PDF
(Download)
|
- Garlic (Allium sativum)
- Uncontrolled Hypertension
| Date:
11-15-2010 | HC# 101021-412
|
Re: Aged Garlic Extract Proven a Useful Adjunct Therapy to Conventional Medications in Uncontrolled Hypertension
Ried K, Frank
OR, Stocks NP. Aged garlic extract lowers blood
pressure in patients with treated but uncontrolled hypertension: a randomized controlled trial. Maturitas. 2010 Oct;67(2):144-150.
Garlic (Allium sativum) supplements have been
associated with a clinically significant blood pressure lowering effect in
patients with untreated hypertension (systolic blood pressure [SBP] ≥ 140 mmHg
or diastolic blood pressure [DBP] ≥ 90 mmHg) similar to that achieved by first
line treatment with antihypertensive medication.1,2 The
antihypertensive properties of garlic have been linked to stimulation of
intracellular nitric oxide (NO) and hydrogen sulfide (H2S)
production, as well as blockage of angiotensin II production, which promote
vasodilation and reduction in BP. Current evidence suggests Aged Garlic Extract® (AGE) to
be a safe and more reliable treatment option than raw or cooked garlic due to
its higher tolerability, superior antihypertensive properties,3and
because its active constituent S-allylcysteine (SAC) is more easily
standardized than the more volatile allicin, an unstable compound created in the
ingestion of garlic powder and some other garlic preparations.4
This
double-blind, parallel, randomized, and placebo-controlled clinical trial was
conducted in Adelaide, South Australia, between March and September 2009 to
investigate the effect, tolerability, and acceptability of AGE as an adjunct
treatment to existing antihypertensive medication in patients with treated,
uncontrolled hypertension. Fifty adult patients (mean age ± standard deviation
[SD]: 66 ± 9 years) treated with conventional antihypertensive medications were
randomly allocated to the treatment or placebo group for 12 weeks. Patients in
the treatment group were assigned 4 capsules daily of Kyolic®
(Garlic High Potency Everyday Formula112, Wakunaga/Wagner®; Vitaco
Health [NZ] Ltd; Auckland, New Zealand) containing 960 mg of AGE, equivalent to
2.4 mg SAC. Placebo capsules were matched to the active capsules in number,
size, color, and odor. Comparison of baseline characteristics revealed no
significant difference between placebo and treatment groups in most parameters
and borderline significance in the mean number of BP medication classes
prescribed.
Primary
outcome measures were SBP and DBP at 4, 8, and 12 weeks compared with baseline.
Tolerability of the trial medication was monitored by questionnaire at the
4-weekly appointments, while acceptability and willingness to continue the
treatment long term were explored by an exit questionnaire using 5-point
Likert-scales and open ended questions. Statistical significance was set at P
< 0.05. Differences between groups at baseline in continuous variables were
assessed by Student's t-test, while categorical variables were assessed by
chi-square test, and absolute CVD (cardiovascular disease) risk by Fisher's
Exact test.
A
significant treatment effect over 12 weeks was apparent between garlic and
control groups in patients with uncontrolled hypertension at baseline (mean
difference in SBP ± SD: −10.2 ± 4.3; P = 0.0361), while no significant
differences were found in the subgroup of patients with controlled
hypertension. Tolerability of trial capsules was generally high, with 24% of
the garlic group reporting minor adverse effects including belching, reflux,
and taste sensations (P = 0.25). Most of the participants found the treatment
easy (93%) and acceptable (92%). Ninety-two percent (92%) of participants in
the garlic group were willing to continue taking garlic supplements compared to
two-thirds (66%) in the control group.
The
authors conclude that AGE's effectiveness in lowering SBP in patients with
uncontrolled, treated hypertension is significantly superior to placebo and
similar to common antihypertensive medication. Further research is needed to
determine the effectiveness of lower dosages of AGE that would have the benefit
of improved tolerability and blinding, as well as reduced costs of treatment.
Future larger trials are needed to investigate dose-response relationships and
examine effect of AGE in association with different conventional BP medication
classes.
—Silvia Giovanelli Ris
References
1Reinhart KM, Coleman CI,
Teevan C, Vachhani P, White CM. Effects of garlic
on blood pressure in patients with and without
systolic hypertension: a meta-analysis. Ann
Pharmacother. 2008;42(12):1766-1771. 2Ried K, Frank OR, Stocks
NP, Fakler P, Sullivan T. Effect of garlic on blood pressure: a systematic review and
meta-analysis. BMC Cardiovasc Disord.
2008;8:13.
3Hoshino T, Kashimoto N, Kasuga
S. Effects of garlic preparations on the gastrointestinal mucosa. J Nutr. 2001;131(3s):1109S-1113S.
4Lawson LD, Gardner CD. Composition, stability, and
bioavailability of garlic products used in a clinical trial. J
Agric Food Chem. 2005;53(16):6254-6261.
|