Nutritional advice

Objectives:
Does orange juice consumption causally improve lipid profile?

Study design:
This review article included 9 RCTs with a total of 386 participants.
The mean age of the participants ranged from 36 to 56 years.
All the RCTs used a parallel study design.
The dosage of orange juice ranged from 250 to 1000 mL/d.
The duration of interventions ranged from 3 to 12 weeks.

Results and conclusions:
The investigators found orange juice consumption significantly reduced LDL cholesterol (bad cholesterol) levels [WMD  = -8.35 mg/dL, 95% CI = -15.43 to 1.26, p = 0.021, I2 = 45.8%, p = 0.055].

The investigators found in subgroup analysis based on the administered dosage, LDL cholesterol levels significantly decreased following the consumption of >500 mL/d orange juice [WMD = -9.85 mg/dL, 95% CI = -18.18 to -1.52, p = 0.02].
Moreover, the subgroup analyses based on the duration of intervention revealed that the effect of orange juice supplementation on LDL cholesterol levels was significantly greater in trials lasting ≤8 weeks [WMD = -7.91 mg/dL, 95% CI = -15.91 to -36, p = 0·04].
Also, studies conducted on both genders were observed to be significantly more likely to reduce blood LDL-C levels [WMD = -12.61 mg/dL, 95% CI = -21.19 to -4.04, p = 0.004].

The investigators concluded that  at least 500 mL/d orange juice consumption causally reduce LDL cholesterol (bad cholesterol) levels.

Original title:
Orange juice intake and lipid profile: a systematic review and meta-analysis of randomised controlled trials by Amini MR, Sheikhhossein F, […], Askarpour M.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10052563/

Additional information of El Mondo:
Find more information/studies on orange juice consumption, cholesterol and cardiovasculair disease right here.
 

Objectives:
Although relationships between the intake of whole grains and refined grains and the incidence of cardiovascular disease (CVD) events and all-cause mortality have been investigated, the conclusions have been inconclusive. Therefore, this review article has been conducted.

Does consumption of whole grains reduce risk of stroke, coronary heart disease, heart  failure, cardiovascular disease and all-cause mortality?

Study design:
This review article included 68 prospective cohort studies (46 for whole grains and 22 for refined grains) with 1,624,407 participants.

The included studies had follow-up periods between 5.4 y and 26 y, with sample sizes varying from 535 to 461,047 participants.

Based on NOS, the mean score of the included studies was 7.74 for whole grains and 7.45 for refined grains.

Egger’s test and funnel plot did not indicate any publication bias for the relationships between 30g/d increases in whole grain consumption and the risk of stroke [p = 0.481], cardiovascular disease [p= 0.144] or all-cause mortality [p = 0.409].

The quality of meta-evidence for the association between whole grain consumption and risks of stroke, coronary heart disease, heart failure, cardiovascular disease and all-cause mortality was moderate, moderate, low, high and high, respectively.
The quality of evidence for refined grain was low.

Results and conclusions:
The investigators found a significantly reduced risk of 3% for stroke per 30-g increase in daily whole grain consumption [RR = 0.97, 95% CI = 0.96 to 0.99, I2 = 0%].

The investigators found a significantly reduced risk of 6% for coronary heart disease (CHD) per 30-g increase in daily whole grain consumption [RR = 0.94, 95% CI = 0.92 to 0.97, I2 = 54.4%].
Sensitivity analyses indicated that the result was stable.

The investigators found a significantly reduced risk of 8% for cardiovascular disease (CVD) per 30-g increase in daily whole grain consumption [RR = 0.92, 95% CI = 0.88 to 0.96, I2 = 82.9%].
Sensitivity analyses indicated that the result was stable.

The investigators found a significantly reduced risk of 6% for all-cause mortality per 30-g increase in daily whole grain consumption [RR = 0.94, 95% CI = 0.92 to 0.97, I2 = 89.8%].
Sensitivity analyses indicated that the result was stable.

The investigators found whole grain consumption was linearly associated with coronary heart disease [p nonlinearity = 0.231] and nonlinearly associated with cardiovascular disease [p nonlinearity = 0.002] and all-cause mortality [p nonlinearity = 0.001].

The investigators concluded that consumption of at least 30g/d whole grains reduce stroke, coronary heart disease, cardiovascular disease and all-cause mortality.

Original title:
Consumption of whole grains and refined grains and associated risk of cardiovascular disease events and all-cause mortality: a systematic review and dose-response meta-analysis of prospective cohort studies by Hu H, Zhao Y, […], Hu D.

Link:
https://www.sciencedirect.com/science/article/pii/S0002916522105186?via%3Dihub

Additional information of El Mondo:
Find more information/studies on whole grain consumption, cardiovasculair disease and stroke right here.

Objectives:
Prospective cohorts are inconsistent regarding the association between dietary calcium intake and the risk of stroke. Therefore, this review article has been conducted.

Does dietary intake of calcium reduce risk of stroke?

Study design:
This review article included 18 prospective cohort studies witth19,557 stroke cases (persons) among 882,181 participants.

Results and conclusions:
The investigators found a nonlinear association between calcium intake and risk of stroke [p nonlinearity 0.003].

The investigators found compared with the lowest value of zero assumed as the reference, dietary intake of 200 mg/day calcium significantly reduced stroke risk with 5% [95% CI = 0.92 to 0.98].
This protective effect was only found in Asian countries.

The investigators found compared with the lowest value of zero assumed as the reference, dietary intake of 300 mg/day calcium significantly reduced stroke risk with 6% [95% CI = 0.90 to 0.98].
This protective effect was only found in Asian countries.

The investigators found compared with the lowest value of zero assumed as the reference, dietary intake of 500 mg/day calcium significantly reduced stroke risk with 5% [95% CI = 0.90 to 0.99].
This protective effect was only found in Asian countries.

The investigators found no protective effect for stroke at dietary intake of 700 mg/day calcium or higher.

The investigators concluded dietary intake of 200-700 mg/day calcium reduces stroke risk among Asians.

Original title:
Dietary calcium intake and the risk of stroke: Meta-analysis of cohort studies by Wang ZM, Bu XX, […], Nie ZL.

Link:
https://pubmed.ncbi.nlm.nih.gov/36958976/

Additional information of El Mondo:
Find more information/studies on calcium and stroke right here.

Objectives:
Is there a causal relationship between drinking green tea and improving risk factors of cardiovascular disease, like cholesterol, fasting blood sugar, blood pressure, HbA1c, HOMA-IR?

Study design:
This review article included 55 RCTs with 63 effect sizes with 2,487 participants in the green tea group and 2,387 in the placebo group (group without green tea).

The participants’ mean age ranged between 18 and 68.7 years and the period of intervention ranged between 2 to 48 weeks.
Some of the studies enrolled only males or females and some of them included both genders.

TC, LDL, HDL, FBS, HbA1c and DBP-related evidence had moderate quality due to the serious inconsistency reasons. Additionally, it was shown that evidence regarding TG, fasting insulin, SBP and CRP had low quality due to serious imprecision and inconsistency reasons. The evidence relating to HOMA-IR was also downgraded to very low quality because of the serious inconsistency, imprecision and publication bias.

Results and conclusions:
The investigators found green tea supplementation significantly reduced total cholesterol levels (TC) [WMD = -7.62, 95% CI = -10.51 to -4.73, p ≤ 0.001, I2 = 90.9%].
This significantly reduced effect was also found if females or both males and females were included, the dosage of supplementation was less than 1,000 mg/d, the baseline BMI was between 25-29.9 kg/m² and the baseline value of TC was more than 200 mg/dL.

The investigators found green tea supplementation significantly reduced LDL cholesterol levels (LDL-C) [WMD = -5.80, 95% CI = -8.30 to -3.30, p ≤ 0.001, I2 = 90.5%].
This significantly reduced effect was also found if males or both males and females were included, the baseline BMI was between 25-29.9 kg/m² and participants were not affected by T2DM.

The investigators found green tea supplementation significantly reduced fasting blood sugar levels (FBS) [WMD = -1.67, 95% CI = -2.58 to -0.75, p ≤ 0.001, I2 = 72.2%].

This significantly reduced effect was also found when the baseline BMI of participants was between 25-29.9 kg/m², female or both male and female were included, the duration of intervention was more than 12 weeks, the dosage of supplementation was less than 1,000 mg/d and baseline values of FBS were less than 100 mg/dL.

The investigators found green tea supplementation significantly reduced HbA1c levels [WMD = -0.15, 95% CI = -0.26 to -0.04, p = 0.008, I2 = 71.3%].
This significantly reduced effect was also found if the duration of intervention was ≤ 12 weeks, the dosage of supplementation was ≥ 1,000 mg/d, baseline values of HbA1c were less than 6.5%, male or both genders were involved and the baseline value of BMI was ≥ 30 kg/m².

The investigators found green tea supplementation significantly reduced diastolic blood pressure (DBP) [WMD = -0.87, 95% CI = -1.45 to -0.29, p = 0.003, I2 = 92.4%].
This significantly reduced effect was also found if the duration of intervention was ≤ 12 weeks, the dosage of supplementation was less than 1,000 mg/d, baseline values of DBP were more than 80 mmHg and the baseline value of BMI was ≥ 30 kg/m².

The investigators found green tea supplementation significantly increased HDL cholesterol levels (HDL-C) [WMD = 1.85, 95% CI = 0.87 to 2.84, p = 0.010, I2 = 94.4%].
This significantly increased effect was also found if females were included, the baseline BMI was lower more than 30 kg/m², there was no past medical history of T2DM, the duration of intervention was more than 12 weeks, the dosage of supplementation was less than 1,000 mg/d and baseline values of HDL were more than 50 mg/dL.

The investigators found sensitivity analysis showed no significant difference in results with removing one single study for all considered cardiovascular risk factors including lipid profiles, glycemic indices, SBP and DBP and CRP.

The investigators concluded drinking ≤1,000 mg/d green tea may causally improve risk factors of cardiovascular disease. May improve because the RCTs are of low quality.

Original title:
The effects of green tea supplementation on cardiovascular risk factors: A systematic review and meta-analysis by Zamani M, Kelishadi MR, […], Asbaghi O.

Link:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9871939/

Additional information of El Mondo:
Find more information/studies on green tea, lowering blood pressure and cardiovascular diseases right here.

Objectives:
Is there a causal relationship between drinking green tea and lowering blood pressure in healthy individuals?

Study design:
This review article included 9 RCTs with 345 healty individuals in the intervention group (group with green tea) and 335 healthy individuals in the control group (group without green tea).

The mean age of the individuals in the intervention group was 35.89 ± 8.52, while the mean age of the control group was 36.48 ± 7.68.
All studies clearly described allocation randomization, none had incomplete outcome data, and all used appropriate statistical analysis.
The completion rate of the consumption of green tea ranged from 85-100%.
No publication bias was observed in the studies.

Results and conclusions:
The investigators found combined results of the studies showed that green tea was effective in lowering systolic blood pressure in healthy individuals [MD = -2.99, 95% CI = -3.77 to -2.22, p 0.00001, I2 = 0%].

The investigators found combined results of the studies showed that green tea was effective in lowering diastolic blood pressure in healthy individuals [MD= -0.95, 95% CI = -1.62 to -0.27, p = 0.006, I2 = 0%]. 

The investigators concluded in healthy individuals, green tea supplementation reduces systolic blood pressure by 2.99 mmHg and diastolic blood pressure by 0.95 mmHg.

Original title:
Effect of Green Tea on Blood Pressure in Healthy Individuals: A Meta-Analysis by Ayaz EY, Dincer B and Mesci B.

Link:
https://pubmed.ncbi.nlm.nih.gov/36689359/

Additional information of El Mondo:
Find more information/studies on green tea, lowering blood pressure and cardiovascular diseases right here.

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

Additional information of El Mondo:
Find more information/studies on cholesterol and cardiovascular disease right here.

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

Additional information of El Mondo:
Find more studies/information on magnesium and lowering blood pressure right here.  

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

Additional information of El Mondo:
Find more information/studies on RCTs, lowering blood pressure and cardiovascular disease right here.

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).