Relation between soy-associated isoflavones and LDL and HDL cholesterol concentrations in humans: a meta-analysis

Soy and Soy Products Intake, All-Cause Mortality, and Cause-Specific Mortality in Japan

Soy and soy products are popular ingredients in the Japanese diet. This study aimed to determine whether soy or soy products intake was associated with all-cause mortality in a community-based cohort in Japan. A total of 11 066 participants were obtained from an annual community-based health examination program. A self-administered questionnaire was used to collect information concerning soy and soy products intake and potential confounding factors. Associations between soy and soy products intake and all-cause mortality were assessed using hazard ratios (HRs). After adjusting for all factors, morality was significantly higher in men with infrequent soy intake (HR = 1.53; 95% confidence interval [CI] = 1.13-2.07) and with almost daily intake (HR = 1.55; 95% CI = 1.19-2.03) compared with intake 1 to 2 times per week. Cancer mortality was higher among men who reported rarely eating soy (HR = 1.74; 95% CI = 1.08-2.79). Soy products intake was not statistically significantly associated with all-cause mortality in both sexes.

Impact of a traditional dietary supplement with coconut milk and soya milk on the lipid profile in normal free living subjects

Background. The effects of coconut fat and soya fat on serum lipids are controversial. This study was designed to investigate the lipid effects of coconut milk and soya milk supplementation on the lipid profile of free living healthy subjects. Methods. Sixty (60) healthy volunteers aged 18–57 years were given coconut milk porridge (CMP) for 5 days of the week for 8 weeks, followed by a 2-week washout period, subsequent to which they received isoenergetic soya milk porridge (SMP) for 8 weeks. Results. The LDL (low density lipoprotein) levels decreased with CMP and reached statistical significance in the total study population and in the >130 baseline LDL group. The HDL (high density lipoprotein) levels rose significantly with CMP supplementation (P = 0.000). Conclusions. We conclude that coconut fat in the form of CM does not cause a detrimental effect on the lipid profile in the general population and in fact is beneficial due to the decrease in LDL and rise in HDL. SMP will be of benefit only in those whose baseline LDL levels are elevated.

Plasma and dietary antioxidant status as cardiovascular disease risk factors: a review of human studies

Extensive evidence has demonstrated that many antioxidants such as vitamin C, vitamin E, carotenoids and polyphenols have protective effects in preventing cardiovascular disease (CVD), a chronic disease that is mediated by oxidative stress and inflammation. This review focuses on evidence from prospective cohort studies and clinical trials in regard to the associations between plasma/dietary antioxidants and cardiovascular events. Long-term, large-scale, population-based cohort studies have found that higher levels of serum albumin, bilirubin, glutathione, vitamin E, vitamin C, and carotenoids were associated with a lower risk of CVD. Evidence from the cohort studies in regard to dietary antioxidants also supported the protective effects of dietary vitamin E, vitamin C, carotenoids, and polyphenols on CVD risk. However, results from large randomized controlled trials did not support long-term use of single antioxidant supplements for CVD prevention due to their null or even adverse effects on major cardiovascular events or cancer. Diet quality indexes that consider overall diet quality rather than single nutrients have been drawing increasing attention. Cohort studies and intervention studies that focused on diet patterns such as high total antioxidant capacity have documented protective effects on CVD risk. This review provides a perspective for future studies that investigate antioxidant intake and risk of CVD.

Isoflavones for hypercholesterolaemia in adults

BACKGROUND

Hypercholesterolaemia is a significant risk factor for cardiovascular diseases. Isoflavones may be effective in improving hypercholesterolaemia.

OBJECTIVES

To assess the effects of isoflavones for hypercholesterolaemia.

SEARCH METHODS

We searched the following databases: The Cochrane Library (Issue 9, 2012), MEDLINE, EMBASE, Chinese BioMedical Database and China National Knowledge Infrastructure (all to September 2012).

SELECTION CRITERIA

We considered randomized controlled clinical trials in hypercholesterolaemic participants comparing isoflavones versus placebo, or soy isolated protein added with isoflavones versus soy isolated protein alone.

DATA COLLECTION AND ANALYSIS

Two review authors independently abstracted relevant population and intervention characteristics. We resolved any disagreements through discussion, or if required by a third party. We assessed the risk of bias of trials against key criteria: random sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, incomplete outcome data, selective reporting and other sources of bias.

MAIN RESULTS

We included five randomized trials (208 participants, 104 in the intervention group and 104 in the control group). Interventions ranged from three to six months. Four trials reported results in non-Asian populations published in English. One trial reported results in Chinese people published in Chinese. Overall, the risk of bias of included trials was high or unclear. There were no outcome data on death from any cause, morbidity, complications, health-related quality of life and costs. Two trials reported adverse effects, including gastrointestinal discomfort (bloating and constipation) and an increased number of hot flushes. None of the trials found serious adverse events. There was a slight significant effect on triglycerides in favour of isoflavones when compared with placebo (mean difference (MD) -0.46 mmol/L (95% confidence interval (CI) -0.84 to -0.09; P = 0.02; 52 participants; 2 trials). No statistically significant effects on total cholesterol, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol were shown in favour of isoflavones.

AUTHORS' CONCLUSIONS

We found no evidence for effects of isoflavones on patient-important outcomes or lowering of cholesterol levels in people with hypercholesterolaemia. Our findings have to be interpreted with caution due to high or unclear risk of bias in several risk of bias domains, and low number of participants in trials.

The short-term effects of soybean intake on oxidative and carbonyl stress in men and women

Beyond other beneficial effects, a soy-rich diet has been shown to reduce the risk of cardiovascular diseases and diabetic complications. Reduction of oxidative and carbonyl stress has been proposed as the underlying mechanism, but the evidence for this is lacking. The aim of our study was to evaluate the effects of short-term increased soy intake on oxidative and carbonyl stress parameters in young volunteers. Young healthy probands (omnivores) of both genders (55 women, 33 men) were given soybeans (2 g/kg bodyweight daily) for one week. Markers of oxidative and carbonyl stress were measured in plasma at the beginning and at the end of one week soybean intake and after another week of a wash-out period. Total antioxidant capacity was increased by soybean intake in both genders. This led to decreased levels of advanced oxidation protein products in women, but not in men. On the contrary, in men, soybean intake increased lipoperoxidation. No effects on carbonyl stress markers (advanced glycation end products-specific fluorescence and fructosamine) were found. Soybean intake has gender-specific effects on oxidative stress in young healthy probands potentially due to divergent action and metabolism of phytoestrogens in men and women. Effects of soybean intake on carbonyl stress should be evaluated in longer studies.

Soya isoflavone consumption in relation to carotid intima-media thickness in Chinese equol excretors aged 40-65 years

Previous studies have suggested that the daidzein metabolite equol rather than daidzein itself contributes to the beneficial effect of soya foods in the prevention of CVD. The aim of the present study is to examine the proportion of equol excretion in Chinese adults and compare plasma lipids and carotid artery intima-media thickness (IMT) between equol excretors and non-excretors, and to evaluate the effect of soya isoflavone intakes on serum lipids and IMT in either equol excretors or non-excretors. Subjects (n 572; women n 362, men n 210) were recruited for the present study. An overnight urine sample was provided by each subject on their usual diet to quantify urinary concentrations of daidzein and equol. Far-wall IMT was determined by B-mode ultrasound in the right carotid at two sites, carotid bulb (CB-IMT) and common carotid artery (CCA-IMT), and fasting serum lipids were measured. Habitual dietary intakes were estimated with a FFQ, and soya isoflavone intake derived from the FFQ was assessed. Of the 572 subjects, the proportion of equol excretors on their usual diet was 25·0 % (n 143). Compared with non-excretors, equol excretors showed significantly lower serum TAG (-38·2 (95 % CI -70·4, -5·9) %, P = 0·012) and CCA-IMT (-4·9 (95 % CI -9·7, -0·3) %, P = 0·033). Equol excretors with higher daily isoflavone intakes (-5·4 mg/d) had significantly lower IMT (-16·2 %, P = 0·035) and tended to have higher HDL-cholesterol (P = 0·055) than did those with lower daily isoflavone intakes (1·5 mg/d), while no association was observed between soya isoflavone intakes and serum lipids or IMT in non-excretors. In conclusion, the benefits of soya isoflavones in preventing CVD may be apparent among equol excretors only.

Association of MYLIP rs3757354 SNP and several environmental factors with serum lipid levels in the Guangxi Bai Ku Yao and Han populations

Background

The association of rs3757354 single nucleotide polymorphism (SNP) in the E3 ubiquitin ligase myosin regulatory light chain-interacting protein (MYLIP, also known as IDOL) gene and serum lipid levels is not well known in the general population. The present study aimed to detect the association of rs3757354 SNP and several environmental factors with serum lipid levels in the Guangxi Bai Ku Yao and Han populations.

Method

A total of 627 subjects of Bai Ku Yao minority and 614 participants of Han nationality were randomly selected from our stratified randomized cluster samples. Genotyping of the rs3757354 SNP was performed by polymerase chain reaction and restriction fragment length polymorphism combined with gel electrophoresis, and then confirmed by direct sequencing.

Results

The levels of serum total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), apolipoprotein (Apo) AI and ApoB were lower in Bai Ku Yao than in Han (P < 0.05-0.001). The frequency of G allele was 49.92% in Bai Ku Yao and 56.27% in Han (P < 0.05). The frequencies of AA, GA and GG genotypes were 25.52%, 49.12% and 25.36% in Bai Ku Yao, and 19.87%, 47.72% and 32.41% in Han (P < 0.05); respectively. There were no significant differences in the genotypic and allelic frequencies between males and females in both ethnic groups. The levels of HDL-C in Bai Ku Yao were different among the genotypes (P < 0.05), the G allele carriers had higher serum HDL-C levels than the G allele noncarriers. The levels TC, HDL-C and ApoAI in Han were different among the genotypes (P < 0.05 for all), the participants with GA genotype had lower serum TC, HDL-C and ApoAI levels than the participants with AA genotype. These findings were found only in females but not in males. The levels of TG and HDL-C in Bai Ku Yao were correlated with the genotypes, whereas the levels of TC in Han, and TC, LDL-C in Han females were associated with the genotypes (P < 0.05 for all). Serum lipid parameters were also correlated with age, sex, alcohol consumption, cigarette smoking, blood pressure, and body mass index in both ethnic groups (P < 0.05-0.001).

Conclusions

The present study suggests that the MYLIP rs3757354 SNP is associated with serum TC, HDL-C and ApoAI levels in the Bai Ku Yao and Han populations. But the association is different between the two ethnic groups.

Food combinations for cholesterol lowering

Reducing elevated LDL-cholesterol is a key public health challenge. There is substantial evidence from randomised controlled trials (RCT) that a number of foods and food components can significantly reduce LDL-cholesterol. Data from RCT have been reviewed to determine whether effects are additive when two or more of these components are consumed together. Typically components, such as plant stanols and sterols, soya protein, β-glucans and tree nuts, when consumed individually at their target rate, reduce LDL-cholesterol by 3-9 %. Improved dietary fat quality, achieved by replacing SFA with unsaturated fat, reduces LDL-cholesterol and can increase HDL-cholesterol, further improving blood lipid profile. It appears that the effect of combining these interventions is largely additive; however, compliance with multiple changes may reduce over time. Food combinations used in ten 'portfolio diet' studies have been reviewed. In clinical efficacy studies of about 1 month where all foods were provided, LDL-cholesterol is reduced by 22-30 %, whereas in community-based studies of >6 months' duration, where dietary advice is the basis of the intervention, reduction in LDL-cholesterol is about 15 %. Inclusion of MUFA into 'portfolio diets' increases HDL-cholesterol, in addition to LDL-cholesterol effects. Compliance with some of these dietary changes can be achieved more easily compared with others. By careful food component selection, appropriate to the individual, the effect of including only two components in the diet with good compliance could be a sustainable 10 % reduction in LDL-cholesterol; this is sufficient to make a substantial impact on cholesterol management and reduce the need for pharmaceutical intervention.

Dietary agents that target gastrointestinal and hepatic handling of bile acids and cholesterol

Several food components have been demonstrated to exhibit cholesterol-lowering properties by interfering with cholesterol absorption and bile-acid trafficking. Such components include stearic acid, plant sterols, soluble fiber, and soy protein. Among saturated fatty acids, stearic acid is unique in its ability to reduce circulatory low-density lipoprotein cholesterol levels. This action is accompanied by an observed suppression in cholesterol absorption, an effect seen repeatedly in animal and human studies. Proposed mechanisms include micellar exclusion of cholesterol by this high melting point fatty acid, as well as the ability of stearate to alter the biliary ratios of primary to secondary bile acids, leading to a reduction in hydrophobicity index and lower overall solubility of sterols in micelles. Another dietary ingredient that interferes with absorption of sterols is soy protein, in which studies in animals and humans have identified that compared to casein, consumption of soy protein reduces intestinal absorption of cholesterol while enhancing fecal cholesterol excretion. Considerable investigation using free amino acid mixtures mirroring the composition of soy versus animal proteins has determined that co-existing agents other than soy's amino acid pattern are likely responsible for the inhibitory action of soy protein on sterol uptake. Recently, it has been shown that hydrolysates of soy protein appear to be effective in reducing sterol absorption; these are now being targeted as the possible factor responsible for the overall effect of this dietary ingredient. Plant sterols appear to impact absorption of sterols through several mechanisms, including competition with cholesterol for incorporation into micelles, co-crystallization with cholesterol to form insoluble crystals, interaction with digestive enzymes, and inhibition of cholesterol transporter proteins. Clinical trials attest to plant sterols lowering cholesterol absorption by 20% to 40%, an extent beyond which cholesterogenesis can compensate to restore normal circulatory cholesterol levels. As such, 2 g/day of plant sterols effectively lowers low-density lipoprotein cholesterol by 8% to 12%. Dietary soluble fiber represents another means of reducing intestinal cholesterol uptake, in part through enhanced bile-acid clearance through the gut. Pectin, β-glucans, fructans, and gums have been identified as agents that can work through the production of a viscous matrix that hinders movement of cholesterol and bile acids into micelles as well as the subsequent uptake of micelles into the enterocyte. Additional work on design of novel fibers that impede sterol absorption is warranted. In summary, a number of novel dietary factors exist that contribute to heart disease risk reduction via mechanisms that involve cholesterol absorption inhibition and/or biliary pathway perturbation.

Can breast cancer patients use soyafoods to help reduce risk of CHD?

Over the past 20 years, the popularity of soyafoods has increased in part because of research suggesting that these foods convey health benefits independent of their nutrient content. For example, in 1999, the US Food and Drug Administration approved a health-claim for soyafoods and CHD based on the hypocholesterolaemic effects of soya protein. However, soyafoods have become controversial in recent years because of concerns that their uniquely rich phyto-oestrogen (isoflavone) content may cause untoward effects in some individuals. Most notable in this regard is the concern that soyafoods are contraindicated for breast cancer patients and women at high risk of developing this disease. Furthermore, the hypocholesterolaemic effects of soya protein have been challenged. However, the results of recently published meta-analyses indicate that soya protein directly lowers circulating LDL-cholesterol levels by approximately 4 %. There is also intriguing evidence that soyafoods reduce CHD risk independent of their effects on lipid levels. In regard to the breast cancer controversy, recently published clinical and epidemiological data do not support observations in rodents that soyabean isoflavones increase breast cancer risk. In postmenopausal women, isoflavone exposure does not adversely affect breast tissue density or breast cell proliferation. Furthermore, both US and Chinese prospective epidemiological studies show that post-diagnosis soya consumption is associated with an improved prognosis. Therefore, soyafoods should be considered by women as healthy foods to include in diets aimed at reducing the risk of CHD regardless of their breast cancer status.

Association of rs5888 SNP in the scavenger receptor class B type 1 gene and serum lipid levels

Background

Bai Ku Yao is a special subgroup of the Yao minority in China. The present study was undertaken to detect the association of rs5888 single nucleotide polymorphism (SNP) in the scavenger receptor class B type 1 (SCARB1) gene and several environmental factors with serum lipid levels in the Guangxi Bai Ku Yao and Han populations.

Methods

A total of 598 subjects of Bai Ku Yao and 585 subjects of Han Chinese were randomly selected from our stratified randomized cluster samples. Genotypes of the SCARB1 rs5888 SNP were determined by polymerase chain reaction and restriction fragment length polymorphism combined with gel electrophoresis, and then confirmed by direct sequencing.

Results

The levels of total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), apolipoprotein (Apo) AI were lower but ApoB was higher in Bai Ku Yao than in Han (P < 0.05-0.001). The frequencies of C and T alleles were 78.3% and 21.7% in Bai Ku Yao, and 73.7% and 26.3% in Han (P < 0.01); respectively. The frequencies of CC, CT and TT genotypes were 60.0%, 36.6% and 3.4% in Bai Ku Yao, and 54.2%, 39.0% and 6.8% in Han (P < 0.01); respectively. The subjects with TT genotype in both ethnic groups had lower HDL-C and ApoAI levels than the subjects with CC or CT genotype (P < 0.05 for all). Subgroup analyses showed that the subjects with TT genotype in Bai Ku Yao had lower HDL-C and ApoAI levels in males than the subjects with CC or CT genotype (P < 0.05 for all), and the T allele carriers had higher TC, LDL-C and ApoB levels in females than the T allele noncarriers (P < 0.05 for all). The participants with TT genotype in Han also had a lower tendency of HDL-C and ApoAI levels in males than the participants with CC or CT genotype, but the difference did not reach statistically significant (P = 0.063 and P = 0.086; respectively). The association of serum HDL-C and ApoAI levels and genotypes was confirmed by the multiple linear regression analysis in both ethnic groups. Serum lipid parameters were also correlated with several environmental factors.

Conclusions

The differences in serum lipid levels between the two ethnic groups might partially attribute to the differences in the SCARB1 rs5888 SNP and several environmental factors.

Soy protein effects on serum lipoproteins: a quality assessment and meta-analysis of randomized, controlled studies

OBJECTIVES

Many randomized controlled trials (RCTs) have assessed the effects of soy protein on serum lipoprotein risk factors for coronary heart disease (CHD). This review and meta-analysis assessed the quality of these RCTs and estimated the effects of soy protein consumption on serum lipoproteins.

DATA SOURCES

A comprehensive search using multiple databases was conducted for the years 1996 through 2008 to identify clinical trials related to soy protein intake and serum lipoprotein changes.

STUDY ELIGIBILITY

RCTs were assessed that met these requirements: soy protein intake compared with nonsoy protein, provided information on serum low-density lipoprotein (LDL)-cholesterol values, provided no more than 65 g of soy protein daily, and obtained LDL-cholesterol measurements between 4 and 18 weeks of treatment. Randomized parallel and crossover studies were evaluated.

METHODS

Studies were graded for quality using 12 criteria with a possible maximum grade of 24. Net changes in lipoproteins with soy protein consumption compared with nonsoy control diets were analyzed by meta-analyses and funnel plots. Confidence intervals were constructed using inverse weighting. Analyses compared parallel to crossover studies and studies with lower and higher grades.

RESULTS

Analyses included 20 parallel-design studies and 23 crossover studies. Parallel studies scored significantly higher (p < 0.001) in study quality, with a mean grade of 15.8 (95% confidence interval [CI], 14.3 to 17.3) compared with 10.1 (95% CI, 8.2 to 11.9) for crossover trials. Soy protein intake was associated with net changes in serum LDL-cholesterol values of -0.23 mmol/l (95% CI, -0.28 to -0.18 mmol/l) or a 5.5% reduction in parallel studies and -0.16 mmol/l (95% CI, -0.22 to -0.11 mmol/l) or a reduction of 4.2% with crossover studies (p < 0.001 for parallel vs crossover). In parallel studies, net serum HDL-cholesterol values were 3.2% higher (p < 0.007) with soy vs control, and fasting serum triacylglycerol values were 10.7% lower (p < 0.008) for soy vs control.

CONCLUSIONS AND IMPLICATIONS

Soy protein consumption with a median of 30 g/d was associated with a significant improvement in lipoprotein risk factors for CHD. Compared with crossover RCTs, parallel RCTs had significantly higher quality grades and were associated with significantly greater improvements in serum LDL-cholesterol values. Regular consumption of 1 to 2 servings of soy protein daily (15 to 30 g) has a significant favorable impact on serum lipoprotein risk factors for CHD.

Effects of soy protein containing isoflavones on women's lipid profile: a meta-analysis

This study evaluated the effects of soy protein containing isoflavones on the lipid profile of women. A meta-analysis including 13 eligible randomized controlled trials was carried out. The literature was systematically searched for randomized controlled trials on the effects of soy protein containing isoflavones on the serum lipids of adult women. The main searched databases were PubMed, Cochrane Library, MedLine, Lilacs and Web of Science. Randomized controlled trials were included if they met the following criteria: published from 1966 to 2005, the study population consisted of women only, had either a crossover or a parallel design and the amounts of soy protein and isoflavones consumed were provided. Weighted mean effect sizes were calculated for net changes in serum lipid concentrations using fixed-effects and random-effects models. Prespecified subgroup analyses were performed to explore the influence of covariates on net lipid change. Soy protein with isoflavones was associated with a significant decrease in total serum cholesterol (by 5.34mg/dL, or 2.4%, p=0.03). No significant associations were detected for low density lipoprotein-cholesterol, triacylglycerols and high density lipoprotein-cholesterol. Amounts of soy protein greater than 40g decreased total cholesterol by 6.56mg/dL (95% CI: -12.35 to -0.39, p=0.04). Soy protein supplementation had small statistically significant effects on the total serum cholesterol of women, but they were clinically insignificant. Furthermore, there were no statistically significant effects on serum low density lipoprotein-cholesterol, high density lipoprotein-cholesterol or triglycerides.

The proprotein convertase subtilisin/kexin type 9 gene E670G polymorphism and serum lipid levels in the Guangxi Bai Ku Yao and Han populations

Background

Proprotein convertase subtilisin-like kexin type 9 (PCSK9) plays a key role in regulating plasma low-density lipoprotein cholesterol (LDL-C) levels. However, the association of E670G (rs505151) polymorphism in the PCSK9 gene and serum lipid levels is inconsistent in several previous studies. The present study was undertaken to detect the association of PCSK9 E670G polymorphism and several environmental factors with serum lipid levels in the Guangxi Bai Ku Yao and Han populations.

Methods

A total of 649 subjects of Bai Ku Yao and 646 participants of Han were randomly selected from our previous samples. Genotypes of the PCSK9 E670G polymorphism were determined via polymerase chain reaction and restriction fragment length polymorphism combined with gel electrophoresis, and then confirmed by direct sequencing.

Results

Serum levels of total cholesterol, high-density lipoprotein cholesterol (HDL-C), LDL-C, and apolipoprotein (Apo) AI were lower in Bai Ku Yao than in Han (P < 0.01 for all). The frequency of G allele was 2.00% in Bai Ku Yao and 4.80% in Han (P < 0.01). There was significant difference in the genotypic and allelic frequencies between Bai Ku Yao and Han (P < 0.01); between normal LDL-C (≤ 3.20 mmol/L) and high LDL-C subgroups (> 3.20 mmol/L, P < 0.01) in Bai Ku Yao; and between normal HDL-C (≥ 0.91 mmol/L) and low HDL-C (< 0.91 mmol/L, P < 0.05), between normal ApoAI (≥ 1.00 g/L) and low ApoAI (< 1.00 g/L, P < 0.05), or between normal ApoAI/ApoB ratio (≥ 1.00) and low ApoAI/ApoB ratio (< 1.00, P < 0.01) subgroups in Han. The G allele carriers in Han had higher serum HDL-C levels and the ratio of ApoAI to ApoB than the G allele noncarriers. The G allele carriers in Han had higher serum HDL-C and ApoAI levels than the G allele noncarriers in males (P < 0.05 for each), whereas the G allele carriers had lower serum ApoB levels and higher the ratio of ApoAI to ApoB than the G allele noncarriers in females (P < 0.05 for all). Serum HDL-C and ApoAI levels in Han were correlated with genotypes (P < 0.05) in males, and serum ApoB levels and the ratio of ApoAI to ApoB were associated with genotypes (P < 0.05) in females.

Conclusions

The PCSK9 E670G polymorphism is mainly associated with some serum lipid parameters in the Han population. The G allele carriers had higher serum HDL-C and ApoAI levels in males, and lower serum ApoB levels and higher the ApoAI/ApoB ratio in females than the G allele noncarriers.

Peroxisome proliferator-activated receptor delta +294T > C polymorphism and serum lipid levels in the Guangxi Bai Ku Yao and Han populations

BACKGROUND

The association of peroxisome proliferator-activated receptor delta (PPARD) +294T > C polymorphism and serum lipid levels is inconsistent in several previous studies. Bai Ku Yao is an isolated subgroup of the Yao minority in China. The present study was undertaken to detect the association of PPARD +294T > C (rs2016520) polymorphism and several environmental factors with serum lipid levels in the Guangxi Bai Ku Yao and Han populations.

METHODS

A total of 609 subjects of Bai Ku Yao and 573 participants of Han Chinese were randomly selected from our previous stratified randomized cluster samples. Genotyping of the PPARD +294T > C polymorphism was performed by polymerase chain reaction and restriction fragment length polymorphism combined with gel electrophoresis, and then confirmed by direct sequencing.

RESULTS

The levels of serum total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), apolipoprotein (Apo) AI and ApoB were lower in Bai Ku Yao than in Han (P < 0.001 for all). The frequency of T and C alleles was 77.50% and 22.50% in Bai Ku Yao, and 72.43% and 27.57% in Han (P < 0.01); respectively. The frequency of TT, TC and CC genotypes was 60.59%, 33.83% and 5.53% in Bai Ku Yao, and 52.18%, 40.50% and 7.32% in Han (P < 0.05); respectively. The subjects with CC genotype in Bai Ku Yao had higher serum LDL-C and ApoB levels and lower the ratio of ApoAI to ApoB than the subjects with TT and TC genotypes in females but not in males. The C allele carriers in Han had higher serum TC levels in males (P < 0.01) and ApoB levels in females (P < 0.05) than the C allele noncarriers. Serum TC and ApoB levels were correlated with genotypes in Han (P < 0.05 for each) but not in Bai Ku Yao. Serum lipid parameters were also correlated with sex, age, body mass index, alcohol consumption, cigarette smoking, and blood pressure in both ethnic groups.

CONCLUSIONS

These results suggest that the association of PPARD +294T > C polymorphism and serum lipid levels is different between the Bai Ku Yao and Han populations. The discrepancy between the two ethnic groups might partly result from different PPARD +294T > C polymorphism or PPARD gene-environmental interactions.

Polymorphism of rs1044925 in the acyl-CoA:cholesterol acyltransferase-1 gene and serum lipid levels in the Guangxi Bai Ku Yao and Han populations

Background

The association of rs1044925 polymorphism in the acyl-CoA:cholesterol acyltransferase-1 (ACAT-1) gene and serum lipid profiles is not well known in different ethnic groups. Bai Ku Yao is a special subgroup of the Yao minority in China. The present study was carried out to clarify the association of rs1044925 polymorphism in the ACAT-1 gene and several environmental factors with serum lipid levels in the Guangxi Bai Ku Yao and Han populations.

Methods

A total of 626 subjects of Bai Ku Yao and 624 participants of Han Chinese were randomly selected from our previous stratified randomized cluster samples. Genotyping of rs1044925 polymorphism in the ACAT-1 gene was performed by polymerase chain reaction and restriction fragment length polymorphism combined with gel electrophoresis, and then confirmed by direct sequencing.

Results

The levels of serum total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), apolipoprotein (Apo) AI and ApoB were lower in Bai Ku Yao than in Han (P < 0.01 for all). The frequency of A and C alleles was 79.0% and 21.0% in Bai Ku Yao, and 87.3% and 12.7% in Han (P < 0.001); respectively. The frequency of AA, AC and CC genotypes was 63.2%, 31.4% and 5.2% in Bai Ku Yao, and 75.6%, 23.2% and 1.1% in Han (P < 0.001); respectively. The levels of TC, LDL-C and ApoB in Bai Ku Yao but not in Han were different between the AA and AC/CC genotypes in females but not in males (P < 0.05 for all). The C allele carriers had lower serum TC, LDL-C and ApoB levels as compared with the C allele noncarriers. The levels of TC, LDL-C and ApoB in Bai Ku Yao but not in Han were correlated with genotypes in females but not in males (P < 0.05 for all). Serum lipid parameters were also correlated with sex, age, body mass index, alcohol consumption, and blood pressure in both ethnic groups (P < 0.05-0.001).

Conclusions

These results suggest that the polymorphism of rs1044925 in the ACAT-1 gene is mainly associated with female serum TC, LDL-C and ApoB levels in the Bai Ku Yao population. The C allele carriers had lower serum TC, LDL-C and ApoB levels than the C allele noncarriers.

Soy protein reduces serum cholesterol by both intrinsic and food displacement mechanisms

The apparently smaller LDL cholesterol (LDL-C)-lowering effect of soy in recent studies has prompted the U.S. FDA to reexamine the heart health claim previously allowed for soy products. We therefore attempted to estimate the intrinsic and extrinsic (displacement) potential of soy in reducing LDL-C to determine whether the heart health claim for soy continues to be justified. The intrinsic effect of soy was derived from a meta-analysis using soy studies (20-133 g/d soy protein) included in the recent AHA Soy Advisory. The extrinsic effect of soy in displacing foods higher in saturated fat and cholesterol was estimated using predictive equations for LDL-C and NHANES III population survey data with the substitution of 13-58 g/d soy protein for animal protein foods. The meta-analysis of the AHA Soy Advisory data gave a mean LDL-C reduction of 0.17 mmol/L (n = 22; P < 0.0001) or 4.3% for soy, which was confirmed in 11 studies reporting balanced macronutrient profiles. The estimated displacement value of soy (13-58 g/d) using NHANES III population survey data was a 3.6-6.0% reduction in LDL-C due to displacement of saturated fats and cholesterol from animal foods. The LDL-C reduction attributable to the combined intrinsic and extrinsic effects of soy protein foods ranged from 7.9 to 10.3%. Thus, soy remains one of a few food components that reduces serum cholesterol (>4%) when added to the diet.

Association of methylenetetrahydrofolate reductase C677T polymorphism and serum lipid levels in the Guangxi Bai Ku Yao and Han populations

Background

The association of methylenetetrahydrofolate reductase (MTHFR) gene polymorphism and serum lipid profiles is still controversial in diverse ethnics. Bai Ku Yao is an isolated subgroup of the Yao minority in China. The aim of the present study was to eveluate the association of MTHFR C677T polymorphism and several environmental factors with serum lipid levels in the Guangxi Bai Ku Yao and Han populations.

Methods

A total of 780 subjects of Bai Ku Yao and 686 participants of Han Chinese were randomly selected from our previous stratified randomized cluster samples. Genotyping of the MTHFR C677T was performed by polymerase chain reaction and restriction fragment length polymorphism combined with gel electrophoresis, and then confirmed by direct sequencing.

Results

The levels of serum total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), apolipoprotein (Apo) AI and ApoB were lower in Bai Ku Yao than in Han (P < 0.05-0.001). The frequency of C and T alleles was 77.4% and 22.6% in Bai Ku Yao, and 60.9% and 39.1% in Han (P < 0.001); respectively. The frequency of CC, CT and TT genotypes was 58.7%, 37.3% and 4.0% in Bai Ku Yao, and 32.6%, 56.4% and 11.0% in Han (P < 0.001); respectively. The levels of TC and LDL-C in both ethnic groups were significant differences among the three genotypes (P < 0.05-0.01). The T allele carriers had higher serum TC and LDL-C levels than the T allele noncarriers. The levels of ApoB in Han were significant differences among the three genotypes (P < 0.05). The T allele carriers had higher serum ApoB levels as compared with the T allele noncarriers. The levels of TC, TG and LDL-C in Bai Ku Yao were correlated with genotypes (P < 0.05-0.001), whereas the levels of LDL-C in Han were associated with genotypes (P < 0.001). Serum lipid parameters were also correlated with sex, age, body mass index, alcohol consumption, cigarette smoking, and blood pressure in the both ethnic groups.

Conclusions

The differences in serum TC, TG, LDL-C and ApoB levels between the two ethnic groups might partly result from different genotypic and allelic frequencies of the MTHFR C677T or different MTHFR gene-enviromental interactions.

Effect of soy proteins Vs soy isoflavones on lipid profile in postmenopausal women

Soy isoflavones and soy proteins are being considered as possible alternatives to postmenopausal hormone replacement therapy. This study was undertaken to evaluate effects of these two preparations on symptoms and lipid profile in postmenopausal women. The study was done in 75 postmenopausal women with FSH levels = 30 mIU/ml. These women were randomly divided into 3 groups (n=25). Study group I was given soy proteins 30gm/day containing 60 mg soy isoflavones. Study group II was given soy isoflavones (60 mg/day). The control group was given casein protein 30 gm/day. The menopausal symptoms were assessed by Kupperman Index. Fasting blood samples were analyzed for serum lipid profile, apolipoprotein A1 and B, Leutenizing Hormone (LH) and Follicle-Stimulating Hormone (FSH) at the beginning of therapy, 4 and 12 weeks after initiation of therapy. A highly significant improvement in postmenopausal symptoms was observed in both the study groups. A highly significant improvement was seen in serum lipid profile and Apolipoprotein A1 and B in women taking soy proteins whereas women taking soy isoflavones demonstrated significant improvement in serum triglycerides only. Both soy proteins and soy isoflavones are helpful in alleviating postmenopausal symptoms but soy proteins offer a greater health advantage due to their beneficial effect on serum lipid profile.

Dietary phyto-oestrogens: molecular mechanisms, bioavailability and importance to menopausal health

Following the high-profile studies on hormone replacement therapy which provided little evidence in support of the drug therapy improving future health, there remains a growing demand for dietary solutions for maintaining health and preventing disease as women age. Although interest in the relative importance of phyto-oestrogens to human health has increased dramatically over the last decade, the effective dose for health benefits and hypothetical issues on safety remain to be resolved. Plausible mechanisms and epidemiological data are available to support the concept that phyto-oestrogen-rich diets exert physiological effects, but optimal doses and sources of these compounds have still not been elucidated for specific health benefits. In addition, much of the current mechanistic data are difficult to interpret as the experiments have incorporated levels of phyto-oestrogens that may not be achievable in vivo and have to date only used aglycones and glycosides of the pure compounds rather than examining the biological effects of gut and liver metabolites. The present review will concentrate on the isoflavone subclass of phyto-oestrogens, as, to date, these compounds have received most attention from both a commercial and research perspective.

Effects of Soy Consumption on Serum Lipids and Apoproteins in Peritoneal Dialysis Patients: A Randomized Controlled Trial

Background

Lipid abnormalities, particularly high serum concentration of lipoprotein(a) [Lp(a)], are one of the major risk factors for cardiovascular disease (CVD) in peritoneal dialysis (PD) patients. The present study was designed to investigate the effects of soy consumption on serum lipids and apoproteins, especially Lp(a), in PD patients.

Methods

This study was a randomized clinical trial in which 40 PD patients (20 males, 20 females) were randomly assigned to either the soy or the control group. Patients in the soy group received 28 g/day textured soy flour (containing 14 g of soy protein) for 8 weeks, whereas patients in the control group received their usual diet, without any soy. At baseline and the end of week 8 of the study, 5 mL of blood was collected from each patient after a 12- to 14-hour fast and serum triglyceride, total cholesterol, low density lipoprotein-cholesterol (LDL-C), high density lipoprote-incholesterol (HDL-C), apoprotein B100 (apo B100), apoprotein AI (apo AI), and Lp(a) were measured.

Results

In the present study, serum Lp(a) concentrations were above the normal range in 86% of the PD patients. Mean serum Lp(a) concentration was reduced significantly, by 41%, in the soy group at the end of week 8 compared to baseline ( p < 0.01); the reduction was also significant compared to the control group ( p < 0.05). During the study, mean serum Lp(a) concentration did not change significantly in the control group. There were no significant differences between the two groups in mean changes in serum triglyceride, total cholesterol, HDL-C, LDL-C, apo B100, or apoAI.

Conclusion

The results of our study indicate that soy consumption reduces serum Lp(a) concentration, which is a risk factor for cardiovascular disease in peritoneal dialysis patients.

Lifestyle approaches and dietary strategies to lower LDL-cholesterol and triglycerides and raise HDL-cholesterol

This article discusses specific dietary factors as well as dietary patterns that affect the major coronary heart disease (CHD) lipid risk factors (ie, LDL-C, HDL-C, and TG). Based on a very large evidence base, it is clear that diet and lifestyle practices can markedly affect these major CHD lipid risk factors, and consequently decrease CHD risk substantively.

The differential effect of the phytoestrogen genistein on cardiovascular risk factors in postmenopausal women: relationship with the metabolic status

CONTEXT

The wide family of the phytoestrogens has become an alternative to the classical hormonal therapy in menopause; nevertheless, some findings are still conflicting.

OBJECTIVE

To examine the effect of genistein administration on metabolic parameters and vascular reactivity considering the basal endocrine status of the patients.

DESIGN AND SETTING

A randomized placebo controlled study was conducted at a university hospital.

PARTICIPANTS

Fifty postmenopausal women participated.

INTERVENTIONS

Thirty subjects (group A) were randomized to receive 54 mg/d genistein while 20 subjects (group B) were treated with the placebo for 24 wk. In group A, we distinguish two subgroups: 14 normoinsulinemic and 12 hyperinsulinemic patients.

MAIN OUTCOME MEASURES

Anthropometric measures, hormonal and lipid assays, oral glucose tolerance test with glycemic, insulin, and C-peptide evaluation, indexes of insulin sensitivity and endothelial function, and euglycemic-hyperinsulinemic clamps were performed.

RESULTS

The insulin basal values significantly decreased in group A, whereas the homeostasis model index of insulin sensitivity and the fasting glucose levels significantly improved compared with placebo group. The genistein administration decreased fasting glucose and area under the curve glucose levels in the normoinsulinemic patients after treatment. In the hyperinsulinemic patients, a significant reduction in fasting insulin, fasting C-peptide, and area under the curve insulin levels as well as an increase in fractional hepatic insulin extraction was shown. In these patients, high-density lipoprotein cholesterol levels were significantly improved. The endothelium-dependent and -independent dilatation improved in the treated group. Normoinsulinemic patients showed both a significantly enhanced flow-mediated and nitrate-mediated dilatation, whereas no significant changes were found in the hyperinsulinemic group.

CONCLUSIONS

The glycoinsulinemic metabolism and the endothelial function were significantly influenced by genistein. In particular, normoinsulinemic patients showed an improvement in glycemic and vascular reactivity indexes. Conversely, an improvement in the insulin sensitivity indexes was noted in hyperinsulinemic patients.

Soy food consumption does not lower LDL cholesterol in either equol or nonequol producers

BACKGROUND

Health claims link soy protein (SP) consumption, through plasma cholesterol reduction, to a decreased risk of heart disease. Soy isoflavones (ISOs), particularly in individuals who produce equol, might also contribute to lipid lowering and thus reduce SP requirements.

OBJECTIVE

The objective was to examine the contributions of SP, ISOs, and equol to the hypocholesterolemic effects of soy foods.

DESIGN

Nonsoy consumers (33 men, 58 women) with a plasma total cholesterol (TChol) concentration >5.5 mmol/L participated in a double-blind, placebo-controlled, crossover intervention trial. The subjects consumed 3 diets for 6 wk each in random order, which consisted of foods providing a daily dose of 1) 24 g SP and 70-80 mg ISOs (diet S); 2) 12 g SP, 12 g dairy protein (DP), and 70-80 mg ISOs (diet SD); and 3) 24 g DP without ISOs (diet D). Fasting plasma TChol, LDL cholesterol, HDL cholesterol, and triglycerides (TGs) were measured after each diet.

RESULTS

TChol was 3% lower with the S diet (-0.17 +/- 0.06 mmol/L; P < 0.05) than with the D diet, and TGs were 4% lower with both the S (-0.14 +/- 0.05 mmol/L; P < 0.05) and SD (-0.12 +/- 0.05 mmol/L; P < 0.05) diets. There were no significant effects on LDL cholesterol, HDL cholesterol, or the TChol:HDL cholesterol ratio. On the basis of urinary ISOs, 30 subjects were equol producers. Lipids were not affected significantly by equol production.

CONCLUSIONS

Regular consumption of foods providing 24 g SP/d from ISOs had no significant effect on plasma LDL cholesterol in mildly hypercholesterolemic subjects, regardless of equol-producing status.

Systematic review, meta-analysis and regression of randomised controlled trials reporting an association between an intake of circa 25 g soya protein per day and blood cholesterol

AIMS

To determine the effect of a daily intake of circa 25 g soya protein on blood lipids in adults with normal or mildly elevated cholesterolaemia.

METHODS

Medline and other scientific databases were searched to identify randomised controlled trials (RCTs); these were systematically reviewed against pre-determined criteria. Eligible RCTs evaluated the effect of 25 g (range 15-40 g) soya protein on measures of blood lipids. Results from RCTs were pooled using standard meta-analysis methods.

RESULTS

Thirty studies containing 42 treatment arms (n=2913), with an average soya protein intake of 26.9 g met the inclusion criteria. Soya protein inclusion led to reductions in standard difference in mean low density lipoprotein (LDL), total cholesterol and blood triglycerides of 0.23 mmol/L (95% confidence interval (CI) -0.160 to -0.306, p<0.0001), 0.22 mmol/L (95% CI -0.142 to -0.291, p<0.0001) and 0.08 mmol/L (95% CI -0.004 to -0.158, p=0.04), respectively. There was no effect on mean difference in apolipoprotein A (ApoA), but ApoB was reduced by 0.021 g/L (p=0.01) in the soya group. Meta-regression analysis indicated no dose response relationship between soya protein intake in the range of 15-40 g and standard difference in LDL or HDL. All data were tested for heterogeneity and none identified.

CONCLUSIONS

The inclusion of modest amounts soya protein (ca. 25 g) into the diet of adults with normal or mild hypercholesterolaemia resulted in small, highly significant reductions in total and LDL cholesterol, equivalent to ca. 6% LDL reduction. This practically achievable intake, particularly when combined with other dietary measures, can make a useful contribution to blood cholesterol management.

The evidence for dietary prevention and treatment of cardiovascular disease

During the past few decades numerous studies have reported the atherogenic potential of saturated fatty acids, trans-fatty acids, and cholesterol, and beneficial effects of fiber, phytostanols/phytosterols, n-3 fatty acids, a Mediterranean diet, and other plant-based approaches. The purpose of this article is to provide a comprehensive and systematic review of the evidence associated with key dietary factors and risk of cardiovascular disease-an umbrella term encompassing diseases that affect the heart and blood vessels, including coronary heart disease, coronary artery disease, dyslipidemia, and hypertension-in conjunction with the work of the American Dietetic Association Evidence Analysis Library review on diet and lipids, updated with new evidence from the past 2 years. The criteria used and results cited provide scientific rationale for food and nutrition professionals and other health professionals for counseling patients. Details of these searches are available within the American Dietetic Association Evidence Analysis Library online (http://adaevidencelibrary.com). Potential mechanisms and needs for future research are summarized for each relevant nutrient, food, or food component.

Effect of hydroalcoholic extracts of Nasturtium officinale leaves on lipid profile in high-fat diet rats

AIM OF THE STUDY

Nasturtium officinale R. Br. (Brassicaceae) is used as a home remedy in Iran as a cardioprotective agent without any scientific background. In this investigation an attempt was made to study the effect of Nasturtium officinale hydroalcoholic extract (NOE) on serum lipid profile which is closely associated with many cardiovascular diseases.

MATERIALS AND METHODS

Accordingly, serum total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) were among the parameters investigated. We also evaluated the activities of serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels as a measure of hepatic cell damages.

RESULTS

Intragastric administration of NOE (500 mg/kg body weight per day) to groups of hypercholesterolaemic rats for 10 days lowered their serum TC, TG and LDL-C by 34.2, 30.1, and 52.9%, respectively, while raised the serum HDL-C level by 27.0% after 10 days of treatments. Treatment with NOE reduced serum ALT and AST levels compared to high-fat diet groups.

CONCLUSIONS

Based on these data, it is concluded that the NOE has definite cardioprotective potential and these results constitute a valid scientific basis for consuming Nasturtium officinale for medicinal application.

Association of dietary intake of soy, beans, and isoflavones with risk of cerebral and myocardial infarctions in Japanese populations: the Japan Public Health Center-based (JPHC) study cohort I

BACKGROUND

Soy and isoflavones have been proposed to reduce the risk of cardiovascular risk factors, but their potential as preventatives for cardiovascular disease remains uncertain. We investigated the association of soy and isoflavone intake with risk of cerebral and myocardial infarctions (CI and MI).

METHODS AND RESULTS

To examine the association of soy and isoflavone intake with the risk of CI and MI, we studied 40,462 Japanese (40 to 59 years old, without cardiovascular disease or cancer at baseline). They completed a food-frequency questionnaire (1990-1992) and received follow-up to 2002. After 503,998 person-years of follow-up, we documented incidence of CI (n=587) and MI (n=308) and of mortality for CI and MI combined (n=232). For women, the multivariable hazard ratios and 95% confidence limits for soy intake > or = 5 times per week versus 0 to 2 times per week were 0.64 (0.43 to 0.95) for risk of CI, 0.55 (0.26 to 1.09) for risk of MI, and 0.31 (0.13 to 0.74) for cardiovascular disease mortality. Similar but weaker inverse associations were observed between intake of miso soup and beans and risk of cardiovascular disease mortality. The multivariable hazard ratios for the highest versus the lowest quintiles of isoflavones in women were 0.35 (0.21 to 0.59) for CI, 0.37 (0.14 to 0.98) for MI, and 0.87 (0.29 to 2.52) for cardiovascular disease mortality. An inverse association between isoflavone intake and risk of CI and MI was observed primarily among postmenopausal women. No significant association of dietary intake of soy, miso soup, and beans and isoflavones with CI or MI was present in men.

CONCLUSIONS

High isoflavone intake was associated with reduced risk of CI and MI in Japanese women. The risk reduction was pronounced for postmenopausal women.

Dietary combination of soy with a probiotic or prebiotic food significantly reduces total and LDL cholesterol in mildly hypercholesterolaemic subjects

OBJECTIVE

We hypothesized that a dietary combination of soy with either a probiotic (yoghurt) or a prebiotic (resistant starch) would result in enhanced lipid-lowering effects compared with a control soy diet, possibly via improvements in isoflavone bioavailability.

SUBJECTS

Mildly hypercholesterolaemic subjects (men and post-menopausal women) older than 45 years were recruited via the local media. Thirty-six subjects commenced the study; five withdrew.

RESULTS

Soy+probiotic significantly decreased total cholesterol (4.7+/-2.0%; P=0.038) and soy+prebiotic significantly decreased total and low-density lipoprotein cholesterol (5.5+/-1.6%; P=0.003 and 7.3+/-2.2%; P=0.005, respectively). The bioavailabilities of daidzein, genistein or equol were not affected by probiotic or prebiotic consumption or associated with lipid changes.

CONCLUSION

Dietary combination of soy with either a probiotic or a prebiotic resulted in significant lipid lowering, not related to isoflavone bioavailability.