Soybean isoflavones belong to isoflavones in flavonoids. Among them, there are two active components genistein, and daidzein is mainly derived from soybean. It is found that there are 12 kinds of soybean isoflavones. Soybean isoflavones are similar to estrogen in structure, can be combined with estrogen receptor alpha and beta, have estrogenic activity and anti estrogen activity, can reduce the occurrence of osteoporosis, breast cancer, improve the role of women’s menopausal syndrome.
1 Absorption of soybean isoflavone
The bioavailability of soy isoflavones depends on the gut bacteria that decompose it. Under the influence of intestinal bacteria, the sugar chain is cut off to become aglycone and absorbed. The bioavailability of daidzein was higher than that of genistein, and the peak time was 2h. Daidzein in the intestinal tract is divided into female alcohol (equol), but only 30% to 40% individuals equol. The production of Equol is related to the species and specific enzymes of intestinal flora. In individuals with equol metabolism, there is higher estrogen and its metabolite profile consistent with low breast cancer, and these individuals have longer menstrual cycles. Soybean isoflavones are excreted by feces and urine, and the decomposition products of isoflavones can be absorbed from the intestinal tract and excreted by urine. When excessive, the plasma concentration of soy isoflavone will be saturated, so as to avoid the occurrence of toxicity.
2 Effect of soybean isoflavone on osteoporosis
Soy and other products can relieve postmenopausal osteoporosis, but the mechanism is not very clear. Non steroidal phytoestrogens differ from traditional estrogens in bone remodeling. There is ER beta on bone, which can be specifically combined with estrogen. Genistein decreases trabecular bone and dense bone loss in ovariectomized rats, which is different from that of estrogen. It can also reduce avian osteoclast activity, reduce bone loss in ovariectomized rats, effects of this phenomenon on bone cells in culture – isoflavone synthesis of ipriflavone can also be observed. Genistein increases bone formation index alkaline phosphatase activity, and this effect can be reduced by estrogen antagonists, suggesting that genistein acts similarly to estrogen. The reduction of bone turnover by daidzein may be due to the effect of growth factors and cytokines. When growth factors and cytokines play a role in osteoclast activity, apoptosis may be induced by genistein or by a variety of tyrosine kinase mediated pathways mediated by genistein.
3 Prevention of cancer by soybean isoflavone
Because of the estrogenic effects of soy isoflavones, it is generally more concerned about whether soy stimulates estrogen dependent tumor growth. The risk of breast cancer is associated with high estrogen concentrations and their metabolites, and is associated with short menstrual cycles, thus extending the duration of estrogen exposure. The concentration of soy isoflavones was negatively correlated with urinary estradiol concentration, and the risk of breast cancer was correspondingly low 1/9. The density of breast tissue is positively correlated with breast cancer.
4 Effect of soybean isoflavone on cognitive function
27 young women, 25 years on average, took high protein diets containing 100mg/d soy isoflavones, and improved short-term and long-term memory and brain flexibility. 53 postmenopausal women took soy isoflavone 110mg/d in June, compared with the control group, the words memory significantly improved.
5 Hormone effects of soybean on different populations
The concentration of soy isoflavones was negatively correlated with serum estradiol and testosterone levels, and positively correlated with plasma SHBG levels. In vitro studies showed that Gen, Dai and equol stimulated SHBG synthesis. Dai reduces testosterone oxidation and testosterone oxidation is associated with ovarian steroid hormone biosynthesis. Phytoestrogens reduce many important anabolic enzymes of steroid hormones, which is one of the mechanisms of phytoestrogens in preventing diseases. Estradiol decreased significantly in luteal phase only in Asian women. The estrogenic activity or anti estrogenic activity of soy isoflavones mainly depends on the hormone metabolism of the subjects themselves. Anti estrogen activity is shown in women with high levels of hormones, such as young animals or estrogen producing animals and young women. Estrogenic activity is observed in low estrogen levels, such as young animals, ovariectomized animals, and natural menopause or surgical menopause women.
6 Prevention of cardiovascular diseases by soybean
27 middle-aged healthy men who took soy protein containing 60mg/d soy isoflavones could reduce the diastolic blood pressure during the 5min stress response and cold stress response. Soy isoflavones can also enhance vascular responses in aged rats. Although soy isoflavones may have other anti atherosclerotic effects, soy isoflavones do not affect lipid levels alone.
7 Prevention of Alzheimer’s disease by soybean isoflavone
53 postmenopausal women took soy isoflavones in June, which improved memory compared with the control group.
8 Effect of soybean on prostate cancer
41 prostate cancer patients with increased prostate specific antigen did not take 60mg/d daidzein, and prostate cancer decreased after June, indicating that soy could reduce the risk of prostate cancer.
9 Effect of soy protein on renal function in patients with diabetic nephropathy
Two studies have shown that soy protein has a good effect on renal function, especially in patients with diabetic nephropathy.
In recent years, with the development of biotechnology and the progress of analytical methods, the research of bioactive substances in soybean has been deepened. The soybean, including soybean isoflavone, has been developed for health food, medicine, food additive and cosmetics. Soybean and its products are regarded as sunrise industries, and soybean isoflavones are also known as vitamin in twenty-first Century, which undoubtedly brings us great business opportunities.
