Karin Ried

Effect of garlic on blood pressure: A systematic review and meta-analysis

BackgroundNon-pharmacological treatment options for hypertension have the potential to reduce the risk of cardiovascular disease at a population level. Animal studies have suggested that garlic reduces blood pressure, but primary studies in humans and non-systematic reviews have reported mixed results. With interest in complementary medicine for hypertension increasing, it is timely to update a systematic review and meta-analysis from 1994 of studies investigating the effect of garlic preparations on blood pressure.MethodsWe searched the Medline and Embase databases for studies published between 1955 and October 2007. Randomised controlled trials with true placebo groups, using garlic-only preparations, and reporting mean systolic and/or diastolic blood pressure (SBP/DBP) and standard deviations were included in the meta-analysis. We also conducted subgroup meta-analysis by baseline blood pressure (hypertensive/normotensive), for the first time. Meta-regression analysis was performed to test the associations between blood pressure outcomes and duration of treatment, dosage, and blood pressure at start of treatment.ResultsEleven of 25 studies included in the systematic review were suitable for meta-analysis. Meta-analysis of all studies showed a mean decrease of 4.6 ± 2.8 mm Hg for SBP in the garlic group compared to placebo (n = 10; p = 0.001), while the mean decrease in the hypertensive subgroup was 8.4 ± 2.8 mm Hg for SBP (n = 4; p < 0.001), and 7.3 ± 1.5 mm Hg for DBP (n = 3; p < 0.001). Regression analysis revealed a significant association between blood pressure at the start of the intervention and the level of blood pressure reduction (SBP: R = 0.057; p = 0.03; DBP: R = -0.315; p = 0.02).ConclusionOur meta-analysis suggests that garlic preparations are superior to placebo in reducing blood pressure in individuals with hypertension.

Does chocolate reduce blood pressure? A meta-analysis

BackgroundDark chocolate and flavanol-rich cocoa products have attracted interest as an alternative treatment option for hypertension, a known risk factor for cardiovascular disease. Previous meta-analyses concluded that cocoa-rich foods may reduce blood pressure. Recently, several additional trials have been conducted with conflicting results. Our study summarises current evidence on the effect of flavanol-rich cocoa products on blood pressure in hypertensive and normotensive individuals.MethodsWe searched Medline, Cochrane and international trial registries between 1955 and 2009 for randomised controlled trials investigating the effect of cocoa as food or drink compared with placebo on systolic and diastolic blood pressure (SBP/DBP) for a minimum duration of 2 weeks. We conducted random effects meta-analysis of all studies fitting the inclusion criteria, as well as subgroup analysis by baseline blood pressure (hypertensive/normotensive). Meta-regression analysis explored the association between type of treatment, dosage, duration or baseline blood pressure and blood pressure outcome. Statistical significance was set at P < 0.05.ResultsFifteen trial arms of 13 assessed studies met the inclusion criteria. Pooled meta-analysis of all trials revealed a significant blood pressure-reducing effect of cocoa-chocolate compared with control (mean BP change ± SE: SBP: -3.2 ± 1.9 mmHg, P = 0.001; DBP: -2.0 ± 1.3 mmHg, P = 0.003). However, subgroup meta-analysis was significant only for the hypertensive or prehypertensive subgroups (SBP: -5.0 ± 3.0 mmHg; P = 0.0009; DBP: -2.7 ± 2.2 mm Hg, P = 0.01), while BP was not significantly reduced in the normotensive subgroups (SBP: -1.6 ± 2.3 mmHg, P = 0.17; DBP: -1.3 ± 1.6 mmHg, P = 0.12). Nine trials used chocolate containing 50% to 70% cocoa compared with white chocolate or other cocoa-free controls, while six trials compared high- with low-flavanol cocoa products. Daily flavanol dosages ranged from 30 mg to 1000 mg in the active treatment groups, and interventions ran for 2 to 18 weeks. Meta-regression analysis found study design and type of control to be borderline significant but possibly indirect predictors for blood pressure outcome.ConclusionOur meta-analysis suggests that dark chocolate is superior to placebo in reducing systolic hypertension or diastolic prehypertension. Flavanol-rich chocolate did not significantly reduce mean blood pressure below 140 mmHg systolic or 80 mmHg diastolic.

Protective effect of lycopene on serum cholesterol and blood pressure: Meta-analyses of intervention trials.

BACKGROUND Cardiovascular disease is associated with oxidative stress, inflammatory processes, and vascular dysfunction. Lycopene, a carotenoid found in tomatoes, is an antioxidant with a protective effect on lipid peroxidation and anti-atherosclerotic capacity. This review summarises current evidence on the effect of lycopene on serum lipid concentrations and blood pressure. METHODS We searched the PubMed and Cochrane databases for intervention studies between 1955 and September 2010 investigating the effect of lycopene on blood lipids or blood pressure for a minimum duration of 2 weeks. We conducted meta-analyses using a random effect model of all studies fitting the inclusion criteria. Additionally, we conducted subgroup meta-analysis of serum lipid concentrations by lycopene dosage and subgroup meta-analysis by baseline blood pressure. RESULTS Twelve studies (13 trial arms) meeting the inclusion criteria investigated the effect of lycopene on serum lipids, and four studies examined its effect on blood pressure. Meta-analysis on serum lipids revealed a significant cholesterol-lowering effect of lycopene for total serum cholesterol (mean change±SE: -7.55±6.15mg/dl; p=0.02) and low-density-lipoprotein (LDL) cholesterol (mean change±SE: -10.35±5.64mg/dl, p=0.0003) in the subgroup of trials using lycopene dosages of ≥25mg daily, whereas subgroup meta-analysis of trials using lower lycopene dosages was not significant. Meta-analysis of the effect of lycopene on systolic blood pressure of all trials suggested a significant blood pressure reducing effect (mean systolic blood pressure change±SE: -5.60±5.26mm Hg, p=0.04). CONCLUSIONS Our meta-analysis suggests that lycopene taken in doses ≥25mg daily is effective in reducing LDL cholesterol by about 10% which is comparable to the effect of low doses of statins in patient with slightly elevated cholesterol levels. More research is needed to confirm suggested beneficial effects on total serum cholesterol and systolic blood pressure.

Aged garlic extract lowers blood pressure in patients with treated but uncontrolled hypertension: A randomised controlled trial

OBJECTIVE To assess the effect, tolerability and acceptability of aged garlic extract as an adjunct treatment to existing antihypertensive medication in patients with treated, but uncontrolled, hypertension. DESIGN A double-blind parallel randomised placebo-controlled trial involving 50 patients whose routine clinical records in general practice documented treated but uncontrolled hypertension. The active treatment group received four capsules of aged garlic extract (960 mg containing 2.4 mg S-allylcysteine) daily for 12 weeks, and the control group received matching placebos. The primary outcome measures were systolic and diastolic blood pressure at baseline, 4, 8 and 12 weeks, and change over time. We also assessed tolerability during the trial and acceptability at 12 weeks. RESULTS In patients with uncontrolled hypertension (SBP ≥ 140 mmHg at baseline), systolic blood pressure was on average 10.2 ± 4.3 mmHg (p=0.03) lower in the garlic group compared with controls over the 12-week treatment period. Changes in blood pressure between the groups were not significant in patients with SBP<140 mmHg at baseline. Aged garlic extract was generally well tolerated and acceptability of trial treatment was high (92%). CONCLUSION Our trial suggests that aged garlic extract is superior to placebo in lowering systolic blood pressure similarly to current first line medications in patients with treated but uncontrolled hypertension.

Aged garlic extract reduces blood pressure in hypertensives: a dose-response trial

Background/objectives:Hypertension affects about 30% of adults worldwide. Garlic has blood pressure-lowering properties and the mechanism of action is biologically plausible. Our trial assessed the effect, dose–response, tolerability and acceptability of different doses of aged garlic extract as an adjunct treatment to existing antihypertensive medication in patients with uncontrolled hypertension.Subjects/methods:A total of 79 general practice patients with uncontrolled systolic hypertension participated in a double-blind randomised placebo-controlled dose–response trial of 12 weeks. Participants were allocated to one of three garlic groups with either of one, two or four capsules daily of aged garlic extract (240/480/960 mg containing 0.6/1.2/2.4 mg of S-allylcysteine) or placebo. Blood pressure was assessed at 4, 8 and 12 weeks and compared with baseline using a mixed-model approach. Tolerability was monitored throughout the trial and acceptability was assessed at 12 weeks by questionnaire.Results:Mean systolic blood pressure was significantly reduced by 11.8±5.4 mm Hg in the garlic-2-capsule group over 12 weeks compared with placebo (P=0.006), and reached borderline significant reduction in the garlic-4-capsule group at 8 weeks (−7.4±4.1 mm Hg, P=0.07). Changes in systolic blood pressure in the garlic-1-capsule group and diastolic blood pressure were not significantly different to placebo. Tolerability, compliance and acceptability were high in all garlic groups (93%) and highest in the groups taking one or two capsules daily.Conclusions:Our trial suggests aged garlic extract to be an effective and tolerable treatment in uncontrolled hypertension, and may be considered as a safe adjunct treatment to conventional antihypertensive therapy.

Dark chocolate or tomato extract for prehypertension: a randomised controlled trial.

BackgroundFlavanol-rich chocolate and lycopene-rich tomato extract have attracted interest as potential alternative treatment options for hypertension, a known risk factor for cardiovascular morbidity and mortality. Treatment of prehypertension (SBP 120–139/DBP 80–89 mmHg) may forestall progression to hypertension. However, there has been only limited research into non-pharmacological treatment options for prehypertension. We investigated the effect of dark chocolate or tomato extract on blood pressure, and their acceptability as an ongoing treatment option in a prehypertensive population.MethodsOur trial consisted of two phases: a randomised controlled three-group-parallel trial over 12 weeks (phase 1) followed by a crossover of the two active treatment arms over an additional 12-week period (phase 2). Group 1 received a 50 g daily dose of dark chocolate with 70% cocoa containing 750 mg polyphenols, group 2 were allocated one tomato extract capsule containing 15 mg lycopene per day, and group 3 received one placebo capsule daily over 8 weeks followed by a 4-week washout period. In phase 2 the active treatment groups were crossed over to receive the alternative treatment. Median blood pressure, weight, and abdominal circumference were measured 4-weekly, and other characteristics including physical activity, general health, energy, mood, and acceptability of treatment were assessed by questionnaire at 0, 8 and 20 weeks. We analysed changes over time using a linear mixed model, and one time point differences using Kruskal-Wallis, Fishers-Exact, or t-tests.ResultsThirty-six prehypertensive healthy adult volunteers completed the 6-month trial. Blood pressure changes over time within groups and between groups were not significant and independent of treatment. Weight and other characteristics did not change significantly during the trial. However, a marked difference in acceptability between the two treatment forms (chocolate or capsule) was revealed (p < 0.0001). Half of the participants allocated to the chocolate treatment found it hard to eat 50 g of dark chocolate every day and 20% considered it an unacceptable long-term treatment option, whereas all participants found it easy and acceptable to take a capsule each day for blood pressure.ConclusionOur study did not find a blood pressure lowering effect of dark chocolate or tomato extract in a prehypertensive population. Practicability of chocolate as a long-term treatment option may be limited.Trial registrationhttp://www.anzctr.org.au Identifier: ACTRN12609000047291

Effect of garlic on serum lipids: an updated meta‐analysis

Hypercholesterolemia is associated with an increased risk of heart disease. The effect of garlic on blood lipids has been studied in numerous trials and summarized in meta-analyses, with conflicting results. This meta-analysis, the most comprehensive to date, includes 39 primary trials of the effect of garlic preparations on total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglycerides. The findings suggest garlic to be effective in reducing total serum cholesterol by 17 ± 6 mg/dL and low-density lipoprotein cholesterol by 9 ± 6 mg/dL in individuals with elevated total cholesterol levels (>200 mg/dL), provided garlic is used for longer than 2 months. An 8% reduction in total serum cholesterol is of clinical relevance and is associated with a 38% reduction in risk of coronary events at 50 years of age. High-density lipoprotein cholesterol levels improved only slightly, and triglycerides were not influenced significantly. Garlic preparations were highly tolerable in all trials and were associated with minimal side effects. They might be considered as an alternative option with a higher safety profile than conventional cholesterol-lowering medications in patients with slightly elevated cholesterol.

Efficacy of Traditional Chinese Herbal Medicine in the management of female infertility: a systematic review.

OBJECTIVES To assess the effect of Traditional Chinese Herbal Medicine (CHM) in the management of female infertility and on pregnancy rates compared with Western Medical (WM) treatment. METHODS We searched the Medline and Cochrane databases and Google Scholar until February 2010 for abstracts in English of studies investigating infertility, menstrual health and Traditional Chinese Medicine (TCM). We undertook meta-analyses of (non-)randomised controlled trials (RCTs) or cohort studies, and compared clinical pregnancy rates achieved with CHM versus WM drug treatment or in vitro fertilisation (IVF). In addition, we collated common TCM pattern diagnosis in infertility in relation to the quality of the menstrual cycle and associated symptoms. RESULTS Eight RCTs, 13 cohort studies, 3 case series and 6 case studies involving 1851 women with infertility were included in the systematic review. Meta-analysis of RCTs suggested a 3.5 greater likelihood of achieving a pregnancy with CHM therapy over a 4-month period compared with WM drug therapy alone (odds ratio=3.5, 95% CI: 2.3, 5.2, p<0.0001, n=1005). Mean (SD) pregnancy rates were 60±12.5% for CHM compared with 32±10% using WM drug therapy. Meta-analysis of selected cohort studies (n=616 women) suggested a mean clinical pregnancy rate of 50% using CHM compared with IVF (30%) (p<0.0001). CONCLUSIONS Our review suggests that management of female infertility with Chinese Herbal Medicine can improve pregnancy rates 2-fold within a 4 month period compared with Western Medical fertility drug therapy or IVF. Assessment of the quality of the menstrual cycle, integral to TCM diagnosis, appears to be fundamental to successful treatment of female infertility.

Potential of garlic (Allium sativum) in lowering high blood pressure: mechanisms of action and clinical relevance.

Garlic supplements have shown promise in the treatment of uncontrolled hypertension, lowering blood pressure (BP) by about 10 mmHg systolic and 8 mmHg diastolic, similar to standard BP medication. Aged garlic extract, which contains S-allylcysteine as the bioactive sulfur compound, in particular is standardizable and highly tolerable, with little or no known harmful interaction when taken with other BP-reducing or blood-thinning medication. Here we describe biologically plausible mechanisms of garlic’s BP-lowering effect. Garlic-derived polysulfides stimulate the production of the vascular gasotransmitter hydrogen sulfide (H2S) and enhance the regulation of endothelial nitric oxide (NO), which induce smooth muscle cell relaxation, vasodilation, and BP reduction. Several dietary and genetic factors influence the efficiency of the H2S and NO signaling pathways and may contribute to the development of hypertension. Sulfur deficiency might play a part in the etiology of hypertension, and could be alleviated with supplementation of organosulfur compounds derived from garlic.

The acute and sub-chronic effects of cocoa flavanols on mood, cognitive and cardiovascular health in young healthy adults: a randomized, controlled trial.

Cocoa supplementation has been associated with benefits to cardiovascular health. However, cocoas effects on cognition are less clear. A randomized, placebo-controlled, double-blind clinical trial (n = 40, age M = 24.13 years, SD = 4.47 years) was conducted to investigate the effects of both acute (same-day) and sub-chronic (daily for four-weeks) 250 mg cocoa supplementation on mood and mental fatigue, cognitive performance and cardiovascular functioning in young, healthy adults. Assessment involved repeated 10-min cycles of the Cognitive Demand Battery (CDB) encompassing two serial subtraction tasks (Serial Threes and Sevens), a Rapid Visual Information Processing task, and a mental fatigue scale over the course of half an hour. The Swinburne University Computerized Cognitive Assessment Battery (SUCCAB) was also completed to evaluate cognition. Cardiovascular function included measuring both peripheral and central blood pressure and cerebral blood flow. At the acute time point, consumption of cocoa significantly improved self-reported mental fatigue and performance on the Serial Sevens task in cycle one of the CDB. No other significant effects were found. This trial was registered with the Australian and New Zealand Clinical Trial Registry (Trial ID: ACTRN12613000626763). Accessible via http://www.anzctr.org.au/TrialSearch.aspx?searchTxt=ACTRN12613000626763&ddlSearch=Registered.