Duo Li

Cardiovascular Disease Mortality and Cancer Incidence in Vegetarians: A Meta-Analysis and Systematic Review

Background: Prospective cohort studies have examined mortality and overall cancer incidence among vegetarians, but the results have been inconclusive. Aims: The objective of the present meta-analysis was to investigate cardiovascular disease mortality and cancer incidence among vegetarians and nonvegetarians. Methods: Medline, EMBASE and Web Of Science databases were searched for cohort studies published from inception to September 2011. Studies were included if they contained the relative risk (RR) and corresponding 95% CI. Participants were from the UK, Germany, California, USA, the Netherlands and Japan. Results: Seven studies with a total of 124,706 participants were included in this analysis. All-cause mortality in vegetarians was 9% lower than in nonvegetarians (RR = 0.91; 95% CI, 0.66–1.16). The mortality from ischemic heart disease was significantly lower in vegetarians than in nonvegetarians (RR = 0.71; 95% CI, 0.56–0.87). We observed a 16% lower mortality from circulatory diseases (RR = 0.84; 95% CI, 0.54–1.14) and a 12% lower mortality from cerebrovascular disease (RR = 0.88; 95% CI, 0.70–1.06) in vegetarians compared with nonvegetarians. Vegetarians had a significantly lower cancer incidence than nonvegetarians (RR = 0.82; 95% CI, 0.67–0.97). Conclusions: Our results suggest that vegetarians have a significantly lower ischemic heart disease mortality (29%) and overall cancer incidence (18%) than nonvegetarians.

Meta-analysis of B vitamin supplementation on plasma homocysteine, cardiovascular and all-cause mortality

BACKGROUND & AIMS Results from randomized controlled trials (RCT) of B vitamin supplementation on risk of cardiovascular disease (CVD) were inconclusive. The aim of the present study was to systematically review the effects of B vitamin supplementation on plasma homocysteine (Hcy), cardiovascular and all-cause mortality in RCT. METHODS RCT publications on the effect of B vitamin supplementation on plasma Hcy, cardiovascular and all-cause mortality were searched from PubMed and web of science database. Data were independently abstracted by 2 investigators using a standardized protocol. The results were pooled with a fixed-effects model using Stata software. RESULTS Data from 19 studies including 47921 participants were analyzed using a fixed-effects model. The overall relative risks with 95% confidence intervals of outcomes for patients treated with B vitamin supplementation compared with placebo were 0.98 (0.94-1.03) for CVD, 0.98 (0.92-1.05) for coronary heart disease (CHD), 0.97 (0.90-1.05) for myocardial infarction (MI), 0.88 (0.82-0.95) for stroke, and 0.97 (0.91-1.02) for cardiovascular death, 0.99 (0.95-1.04) for all-cause mortality. Blood Hcy levels were decreased in all included RCTs. CONCLUSIONS B vitamin supplementation has a significant protective effect on stroke, but none on the risk of CVD, MI, CHD, cardiovascular death, or all-cause mortality.

Increased plasma n-3 polyunsaturated fatty acid is associated with improved insulin sensitivity in type 2 diabetes in China.

Increased tissue n-3 polyunsaturated fatty acid (PUFA) is associated with improved insulin sensitivity in type 2 diabetes. However, this relationship among Chinese is not clear. To investigate the relationship between plasma phospholipids (PL) fatty acid composition and insulin resistance (IR) in type 2 diabetes mellitus, 186 type 2 diabetes and 180 healthy subjects were studied in this case-control study. In the sex, age and BMI controlled partial correlation, homeostasis model assessment (HOMA)-IR and blood glucose was significantly negatively correlated with plasma PL n-3 PUFA, 20:5n-3 and ratio of n-3:n-6 (p<0.01), and positively correlated with n-6 PUFA (p<0.001) and saturated fatty acid (p<0.05) in the diabetes patients. PL 22:6n-3 was also significantly negatively correlated with HOMA-IR (p<0.01), but not with blood glucose. Fasting insulin was significantly negatively correlated with plasma PL n-3 PUFA, 20:5n-3, 22:6n-3 and ratio of n-3:n-6 (p<0.01). The 18:3n-3 was not associated with HOMA-IR and fasting insulin. The results suggested that increased plasma PL n-3 PUFA, 20:5n-3, 22:6n-3 and ratio of n-3:n-6 PUFA was associated with decreased HOMA-IR in type 2 diabetes. Increased plasma PL n-3 PUFA improves insulin sensitivity in type 2 diabetes.

Docosahexaenoic acid decreases plasma homocysteine via regulating enzyme activity and mRNA expression involved in methionine metabolism

OBJECTIVE The objective of this study was to investigate the regulatory effect of fish oil rich in omega-3 polyunsaturated fatty acids (PUFAs) on critical enzyme activity and mRNA expression involved in homocysteine (Hcy) metabolism. METHODS Thirty-six male Sprague-Dawley rats aged 3 wk, weighing 120 +/- 10 g, were randomly divided into three groups: the olive oil (OO) group, the tuna oil (TO) group, and the salmon oil (SO) group. The oil was orally administered every day using a stomach tube. Eight weeks later, plasma Hcy, phospholipids, omega-3 PUFAs, enzyme activity, and mRNA expression in tissues were determined. RESULTS Compared with the control group, phospholipids, total omega-3 PUFAs, and omega-3/omega-6 PUFAs in the liver and lung were significantly elevated in the TO and SO groups; 22:6omega-3 in the liver and lung was significantly increased in the TO group; and 20:5omega-3 in the two tissues was significantly elevated in the SO group. The level of plasma Hcy was significantly decreased with TO; methionine adenosyl transferase (MAT) activity was significantly increased and MAT mRNA expression was significantly upregulated with TO; cystathionine-gamma-lyase mRNA expression in TO was significantly upregulated; however, cystathionine beta-synthase and S-adenosylhomocysteine hydrolases were not significantly changed when compared with control. CONCLUSION TO rich in 22:6omega-3 decreases the concentration of Hcy despite increasing MAT activity and upregulating MAT mRNA expression through compensatory cystathionine-gamma-lyase mRNA expression, both of which are involved in Hcy metabolism.

Effect of n-3 polyunsaturated fatty acid on gene expression of the critical enzymes involved in homocysteine metabolism

BackgroundPrevious studies showed that plasma n-3 polyunsaturated fatty acid (PUFA) was negatively associated with plasma homocysteine (Hcy).ObjectiveWe investigated the regulatory effect of n-3 PUFA on mRNA expression of the critical genes encoding the enzymes involved in Hcy metabolism.MethodsHepG2 cells were treated with docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), alpha-linolenic acid (ALA) respectively for 48 h. The cells were collected and total RNA was isolated. The mRNA expression levels of the genes were determined by using Real Time-PCR.ResultsCompared with controls, the mRNA expression levels of 5-methyltetrahydrofolate reductase (MTHFR) were significantly increased in the DHA group (p < 0.05) and ALA group (p < 0.05); Significantly down-regulated mRNA expression of methionine adenosyltransferase (MAT) was observed with the treatments compared with the controls; the level of MAT expression was significant lower in the DHA group than the ALA group (p < 0.05); Cystathionine-γ-lyase (CSE) expression was significantly increased in the DHA (p < 0.05) and EPA groups (p < 0.05) compared with control. No significant changes were shown in mRNA expression levels of S-adenosylhomocysteine hydrolases (SAHH), cystathionine β-synthase (CBS), and 5-methyltetrahydrofolate-homocysteine methyltransferase (MTR).ConclusionsOur results suggest that DHA up-regulates CSE and MTHFR mRNA expression and down-regulates MAT mRNA expression involved in Hcy metabolism.

High consumption of Ω-3 polyunsaturated fatty acids decrease plasma homocysteine: a meta-analysis of randomized, placebo-controlled trials.

OBJECTIVE High consumption of ω-3 polyunsaturated fatty acids (PUFAs) has been associated with lower plasma homocystine (Hcy) levels, but intervention studies in humans have been inconclusive. The objective was to systematically evaluate the effects of ω-3 PUFA supplementation on plasma Hcy levels. METHODS A comprehensive search of Medline, EMBASE, the Cochrane Clinical Trials Registry, and bibliographies of relevant articles published from 1966 through September 2010 was undertaken. All randomized, placebo-controlled trials that compared ω-3 PUFA supplementation with placebo were included. Two investigators performed data extraction and quality scoring independently, with discrepancies resolved by consensus. RESULTS Eleven trials including 702 subjects were analyzed. The outcomes studied were plasma Hcy level. Eleven randomized, placebo-controlled trials were included in this meta-analysis. Supplementation with ω-3 PUFAs was associated with a significant decrease in plasma Hcy level (weighted mean difference -1.59 μmol/L, 95% confidence interval -2.34 to -0.83) compared with control subjects. CONCLUSION This meta-analysis suggested that ω-3 PUFA supplementation can decrease plasma Hcy levels. The implications of these findings remain to be elucidated.

Plasma phospholipids n‐3 polyunsaturated fatty acid is associated with metabolic syndrome

The relationship between n-3 PUFA and metabolic syndrome (MS) is not clear. The aim of this study was to examine relationships between plasma phospholipids (PL) n-3 PUFA and MS in Chinese subjects. Nine hundred and twenty-nine subjects were recruited in Hangzhou, China. Two hundred and ten (183 males, 27 females) with MS and 719 (545 males, 174 females) healthy subjects were identified in this cross-sectional study. The prevalence of MS in females (24.56%) was significantly higher than that in males (10.04%) in this population. Total PUFA (p<0.001), n-3 PUFA (p<0.001), and n-3:n-6 (p<0.001) were significantly lower in MS subjects compared to healthy subjects. Plasma phospholipid (PL), n-3 PUFA was significantly inversely associated with MS (p = 0.013). In addition, subjects with high levels of PL total fatty acids (FA) had a more than threefold higher likelihood of MS (OR = 3.44, 95% CI = 1.60-7.39) than the subjects with low levels of PL total FA. Our results suggest that plasma PL n-3 PUFA was significantly inversely associated with MS, while high total FA were positively associated with MS in Chinese.

Punicic Acid from Trichosanthes kirilowii Seed Oil Is Rapidly Metabolized to Conjugated Linoleic Acid in Rats

The incorporation and metabolism of orally administered punicic acid (PA), one isomer of conjugated linolenic acid (CLNA), in rat tissues and plasma were studied over a 24-hour period. The punic acid was derived from Trichosanthes kirilowii Maxim seed oil, a unique PA-containing material, and identified and analyzed by high-performance liquid chromatography and gas chromatography-mass spectrometry. The results show that PA was incorporated and metabolized to 9c,11t-conjugated linoleic acid (CLA) in rat plasma, liver, kidney, heart, brain, and adipose tissue. The level of PA and CLA in liver and plasma was higher than in brain, heart, kidney, and adipose tissue, and the lowest accumulation occurred in the brain. The observation that PA can be converted into 9c,11t-CLA has gained increased importance since it has been demonstrated that 9c,11t-CLA exerts many biological activities. Therefore natural resources containing CLNA, especially edible T. kirilowii seed, could be a potential dietary source of CLA, following PA metabolism. PA is expected to be used as a functional food and nutraceutical.

Diacylglycerol-induced improvement of whole-body insulin sensitivity in type 2 diabetes mellitus: A long-term randomized, double-blind controlled study

BACKGROUND & AIMS Diacylglycerol oil has been shown to lower postprandial and fasting serum triacylglycerol levels and reduce body fat. The aim of this study was to investigate the effect of diacylglycerol oil on risk factors of type 2 diabetes mellitus (DM) and cardiovascular disease in type 2 DM patients. METHODS This was a double-blind controlled parallel study with 127 type 2 DM patients (aged 40-65) recruited in Hangzhou, China. All subjects consumed triacylglycerol oil in the lead-in period (14 days), then they were randomly divided into two groups and consumed diacylglycerol or triacylglycerol oil with a similar fatty acid composition (25 g/day) for 120 days. Blood samples were collected on days 0, 60 and 120 and risk factors of type 2 DM and cardiovascular disease and biochemical parameters were measured by standard methods. RESULTS There were a total of 112 subjects who completed the study. Diet intake did not differ significantly between groups. Body weight, BMI, waist circumference, HOMA-IR, serum insulin and leptin levels were significantly reduced from baseline in the diacylglycerol oil group but not in the triacylglycerol oil group. Serum glucose was also significantly improved in patients with higher glucose levels at baseline (>7.00 mmol/L) in the diacylglycerol oil group. Parameters of liver and kidney functions and essential fatty acids in serum phospholipids did not differ between groups. CONCLUSIONS Diacylglycerol oil consumption improved biomarkers and anthropometric parameters of type 2 DM compared with triacylglycerol oil. No adverse reactions were observed with diacylglycerol oil consumption for type 2 DM patients. Diacylglycerol oil has an equivalent bioavailability as triacylglycerol oil in relation to providing essential fatty acids.

Omega-3 polyunsaturated fatty acids and non-communicable diseases: meta-analysis based systematic review.

The aim of this updated systematic review is to summarize the evidence of the effect of omega-3 polyunsaturated fatty acids (n-3 PUFA) on non-communicable diseases (NCDs). Publications of meta-analysis up to August 2014 were systematically searched from PubMed, the Cochrane and EMBASE databases. N-3 PUFAs have the following beneficial effects; cardio-protective effects, reduce ischemic stroke risk in both men and women and total stroke risk in women, increase insulin sensitivity in Asians, decrease risk of breast cancer and colorectal cancer in men. However, n-3 PUFAs may have unfavourable effects on type 2 diabetes in Caucasians. In conclusion, n-3 PUFA plays a crucial role in the prevention of NCDs, however, unfavourable effects should be considered in subjects with certain clinical conditions. Cross-cultural studies on the effect of n-3 PUFA on type 2 diabetes are needed to verify why diabetic patients with different ancestries have a different response to n-3 PUFA.