Allium sativum L., commonly known as garlic, is a species in the onion family Alliaceae. Its close relatives include the onion, shallot, and leek. Garlic has been used throughout recorded history for both culinary and medicinal purposes. It has a characteristic pungent, ‘hot’, flavour that mellows and sweetens considerably with cooking. A ‘head’ of garlic, the most commonly used plant part, comprises numerous discrete ‘cloves’. The leaves and stems are sometimes eaten, particularly while immature and tender.
Garlic has been used as both food and medicine in many cultures for thousands of years, dating as far back as the time that the Egyptian pyramids were built. Garlic is claimed to help prevent heart disease, including atherosclerosis, high cholesterol, high blood pressure, and to improve the immune system. Garlic may also protect against cancer.
While the science is not definitive at this point, much of the research is showing promise, and many clinicians continue to report improvements in the areas of cancer protection and heart-related risk factors for patients.
Garlic has antioxidant properties. Antioxidants help destroy free radicals - particles that can damage cell membranes, interact with genetic material, and possibly contribute to the aging process as well as the development of a number of conditions including heart disease and cancer. Free radicals occur naturally in the body, but environmental toxins (including ultraviolet light, radiation, cigarette smoking, and air pollution) can also increase the number of these damaging particles. Antioxidants can neutralise free radicals and may reduce or even help prevent some of the damage they cause over time.
There are several types of garlic preparations. Most clinical studies have been performed on aged garlic extract (AGE) or enteric coated, dried garlic tablets. The conditions for which garlic is showing the most promise include:
Cardiovascular disease Studies report that garlic consumption may decrease the progression of cardiovascular disease. Cardiovascular disease is associated with several factors, including raised serum total cholesterol, raised low density lipoprotein (LDL), and an increase in LDL oxidation (free radical damage), increased platelet aggregation (clumping), hypertension, and smoking. Garlic may help decrease LDL and total cholesterol levels while raising good cholesterols (high density lipoprotein, or HDL), decrease platelet aggregation (helps the blood flow more easily), and decrease blood pressure. Recently, garlic was also found to decrease two other markers of cardiovascular disease, homocysteine and C-reactive protein.
Garlic may also decrease blood pressure. Numerous studies have reported small reductions in systolic and diastolic blood pressure associated with the use of oral garlic.
Common cold A well-designed study of nearly 150 people supports the value of garlic for preventing and treating the common cold. In this study, people received either garlic supplements or placebo for 12 weeks during “cold season” (between the months of November and February). Those who received the garlic had significantly fewer colds than those who received placebo. Plus, when faced with a cold, the symptoms lasted a much shorter time in those receiving garlic compared to those receiving placebo.