Modern Pharmacological Research on Garlic
Garlic is derived from the fresh rhizome of a lily family plant. According to Traditional Chinese Medicine, it promotes digestion, warms the spleen and stomach, eliminates accumulations, detoxifies, and kills parasites. It treats conditions such as food stagnation, cold abdominal pain, edema, distension, dysentery, diarrhea, carbuncles, swelling, insect bites, malaria, and fungal skin diseases. Recent studies using modern scientific methods have yielded significant findings regarding garlic’s pharmacological components and functions:
1. Lipid-lowering and glucose-lowering effects: Garlic extract markedly reduces serum lipids and low-density lipoprotein in hyperlipidemic rabbits, increases high-density lipoprotein, and decreases aortic lipid content by 72%, significantly reducing atherosclerotic plaques—superior to clofibrate. Garlic essential oil effectively prevents lipid elevation, maintaining serum and hepatic cholesterol and triglycerides within normal ranges. Its mechanism may involve lowering serum esterified cholesterol. Garlic also affects hepatic glycogen synthesis and increases plasma insulin levels, showing beneficial therapeutic effects in diabetic patients.
2. Effects on the cardiovascular system: Recent animal experiments and clinical trials consistently show that allicin has significant antihypertensive effects. It improves microcirculation, increases peripheral blood flow and tissue plasminogen activator activity, inhibits coagulation factor activity, reduces plasma malondialdehyde levels, and exhibits clear anti-atherosclerotic properties. Garlic essential oil offers protective effects against aortic atherosclerosis induced by hypercholesterolemia.
3. Antimicrobial action: Garlic is known as a natural antibiotic, capable of killing or inhibiting various pathogens including Streptococcus pyogenes, Staphylococcus aureus, Neisseria meningitidis, Streptococcus pneumoniae, Mycobacterium tuberculosis, Shigella spp., Salmonella typhi, Escherichia coli, Vibrio cholerae, without inducing drug resistance. Among its active components, allicin and garlic essential oil with refractive index above 1.57 exhibit the strongest antibacterial effects. Garlic extracts show varying degrees of inhibition against common dermatophytes. Some researchers suggest the presence of a non-volatile oily compound with antimicrobial-like properties. Additionally, garlic demonstrates good inhibitory effects on cytomegalovirus, with efficacy increasing proportionally with concentration.
4. Anti-aging effects: Comparing garlic with ginseng, studies found that alliin and ethanol extracts of garlic exhibit stronger in vitro antioxidant activity than ginseng. In vivo, garlic suppresses superoxide dismutase activity in the liver more effectively than ginseng, though slightly less in the brain—indicating garlic may help delay aging.
5. Immunomodulatory effects: Research shows allicin induces human lymphocyte transformation; natural garlic juice enhances T-lymphocyte transformation, boosts macrophage and lymphocyte activity, and strengthens immune function.
6. Antiplatelet aggregation: Oral allicin significantly reduces platelet adhesion rate and prolongs clotting time in animals. Garlic essential oil also exhibits fibrinolytic and antiplatelet aggregation effects.
7. Anticancer effects: Recent foreign studies found that oral garlic oil can inhibit the development of skin cancer induced by benzo[a]pyrene, possibly by suppressing activation of the aryl hydroxylase system, thus blocking carcinogenic processes at the initiation stage of cellular transformation. Other studies indicate garlic effectively interferes with pre-cancerous liver lesions induced by nitrosamines. Garlic essential oil participates in normal DNA replication and repair processes; deficiency leads to abnormal DNA, creating conditions conducive to lung, liver, and esophageal cancers. Garlic oil also increases neutrophil and macrophage counts. Raw garlic inhibits growth of nitrate-reducing bacteria in the stomach, reducing gastric nitrite levels formed by bacterial action. Diallyl sulfide and calcium salts in garlic are two crucial anticancer factors that prevent carcinogen formation, interfere with carcinogen activation, enhance detoxification, eliminate reactive metabolites, and avoid normal cell transformation into cancer cells. Its active components also act on tumor promotion stages through stimulating immune responses, blocking peroxidation, and inhibiting proliferation, further preventing tumor cell formation.
8. Detoxification: Recently, a study used 0.3 g of garlic tablets three times daily orally to treat lead poisoning, achieving 100% effectiveness. Studies on mice showed garlic effectively antagonizes mercury toxicity via ATPase changes.
9. Other effects: Garlic also exhibits radioprotective and membrane-protective properties. A 0.5% garlic solution renders vaginal trichomonads inactive within 5 minutes. Garlic can be used for prevention and treatment of periodontal disease, epistaxis, colds, and chronic gastritis. Garlic extract increases mortality of mosquito larvae, and even a millionth dilution shows repellent effects on female mosquitoes.