Garlic (Allium sativum) is one of the most studied and widespread plant products. It has been used since ancient times as a traditional medicine for a variety of health-related disorders and as an ingredient in foods. Its properties result from a combination of biologically active substances which are responsible for any therapeutic effects it has
Garlic health benefits: include anti-cancer, anti-hypertensive, hypolipidemic, anti-atherosclerotic, antimicrobial, immunomodulatory and hypoglycemic-lowering blood glucose properties. Also, anticoagulant, hepatoprotective, neuroprotective and antioxidant activity.
The properties of garlic result from a combination of biologically active substances - phytochemicals. Garlic mainly contains sulfides, both water-soluble and fat-soluble, and a variety of phenolic compounds. It contains a large amount of bioactive products such as volatile, water-soluble and fat-soluble organosulfide compounds, e.g. DAS, DADS, DATS as well as essential oils, dietary fiber, sugars 32% including inulin, flavonoids and pectin. Organic sulfides include alliin and A, B scordine. In addition, several new cyclic sulfoxides called ¨scordinins¨ have recently been isolated from acetone-garlic extracts. Thiosulfates (e.g. allicin), azoenes (e.g. E-azoene, Z-azoene), vinyldithienes (e.g. vinyl-1,3-dithiene, vinyl-1,2-dithiene) and sulfides (e.g. .DADS, DATS) are degradation products of existing cysteine, sulfoxide, and alliin.
Caution: Garlic has antiplatelet-anticoagulant properties that increase the risk of bleeding. These properties are obviously enhanced when used in combination with anticoagulant and antiplatelet substances such as aspirin, heparin, warfarin, etc. Many surgeons may recommend stopping high doses of garlic for up to 7 to 10 days before surgery.
Aged Garlic Extract:
Aged garlic extract (AGE), made from aged garlic is a herbal remedy that has been shown to boost the immune system and thus help against cancer and heart disorders.
Aged garlic extract is made by soaking raw garlic cloves in a 15–20% ethanol solution (water + ethanol) for up to 20 months at room temperature. The extract is then filtered and concentrated under reduced pressure at low temperature. During this aging, the odors and harsh irritant compounds in garlic are converted to odorless, non-irritating, safe sulfur compounds. This process causes loss of allicin but increases the activity of other compounds.
Allicin:
Allicin [S-(2-propenyl)-2-propene-1-sulfinothioate], the most biologically active sulfur-containing compound in garlic, is responsible for its odor and flavor. It is a fat-soluble yellow oily sulfur compound, which can be easily destroyed by cooking as well as at room temperature. Apart from the beneficial effects, it can cause intolerance, allergic reactions and gastrointestinal disturbances
Suggested:
Suggested average daily doses include 2 to 5 g of fresh raw garlic; 0.4 to 1.2 g of dried garlic powder; 2 to 5 mg of garlic oil; 300 to 1,000 mg of garlic extract (as solid material); and 2,400 mg/day of aged garlic extract (liquid).
The generally recommended doses of daily garlic intake for the elderly are 4 g raw garlic or 7.2 g AGE or one dried garlic powder tablet two to three times a day
Although the US Food and Drug Administration (FDA) considers garlic safe for humans, it can cause gastric irritation, especially if ingested in high doses by sensitive individuals. Side effects that may be observed are insomnia, vomiting, heartburn, dizziness, diarrhea, tachycardia, nausea, bloating, flushing, headache, mild orthostatic hypotension, sweating, offensive body odor, and flatulence. Ingesting raw garlic in high doses on an empty stomach can cause changes in intestinal flora, flatulence and gastrointestinal disturbances.
More common are garlic supplements. According to a meta-analysis of randomized controlled trials, garlic supplements have contributed to improved blood glucose control at 1-2 weeks as well as at 24 weeks in type II diabetes mellitus and have a positive role in cholesterol regulation within 12 weeks (Wang J et al., 2017).
Pro advice:
Sometimes we hear speculation about food. E.g. garlic helps with hypertension. This is indeed true, but we must ask ourselves. How much garlic, for how long, in what form? Does it lose its properties if I cook it?
References:
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Ankri S, Mirelman D. Antimicrobial properties of allicin from garlic. Microbes Infect. 1999 Feb;1(2):125-9. doi: 10.1016/s1286-4579(99)80003-3. PMID: 10594976.
Rauf A, Abu-Izneid T, Thiruvengadam M, Imran M, Olatunde A, Shariati MA, Bawazeer S, Naz S, Shirooie S, Sanches-Silva A, Farooq U, Kazhybayeva G. Garlic (Allium sativum L.): Its Chemistry, Nutritional Composition, Toxicity, and Anticancer Properties. Curr Top Med Chem. 2022;22(11):957-972. doi: 10.2174/1568026621666211105094939. PMID: 34749610.
Elosta A, Slevin M, Rahman K, Ahmed N. Aged garlic has more potent antiglycation and antioxidant properties compared to fresh garlic extract in vitro. Sci Rep. 2017 Jan 4;7:39613. doi: 10.1038/srep39613. PMID: 28051097; PMCID: PMC5209668.
Wang J, Zhang X, Lan H, Wang W. Effect of garlic supplement in the management of type 2 diabetes mellitus (T2DM): a meta-analysis of randomized controlled trials. Food Nutr Res. 2017 Sep 27;61(1):1377571. doi: 10.1080/16546628.2017.1377571. PMID: 29056888; PMCID: PMC5642189.