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Garlic is cultivated all over the world and used universally as a spice and food. It is difficult to go out to eat in the United States without getting a dish seasoned with garlic. Garlic isn’t only used for its flavor - it has been used as a remedy for various ailments since the ancient and middle centuries. In fact, King Tutankhamen’s tomb was found with cloves of garlic in it when it was excavated. The Codex Ebers, a revered text from ancient Egypt, is one of the oldest written records prescribing garlic for abnormal growths, circulatory ailments, general malaise and infestations with insects and parasites.*
In 1997, a clinical study examined the effects of garlic and fish oil on patients with high cholesterol. Patients were split into four groups: (1) garlic, (2) fish oil, (3) garlic and fish oil, and(4) placebo. The placebo group did not see changes in their cholesterol or triglyceride levels. Total cholesterol and LDL-C were lowered for the garlic group and the garlic and fish oil group, but not in the fish oil group. Garlic taken by itself did not have any effect on triglyceride levels. An earlier study in 1993 also found that 12 weeks of garlic supplementation reduced total cholesterol and LDL-cholesterol, but did not affect HDL-cholesterol or triglycerides.
A meta-analysis was performed in 2008. Medline and Embase databases were searched for all randomized, placebo-controlled studies on garlic for blood pressure from 1955 to 2007. 11 studies met the criteria and were reviewed. The conclusion of the analysis is that garlic is a successful treatment for patients with hypertension. Another study on garlic for hypertension was performed after the 2008 meta-analysis. This 2013 study found that garlic reduced systolic and diastolic blood pressure over a 24-week period.
Effect of garlic and fish-oil supplementation on serum lipid and lipoprotein concentrations in hypercholesterolemic men.
Adler AJ, Holub BJ., The American Journal of Clinical Nutrition, 1997
Effect of garlic on blood pressure: A systematic review and meta-analysis
Ried K, Frank OR, Stocks NP, Fakler P, and Sullivan T., BMC Cardiovascular Disorders, 2008
Effects of Allium sativum (garlic) on systolic and diastolic blood pressure in patients with essential hypertension.
Ashraf R, Khan RA, Ashraf I, Qureshi AA., Pakistan journal of pharmaceutical sciences, 2013
Can garlic reduce levels of serum lipids? a controlled clinical study.
Jain AK, Vargas R, Gotzkowsky S, McMahon FG., The American Journal of Medicine, 1993
Garlic has been taken for centuries for its immune system properties, and clinical research has attempted to confirm its traditional usage. 146 volunteers participated in a 2001 study on garlic for cold and flu prevention. The placebo group recorded 65 incidences of cold symptoms during the 12-week trial, compared to only 24 incidences of cold symptoms among the treatment group. Placebo patients also reported 366 sick days, compared to only 111 days in the treatment group. This study suggests garlic prevents colds and helps people recover quicker from symptoms.
Another double-blind, placebo-controlled study examined 120 healthy subjects for 90 days. The groups did not show a difference in incidence of cold; however, the garlic extract appeared to reduce severity of symptoms, number of days sick, and number of work or school days missed. A 2016 study on the same number of subjects found almost identical results.
Preventing the common cold with a garlic supplement: a double-blind, placebo-controlled survey.
Josling P, Advances in therapy, 2001
Supplementation with aged garlic extract improves both NK and γδ-T cell function and reduces the severity of cold and flu symptoms: a randomized, double-blind, placebo-controlled nutrition intervention.
Nantz MP, Rowe CA, Muller CE, Creasy RA, Stanilka JM, Percival SS., Clinical Nutrition, 2012
Aged Garlic Extract Modifies Human Immunity
Percival SS. , The Journal of Nutrition, 2016