Health Benefits and Uses of
Garlic
Garlic health benefits and medicinal properties have long been known . Garlic
has long been considered a herbal "wonder drug", with a reputation for
preventing everything from the common cold and flu to the Plague! It has been
used extensively in herbal medicine (phototherapy, sometimes spelt
phototherapy). Raw garlic is used by some to treat the symptoms of acne and
there is some evidence that it can assist in managing high cholesterol levels.
It can even be effective as a natural mosquito repellent.
In general, a stronger tasting clove of garlic has more sulphur content and
hence more medicinal value. Some people have suggested that organically grown
garlic tends towards a higher sulphur level and hence greater benefit to health.
In my experience it certainly tastes better and I buy organic whenever possible.
Some people prefer to take garlic supplements. These pills and capsules have the
advantage of avoiding garlic breath.
Healthy Antioxidant:
Studies have shown that garlic - especially aged garlic - can have a powerful
antioxidant effect. Antioxidants help to protect the body against damaging "free
radicals".
Health Effects of Garlic
Garlic has long been used medicinally, most recently for its cardiovascular,
antineoplastic, and antimicrobial properties. Sulfur compounds, including
allicin, appear to be the active components in the root bulb of the garlic
plant. Studies show significant but modest lipid-lowering effects and
antiplatelet activity. Significant blood pressure reduction is not consistently
noted. There is some evidence for antineoplastic activity and insufficient
evidence for clinical antimicrobial activity. Side effects generally are mild
and uncommon. Garlic appears to have no effect on drug metabolism, but patients
taking anticoagulants should be cautious. It seems prudent to stop taking high
dosages of garlic seven to 10 days before surgery because garlic can prolong
bleeding time.
Uses and Efficacy:
Garlic has been
studied extensively in vitro, in animal and human clinical trials, and in
epidemiologic evaluations for its multiple medicinal properties. The quality of
human trials has been variable, making comparisons among the trials difficult.
Some trials are not well blinded; some are only of short duration; some have
only small numbers of patients; and many are not well controlled. In addition,
many different garlic preparations have been used, with unpredictable release of
active ingredients.
ANTIHYPERTENSIVE EFFECTS:
The antihypertensive effects of garlic have been studied but remain
controversial. In a 1994 meta-analysis15 assessing the effect of garlic on
hypertension, three trials showed significant reductions in systolic blood
pressure (7.7 mm Hg greater reduction), and four trials showed reductions in
diastolic blood pressure (5 mm Hg greater reduction) with garlic treatment
compared with placebo. In a more recent meta-analysis, 23 placebo-controlled
trials were analyzed. Only three trials showed a statistically significant
reduction in diastolic blood pressure (2 to 7 percent), and one showed a
statistically significant reduction in systolic blood pressure (approximately 3
percent) in patients treated with garlic compared with placebo.
OTHER CARDIOVASCULAR-RELATED EFFECTS:
A recent review10 of 10 trials assessing the effect of garlic on thrombotic
risk showed modest but significant decreases in platelet aggregation with garlic
compared with placebo, but mixed results on fibrinolytic activity and plasma
viscosity were reported. The same review analyzed 12 trials of garlic
supplementation in diabetic and nondiabetic adults; only one trial showed a
significant decrease in glucose levels in nondiabetic patients who took garlic
when compared with placebo. Atherosclerotic plaque volume reduction in humans
also has been noted in two trials comparing garlic treatment with placebo. One
observational study19 showed that regular garlic powder intake weakened age- and
pressure-related increases in aortic stiffness.
ANTINEOPLASTIC EFFECTS:
Epidemiologic evidence, primarily from case-control and some cohort studies, has
shown a decreased risk of stomach and colon cancer with the high consumption of
garlic and other alliums vegetables (e.g., onions, leeks, shallots, chives), but
many of these studies were not well controlled. In one cohort study, garlic
supplementation did not confer the same protective benefit, but there are no
studies assessing the use of particular garlic supplements and cancer incidence.
Contraindications, Adverse Effects, Interactions:
The ingestion of one to two cloves of raw garlic per day is considered safe in
adults. The most common side effect of ingested garlic is breath and body odor.
Consumption of excessive amounts of raw garlic, especially on an empty stomach,
can cause gastrointestinal upset, flatulence, and changes in the intestinal
flora. There have been reports of allergic dermatitis, burns, and blisters from
topical application of raw garlic.
Garlic appears to have no effect on drug metabolism,22 although recent
studies23,24 in healthy volunteers show conflicting results related to garlic's
effect on protease inhibitor pharmacokinetics. It has been suggested that
patients taking anticoagulants use caution when taking garlic because of its
antithrombotic properties.10,22 It seems prudent to stop taking high dosages of
garlic seven to 10 days before surgery because garlic can prolong bleeding time
and has been associated (in one case report) with spontaneous spinal epidural
hematoma.
Contraindications, Adverse Effects, Interactions:
The ingestion of one to two cloves of raw garlic per day is considered safe
in adults. The most common side effect of ingested garlic is breath and body
odor. Consumption of excessive amounts of raw garlic, especially on an empty
stomach, can cause gastrointestinal upset, flatulence, and changes in the
intestinal flora. There have been reports of allergic dermatitis, burns, and
blisters from topical application of raw garlic.
Garlic appears to have no effect on drug metabolism,22 although recent
studies23,24 in healthy volunteers show conflicting results related to garlic's
effect on protease inhibitor pharmacokinetics. It has been suggested that
patients taking anticoagulants use caution when taking garlic because of its
antithrombotic properties.10,22 It seems prudent to stop taking high dosages of
garlic seven to 10 days before surgery because garlic can prolong bleeding time
and has been associated (in one case report) with spontaneous spinal epidural
hematoma.
