Nutritional advice

Objectives:
Does vitamin K reduce risk of cardiovascular disease (CVD) events and mortality?

Study design:
This review article included 21 articles with 222,592 participants.

Results and conclusions:
The investigators found dietary phylloquinone (vitamin K1) intake significantly reduced risk of total cardiovascular disease with 8% [pooled HR = 0.92, 95% CI = 0.84 to 0.99, I2 = 0%, 4 studies].
Significant means that there is an association with a 95% confidence.

The investigators found dietary menaquinone (vitamin K2) intake significantly reduced risk of total cardiovascular disease with 30% [pooled HR = 0.70, 95% CI = 0.53 to 0.93, I2 = 32.1%, 2 studies].
Significant because HR of 1 was not found in the 95% CI of 0.53 to 0.93. HR of 1 means no risk/association.

The investigators found no significant association between dietary vitamin K and all-cause mortality, cardiovascular disease mortality or stroke.

The investigators found elevated plasma desphospho-uncarboxylated MGP (dp-ucMGP), a marker of vitamin K deficiency, was associated with an increased risk of 84% [HR = 1.84, 95% CI = 1.48 to 2.28, I2 = 16.8%, 5 studies] for all-cause mortality.

The investigators found elevated plasma desphospho-uncarboxylated MGP (dp-ucMGP), a marker of vitamin K deficiency, was associated with an increased risk of 96% [HR = 1.96, 95% CI = 1.47 to 2.61, I2 = 0%, 2 studies] for cardiovascular disease mortality.

The investigators found no significant association between circulating total osteocalcin and all-cause mortality or total cardiovascular disease.

The investigators concluded higher dietary vitamin K consumption reduces risk of cardiovascular disease and higher plasma dp-ucMGP concentration, but not total circulating osteocalcin, increases risk of all-cause and cardiovascular disease mortality. However, causal relations cannot be established because of limited number of available studies and larger prospective studies and randomized clinical trials are needed to validate these findings.  

Original title:
Association of vitamin K with cardiovascular events and all-cause mortality: a systematic review and meta-analysis by Chen HG, Sheng LT, […], Pan A.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31119401

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100 grams of fresh parsley provide 548 micrograms (548 mcg) of vitamin K1 or 4.5 days.
 

Objectives:
Is there a causal relationship between grape product supplementation and improved lipid profiles in adults?

Study design:
This review article included 48 RCTs.

Results and conclusions:
The investigators found meta-analysis indicated that consumption of grape products significantly reduced the concentration of total cholesterol [MD = -6.196 mg/dL, 95% CI = -9.203 to -3.189], low-density lipoprotein cholesterol (bad cholesterol) [MD = -4.964 mg/dL, 95% CI = -7.594 to -2.334] and triglyceride [MD = -7.641 mg/dL, 95% CI = -12.120 to -3.162].

The investigators found grape product supplementation changed the HDL and LDL in a non-linear fashion based on the dose of polyphenols.

The investigators concluded that grape products have a favorable role in the achievement of a lipid profile target in adults, particularly total cholesterol, low-density lipoprotein cholesterol (bad cholesterol) and triglyceride levels.

Original title:
Effects of grape products on blood lipids: a systematic review and dose-response meta-analysis of randomized controlled trials by Ghaedi E, Moradi S, [...], Mohammadi H.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31517353

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Objectives:
Does green coffee bean extract (GCBE) supplementation reduce blood pressure?

Study design:
This review article included 9 RCTs.

Results and conclusions:
The investigators found a significant reduction in systolic blood pressure (SBP) [WMD = -3.093 mmHg, 95% CI = -3.914 to -2.273, I2 = 0.0%] and diastolic blood pressure (DBP) [WMD = -2.170 mmHg, 95% CI = -2.749 to -1.590, I2 = 46.5%] after green coffee supplementation with low heterogeneity among the studies.

The investigators found in subgroup analysis, a significant reduction in systolic blood pressure and diastolic blood pressure in studies with hypertensive patients, green coffee dosage 400 mg per day and administered for 4 weeks.

The investigators concluded 400 mg coffee bean extract supplementation per day during 4 weeks reduces systolic blood pressure and diastolic blood pressure in hypertensive patients.

Original title:
The effect of green coffee extract supplementation on blood pressure: A systematic review and meta-analysis of randomized controlled trials by Han B, Nazary-Vannani A, […], Kord-Varkaneh H.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/31429515

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Objectives:
Do dietary intakes or circulating concentration of major dietary antioxidants, like vitamin C, E and beta-carotene reduce risk of total cardiovascular mortality?

Study design:
This review article included a total of 15 prospective cohort studies and 3 prospective evaluations within interventional studies with 320,548 participants and 16,974 deaths from total cardiovascular mortality.

Results and conclusions:
The investigators found compared to the lowest category, the highest category of dietary vitamin C intake significantly reduced risk of total cardiovascular mortality with 21% [relative risk = 0.79, 95% CI = 0.68 to 0.89, I2 = 46%, n = 10].

The investigators found compared to the lowest category, the highest category of circulating concentration of vitamin C significantly reduced risk of total cardiovascular mortality with 40% [relative risk = 0.60, 95% CI = 0.42 to 0.78, I2 = 65%, n = 6].

The investigators found compared to the lowest category, the highest category of circulating concentration of vitamin E (α-tocopherol) significantly reduced risk of total cardiovascular mortality with 18% [relative risk = 0.82, 95% CI = 0.76 to 0.88, I2 = 0%, n = 5].

The investigators found compared to the lowest category, the highest category of circulating concentration of β-carotene significantly reduced risk of total cardiovascular mortality with 32% [relative risks = 0.68, 95% CI = 0.52 to 0.83, I2 = 50%, n = 6].

The investigators found dose-response meta-analyses demonstrated that the circulating biomarkers of antioxidants were more strongly associated with risk of total cardiovascular mortality than dietary intakes.

The investigators concluded that higher dietary vitamin C intakes and higher circulating concentrations of vitamin C, vitamin E and β-carotene are associated with a lower risk of total cardiovascular mortality.

Original title:
Dietary and circulating vitamin C, vitamin E, β-carotene and risk of total cardiovascular mortality: a systematic review and dose-response meta-analysis of prospective observational studies by Jayedi A, Rashidy-Pour A, […], Shab-Bidar S.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30630552

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Circulating concentration of vitamin C in blood can be increased by eating foods that are high in vitamin C and/or taking vitamin C supplements.

Objectives:
Dietary polyphenols, including flavonoids, have been the focus of major recent attentions due to their wide content in a variety of foods commonly consumed and the findings from numerous studies showing evidence of an association with positive outcomes on human health. Therefore, this review article has been conducted.

Does dietary intake of flavonoids (e.g., anthocyanins, isoflavones, flavones, flavonols, flavanones, flavan-3-ols) reduce hypertension?

Study design:
This review article included 15 cross-sectional investigations and 7 prospective cohort studies (1 study reported on 3 prospective cohort studies).
5 prospective cohort studies, comprising 200,256 individuals and 45,732 cases of hypertension were included in the quantitative analysis.

All studies included covariates that may have significantly influenced the endpoint outcome (hypertension), such as age, sex (when not analyzed separately), BMI, education, physical activity and smoking status. However, not all studies adjusted for key dietary factors that might influence risk of hypertension, such as sodium and potassium intake.

There was no publication bias.

Results and conclusions:
The investigators found analysis by extreme quantiles of intake of flavonoid showed a non-significant association with decreased risk of hypertension [risk ratio = 0.96, 95% CI = 0.89 to 1.03, I2 = 74%, p = 0.01].
Non-significant because RR of 1 was found in the 95% CI of 0.89 to 1.03. RR of 1 means no risk/association.

The investigators found taking into consideration individual flavonoid subclasses, dietary intake of anthocyanins was associated with 8% reduction in risk of hypertension, when comparing highest vs. lowest exposure [risk ratio = 0.92, 95% CI = 0.88 to 0.97].
Significant because RR of 1 was not found in the 95% CI of 0.88 to 0.97. RR of 1 means no risk/association.

The investigators concluded dietary intakes of anthocyanins reduce risk of hypertension. However, further studies are needed to elucidate the retrieved association between polyphenol consumption and decreased risk of hypertension and to clarify whether individual subclasses, rather than the total content of polyphenols, may exert beneficial effects on blood pressure.

Original title:
Dietary Polyphenol Intake, Blood Pressure, and Hypertension: A Systematic Review and Meta-Analysis of Observational Studies by Godos J, Vitale M, […], Grosso G.

Link:
https://www.mdpi.com/2076-3921/8/6/152/htm

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Objectives:
Preventing cardiovascular disease (CVD) is the top priority in public health. Hyperlipidemia and hypertension are key contributors to cardiovascular disease which can be easily modified with dietary and lifestyle interventions. Therefore, this review article has been conducted.

Does cashew consumption reduce blood lipids levels (i.e., triglyceride, total cholesterol, HDL cholesterol (good cholesterol) and LDL cholesterol (bad cholesterol) and blood pressure?

Study design:
This review article included 5 RCTs with 246 participants receiving cashew nut (intervention group) and 235 receiving placebo (placebo group).

There was no publication bias.

Results and conclusions:
The investigators found overall analysis showed a statistically significant reducing effect of cashew nut consumption on triglyceride levels [WMD = -14.39, 95% CI = -27.30 to -1.49, I2 = 82%].
Significant means that there is an association with a 95% confidence.

The investigators found overall analysis showed a statistically significant reducing effect of cashew nut consumption on systolic blood pressure [WMD = -1 mm/Hg, 95% CI = -5.12 to -3.01, I2 = 0%].

The investigators found overall analysis showed a statistically significant reducing effect of cashew nut consumption on diastolic blood pressure [WMD = -4.06 mm/Hg, 95% CI = -1.65 to -0.35, I2 = 0%].

The investigators found, however, no statistically significant changes of other cardiovascular risk markers including total cholesterol [WMD = -1.89, 95% CI = -9.17 to 5.39, p = 0.61], LDL cholesterol [WMD = -5.49, 95% CI = -16.76 to 5.78, p = 0.34] and HDL cholesterol [WMD = -0.67, 95% CI = -2.54 to 1.19, p = 0.48] were observed after cashew nut consumption.
No statistically significant because the calculated p-values of e.g. 0.61 or 0.34 were larger than the p-value of 0.05.

The investigators concluded that cashew consumption improves triglyceride levels as well as systolic and diastolic blood pressure with no significant effects on other cardiometabolic factors (i.e., total cholesterol, HDL cholesterol (good cholesterol) and LDL cholesterol (bad cholesterol)). Further studies are warranted with different calories and dietary compositions.

Original title:
The Effect of Cashew Nut on Cardiovascular Risk Factors and Blood Pressure: A Systematic Review and Meta-analysis (P06-117-19) by Mahboobi S.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6573847/

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Objectives:
Does coenzyme Q10 (CoQ10) supplementation improve biomarkers of inflammation and oxidative stress among patients with coronary artery disease (CAD)?

Study design:
This review article included 13 RCTs.

Given the presence of heterogeneity, random-effects model or fixed-effect model were used to pool standardized mean differences (SMDs) as summary effect sizes.

Results and conclusions:
The investigators found pooled findings for biomarkers of inflammation and oxidative stress demonstrated that coenzyme Q10 supplementation significantly increased superoxide dismutase (SOD) [SMD = 2.63, 95% CI = 1.17 to 4.09, p  0.001, I2 = 94.5%] and catalase (CAT) levels [SMD = 1.00, 95% CI = 0.57 to 1.43, p  0.001, I2 = 24.5%] among patients with coronary artery disease.

The investigators found pooled findings for biomarkers of inflammation and oxidative stress demonstrated that coenzyme Q10 supplementation significantly reduced malondialdehyde (MDA) [SMD = -4.29, 95% CI = -6.72 to -1.86, p = 0.001, I2 = 97.6%] and diene levels [SMD = -2.40, 95% CI = -3.11 to -1.68, p  0.001, I2 = 72.6%] among patients with coronary artery disease.

The investigators found among patients with coronary artery disease no significant effect of coenzyme Q10 supplementation on:
-C-reactive protein (CRP) [SMD = -0.62, 95% CI = -1.31 to 0.08, p = 0.08, I2 = 87.9%];
-tumor necrosis factor alpha (TNF-α) [SMD = 0.22, 95% CI = -1.07 to 1.51, p = 0.73, I2 = 89.7%];
-interleukin-6 (IL-6) [SMD = -1.63, 95% CI = -3.43 to 0.17, p = 0.07, I2 = 95.2%] and;
-glutathione peroxidase (GPx) levels [SMD = 0.14, 95% CI = -0.77 to 1.04, p = 0.76, I2 = 78.7%].
No significant because the calculated p-values were larger than the p-value of 0.05.

The investigators concluded coenzyme Q10 supplementation increases superoxide dismutase and catalase and decreases malondialdehyde and diene levels, but has no affect on C-reactive protein, tumor necrosis factor alpha, interleukin-6 and glutathione peroxidase levels among patients with coronary artery disease.

Original title:
The effects of coenzyme Q10 supplementation on biomarkers of inflammation and oxidative stress in among coronary artery disease: a systematic review and meta-analysis of randomized controlled trials by Jorat MV, Tabrizi R, […], Asemi Z.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30758695

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Malondialdehyde and diene are biomarkers of oxidative stress. Oxidative stress can arise when human cells cannot adequately destroy the excess of free radicals formed.

Free radicals can be rendered harmless by antioxidants such as vitamins C and E and by antioxidative enzymes such as superoxide dismutase and catalase.

Objectives:
Does kiwifruit improve metabolic health in participants with cardiovascular risk factors, including hypercholesterolemia, hypertension, diabetes type 2 and smokers?

Study design:
This review article included 5 RCTs involving 489 participants.

Results and conclusions:
The investigators found no significant effect of kiwifruit on:
-systolic blood pressure (SBP) [MD = -1.72 mmHg, 95% CI = -4.27 to 0.84];
-diastolic blood pressure (DBP) [MD = -2.35 mmHg, 95% CI = -5.10 to 0.41];
-total cholesterol (TC) [MD = -0.14 mmol/L, 95% CI = -0.71 to 0.43];
-triglyceride (TG) [MD = -0.23 mmol/L, 95% CI = -0.66 to 0.20];
-low-density lipoprotein cholesterol (bad cholesterol or LDL) [MD = -0.41 mmol/L, 95% CI = -0.99 to 0.18];
-high-density lipoprotein cholesterol (good cholesterol or HDL) [MD = 0.15 mmol/L, 95% CI = -0.18 to 0.48];
-fasting plasma glucose (FPG) [MD = -0.08 mmol/L, 95% CI = -0.37 to 0.21];
-homeostasis model assessment of insulin resistance (HOMA-IR) [MD = -0.29, 95% CI = -0.61 to 0.02] and;
-body weight (BW) [MD = 1.08 kg, 95% CI = -4.22 to 2.05].

The investigators found subgroup analysis limiting to studies of whole kiwifruit and duration of intervention of at least 8 weeks again revealed no such effect of kiwifruit on total cholesterol, triglyceride, LDL cholesterol and HDL cholesterol.

The investigators concluded kiwifruit has no effect on metabolic health, as measured by systolic blood pressure, diastolic blood pressure, total cholesterol, triglycerides, LDL cholesterol and HDL cholesterol, fasting plasma glucose, homeostasis model assessment of insulin resistance (HOMA-IR) and body weight in participants with cardiovascular risk factors including hypercholesterolemia, hypertension, diabetes type 2 and smokers. Due to limited evidence and high heterogeneity of the study results, the potential of kiwifruit as a nonpharmaceutical alternative for metabolic health should be further evaluated in well-defined, well-controlled trials with larger sample size and standardized preparation.

Original title:
Effect of kiwifruit on metabolic health in patients with cardiovascular risk factors: a systematic review and meta-analysis by Suksomboon N, Poolsup N and Lin W.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6350646/

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Objectives:
Several epidemiological studies have investigated the association between dietary fat intake and cardiovascular disease. However, dietary recommendations based on systematic review and meta-analysis might be more credible. Therefore, this review article has been conducted.

Does dietary fat intake increase cardiovascular disease risk?

Study design:
This review article included 56 cohort studies.
Egger test showed no evidence of significant publication bias.

Results and conclusions:
The investigators found highest versus lowest levels of total dietary fat were not associated with cardiovascular disease risk [RR = 0.97, 95% CI = 0.93-1.01, I2 = 54.0%].
Sensitivity analysis showed that no individual study had an excessive influence on the pooled effect.
In addition, the analysis was repeated stratified according to each covariate. The results were consistent with that observed in meta-regression.

The investigators found highest versus lowest levels of dietary trans fatty acids intake were associated with a 14% increase of the risk of cardiovascular disease [RR = 1.14, 95% CI = 1.08-1.21, I2 = 26.1%].
Sensitivity analysis showed that no individual study had an excessive influence on the pooled effect.

The investigators found dose-response analysis showed the risk of cardiovascular disease significantly increased with 16% [RR = 1.16, 95% CI = 1.07-1.25, p-linearity = 0.033] for an increment of 2% energy/day (2 En%/day) of dietary trans fatty acids intake.

The investigators found highest versus lowest levels of dietary saturated fatty acids intake were not associated with the risk of cardiovascular disease [RR = 0.97, 95% CI = 0.93-1.02, I2 = 56.8%].
Sensitivity analysis showed that no individual study had an excessive influence on the pooled effect
In addition, the analysis was repeated stratified according to each covariate. The results were consistent with that observed in meta-regression.

The investigators found highest versus lowest levels of dietary monounsaturated fatty acids intake were not associated with the risk of cardiovascular disease [RR = 0.97, 95% CI = 0.93-1.01, I2 = 50.3%].
Sensitivity analysis showed that no individual study had an excessive influence on the pooled effect.
In addition, the analysis was repeated stratified according to each covariate. The results were consistent with that observed in meta-regression.

The investigators found highest versus lowest levels of dietary polyunsaturated fatty acids intake were not associated with the risk of cardiovascular disease [RR = 0.97, 95% CI = 0.93-1.004, I2 = 55.8%].
Sensitivity analysis showed that no individual study had an excessive influence on the pooled effect.
In addition, the analysis was repeated stratified according to each covariate. The results were consistent with that observed in meta-regression.

The investigators found in studies that has been followed up more than 10 years, that dietary polyunsaturated fatty acids intake significantly reduced cardiovascular disease risk with 5% [RR = 0.95, 95% CI = 0.91-0.99, I2 = 62.4%].

The investigators concluded there is a cardio-protective effect of dietary polyunsaturated fatty acids intake in studies that has been followed up more than 10 years. While, an increment of 2% energy/day (2 En%/day) of dietary trans fatty acids intake increases risk of cardiovascular disease.

Original title:
Dietary total fat, fatty acids intake, and risk of cardiovascular disease: a dose-response meta-analysis of cohort studies by Zhu Y, Bo Y and Liu Y.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6451787/

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Objectives:
Several studies have been conducted on the effects of peanut consumption on cardiovascular diseases (CVD) risk factors. However, the findings are conflicting and appear inconsistent. Therefore, this review article has been conducted.

Does peanut consumption reduce cardiovascular disease risk?

Study design:
This review article included 13 RCTs.

Results and conclusions:
The investigators found peanuts consumption had no significant effect on:
-weight [WMD = -0.11 kg, p = 0.773];
-waist circumference [WMD = -1.41 cm, p = 0.139];
-body mass index [WMD = -0.14 kg/m², p = 0.428];

-systolic and diastolic blood pressure [WMD = -0.09 mmHg, p = 0.939 and WMD = 0.60 mmHg, p = 0.652, respectively];
-low-density lipoprotein (LDL or bad) cholesterol [WMD = -3.31 mg/dL, p = 0.472];
-triglyceride [WMD = -7.59 mg/dL, p = 0.180];
-total cholesterol [WMD = 3.15 mg/dL, p = 0.171];
-fasting blood sugar [WMD = 0.57 mg/dL, p = 0.604] and;
-serum insulin [WMD = -0.40, p = 0.582].

The investigators found peanuts consumption had a positive significant effect on high-density lipoprotein (HDL or good) cholesterol [WMD = 2.72 mg/dL, p = 0.001].
Significant because the calculated p-value of 0.001 was smaller than the p-value of 0.05.

The investigators found peanut consumption had a positive significant effect on HDL cholesterol, especially at the type of peanut oil, high-oleic peanut and peanut sprout and in healthy subjects and for consumption more than 12 weeks, while had no significant effect on other cardiovascular diseases risk factors.

The investigators concluded both high-oleic peanut and peanut sprout consumption during at least 12 weeks increases HDL cholesterol (good cholesterol) in healthy subjects.

Original title:
Peanut and cardiovascular disease risk factors: A systematic review and meta-analysis by Jafari Azad B, Daneshzad E and Azadbakht L.

Link:
https://www.ncbi.nlm.nih.gov/pubmed/30638042

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Objectives:
Low glycaemic index (GI) diets are beneficial in the management of hyperglycemia. Cardiovascular diseases are the major cause of mortality in diabetes therefore it is important to understand the effects of GI on blood lipids. Therefore, this review article has been conducted.

Does a low GI diet lower the cholesterol levels?

Study design:
This review article included 28 RCTs comparing low with high GI diets over at least 4 weeks. These 28 RCTs contained 1272 participants with studies ranged from 6 to 155 participants, one was powered on blood lipids and 3 had adequate allocation concealment.

Results and conclusions:
The investigators found that compared to high GI diet low GI diet significantly reduced total cholesterol by 0.13 mmol/L [95% CI = -0.22 to -0.04, p = 0.004, 27 trials, 1441 participants]. Significantly means, it can be said with 95% confidence that low GI diet really lowered the total cholesterol levels with 0.13 mmol/L.

The investigators found that compared to high GI diet low GI diet significantly reduced LDL-cholesterol by 0.16 mmol/L [95% CI = -0.24 to -0.08, p 0.0001, 23 studies, 1281 participants]. Significantly, because the p-value was less than 0.05.

The investigators found subgroup analyses suggested that reductions in LDL-cholesterol were greatest in studies of shortest duration and greatest magnitude of GI reduction. Furthermore, lipid improvements appeared greatest and most reliable when the low GI intervention was accompanied by an increase in dietary fiber.

The investigators found sensitivity analyses, removing studies without adequate allocation concealment, lost statistical significance but retained suggested mean falls of 0.10 mmol/L in both.

The investigators found no effects on HDL-cholesterol [MD = -0.03 mmol/L, 95% CI = -0.06 to 0.00, I2 = 0%], or triglycerides [MD was 0.01 mmol/L, 95% CI = -0.06 to 0.08, I2 = 0%].

The researchers concluded that low GI diets reduce total and LDL-cholesterol (bad cholesterol) but had no effect on HDL-cholesterol (good cholesterol) or triglycerides.

Original title:
Low glycemic index diets and blood lipids: A systematic review and meta-analysis of randomized controlled trials by Goff LM, Cowland DE, [...], Frost GS.

Link:
http://www.sciencedirect.com/science/article/pii/S0939475312001524

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High LDL-cholesterol levels and high triglyceride levels increase the risk of getting cardiovascular diseases whereas high HDL-cholesterol levels decrease the risk of getting cardiovascular diseases.

A low GI diet is a diet with a GI value of 55 or lower.

Objectives:
An increased intake of magnesium might lower blood pressure (BP), yet evidence from clinical trials is inconsistent, perhaps as a result of small sample size or heterogeneity in study design. Therefore, this review article (meta-analysis) has been conducted.

Are there dose-dependent effects of magnesium supplementation on blood pressure?

Study design:
This review article included 20 RCTs included 14 of hypertensive and 6 of normotensive persons totaling 1220 participants.
The doses of magnesium ranged from 10 to 40 mmol/day (median: 15.4 mmol/day or 370 mg per day).

Results and conclusions:
The investigators found magnesium supplementation resulted in only a small overall non-significant reduction in blood pressure. The pooled net estimates of blood pressure change were -0.6 mmHg [95% CI = -2.2 to 1.0] for systolic blood pressure and -0.8 mmHg [95% CI = -1.9 to 0.4] for diastolic blood pressure.

However, the investigators found an apparent dose-dependent effect of magnesium, with significant reductions of 4.3 mmHg systolic blood pressure [95% CI = 6.3 to 2.2, p 0.001) and non-significant reductions of 2.3 mmHg diastolic blood pressure [95% CI = 4.9 to 0.0, p = 0.09) for each 10 mmol/day (240 mg/day) increase in magnesium dose.

The investigators concluded there is a dose-dependent blood pressure reductions, especially systolic blood pressure from magnesium supplementation. However, adequately powered trials with sufficiently high doses of magnesium supplements need to be performed to confirm this relationship.

Original title:
The effect of magnesium supplementation on blood pressure: a meta-analysis of randomized clinical trials by Jeea SH, Miller ER, [...], Klagb MJ.

Link:
http://www.sciencedirect.com/science/article/pii/S0895706102029643

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Objectives:
Previous systematic reviews suggest beneficial effects of flavonoids on biomarkers of cardiovascular disease (CVD) risk, but have overlooked the impact of dose response or food complexity. Therefore, this review article has been conducted.

Do taking flavonoid supplements improve flow-mediated dilation (FMD) and blood pressure?

Study design:
This review article included 63 RCTs.

Results and conclusions:
The investigators found meta-analyses of combined flavonoid subclasses showed significant improvements in FMD [chronic: 0.73%, 95% CI = 0.17 to 1.30, 14 RCTs and acute: 2.33%, 95% CI = 1.58 to 3.08, 18 RCTs].

The investigators found meta-analyses of combined flavonoid subclasses showed significant improvements in blood pressures [systolic: -1.46 mmHg, 95% CI = -0.38 to -0.53, 63 RCTs and diastolic: -1.25 mmHg, 95% CI = -1.82 to -0.67, 63 RCTs].

The investigators found similar benefits were observed for the flavan-3-ol, catechol flavonoids (catechins, quercetin, cyanidin etc.), procyanidins, epicatechin and catechin subgroups.

The investigators found dose-response relationships were non-linear for FMD (R2 ≤ 0.30), with greater associations observed when applying polynomial regression analyses (R2 ≤ 0.72). However, there was no indication of a dose response for blood pressure.

The investigators concluded flavonoid subclasses supplements show significant improvements in FMD and blood pressure. However, the flavonoid bioactivity does not follow a classical linear dose-response association and this may have important biological implications.

Original title:
Relative impact of flavonoid composition, dose and structure on vascular function: A systematic review of randomised controlled trials of flavonoid-rich food products by Kay CD, Hooper L, […], Cassidy A.

Link:
http://onlinelibrary.wiley.com/doi/10.1002/mnfr.201200363/abstract;jsessionid=2CCB9E4E779A221E42AA38998C865DA6.d02t03?deniedAccessCustomisedMessage=&userIsAuthenticated=false

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The optimal blood pressure for a healthy adult is120 mmHg systolic pressure and 80 mmHg diastolic pressure.

When blood flow increases through a vessel, the vessel dilates. This phenomenon has been coined flow-mediated dilatation (FMD). Flow-mediated dilation is an accepted technique to quantify endothelial function and has shown to have prognostic value for future cardiovascular disease (CVD).