The effect of garlic on vascular function: A systematic review of randomized clinical trials

Improved microvascular reactivity after aged garlic extract intake is not mediated by hydrogen sulfide in older adults at risk for cardiovascular disease: a randomized clinical trial

PURPOSE

This study aimed to investigate the effects of AGE on microvascular reactivity, systolic blood pressure (SBP), and diastolic blood pressure (DBP) in older individuals at high risk for cardiovascular disease (CVD). Urinary thiosulfate was also investigated as an indirect marker of endogenous hydrogen sulfide (H₂S) synthesis. The study was conducted in a randomized, double-blind, crossover, and placebo-controlled way.

METHODS

Twenty-eight participants (14 male), 67 ± 6 years old with CVD risk factors, ingested 2.4 g of AGE or placebo (PLA). Near-infrared spectroscopy evaluated tissue oxygen saturation (StO₂) during a vascular occlusion test (30 s baseline, 5 min occlusion, and 2 min reperfusion). The upslope of StO₂ signal after cuff release was calculated to measure microvascular reactivity. Urinary thiosulfate levels were measured using a high-performance liquid chromatography system.

RESULTS

The upslope of StO₂ was significantly faster after AGE (1.01 ± 0.37% s^-1) intake compared to PLA (0.83 ± 0.35% s^-1; P < 0.001; d = 0.50). Relative changes in Δ% SBP from pre- to post-AGE intake (- 5.17 ± 5.77%) was significantly different compared to Δ% PLA (0.32 ± 5.99%; P = 0.001; d = 0.93). No significant changes in urinary thiosulfate concentrations were observed between interventions. Moreover, no significant gender effect in any parameter assessed was found.

CONCLUSION

This study demonstrated that a single dose of AGE improved microvascular reactivity in older adults at risk of CVD despite such an effect was not linked with urinary thiosulfate levels. This trial was registered at clinicaltrials.gov as NCT04008693 (May 19, 2020).

The effect of Nigella sativa oil on vascular dysfunction assessed by flow-mediated dilation and vascular-related biomarkers in subject with cardiovascular disease risk factors: A randomized controlled trial

Cardiovascular diseases (CVD) are the leading causes of mortality worldwide. Flow-mediated dilation (FMD) is a marker of vascular function. Beneficial cardiometabolic effects of Nigella sativa (N. sativa) have been observed. We evaluated the effect of N. sativa oil on FMD, plasma nitrite, and nitrate (NOx) as nitric oxide (NO) metabolites, and inflammatory markers in subjects with CVD risk factors. Fifty participants were randomly assigned to either the N. sativa (two capsules of 500 mg N. sativa oil) or the placebo group (two capsules of 500 mg mineral oil), for 2 months. The brachial FMD, plasma NOx, vascular cellular adhesion molecule-1 (VCAM-1), and intracellular adhesion molecule-1 (ICAM-1) were measured. FMD and plasma NOx levels was significantly increased in the N. sativa group compared to the placebo group (changes: 2.97 ± 2.11% vs. 0.71 ± 3.19%, p < 0.001 for FMD and 4.73 ± 7.25 μmol/L vs. 0.99 ± 5.37 μmol/L, p = 0.036 for plasma NOx). However, there was no significant difference in ICAM-1 and VCAM-1 levels between groups. Therefore, N. sativa oil improves vascular NO and FMD in subjects with cardiovascular risk factors. However, more studies are warranted to confirm the beneficial impacts of the N. sativa oil on vascular inflammation.

The association of garlic intake and cardiovascular risk factors: A systematic review and meta-analysis

Garlic is a common cooking ingredient and used in traditional medicine in Asian countries. There is a growing attention on garlic due to its preventive characteristics in cardiovascular diseases (CVDs). Many studies have reviewed the association between garlic intake and CVDs; however, no consistent conclusions have been drawn. New clinical trials have also been conducted and could contribute to more solid statements. In order to systematically review the reliability of previous studies regarding the implication of garlic in the management of CVDs, we performed in-depth meta-analysis using the most up-to-date randomized clinical trials (RCTs) data with more systematic controls. According to the 22 studies included, the effects of garlic intake on lowering total cholesterol (TC) and low-density lipoprotein (LDL) are more noticeable with lower dosage and longer duration, especially in patients with CVDs. In addition, subgroup analysis indicated that appropriate diet intervention could be an important control factor that should be taken into consideration in any future study designs.

The effect of barberry (Berberis vulgaris) consumption on flow-mediated dilation and inflammatory biomarkers in patients with hypertension: A randomized controlled trial

Hypertension is considered as an important cardiovascular risk factor and evidence suggests that hypertension and endothelial dysfunction reinforce each other. Polyphenol-rich foods, such as barberry can reduce the risk of cardiovascular disease. Our aim was to investigate the effects of barberry consumption on vascular function and inflammatory markers in hypertensive subject. In this randomized controlled parallel trial, 84 hypertensive subjects of both genders (aged 54.06 ± 10.19 years; body mass index 28.02 ± 2.18 kg/m2 ) were randomly allocated to consume barberry (10 g/day dried barberry) or placebo for 8 weeks. Before and after the intervention, changes in brachial flow-mediated dilation (FMD) and plasma macrophage/monocyte chemo-attractant protein-1 (MCP-1), vascular cellular adhesion molecule-1, and intracellular adhesion molecule-1 (ICAM-1) were measured. An intention-to-treat analysis was performed. Compared to placebo (n = 42), barberry consumption (n = 42) improved FMD (B [95% CI] was 6.54% [4.39, 8.70]; p < .001) and decreased plasma ICAM-1 (B [95% CI] was -1.61 ng/ml [-2.74, -0.48]; p = .006). MCP-1 was significantly lower in the barberry group compared with the placebo group (B [95% CI] was -37.62 pg/ml [-72.07, -3.17]; p = .033). Our results indicate that barberry consumption improves FMD and has a beneficial effect on plasma ICAM-1 and MCP-1 in hypertensive patients. This trial was registered at the Iranian Registry of Clinical Trial (IRCT) with number IRCT20160702028742N8.

The effect of egg and its derivatives on vascular function: A systematic review of interventional studies

BACKGROUND & AIMS

Cardiovascular diseases (CVDs) are considered as a major cause of health loss for all regions of the world. Atherosclerosis is one of the most important underlying causes of CVDs. Vascular dysfunction is the primary marker of atherosclerosis. Various studies have investigated the effect of egg intake on CVDs. This study aimed to determine the effect of egg and its derivatives consumption on vascular function.

METHODS

Using a comprehensive search strategy, the searching was conducted on PubMed, Scopus and Google Scholar search engines resources (from inception up to Feb 2020). Intended exposure and outcome were egg or its derivatives intake, and vascular function measuring methods, respectively.

RESULTS

A total of 35 papers were found through search databases. Finally, seven trials were included, which were published between 2005 and 2018. Results showed that acute and chronic consumption of whole eggs did not have a significant adverse effect on flow-mediated dilatation (FMD). Also, lutein-enriched egg yolk and egg ovalbumin-derived protein hydrolysate did not have significant positive effects on FMD and pulse wave velocity (PWV), respectively. However, one month egg-yolk-derived phospholipid (PL) preparation intervention increased FMD by 3.4% (p < 0.05), and replacing a portion of a glucose challenge with whole eggs or egg whites improved postprandial FMD (p < 0.05).

CONCLUSIONS

We concluded that consumption of whole egg, despite being rich in cholesterol, has no adverse effect on vascular function, and even some of egg derivatives may improve vascular function. Further research is needed to justify the potential effects of egg or its derivatives on vascular function.