Zhao-min Liu

The effect of coffee consumption on serum lipids: a meta-analysis of randomized controlled trials

Background/objectives:Numbers of epidemiological studies assessing coffee consumption and serum lipids have yielded inconsistent results. We aimed to evaluate the effects of coffee intake on serum lipids.Subjects/methods:We searched several English and Chinese electronic databases up to September 2011 for randomized controlled trials of coffee on serum lipids. Weighted mean effect size was calculated for net changes in serum lipids by using random-effect models or fixed-effect models. Subgroup and meta-regression analyses were conducted to explore possible explanations for heterogeneity among trials.Results:Twelve studies conducted in Western countries with a total of 1017 subjects were identified. Meta-analyses showed, on average, drinking coffee for 45 days was associated with an increase of 8.1 mg/dl (95% confidence interval (CI): 4.5, 11.6; P<0.001) for total cholesterol (TC), 5.4 mg/dl (95% CI: 1.4, 9.5; P=0.009) for low-density lipoprotein cholesterol (LDL-C) and 12.6 mg/dl (95% CI: 3.5, 12.6; P=0.007) for triglyceride (TG). The increase in TC were greater in trials using unfiltered coffee and caffeinated coffee as the treatment group. Those who had hyperlipidemia were more sensitive to the cholesterol-raising effect of coffee. Meta-regression analysis revealed a positive dose-response relation between coffee intake and TC, LDL-C and TG.Conclusion:The intake of coffee especially unfiltered coffee is contributed significantly to the increase in TC, LDL-C and TG, and the changes were related to the level of intake. Studies of coffee intake on serum lipids in Asian populations should be performed.

Effects of soy protein and isoflavones on glycemic control and insulin sensitivity: a 6-mo double-blind, randomized, placebo-controlled trial in postmenopausal Chinese women with prediabetes or untreated early diabetes

BACKGROUND In vitro and animal studies have suggested that soy protein and isoflavones have favorable effects on glucose and insulin regulation, but intervention studies in humans are limited, and the results are controversial. OBJECTIVE We investigated whether soy protein with isoflavones and soy isoflavone extracts could improve glycemic control and insulin sensitivity in postmenopausal women with early hyperglycemia. DESIGN This was a randomized, double-blind, placebo-controlled trial that included 180 postmenopausal Hong Kong Chinese women with prediabetes or early untreated diabetes. After a 2-wk adaptation period, participants were randomly assigned to 1 of 3 arms to receive 15 g soy protein and 100 mg isoflavones, 15 g milk protein and 100 mg isoflavones, or 15 g milk protein on a daily basis for 6 mo. RESULTS Three- or 6-mo treatments with soy protein with or without isoflavone supplementation did not result in favorable changes in the descriptors for glycemic control and insulin resistance, namely fasting and 2-h postload glucose, fasting and postload insulin, glycated serum protein, and homeostasis model assessment for insulin resistance and beta-cell function. CONCLUSIONS This 6-mo randomized controlled trial did not support the hypothesis that soy protein with or without isoflavone supplementation had favorable effects on glycemic control and insulin sensitivity among postmenopausal Chinese women. The favorable change in postload glucose needs to be further confirmed.

Effects of soy intake on glycemic control: a meta-analysis of randomized controlled trials

BACKGROUND Evidence from animal and observational studies has supported the beneficial effects of soy intake on glycemic control, but intervention studies in humans have generated mixed results and have not been systematically examined. OBJECTIVE We aimed to quantitatively evaluate the effects of soy intake on measures of glycemic control. DESIGN We conducted a structured electronic search of PubMed, EMBASE, the Cochrane Library, and the China National Knowledge Infrastructure (updated to March 2010) databases for randomized controlled trials that described the effectiveness of different soy regimes on measures of glycemic control [homeostatic model assessment of insulin resistance (HOMA-IR) and fasting glucose and insulin, glycated hemoglobin (Hb A(1c)), and 2-h glucose and insulin concentrations]. Data on participants, interventions, outcomes, and potential effect modifiers were extracted independently. Weighted mean effect sizes were calculated for net changes by using fixed-effects or random-effects models. We performed prespecified subgroup analyses to explore the influence of covariates on net changes of fasting glucose and insulin concentrations. RESULTS Twenty-four trials with a total of 1518 subjects were included in the meta-analysis. Soy consumption did not significantly affect measures of glycemic control. The mean (95% CI) difference was -0.69 mg/dL (-1.65, 0.27 mg/dL) for fasting glucose concentrations in the fixed-effects model (P = 0.16) and -0.18 mg/dL (-0.70, 0.34 mg/dL) for fasting insulin concentrations in the random-effects model (P = 0.50). Significant heterogeneity was noted in the results of fasting insulin concentrations and HOMA-IR. CONCLUSIONS There was not a significant overall effect of soy intake on improvements of fasting glucose and insulin concentrations; however, a favorable change in fasting glucose concentrations was observed in studies that used whole soy foods or a soy diet in the subgroup analysis. Evidence for other glycemic variables such as Hb A(1c) and 2-h postchallenge glucose and insulin concentrations was limited because of the small number of trials.

The Role of Vitamin D in Blood Pressure, Endothelial and Renal Function in Postmenopausal Women

Background: Vitamin D is a pro-hormone that plays an essential role in the vasculature and in kidney function. Aims: To review the extra-skeletal effects of vitamin D on blood pressure, endothelial and renal function with emphasis on recent findings in postmenopausal women. Methods: Included in this review was a PubMed database search for English language articles through March 2013. This review discussed the physiology and definition of vitamin D deficiency, the recent evidence for the role vitamin D in blood pressure, vascular and renal function. Results: Experimental and epidemiological data suggest that vitamin D plays an important role in the vasculature and in kidney function. Low vitamin D concentrations appear to significantly associate with hypertension, endothelial and renal dysfunction. However, the results of clinical trials have generally been mixed. Studies specifically conducted among postmenopausal women are limited and findings are still inconsistent. Conclusions: Definitive studies are warranted to elucidate the effects of vitamin D supplementation on vascular and renal function and a more detailed work is needed to outline the route, duration and optimal dose of supplementation. It is premature to recommend vitamin D as a therapeutic option in the improvement of vascular and renal function at the current stage.

Effect of soy protein and isoflavones on blood pressure and endothelial cytokines: a 6-month randomized controlled trial among postmenopausal women.

Background: Despite data from animal models and observational studies that are generally supportive for the soy/isoflavones lowering blood pressure (BP) and improving vascular function, the current findings from clinical trials are still inconclusive. Objectives: To examine whether soy protein with isoflavones or isoflavones alone reduce BP and endothelial cytokines, and whether the effects differed by baseline BP level. Methods: A double-blind randomized, placebo-controlled trial was conducted among 180 postmenopausal Chinese women with mild hyperglycemia. Participants were randomly assigned to one of the three arms to receive either 15 g soy protein and 100 mg isoflavones (Soy group), or 15 g milk protein and 100 mg isoflavones (Iso group), or 15 g milk protein (placebo group) on a daily basis for 6 months. Results: No significant difference was observed in the change and %change of BP and endothelial cytokine levels among the three study groups. However, a subgroup analysis among 130 pre and hypertensive women suggested that soy protein and isoflavones significantly reduced SBP [−4.25%, 95% confidence interval (CI) −7.9 to −0.6%, P = 0.02] and the level of soluble intercellular adhesion molecule (sICAM)-1 (−22.6%, 95% CI −42.8 to −2.3%, P = 0.02) relative to milk protein after 6-month intervention. Conclusions: Our 6-month randomized controlled trial in prediabetic postmenopausal women indicated that soy protein and isoflavones had no significant effect on BP and endothelial molecules; however, a favorable reduction on SBP, sICAM-1 and E-selectin was observed among women with initial elevated BP.

Cardiovascular Risks in Relation to Daidzein Metabolizing Phenotypes among Chinese Postmenopausal Women

Background Studies suggested that the inter-individual differences in metabolizing isoflavone daidzein to equol or O-desmethylangolensin (ODMA) might explain the inconsistency of the soy/isoflavones efficacy on cardiovascular health. Objectives The study aims to evaluate the relationship between equol and ODMA phenotypes and cardiovascular risks with habitual isoflavone consumption in Chinese postmenopausal women. Methods This is a cross-sectional study among 726 prehypertensive postmenopal women who were screened for a randomized controlled trial. 648 women returned a daidzein-challenged urine samples for determination of equol and O-DMA production. 595 attended clinic visits for assessment of cardiovascular risks including body composition, blood pressure (BP), serum lipids, uric acid, high sensitivity C-reactive protein (hs-CRP), fasting glucose and free fatty acid (FFA). Results The prevalences of equol and O-DMA producers were 53.2% and 60.9% respectively. Equol producers had higher fat free mass (p = 0.001), lower systolic (p = 0.01) and diastolic (p = 0.01) BP, serum triglyceride (p = 0.023), hs-CRP (p = 0.015) and FFA (p = 0.001) than non-producers. O-DMA producers had lower body fat% (p = 0.032), SBP (p = 0.02), total cholesterol (p = 0.002) than non-producers. The significant differences remained after further adjustment for potential confounders. The habitual soy isoflavones intake had little relation to cardiovascular risk factors in either equol/O-DMA producer phenotypes. Conclusion Equol/O-DMA producers had more favorable cardiovascular risk profiles than non-producers in prehypertensive postmenopausal women.

Greater Fruit Intake was Associated With Better Bone Mineral Status Among Chinese Elderly Men and Women: Results of Hong Kong Mr. Os and Ms. Os Studies

OBJECTIVES Although studies in white populations have reported the beneficial effects of intakes of fruit and vegetables (F&V) on bone mass, limited data are available in Asians, especially among the elderly population. We examined the association of F&V intakes and bone mineral status in Chinese elderly adults and explored the potential mechanisms. DESIGN, SETTING, AND PARTICIPANTS The study was a population-based cross-sectional study among 4000 Hong Kong Chinese men and women aged 65 years and older. MEASUREMENTS Habitual F&V intakes were ascertained from a validated food frequency questionnaire. Bone mineral measurements of the whole body, hip, lumber spine, and femoral neck were made by dual-energy X-ray absorptiometry. Information on demographic, health, and lifestyles factors was obtained by standardized questionnaire. Relations between F&V intakes and bone mass at various sites were assessed by regression models. RESULTS Whole-body and femoral neck bone mineral density and content were significantly and positively associated with fruit intake in both men and women, even when adjustment for a range of potential confounders was made. A daily increase of 100 g/kcal total fruit intake was associated with 4.5% and 6.4% increase of BMD at whole body, and 3.9% and 4.8% increase at the femoral neck in men and women, respectively. No significant association was found between vegetable intake and bone mass. The adjustment for vitamin C intake, but not dietary acid load, attenuated the association between fruit intake and bone mass. CONCLUSIONS Greater fruit intake was independently associated with better bone mineral status among Chinese elderly men and women. The association is probably modified by dietary vitamin C.

Effect of whole soy and purified daidzein on ambulatory blood pressure and endothelial function—a 6-month double-blind, randomized controlled trial among Chinese postmenopausal women with prehypertension

Background/Objectives:Although observational studies suggest that soy foods or isoflavones are cardio-protective, clinical trials on whole soy or isoflavone daidzein (one major isoflavone and the precursor of equol) on blood pressure (BP) and endothelial function (EF) are few and have not been specifically conducted among equol producers, a population most likely to benefit from soy treatment.Subjects/Methods:We performed a 6-month double-blind, randomized, placebo-controlled trial to examine the effect of whole soy (soy flour) or purified daidzein on BP and EF in prehypertensive or untreated hypertensive postmenopausal women verified to be equol producers. A total of 270 eligible women were recruited and randomized to either one of the three treatment groups, 40 g soy flour (whole soy group), 40 g low-fat milk powder+63 mg daidzein (daidzein group) or 40 g low-fat milk powder (active control group) daily, each given as a solid beverage powder for 6 months. The primary outcome measures were 24 h ambulatory BP (ABP) and EF assessed by flow-mediated dilation using brachial artery ultrasound.Results:A total of 253 subjects completed the study according to protocol. Urinary isoflavones indicated good compliance with the interventions. Intention to treat and per-protocol analysis indicated that there was no significant difference in the 6-month changes or % changes in parameters of ABP and brachial flow-mediated dilation among the three treatment groups. A further subgroup analysis among hypertensive women (n=138) did not alter the conclusions.Conclusions:Whole soy and purified daidzein had no significant effect on BP and vascular function among equol-producing postmenopausal women with prehypertension or untreated hypertension.

Soy food consumption, cardiometabolic alterations and carotid intima-media thickness in Chinese adults

BACKGROUND AND AIM The associations between soy food consumption, cardiometabolic disturbances and subclinical atherosclerosis remain controversial due to limited evidence. We examined the associations of habitual soy food consumption with cardiometabolic disturbances and carotid intima-media thickness (CIMT). METHODS AND RESULTS We included 2939 subjects (2135 women and 804 men) aged 50-75 years in this community-based cross-sectional study. Dietary data and other covariates were collected using interviewer-administered questionnaires. We determined CIMT in relation to each subjects common carotid artery, internal carotid artery, carotid bifurcation, blood lipids, glucose and urine acid, blood pressure and waist circumference. A logistic regression model was applied to estimate the odd ratios (ORs) and 95% confidence intervals (CIs), and linear regression was used to estimate the regression coefficient and 95% CIs. After adjusting for potential confounders, we found that greater consumption of soy protein (6.1 vs. 0.5 g/d) was inverse associated with the presence of elevated total cholesterol (TC), dyslipidemia, abdominal obesity and hyperuricemia in women, and with abdominal obesity in men, although no significant sex-soy interactions were observed (P: 0.145-0.985). The consumption of soy protein and isoflavones was inversely associated with the number of cardiometabolic disturbances among women, but not men. There were no significant associations of soy protein and isoflavones with CIMT thickening and other cardiometabolic disturbances. CONCLUSION Greater soy consumption was associated with a lower presence of elevated TC, dyslipidemia, hyperuricemia and less number of cardiometabolic disturbances components in women.

Randomized controlled trial of whole soy and isoflavone daidzein on menopausal symptoms in equol-producing Chinese postmenopausal women.

ObjectiveDietary supplements containing soy or isoflavones are widely used as alternatives to hormone therapy. However, their efficacy is still inconclusive, and limited data on equol producers are available. The aim of this study was to examine the effect of whole soy (soy flour) or purified daidzein (one major soy isoflavone and the precursor of equol) on menopausal symptoms in equol-producing postmenopausal women, a population most likely to benefit from soy intervention. MethodsThis is a 6-month parallel-group, double-blind, randomized, placebo-controlled trial. Two hundred seventy equol-producing prehypertensive Chinese postmenopausal women were randomized to one of three treatment groups: 40 g of soy flour (whole soy group), 40 g of low-fat milk powder + 63 mg of daidzein (daidzein group), or 40 g of low-fat milk powder (placebo group) daily, each given as a solid beverage for 6 months. Changes in menopausal symptoms were assessed by a validated and structured symptom checklist at baseline and 6 months. ResultsTwo hundred fifty-three participants completed the study according to protocol. Urinary isoflavones indicated good compliance with the interventions. Baseline menopausal symptoms were comparable among the three study groups. Intention-to-treat analysis indicated that there was no significant difference in the 6-month changes or percent changes in the total number of menopausal symptoms, in the five dimensions of symptoms, and in the frequencies of individual symptoms among the three treatment groups. ConclusionsWhole soy and purified daidzein have no significant effect on alleviation of menopausal symptoms among equol-producing postmenopausal women with prehypertension.