Isoflavones as Putative Anti‐aging Food Factors in Asia and Effects of Isoflavone Aglycone‐rich Fermented Soybeans on Bone and Glucose Metabolisms in Post‐menopausal Women

Abstract

Objective: Since soy isoflavone intake, high in Japanese and Asian populations was epidemiologically associated with lower risks of cardiovascular diseases(CVD), we focused on soy isoflavone effects on other risks of lifestyle-related diseases and investigated whether or not the intake of isoflavone aglycone-rich fermented soybeans affected bone and glucose metabolisms in post-menopausal women.Methods: Healthy post-menopausal women aged 47 to 70 years, 65 in total, were invited to a test diet-placebo independent parallel double-blind dietary intervention study, and were randomized for taking isoflavone aglycone-rich fermented soybean soup (isoflavone aglycone 24 mg/day) or placebo soup for 4 weeks. Blood and 24-hour urine samples were collected before and after the intake. We analyzed the markers of bone and glucose metabolisms. The subjects refrained from consuming other soybean-based foods and isoflavone supplements for 9 weeks, starting at 5 weeks in advance of the intervention. Results:We analyzed 56 subjects from whom complete 24-hour urine samples could be collected, and obtained the following results: 1. Urinary total isoflavone level was significantly higher at 4 weeks in the fermented soybean group (S) than that in the placebo group (P). 2. In P, the urinary excretion of deoxypyridinoline (bone resorption marker) was significantly increased at 4 weeks from the baseline value but did not show any significant change in S. In contrast the serum osteocalcin (bone formation marker) level was significantly increased at 4 weeks from the baseline value in S, but showed no significant change in P. 3. Serum insulin level was significantly lower at 4 weeks in S than in P, while blood glucose levels were similar in S and P. Thus, insulin resistance (the homeostasis model assessment of insulin resistance) was significantly lower at 4 weeks in S than in P. Conclusion:Four-week intake of fermented soybean soup containing 24 mg of isoflavone aglycone improved bone and glucose metabolisms in post-menopausal women, suggesting that the continuous intake of fermented soybeans could prevent bone loss and improve insulin resistance after menopause.

Better together: evaluating single and combined biomarkers of fermented food intake and their associations with cardiometabolic health

“…Beyond definitions based on technology or outcomes, biomarkers can also be classified based on their intended use. For instance, food intake biomarkers (FIBs) can be used to assess the intake of a specific food with a distinct dose-and time-dependent response, while effect biomarkers can help indicate a physiological or health state following the exposure to a food or diet (109). FIBs can also be used to monitor compliance to interventions in clinical trials (110), and may provide valuable information beyond self-reported intake particularly when food composition data are not available or limited.…”

“…Analysis of several fermented soy products, including Chungkookjang, tempeh, doenjang, and miso, revealed higher levels of isoflavones (genistin, daidzin, glycitin, genstein, daidzein) and/or amino acids (in particular glutamate) compared to unfermented soybean (105). In addition to soy isoflavones and aglycones, vitamins B2 and B12, and gamma aminobutyric acid (GABA), are increased in fermented soy products (106), and a variety of bioactive peptides have been identified, such as F2-2-2 and Fr-2-3 in chungkujang, Arginine-Proline in doenjang, Phenylalanine-Isoleucine-Glycine (1:2:5) in dou-chi, and Valine-Proline-Proline and Isoleucine-Proline-Proline in miso paste containing casein (107)(108)(109). While many of these compounds are present across other foods as well (e.g., vitamin B12), which limits their usefulness as FIBs for fermented soy intake, their combination in a multi-marker approach warrants investigation.…”