NIS - libdoc.who.int - World Health Organization

WHO monographs on medicinal plants commonly used in the Newly Independent States (NIS)
and unpublished) (116) and selected 16 with data from 952 subjects to
include in the analysis. Fourteen of the trials used a parallel group design,
and the remaining two were cross-over studies. Two of the studies
were conducted in an open-label fashion, two others were single-blind,
and the remainder were double-blind. The total daily dose of garlic was
600–900 mg of dried garlic powder, or 10 g of raw garlic, or 18 mg of
garlic oil, or aged garlic extracts (dosage not stated). The median duration
of the therapy was 12 weeks. Overall, the subjects receiving garlic
supplementation (powder or non-powder) showed a 12% reduction (average)
in total cholesterol, and a 13% reduction (powder only) in serum
triglycerides. Meta-analysis of the clinical studies confirmed the lipidlowering
action of garlic. However, the authors concluded that the overall
quality of the clinical trials was poor and that favourable results of
better-designed clinical studies should be available before garlic can be
routinely recommended as a lipid-lowering agent. However, current
available data support the hypothesis that garlic therapy is at least beneficial
(116). Another metaanalysis of the controlled trials of garlic’s
effects on total serum cholesterol reached similar conclusions (117). A
systematic review of the lipid-lowering potential of a dried garlic powder
preparation in eight studies with 500 subjects had similar findings
(118). In seven of the eight studies reviewed, a daily dose of 600–900 mg
of garlic powder reduced serum cholesterol and triglyceride levels by
5–20%. The review concluded that garlic powder preparations do have
lipid-lowering potential (118).
An increase in fibrinolytic activity in the serum of patients suffering
from atherosclerosis was observed after administration of aqueous garlic
extracts, the essential oil, and garlic powder (119, 120). Clinical studies
have demonstrated that garlic activates endogenous fibrinolysis, that the
effect is detectable for several hours after administration of the drug, and
that the effect increases as the drug is taken regularly for several months
(43, 121). Investigations of the acute haemorheological (blood flow) effect
of 600–1200 mg of dry garlic powder demonstrated that the drug decreased
plasma viscosity, tissue plasminogen activator activity and the
haematocrit level (118).
The effects of the drug on haemorheology in conjunctival vessels was
determined in a randomized, placebo-controlled, double-blind, crossover
trial. Garlic powder (900 mg) significantly increased the mean diameter
of the arterioles (by 4.2%) and venules (by 5.9%) as compared with
controls (122). In another double-blind, placebo-controlled study, patients
with stage II peripheral arterial occlusive disease were given a daily
dose of 800 mg of garlic powder for 4 weeks (123, 124). Increased capil-
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