Active Ingredient Garlic (allium Sativum L.)

allium sativum. one of the liliaceae used as a spice and traditional remedy. it contains allicin, the pungent active ingredient, which may reduce blood cholesterol and inhibit platelet aggregation.

Source:

medlineplus herbs and supplements: garlic (allium sativum l.)

Medical Condition	Uses based on scientific evidence	Grade*
acute upper respiratory infections of unspecified site	preliminary reports suggest that garlic may reduce the severity of upper respiratory tract infections. however, this has not been demonstrated in well-designed human studies.	c
alopecia areata	application of garlic gel on the skin may be beneficial in the treatment of alopecia areata (hair loss). additional study is needed.	c
atherosclerosis	preliminary research in humans suggests that deposits of cholesterol in blood vessels may not grow as quickly in people who take garlic. it is not clear if this is due to the ability of garlic to lower cholesterol levels or to other effects of garlic.	c
cryptococcal meningitis	preliminary study documented potential benefits of oral plus intravenous garlic in the management of cryptococcal meningitis. further research is needed before recommending for or against the use of garlic in the treatment of this potentially serious condition, for which other treatments are available.	c
diabetes mellitus without mention of complication	animal studies suggest that garlic may lower blood sugar and increase the release of insulin, but studies in humans do not confirm this effect.	d
diffuse cystic mastopathy	taking garlic supplements by mouth may improve some symptoms of benign breast disease. additional study is needed.	c
gastric ulcer unspecified as acute or chronic without mention of hemorrhage or perforation	early studies in humans show no effect of garlic on gastric or duodenal ulcers.	d
neoplasms	preliminary human studies suggest that regular consumption of garlic (particularly unprocessed garlic) may reduce the risk of developing several types of cancer including gastric and colorectal malignancies. some studies use multi-ingredient products so it is difficult to determine if garlic alone may play a beneficial role. further well-designed human clinical trials are needed to conclude whether eating garlic or taking garlic supplements may prevent or treat cancer.	c
other peripheral vascular disease	some human studies suggest that garlic may improve circulation in the legs by a small amount, but this issue remains unclear. better-designed studies are needed.	c
pre-eclampsia or eclampsia superimposed on pre-existing hypertension	there is not enough evidence to recommend increased garlic intake for preventing pre-eclampsia and its complications.	c
pure hypercholesterolemia	multiple studies in humans have reported small reductions in total blood cholesterol and low-density lipoproteins ("bad cholesterol") over short periods of time (4 to 12 weeks). it is not clear if there are benefits after this amount of time. effects on high-density lipoproteins ("good cholesterol") are not clear. this remains an area of controversy. well-designed and longer studies are needed in this area.	b
pure hypercholesterolemia	familial hypercholesterolemia is a genetic disorder in which very high cholesterol levels run in families. research in children with an inherited form of high cholesterol suggests that garlic does not have a large effect on lowering cholesterol levels in these patients.	c
qualitative platelet defects	the effects of garlic on platelet aggregation have been assessed in several human trials. because garlic has been associated with several cases of bleeding, therapy should be applied with caution (particularly in patients using other agents that may precipitate bleeding).	c
sickle-cell trait	initial evidence suggests the antioxidant activity of garlic may benefit sickle cell anemia. further study is necessary.	c
systemic sclerosis	there is insufficient evidence to recommend the use of garlic in systemic sclerosis.	c
tick-borne fever	in early study, self-reports of tick bites were significantly less in people receiving garlic over a placebo "sugar" pill. further well-designed study is needed to confirm these results.	c
unspecified essential hypertension	numerous human studies report that garlic can lower blood pressure by a small amount, but larger, well-designed studies are needed to confirm this possible effect.	c
unspecified viral infection	in initial studies, garlic has been shown to be effective against bacteria, mycobacteria, viruses, and fungi. small studies have been conducted using garlic for acute viral respiratory infections in children. other studies have shown that garlic may have some effect on athlete's foot. more high-quality human studies are necessary to recommend garlic to treat or prevent infections.	c

*Key to grades
A: Strong scientific evidence for this use;
B: Good scientific evidence for this use;
C: Unclear scientific evidence for this use;
D: Fair scientific evidence against this use;
F: Strong scientific evidence against this use.