Diet and individuality in detoxification

Garlic Lowers Blood Pressure in Hypertensive Individuals, Regulates Serum Cholesterol, and Stimulates Immunity: An Updated Meta-analysis and Review

BACKGROUND

Garlic has been shown to have cardiovascular protective and immunomodulatory properties.

OBJECTIVES

We updated a previous meta-analysis on the effect of garlic on blood pressure and reviewed the effect of garlic on cholesterol and immunity.

METHODS

We searched the Medline database for randomized controlled trials (RCTs) published between 1955 and December 2013 on the effect of garlic preparations on blood pressure. In addition, we reviewed the effect of garlic on cholesterol and immunity.

RESULTS

Our updated meta-analysis on the effect of garlic on blood pressure, which included 20 trials with 970 participants, showed a mean ± SE decrease in systolic blood pressure (SBP) of 5.1 ± 2.2 mm Hg (P < 0.001) and a mean ± SE decrease in diastolic blood pressure (DBP) of 2.5 ± 1.6 mm Hg (P < 0.002) compared with placebo. Subgroup analysis of trials in hypertensive subjects (SBP/DBP ≥140/90 mm Hg) at baseline revealed a larger significant reduction in SBP of 8.7 ± 2.2 mm Hg (P < 0.001; n = 10) and in DBP of 6.1 ± 1.3 mm Hg (P < 0.001; n = 6). A previously published meta-analysis on the effect of garlic on blood lipids, which included 39 primary RCTs and 2300 adults treated for a minimum of 2 wk, suggested garlic to be effective in reducing total and LDL cholesterol by 10% if taken for >2 mo by individuals with slightly elevated concentrations [e.g., total cholesterol >200 mg/dL (>5.5 mmol/L)]. Garlic has immunomodulating effects by increasing macrophage activity, natural killer cells, and the production of T and B cells. Clinical trials have shown garlic to significantly reduce the number, duration, and severity of upper respiratory infections.

CONCLUSIONS

Our review suggests that garlic supplements have the potential to lower blood pressure in hypertensive individuals, to regulate slightly elevated cholesterol concentrations, and to stimulate the immune system. Garlic supplements are highly tolerated and may be considered as a complementary treatment option for hypertension, slightly elevated cholesterol, and stimulation of immunity. Future long-term trials are needed to elucidate the effect of garlic on cardiovascular morbidity and mortality.

Metabolic fingerprint of dimethyl sulfone (DMSO2) in microbial-mammalian co-metabolism

There is growing awareness that intestinal microbiota alters the energy harvesting capacity of the host and regulates metabolism. It has been postulated that intestinal microbiota are able to degrade unabsorbed dietary components and transform xenobiotic compounds. The resulting microbial metabolites derived from the gastrointestinal tract can potentially enter the circulation system, which, in turn, affects host metabolism. Yet, the metabolic capacity of intestinal microbiota and its interaction with mammalian metabolism remains largely unexplored. Here, we review a metabolic pathway that integrates the microbial catabolism of methionine with mammalian metabolism of methanethiol (MT), dimethyl sulfide (DMS), and dimethyl sulfoxide (DMSO), which together provide evidence that supports the microbial origin of dimethyl sulfone (DMSO2) in the human metabolome. Understanding the pathway of DMSO2 co-metabolism expends our knowledge of microbial-derived metabolites and motivates future metabolomics-based studies on ascertaining the metabolic consequences of intestinal microbiota on human health, including detoxification processes and sulfur xenobiotic metabolism.

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.

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.