Longitudinal study of soy food intake and blood pressure among middle-aged and elderly Chinese women

Greater habitual soyfood consumption is associated with decreased carotid intima-media thickness and better plasma lipids in Chinese middle-aged adults

Many clinical studies have shown high-dose supplemental soy protein has beneficial effects on cardiovascular risk factors. We examined the association between habitual soyfood intake and carotid intima-media thickness (IMT) and plasma lipids in a cross-sectional study including 406 (M 134, F 272) middle-aged Chinese adults (40-65 years) without confirmed relevant diseases. We found significantly dose-respondent decreases in bifurcation IMT, total and LDL cholesterol associated with increased usual soyfood intake after adjusting for potential confounders (p for trend, all p<0.05). Covariate-adjusted mean bifurcation IMT, total and LDL cholesterol decreased by 9.4%, 6.2% and 10.4% in women (p=0.020, 0.035, 0.110), 16.0%, 12.3% and 19.6% in men (p=0.036, 0.005, 0.002), and 9.9%, 9.3% and 15.4% in total men and women combined (p=0.010, <0.001, <0.001) when the mean intake of soy protein increased from 0.87 (F) or 0.64 (M) g/day (1st tertile) to 8.35 (F) or 7.48 (M) g/day (3rd tertile), respectively. Significant interaction between sex and soy consumption on bifurcation IMT was observed (p=0.008). In conclusion, higher habitual soyfood consumption is associated with decreased bifurcation IMT, plasma TC and LDL-c in middle-aged Chinese adults. The association is more apparent in men than in women.

Early life and adult exposure to isoflavones and breast cancer risk

Soy and red-clover isoflavones are commonly consumed within the diet or as a dietary supplement due to a range of presumed beneficial health benefits. These isoflavones are thought to protect against heart diseases as well as breast and other types of cancer. Isoflavones are structurally similar to estrogens and may act as estrogen agonists or antagonists by binding to estrogen receptors. Because of an increased use of isoflavones in processed foods and dietary supplements as well as the greater consumption of soy products, dietary intakes of isoflavones are increasing in children and adolescents in North America. Estrogens are a known component of numerous hormone related cancers including breast cancer. It is with these facts in mind that we review the existing epidemiological and experimental animal studies for a resolution to a proposed correlation between increased isoflavone consumption and breast cancer. There is conflicting evidence from epidemiological, intervention and experimental animal studies regarding the chemopreventing effects of soy isoflavones in breast cancer. Isoflavones are weak estrogens and their effect depends upon the dose, time of exposure and species involved. It would, therefore, not be safe to indisputably accept soy or red-clover as a source of isoflavone resource to prevent breast cancer.

[Usefulness of phyto-oestrogens in reduction of blood pressure. Systematic review and meta-analysis]

OBJECTIVES

To determine whether treatment with phyto-oestrogens or soya protein succeeds in lowering blood pressure.

DESIGN

A systematic review, evaluating all the observation studies and clinical trials, was conducted, followed by a meta-analysis to evaluate blood pressure variations in patients treated with phyto-oestrogens. SEARCH: The search strategy adopted used the terms "phyto-oestrogens," "soya meals," "hypertension," and "blood pressure."

DATA SOURCES

The data bases MEDLINE, EMBASE, Cochrane, OVID were used, without time or language restrictions. References in the relevant articles were searched for manually.

STUDY SELECTION

Two independent reviewers analysed the studies found in the search.

DATA EXTRACTION

The Jadad scale was used for the clinical trials and the numerical data in the text or referred to in tables were extracted. Evaluation was made of which observational and experimental articles showed a drop in blood pressure with phyto-oestrogens and which did not. In the meta-analysis, data on sample size, difference in blood pressure before and after intervention and standard deviation were extracted from each study. The weighted difference of means was used with the model of randomised effects. The Review Manager v4.2.9 programme was used.

RESULTS

No significant variations in blood pressure were found, whether systolic (-1.20 mm Hg; 95% CI, -2.80 to 0.41 mm Hg) or diastolic (-1.31 mm Hg; 95% CI, -2.73 to 0.11). If there were any variations, they are clinically of little importance. There was also an important degree of both statistical and clinical heterogeneity.

CONCLUSIONS

There are no statistically significant or clinically important differences in blood pressure between patients treated with phyto-oestrogens and those not treated.

Effect of meal replacement on metabolic risk factors in overweight and obese subjects

AIM

Our objective was to assess alterations in metabolic risk factors, body weight, fat mass and hormonal parameters following 6 weeks of lifestyle intervention with increased physical activity and either a meal-replacement regimen or a low calorie diet.

RESEARCH METHODS AND PROCEDURES

90 overweight or obese subjects (age 47 +/- 7.5 years, weight 90.6 +/- 11.3 kg, BMI 31.5 +/- 2.3) were included in this randomized controlled clinical trial. Subjects in the fat-restricted low-calorie-diet group (LCD-G; n = 30) received 2 dietary counseling sessions and instructions on how to increase physical activity. Subjects in the meal-replacement-diet group (MRD-G; n = 60) received the same lifestyle education and were instructed to replace 2 daily meals by a low-calorie high soy-protein drink.

RESULTS

Subjects in the MRD-G lost significantly more weight (6.4 vs. 3.1 kg, p < 0.01) and fat mass (5.1 vs. 2.8 kg, p < 0.01) than the LCD-G. Most metabolic risk parameters were reduced in both the MRD-G and the LCD-G; however, subjects in the MRD-G showed a higher reduction in waist circumference (6.1 vs. 1.8 cm, p < 0.01) and a larger decrease in triglycerides (-19.6 vs. +12.5 mg/dl, p < 0.01). The prevalence of the metabolic syndrome was reduced in subjects in the MRD-G only (-12%, p < 0.05) compared to an unchanged risk score in the LCD-G. The reductions in leptin (18.2 vs. 6.97 ng/ml) and insulin (4.92 vs. 0.58 microU/ml) were only significant in the MRD-G (p < 0.01).

DISCUSSION

Our data suggest that even over a short period of time, a meal-replacement diet is more effective in reducing metabolic risk factors, insulin, and leptin, and in improving anthropometric measures than a fat-restricted low-calorie diet.

Pasta naturally enriched with isoflavone aglycons from soy germ reduces serum lipids and improves markers of cardiovascular risk

Most studies of soy and cholesterol have tested foods made from purified soy proteins containing mainly isoflavone glycosides. Fermented soy foods have mainly isoflavone aglycons and account for a high proportion of the soy protein source in Asia, where there is an inverse relationship between soy intake and serum cholesterol. The aim of this study was to compare a novel soy germ pasta, naturally enriched in isoflavone aglycons as a result of the manufacturing process, with conventional pasta for effects on serum lipids and other cardiovascular risk markers. In this randomized, controlled, parallel study design of 62 adults with hypercholesterolemia who consumed a Step II diet that included one 80-g serving/d of pasta, we measured serum lipids, high sensitivity C-reactive protein (hsCRP), urinary isoprostanes, and brachial artery flow-mediated vasodilatation at baseline and after 4 and 8 wk. The pasta delivered 33 mg of isoflavones and negligible soy protein and led to a serum isoflavone concentration of 222 +/- 21 nmol/L; 69% of subjects were equol producers. Soy germ pasta reduced serum total and LDL cholesterol by 0.47 +/- 0.13 mmol/L (P = 0.001) and 0.36 +/- 0.10 mmol/L (P = 0.002) more than conventional pasta, representing reductions from baseline of 7.3% (P = 0.001) and 8.6% (P = 0.002), respectively. Arterial stiffness (P = 0.003) and hsCRP (P = 0.03) decreased and improvements in all the above risk markers were greatest in equol producers. All measures returned to baseline when patients were switched to conventional pasta. In conclusion, pasta naturally enriched with isoflavone aglycons and lacking soy protein had a significant hypocholesterolemic effect beyond a Step II diet and improved other cardiovascular risk markers.

Are soy foods protective against ischemic stroke?

Ischemic stroke is one of the leading causes of mortality and morbidity in the world. A large number of studies have observed the beneficial effects of soy protein and soy polyunsaturated fat in lowering blood cholesterol, reducing blood pressure and improving cardiovascular health. This study aims to investigate the potential of a soy food diet in the prevention of ischemic stroke through evaluation of evidence from clinical trials, meta-analyses, experimental and epidemiological studies.

Estimated Asian adult soy protein and isoflavone intakes

There is substantial interest in the possible anticancer effects of soy foods. In part, this is because of the historically low incidence rates of breast and prostate cancer in Asia. Of the several putative soybean chemopreventive agents, isoflavones have received the most attention. Awareness of this research has led increasing numbers of consumers to use soy foods, isoflavone-fortified foods, and isoflavone supplements. Therefore, there is a need for guidance regarding appropriate isoflavone intake levels. To this end, this article analyzed soy protein (as a surrogate for isoflavones) and isoflavone intake of the major soy food-consuming countries using individual dietary surveys for the bulk of the information. In total, 24 surveys from 4 countries that met the inclusion criteria were identified: Japan (n = 11), China (n = 7), Hong Kong (n = 4), and Singapore (n = 2). The results indicate that older Japanese adults consume approximately 6-11 g of soy protein and 25-50 mg of isoflavones (expressed as aglycone equivalents) per day. Intake in Hong Kong and Singapore is lower than in Japan, whereas significant regional intake differences exist for China. Evidence suggests that < or =10% of the Asian population consumes as much as 25 g of soy protein or 100 mg of isoflavones per day. The applicability of these findings for making soy intake recommendations for non-Asians is discussed.

Cardiovascular consequences of life-long exposure to dietary isoflavones in the rat

Dietary soy intake in man is proposed to provide cardiovascular protection, but it is not established whether this property is attributable to the soy protein per se or to associated dietary isoflavones. This investigation aimed to establish whether the dietary isoflavones in soy protein affect cardiovascular function. Ten days prior to mating, male and female Wistar rats were habituated to either a soy based isoflavone rich diet (plasma concentration 1.87 micromol l(-1) isoflavones) or the same diet after isoflavone elution (plasma isoflavone not detectable). Offspring were weaned onto and maintained on the same diet as their dam and sire for 6 months. Blood pressure, and constrictor and dilator responses in the aorta and mesenteric resistance arteries were assessed at 3 and 6 months of age. There was no effect of isoflavone removal from the diet on blood pressure, heart rate, aortic function or mesenteric artery contractile function, at either 3 or 6 months of age. Resistance mesenteric arteries from 6-month-old female rats fed the isoflavone rich diet demonstrated a modest increase in arterial distensibility compared with those fed the depleted diet, and mesenteric arteries from male and female rats fed the isoflavone rich diet showed increased sensitivity to acetylcholine. In summary, the isoflavone content of soy protein has no influence on blood pressure in healthy rats fed a diet based on soy protein, but influences small artery function.

The Shanghai Women's Health Study: rationale, study design, and baseline characteristics

Although cancer is a major cause of morbidity and mortality in most nations, the spectrum of cancer occurrence varies substantially worldwide. Most previous epidemiologic studies investigating cancer etiology were conducted in North American and western European countries that are relatively homogenous in terms of cancer spectrums and many lifestyle exposures. These limitations may have hindered these studies from evaluating some important etiologic hypotheses. From 1996 to 2000, the Shanghai Women's Health Study recruited 74,942 adult Chinese women from selected urban communities, with a 92% response rate. All participants completed a detailed baseline survey and anthropometrics. Approximately 88% of cohort members donated a urine sample (n = 65,755) and a blood (n = 56,832) or exfoliated buccal cell (n = 8,934) sample. Noteworthy characteristics of this cohort include low consumption of alcohol (1.9%) and use of tobacco (2.4%); high intake of fish (mean, 50.8 g/day), soy foods (mean, 142.3 g/day), and certain vegetables; low prevalence of obesity (5.1%); and nearly 100% employment outside the home. Currently, this cohort of women is being followed via biennial in-person recontact and periodic linkage to cancer and vital statistics registries. The resources from the cohort will be valuable in future studies of environmental exposures and biomarkers for the risk of cancer and other chronic diseases.