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.

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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More Health Benefits of Allicin

This is part of our ongoing The Best Kept Secrets to Healthy Aging spotlight. Each day, we will be posting some of the great information that’s packed into our book, The Best Kept Secrets to Healthy Aging.

Today’s topic:
More on Allicin

Support the Body’s Stress Response and Increase Energy

Research into the energy-enhancing and stress-supportive effects of garlic has yielded a number of mechanisms that begin to explain the tonifying ability of this ancient food. Scientists believe that the ability of garlic to enhance peripheral circulation, its antioxidant effects that protect the brain and peripheral tissues, its ability to support and promote a healthy immune defense, and simply its nutritional value lend it to be well-suited for these benefits. Garlic is a good source of numerous essential vitamins and minerals. The attributes of its various constituents play a vital role in the tonic abilities of this herb. However, researchers feel the fact that the constituents of whole garlic exert synergistic effects in the presence of one another are a more likely explanation of it benefits. Several animal experiments and some human experiments have shown stress-relieving and endurance-enhancing abilities of this herb.10 Whatever the reasons may be, what was true in ancient times remains so now – garlic is a mental and physical rejuvenator.

And If that’s Not Enough…

The benefits of allicin are not limited to the cardiovascular system. Daily dietary supplementation with allicin can increase the activity of the human “immunosurveillance system” – that is, the vigilance of the immune system to seek out and repair damaged cells.11,12 This innate “Homeland Security Force” serves to preserve and protect the “normality” of the complex internal cellular network that is your body. Keeping your immunosurveillance set to “high alert” and on constant patrol supports and defends the healthy function of every organ and tissue.

Next Best Kept Secrets to Healthy Aging topic:
CoQ10 – The Vital Link Between Energy and Your Heart

10. Morihara N, Nishihama T, Ushijima M, Ide N, Takeda H, Hayama M. Garlic as an anti-fatigue agent.Mol Nutr Food Res 2007;51(11):1329- 34.
11. Patya M, Zahalka MA, Vanichkin A, Rabinkov A, Miron T, Mirelman D, Wilchek M, Lander HM, Novogrodsky A. Allicin stimulates lymphocytes and elicits an antitumor effect: A possible role of p21ras. Int Immunol 2004;16:275-281.
12. Zhang ZM, Zhong N, Gao HQ, Zhang SZ, Wei Y, Xin H, Mei X, Hou HS, Lin XY, Shi Q. Inducing apoptosis and upregulation of Bax and Fas ligand expression by allicin in hepatocellular carcinoma in Balb/c nude mice. Chin Med J 2006;119:422-425.

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Allicin and Cardiovascular Health

This is part of our ongoing The Best Kept Secrets to Healthy Aging spotlight. Each day, we will be posting some of the great information that’s packed into our book, The Best Kept Secrets to Healthy Aging.

Today’s topic:
Allicin: Enhancing Important Aspects of Cardiovascular Well-being

Humans convert some allicin into diallyl disulfide and diallyl trisulfide. These secondary phytonutrients were shown recently to impact the sequence of cholesterol synthesis in the human liver.7 The effect of these garlic compounds in modulating healthy cholesterol metabolism and supporting antioxidant effects on blood lipids, thereby protecting their integrity and function, all add up to extremely powerful support for long-lasting healthy cardiovascular function. By impacting areas as diverse as cholesterol metabolism, arterial health, and blood sugar metabolism, garlic and its important phytonutrient constituents have become an integral part of a comprehensive plan designed to support cardiovascular wellness.

Support Blood Pressure Levels that are Normal

It turns out that garlic and various garlic extracts may have additional direct cardiovascular benefits in humans. A comprehensive review of the literature was carried out and published in 2008. The authors of this meta-analysis reviewed papers in the literature dealing with the blood-pressure regulating properties of garlic in humans and found that the intake of garlic in foods and supplements contributes to the maintenance of blood pressure levels that are considered healthy in humans.8 The researchers concluded that the blood-pressure regulating compound in garlic is allicin and that garlic’s hydrogen sulfide production is also a contributory factor. A second group of researchers also conducted an independent review of the studies associating the intake of garlic supplements with blood pressure effects.9 In their review, they also concluded that garlic supplements had an ability to support the maintenance of blood pressure levels that are already in the normal range.

The consensus is that garlic intake supports healthy blood pressure, just another of the many reasons to consider adding garlic to your daily nutritional regimen.

Next Best Kept Secrets to Healthy Aging topic:
More on Allicin

7. Singh DK, Porter TD. Inhibition of sterol 4a-methyl oxidase is the principal mechanism by which garlic decreases cholesterol synthesis. J Nutr 2006;136(Suppl.):759S-764S.
8. Ried K, Frank OR, Stocks NP, Fakler P, Sullivan T. Effect of garlic on blood pressure: a systematic review and meta-analysis. BMC Cardiovasc Disord 2008;8:13.
9. Reinhart KM, Coleman CI, Teevan C, Vachhani P, White CM. Effects of garlic on blood pressure in patients with and without systolic hypertension: a meta-analysis. Ann Pharmacother 2008;42(12):1766- 71.

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