Garlic ranks highest in popularity and efficacy among health promoting herbs. A staple remedy in traditional medicine for thousands of years, garlic’s ability to prevent a wide range of age-related diseases has been confirmed by modern science. Studies show that garlic, rich in organosulfur compounds and high in antioxidant activity, lowers cholesterol, helps protect against cardiovascular disease and inflammation, and has potential to lower the risk of dementia, including Alzheimer’s disease.
Despite its advantages in supporting good health many shun garlic because of its pungent odor that lingers on the breath and skin and its ability to cause gastrointestinal problems in some people. But, as science has shown, garlic does not have to be eaten raw or fresh to be effective, nor is its potent odor needed for its healthy effects. Aged garlic extract (Kyolic), produced by the Wakunaga Company from fresh organic garlic, by slow extraction and aging, is odorless, high in antioxidants and often works better than fresh garlic.
Among the available commercial forms of garlic, including the fresh bulb, aged garlic extract (AGE) has been the preferred preparation in experimental and clinical studies and the most consistent in showing health benefits. The supplement contains mostly stable water soluble organosulfur compounds that provide most of AGE’s benefits; these include S-allyl cysteine and S-allyl mercaptocysteine, which is unique to AGE. S-allyl cysteine that is used to standardize AGE, is highly bioavailable, with a 98 percent absorption into the circulation.
Cardiovascular Disease and Dementia
Mid-life risk factors for cardiovascular disease (CVD), which include high cholesterol, hypertension, high homocysteine, and inflammation, increase the risk of dementia in later years. High cholesterol and hypertension show a consistent association with increased risk of Alzheimer’s disease (AD) and vascular dementia. Homocysteine, whose levels increase with age, is an independent risk factor for CVD, stroke, and AD. A source of free radical activity and oxidative stress, homocysteine has many damaging effects, including the impairment of DNA repair in the hippocampus where memory resides.
Elevated cholesterol promotes the formation of atherosclerotic plaques that increase the risk of heart attack and stroke. Stroke, associated with deprivation of blood supply to the brain (ischemia), results in neuronal death that can lead to dementia. High cholesterol is also associated with increased levels of a small protein in the brain, called ß-amyloid peptide (Abeta) that is a hallmark of AD. Abeta generates toxic free radicals that induce neuronal death by a programmed cell suicide, called apoptosis. Hypertension, an important risk factor in heart disease, can contribute to cognitive decline, seen in AD, by damaging small blood vessels that lead to brain cell death.
Garlic Prevents Cardiovascular Disease
Garlic has been shown to reduce cardiovascular risk factors in both clinical and preclinical settings. Studies with AGE show garlic’s ability to inhibit aggregation and stickiness of platelets, reducing their role in atherosclerotic plaque formation; AGE lowers LDL cholesterol (the bad cholesterol) homocysteine and blood pressure, while elevating protective HDL cholesterol. AGE was also found to inhibit the production of prostaglandins, hormone-like substances involved in inflammation, a known risk factor for CVD.
An important function of garlic, shown in studies with AGE, has been to protect endothelial cells that line blood vessels, from oxidative damage, increase blood flow and improve microcirculation. These protective effects are most significant as people age as well as in diabetes — conditions where the stiffening of arteries by calcification, damage microvasculature, increasing the risk of CVD as well as dementia. Experimental and clinical studies with AGE show garlic increases the production of an endothelial-relaxing factor, cellular nitric oxide (NO) that improves endothelial function and reduces blood pressure.
Garlic Reduces the Risk of Heart Attacks
Calcium deposits in coronary arteries are an early feature of atherosclerotic plaques that can dislodge and cause heart attacks and stroke. The efficacy of AGE in dramatically blocking calcification and cutting the risk of heart attack was shown in breakthrough double-blind placebo-controlled randomized clinical trials at the University of California in Los Angeles. Dr. Mathew J. Budoff and colleagues showed AGE given for one year at 1200 mg a day to heart-diseased patients, prevented the progression of coronary artery calcification, as compared to placebo. Plaque-formation progressed at a rate of 22 percent a year, in the placebo group, while AGE consumption reduced progression to 7.5 percent. The garlic extract also elevated HDL and decreased the risk factors LDL, triglycerides and homocysteine, compared to placebo. As all patients were on statin and aspirin therapy, any improvement was due to the sole effects of AGE.
In another year long placebo-controlled double-blind, randomized trial, the same group found that patients at intermediate risk for CVD, who received daily either a placebo capsule or a capsule containing AGE, vitamin B12, folic acid, vitamin B6 and L-arginine. Showed reduced calcification progression, lowered LDL, homocysteine and oxidative markers, and increased HDL, compared to placebo. This study further confirmed the efficacy of AGE in producing a “favorable improvement in oxidative biomarkers, vascular function, and reduced progression of atherosclerosis.”
Garlic and Dementia
Various types of dementia, including Alzheimer’s disease (AD), its most common form, are devastating age-related forms of mental deterioration. Vascular factors, such as homocysteine, and cholesterol, as well as aging and a history of stroke increase the risk of vascular dementia and Alzheimer’s disease. The efficacy of garlic and AGE in reducing the risk of CVD indicate their potential role in lowering the risk of vascular dementia and AD.
Garlic, Homocysteine and Dementia
Both epidemiological and case control studies have shown an association between high homocysteine and dementia. People with vascular dementia and AD had elevated homocysteine compared to healthy people, while healthy adults with intact cognition, showed an increase in the incidence of dementia, including AD, following a long-term exposure to high plasma homocysteine.
Elevated homocysteine produces endothelial dysfunction and impairment of blood pressure regulation, due to increased vascular oxidant stress that decreases the available nitric oxide (NO), an endothelial-relaxing factor. Endothelial dysfunction is associated with a poor prognosis in existing coronary artery disease and predicts coronary disease progression and heart disease. Studies by Dr. N. Ide and colleagues showed that AGE enhance the production of cellular antioxidants such as glutathione, minimized oxidant stress, and stimulate the production of NO in endothelial cells, thus protecting against homocysteine-related vascular damage and enhancing circulation. A placebo-controlled, blinded, clinical trial found AGE reduced endothelial dysfunction caused by high homocysteine.
Garlic and Neuroprotection
Garlic is a potent neuroprotective agent, potentially defending against Alzheimer’s disease, a disease in which oxidative damage and inflammation result in neuronal death by apoptosis.
AGE and S-allyl cysteine, help prevent cognitive decline in a number of ways; by protecting neuronal cells against apoptosis induced by beta amyloid peptides, by suppressing free radical generation, enhancing internal antioxidant and by blocking the action of the apoptosis inducing enzyme caspase 3. Feeding AGE to experimental models with accelerated Abeta formation prevented deterioration of hippocampal-based memory tasks, suggesting that aged garlic extract may have a potential ability to prevent AD progression.
Preclinical studies in models that are genetically prone to early senescence show that AGE has protective effects on brain function. Treatment with AGE or S-allyl cysteine, prevented frontal lobe degeneration, improved learning and memory retention and extended life span. Isolated neurons from the hippocampus, grown in the presence of aged garlic extract or S-allyl cysteine, had a unique ability to grow and branch out, suggesting that this phenomenon may be associated with the efficacy of the garlic extract to increase learning and cognition.
In a recent study using a mouse model for AD, investigators found AGE and its organosulfur components inhibited inflammation and prevent Abeta deleterious effects. The study showed AGE was the most effective supplement, followed by S-allyl cysteine and the lipid-soluble di-allyl-disulfide (DAD). The authors suggested that dietary intervention with aged garlic extract, which has a wide range of benefits and no adverse side effects, might provide greater therapeutic benefit in treating AD than a single-ingredient synthetic pharmaceutical drug, which may have serious side effects.
An accumulating body of evidence shows that risk factors for cardiovascular disease, are also risk factors for dementia; these include high LDL cholesterol and triglycerides, calcification of the arteries and atherosclerosis, hypertension, high homocysteine, inflammation, and oxidative stress. When occurring in the brain following ischemia or increased levels of Abeta peptides, neurons die by apoptosis with resulting dementia, including Alzheimer’s disease.
Garlic and its components can reduce these risk factors. Among the many studies on the protective effects of garlic, the most consistent results, reported in hundreds of scientific and medical publications, are from preclinical and clinical research with Kyolic aged garlic extract (AGE), made by Wakunaga. Odorless and highly standardized, AGE contains mostly bioavailable water-soluble organosulfur compounds as well as lipid soluble organosulfur components and other phytochemicals and nutrients, Aged garlic extract has a higher antioxidant activity than fresh garlic with none of its adverse effects. Although more clinical studies are warranted, available evidence supports the potential benefits of garlic in the form of Kyolic AGE in helping protect against cancer.