Feasibility and effect on blood pressure of 6-week trial of low sodium soy sauce and miso (fermented soybean paste).
(1/263)
A double-blind, randomized placebo-controlled study was conducted to evaluate the feasibility of the long-term use of low-sodium soy sauce and miso in the general Japanese population and its effect on blood pressure (BP). Forty men and 24 women were randomly allocated to a low-sodium group (n=32) or a control group (n=32). Low-sodium soy sauce and miso, which were approximately 25% and 20% lower in salt content than common soy sauce and miso, were used in the study. The change in BP after a 6-week intervention was evaluated. There were no significant differences in age, sex, body mass index, BP or hypertension between the 2 groups before intervention. After the 6-week intervention, no significant change in BP was observed in the entire cohort. However, in those aged 40 years and older, 6.4 mmHg net reduction in diastolic BP with no significant change in systolic BP was noted in the low-sodium group. Taste evaluation for the low-sodium seasoning was considerably good. Replacing soy sauce and miso of the common type with the low-sodium alternative is feasible in the general population and could be the basis for a salt reduction strategy in the Japanese diet. (+info)
Angiotensin I-converting enzyme (ACE) inhibitory activity was observed in a tofuyo (fermented soybean food) extract with an IC(50) value of 1.77 mg/ml. Two ACE inhibitors were isolated to homogeneity from the extract by adsorption and gel filtration column chromatography, and by reverse-phase high-performance liquid chromatography (HPLC). The purified substances reacted with 2,4,6-trinitrobenzensulfonic acid sodium salt. The amino acid sequences of these inhibitors determined by Edman degradation were Ile-Phe-Leu (IC(50), 44.8 microM) and Trp-Leu (IC(50), 29.9 microM). The Ile-Phe-Leu sequence is found in the alpha- and beta-subunits of beta-conglycinin, while the Trp-Leu sequence is in the B-, B1A- and BX-subunits of glycinin from soybean. Both of the peptides are non-competitive inhibitors. The inhibitory activity of Trp-Leu was completely preserved after a treatment with pepsin, chymotrypsin or trypsin. Even after successive digestion by these gastrointestinal proteases, the activity remained at 29% of the original value. (+info)
Soy and isoflavone consumption in relation to prostate cancer risk in China.
(3/263)
This case-control study in China evaluated the effect of soy food consumption and isoflavones (genistein and daidzein) on the risk of prostate cancer. One hundred and thirty-three cases and 265 age- and residential community-matched controls between the ages of 50 and 89 years were interviewed in person between 1989 and 1992. Usual consumption of soy foods and isoflavones was assessed using a food frequency questionnaire developed in China and a nutrient database developed and validated in Asian-American populations. The age- and total calorie-adjusted odds ratio (OR) of prostate cancer risk comparing the highest tertile of tofu intake to the lowest tertile was 0.58 [95% confidence interval (CI), 0.35-0.96]. There were also statistically significant associations comparing the highest quartile of intake of soy foods (OR, 0.51; 95% CI, 0.28-0.95) and genistein (OR, 0.53; 95% CI, 0.29-0.97) with the lowest quartiles. There was also an indication of a reduced risk associated with intake of daidzein (OR, 0.56; 95% CI, 0.31-1.04 for the highest versus lowest quartile). Our results indicate a reduced risk of prostate cancer associated with consumption of soy foods and isoflavones. These findings should be confirmed in longitudinal follow-up studies in populations with varying risk of prostate cancer. (+info)
Serum isoflavones and soya food intake in Japanese, Thai and American end-stage renal disease patients on chronic haemodialysis.
(4/263)
BACKGROUND: Soya foods, a staple in several Asian countries, have received increasing attention because of their nutritional properties and their high isoflavone content. We have shown recently abnormal pharmacokinetics of soya isoflavones following acute oral intake, in soya-naive end-stage renal disease (ESRD) patients. No information is available, however, about blood levels of soya isoflavones in ESRD patients with habitual soya intake. Additionally, no information is available about the conjugation profile of these compounds in ESRD patients. METHODS: To assess the relationship between habitual soya intake on blood isoflavone levels in ESRD patients, we recorded dietary soya food intake and analysed circulating levels of soya isoflavones in randomly selected, clinically stable haemodialysis patients from the United States (n = 20), Thailand (n = 17) and Japan (n = 20). Dietary records and three weekly blood samples were collected from each participant. Combined isoflavones and individual genistein, daidzein, glycitein and O-desmethylangolensin (DMA) were analysed in serum by liquid chromatography/mass spectrometry. Lipid phase micronutrients, including tocopherols, carotenoids and retinol were also measured to compare ethnic differences in isoflavones with those of more common lipid soluble antioxidant micronutrients. RESULTS: Soya intake was higher in Japanese than in Thai patients and it was negligible in the US patients. Blood levels of genistein were very elevated and significantly higher in the Japanese patients (1128 +/- 205 nM), as compared with the Thai and US patients (258 +/- 64 and 168 +/- 49 nM, respectively; P < 0.001). The other isoflavones followed the same trend. Daidzein was more concentrated than genistein in the dialysis patients. Robust correlation was present between weekly soya intake and blood isoflavone levels (r = 0.56, P < 0.001). Despite very high total isoflavone concentrations, the levels of unconjugated and sulphated isoflavones in the Japanese patients were comparable to those described in healthy subjects. Compared with the striking difference in isoflavones, more easily accessible dietary antioxidants, including tocopherols, carotenoids and retinol, differed only minimally or not at all in the three groups. CONCLUSIONS: ESRD patients appear to accumulate isoflavones as a function of dietary soya intake, resulting in blood concentrations that are higher than those reported in subjects with preserved kidney function. Even in the presence of very elevated total isoflavone levels, the concentrations of the unconjugated and sulphated fractions are comparable to those of healthy subjects. A discrepancy is noted between accumulation of soya isoflavones and other more common lipid-soluble antioxidant micronutrients. (+info)
Effect of gamma-aminobutyric acid-enriched tempeh-like fermented soybean (GABA-Tempeh) on the blood pressure of spontaneously hypertensive rats.
(5/263)
GABA-enriched tempeh-like fermented soybean (GABA-tempeh) was supplemented to the AIN-76 diet and fed for 2 months to spontaneously hypertensive rats (SHRs), an animal model of spontaneously developed hypertension, to compare the antihypertensive activity with that of authentic GABA. The elevation of systolic blood pressure in SHRs was significantly retarded in the GABA-tempeh group as well as that with authentic GABA when compared with the controls, and the effect lasted for two months of the feeding period. The blood urea nitrogen level tended to be higher in the control group than in the GABA-supplemented groups. On the other hand, no effect was apparent on the plasma levels of cholesterol, triacylglycerol and glucose, or on the urinary excretion of Na and K. (+info)
Interactions of phytoestrogens with estrogen receptors alpha and beta (III). Estrogenic activities of soy isoflavone aglycones and their metabolites isolated from human urine.
(6/263)
Two glucuronides (4'-O-, and 7-O-) and a glucuronyl (7-O-) sulfate (4'-O-) of genistein, two glucuronides (4'-O-, and 7-O-) and a glucuronyl (7-O-) sulfate (4'-O-) of daidzein, 7-O-glucuronides of glycitein, dihydrodaidzein and O-desmethylangolensin were isolated from the urine of volunteer subjects fed soy bean curds (Tofu). The estrogenic activities, i.e., i) the effect on the estrogen-dependent growth of MCF-7 cells, ii) the binding ability to human estrogen receptors (hERs) alpha and beta, and iii) the effect on hER-dependent beta-galactosidase induction, of these isoflavone metabolites were examined. Two synthetic isoflavone aglycones (dihydrodaidzein and O-desmethylangolensin) and four synthetic sulfates (4'-O- and 4'-, 7-di-O-) of genistein and daidzein were also studied for their estrogenic activities for the purpose of comparison. With respect to estrogenic acivity, the tested isoflavone metabolites were classified into three groups. The first group shows a very poor stimulatory effect toward the growth of MCF-7 cells, binding activity, and beta-galactosidase induction. The sulfates belong to this group. The second group shows a moderate binding activity but poor stimulation and beta-galactosidase induction. Some glucuronyl conjugates belong to this group. The last group shows a moderate stimulation and beta-galactosidase induction but poor binding activity. A mixed type of conjugates having glucuronyl and sulfony moieties belong to this group. (+info)
Usefulness of the monkey model to investigate the role soy in postmenopausal women's health.
(7/263)
Some of the important health issues for postmenopausal women include cardiovascular disease, osteoporosis, breast cancer, and relief of menopausal symptoms. Ovariectomized cynomolgus monkeys (Macaca fascicularis) have many strengths as models for research in this area including a close phylogenetic relationship to humans, similarities in lipid/lipoprotein metabolism and coronary artery anatomy, similar skeletal anatomical and morphological characteristics, mammary glands with similar pathophysiological characteristics, and a 28-day menstrual cycle with similar hormonal fluctuations. Monkeys (macaques) also experience declining ovarian function and irregular menstrual cycles (natural menopause) when they approach 24 to 29 yr of age. However, because of their very short life span after natural menopause, ovariectomized macaques are used to model postmenopausal women. The cynomolgus monkey model has been useful in defining the potential cardiovascular benefits of soy foods and soy supplements; however, it remains unclear whether the observations are generalizable to all women or only to those who, like cynomolgus monkeys, convert the soy isoflavone daidzein to the metabolite equol. Particularly important has been the use of the cynomolgus monkey model to understand the effects of soy on breast health. There is evidence from a cynomolgus monkey trial to suggest that soy/soy phytoestrogens have no estrogen agonist effects for breast. Finally, soy/soy phytoestrogens do not appear to be an adequate alternative to postmenopausal hormone therapy. Nevertheless, important attributes of soy have been identified, and it may have potential as a complementary component to hormone therapy. (+info)
Not all soy products are created equal: caution needed in interpretation of research results.
(8/263)
Interest in the health benefits of soy foods has been intense among the research community, health professionals, and the public. At the same time, potential concerns associated with soy consumption, especially as related to soy isoflavones, have tempered the enthusiasm for making public health recommendations. On both accounts, the primary soybean isoflavone, genistein, has received the most attention. Because consumers are becoming increasingly confused by the often conflicting dietary messages, a balanced and accurate view of the risks and benefits of soy foods and soy food components is essential. Even among health professionals, confusion exists about proper nomenclature and about the precise composition of the agents under investigation. Levels of isoflavones are frequently assumed to be constant within categories of soy foods, and intakes are estimated rather than being directly analyzed. Furthermore, all too often research dealing singularly with genistein is interpreted by both health professionals and the media as equating directly with soy. Researchers often fail to fully understand the implications of their research outcomes and the context in which those outcomes should be placed. With the hundreds of publications yearly on soy and isoflavones, it is especially important to consider the literature in its entirety when making pronouncements about health effects. Efforts are needed by all to reduce the public confusion by adapting standardized approaches to the reporting of data. This paper provides a framework for both standardization of nomenclature and appropriate interpretation of data. (+info)