NPF Science Update: Garlic and Immunity
Posted Thursday, February 9, 2012

Garlic and Immunity
By Lise Alschuler, ND, FABNO

Human immunity, far from being a static and fixed entity, is a dynamic and adaptive system. Our immune system is made up of diverse cells with elaborate communication networks. Numerous vitamins, minerals, herbs, and other nutrients impact this elaborate system. One of the unsung heroes of immune support is garlic.

Garlic is one of the most extensively eaten foods in the world. Although eaten for its culinary attributes, garlic has potent immune actions.  Garlic also has anti-microbial activities against bacteria, viruses, fungal organisms and parasites. Aged garlic extract increases the activity of several major immune cells including B-cells’ production of antibodies, macrophage activity, and the cell-killing actions of T-cells and natural killer cells. Studies have demonstrated that aged garlic extract protects lymphocytes (immune-supportive cells found in the blood and lymphatic system) from radiation destruction. Clinical studies have demonstrated that garlic shields beneficial bacteria in our intestines while destroying disease-causing fungal, viral, parasitic and bacterial organisms.

Regular consumption of garlic provides some measure of protection against infection. Garlic can also be used to support the body’s immune response to active infections, particularly sinusitis, bladder infections, digestive tract infections and the common cold. There are some additional benefits to garlic consumption and garlic supplementation. In addition to its immune-supportive actions, numerous studies have shown that aged garlic extract lowers multiple risk factors for heart disease. It helps to support healthy cholesterol levels, although it does not appear to have a significant cholesterol lowering effect in people with elevated cholesterol, reduces the risk of plaque formation (atherosclerosis), and exerts anti-inflammatory and antioxidant effects, lowering certain markers of inflammation such as homocysteine. Garlic also improves blood flow dynamics and can help to maintain blood pressure within normal ranges. Additionally, aged garlic extract supports normal liver detoxification of heavy metals.

Raw garlic contains beneficial sulfur compounds. However, consuming raw garlic, while delicious, can be challenging due to the odorous nature of garlic. One way to obtain the health benefits of garlic without having to endure the odor is to take an odorless or aged garlic extract. Garlic can be aged without the use of heat for two years. The slow aging process transforms the volatile and odoriferous constituents in garlic into stabilized, sulfur-containing amino acids with antimicrobial benefits and with benefits to cardiovascular health. Aged garlic extract is by far the most widely studied garlic product available, although there are a variety of other potent garlic extracts including those standardized to allicin and alliin, considered two of the major antimicrobial constitutents of garlic.

Generally, standardized extract garlic and aged garlic capsules are taken in dosages ranging from 600mg to 1500mg daily. The safety of aged garlic extracts is well established, with more than 500 clinical studies on more than 1,000 subjects reporting no side effects with long term consumption. Although garlic extract is safe to take with most medications, in order to avoid drug-herb interactions, people taking daily medications should first consult with a licensed naturopathic or integrative healthcare provider.


Story Source: Lise Alschuler, ND, FABNO, is the Vice President of Quality and Education at Emerson Ecologics. Dr. Alschuler is board certified in naturopathic oncology and has been practicing naturopathic medicine since 1994. Dr. Alschuler is past-President of the American Association of Naturopathic Physicians and is a current member of the NPF Board of Directors.

Selected References: Gardner CD, Lawson LD, Block E, Chatterjee LM, Kiazand A, Balise RR, Kraemer HC. Effect of raw garlic vs commercial garlic supplements on plasma lipid concentrations in adults with moderate hypercholesterolemia: a randomized clinical trial. Arch Intern Med. 2007 Feb 26;167(4):346-53.

Ishikawa H, Saeki T, Otani T, Suzuki T, Shimozuma K, Nishino H, Fukuda S, Morimoto K. Aged garlic extract prevents a decline of NK cell number and activity in patients with advanced cancer. Source J Nutr. 2006 Mar;136(3 Suppl):816S-820S.

Josling P. Preventing the common cold with a garlic supplement: a double-blind, placebo-controlled survey. Adv Ther. 2001 Jul-Aug;18(4):189-93.

Lamm DL, Riggs DR. The potential application of Allium sativum (garlic) for the treatment of bladder cancer. Urol Clin North Am. 2000 Feb;27(1):157-62, xi.

Ried K, Frank OR, Stocks NP. Aged garlic extract lowers blood pressure in patients with treated but uncontrolled hypertension: a randomised controlled trial. Maturitas. 2010 Oct;67(2):144-50. Epub 2010 Jul 1.


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