Allicin

 

For many centuries alliums have been grown for their characteristic flavors and beautiful flowers. In addition to its esthetic and culinary attributes, the root bulb (“clove”) of garlic (Allium sativum) has been cherished by many cultures as a powerful promoter of good health.

Sanskrit records contain evidence that garlic was being used “medicinally” about 5,000 years ago and about 4500 years ago Charak, the father of Ayurvedic medicine, claimed that garlic maintains the fluidity of blood and strengthens the heart. The 3500-year old Egyptian Codex Ebers touts garlic, Hippocrates and Pliny the Elder were garlicophiles, Pasteur wrote about garlic’s activity in 1858 and garlic preparations were used on the battlefield in the 20th century.

Garlic and Healthy Blood Vessels

Modern research continues to affirm the health benefits that can be obtained by including raw garlic, whole garlic powders or extracts of garlic in the diet or consuming them as dietary supplements. As pointed out by the authors of a review published recently in the Journal of Nutrition, the evidence from studies in humans shows that the consumption of garlic supports many aspects of blood vessel health.1 The blood vessels are the all-important corridors of the cardiovascular system. While the heart is the engine that pumps our blood, without healthy blood vessels, it can’t reach the tissues where it’s needed.

As an example of garlic’s blood vessel-supportive prowess, the results of a human clinical trial published recently in the Journal of Nutrition indicated that the daily consumption of a modest amount of an extract of whole garlic cloves for 6 weeks on average doubled the ability of the brachial artery to expand in response to increased need for blood flow in healthy men and women.2 Not only were the big blood vessels affected – the small capillaries in the skin also increased their ability to circulate fresh blood after 6 weeks of garlic consumption. Increased ability of an artery to respond to increased demand for blood flow to tissues without impacting blood pressure (“arterial compliance”) and increased capacity of the small blood vessels within tissues to distribute that blood reflect a healthy cardiovascular system; this investigation provides persuasive evidence that garlic consumption is a major contributor to healthy cardiovascular function.

The results of other studies in healthy humans, also published recently in the Journal of Nutrition may explain how garlic can help maintain pliable arteries and open vessel channels in tissues.3,4 In these studies investigators found that garlic has potent antioxidant properties and slows the rate of oxidation of circulating low-density lipoprotein (LDL) particles and promotes the integrity of blood vessel walls. Researchers agree that these two factors are of primary importance to maintaining excellent cardiovascular health. Keeping arteries healthy and discouraging the oxidation of lipids and fats in the blood go a long way to living a productive and heart-healthy life.

Another way garlic supports healthy blood vessels is by promoting the healthy metabolism of glucose in the blood. High blood glucose levels may adversely impact blood vessel health over time by reacting with proteins in the blood and vessels. This reaction effectively damages the protein, leading it to lose its functionality. Research published recently in the Journal of Nutrition shows how the bioactive compounds in garlic can prevent the formation of these sugar-protein complexes and keep your blood vessels healthy.5 Let the proteins play their role and let blood sugar perform its function and go where it’s meant to.

Where Does Allicin Come In?

A clove of garlic contains an extremely large amount of biologically active sulfur-containing phytonutrients. However, allicin, the most intensively studied phytonutrient associated with garlic and the source of garlic’s distinctive fragrance, is not found in the clove but instead is formed when a clove is chopped, crushed, cut or chewed (breaking up the garlic cells in the clove stimulates an enzyme to produce allicin quickly). Allicin is absorbed into the human bloodstream and either exerts its benefits directly or is converted into an effective alternative compound.

Experiments in mice published recently in Pathobiology “connect the dots” linking allicin to garlic’s vascular protective actions.6 Dietary supplementation with pure allicin resulted in the incorporation of allicin into all lipid-containing particles produced by the intestines and liver. As the lipid particles contained allicin, they contained less cholesterol and were more resistant to oxidation. This experiment was conducted in mice that were genetically programmed to produce numerous arterial plaques as a model for atherosclerosis. The daily consumption of pure allicin drastically decreased the size of the plaques that were formed. While these mice had a genetic predisposition to a chronic condition, this dramatic illustration suggests that healthy humans with no pre-existing cardiovascular disease may benefit greatly from the consumption of garlic and allicin, as this compound promotes arterial health and wellness. The dose used in this mouse study was the equivalent of daily supplementation in humans with about 500 to 600 mg of pure allicin daily.

References:
1. Rahman K, Lowe GM. Garlic and cardiovascular disease: A critical review. J Nutr 2006;136(Suppl.):736S-740S.
2. Weiss N, Ide N, Abahji T, Nill L, Keller C, Hoffmann U. Aged garlic extract improves homocysteine-induced endothelial dysfunction in macro- and microcirculation. J Nutr 2006;136(Suppl.):750S-754S.
3. Lau BH. Suppression of LDL oxidation by garlic compounds is a possible mechanism of cardiovascular health benefit. J Nutr 2006;136(Suppl.):765S-768S.
4. Ide N, Keller C, Weiss N. Aged garlic extract inhibits homocysteineinduced CD36 expression and foam cell formation in human macrophages. J Nutr 2006;136(Suppl.):755S-758S.
5. Ahmad MS, Ahmed N. Antiglycation properties of aged garlic extract: Possible role in prevention of diabetic complications. J Nutr 2006;136(Suppl.):796S-799S.
6. Gonen A, Harats D, Rabinkov A, Miron T, Mirelman D, Wilchek M, Weiner L, Ulman E, Levkovitz H, Ben-Shushan D, Shaish A. The antiatherogenic effect of allicin: Possible mode of action. Pathobiology 2005;72:325-334.

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