryzae.
The health benefits of these bioactive components, produced during the fermentation process of both natto and miso, have been identified and accentuated. These components add value to traditional soy foods, boosting their potential in promoting health. The wealth of bioactive nutrients in these foods indicate the reiterate the importance of traditional fermented foods in dietary practices.
Traditional fermented products made from soybeans and rice, commonly consumed in the Japanese diet, show significant potential in preventing the progression of fatty liver disease.
2021 Foods Protection of Fatty Liver by the Intake of Fermented Soybean Paste, Miso, and Its Pre-Fermented Mixture Kanno R, Koshizuka T, Miyazaki N, Kobayashi T, Ishioka K, Ozaki C, et al.
Animal Study Fatty Liver Disease Miso Soybean
In the study, C57BL/6J mice were first acclimated for two weeks. Following this period, they were segregated into groups and fed on different diets for a duration of 20 weeks. These diets included a Normal Diet (ND), a High-Fat Diet (HFD), an HFD containing 5% of the fermented soybean and rice product (denoted as HFD+M), and an HFD with 5% of a pre-fermented form of the product (HFD+PFM). The focus was on assessing the impact of these diets on the development of fatty liver disease in the subjects.
The mice consuming solely the high-fat diet developed the symptoms of a typical fatty liver, as anticipated. However, the mice fed with diets that included either the fermented soybean and rice product or its pre-fermented variety showed a substantial reduction in the progression of the fatty liver disease, notably in the female subjects. This was observed in terms of diminished liver weight. Moreover, a decrease was noted in the levels of leptin and resistin, hormones linked with obesity and insulin resistance, in the serum of these groups. The male subjects also showed resistance against fatty liver disease progression upon the consumption of these diets. This study therefore demonstrates the value of including such traditional fermented food products in the diet as possible deterrents against lifestyle-induced ailments like metabolic syndrome.