Garlic has been used for thousands of years to both flavor foods and treat illnesses, dating back to ancient China, Egypt, and Rome. In the 19th century, Louis Pasteur described garlic's antibacterial properties, and during World War I Albert Schweitzer, MD, recommended it for dysentery. A study published in 1944 documented garlic's broad-spectrum antibacterial properties. In addition to its immune-enhancing effects, garlic can also help maintain a healthy cardiovascular system. And that's just the tip of the iceberg when it comes to this multitalented plant's beneficial properties.
Technically an herb, garlic (Allium sativum) belongs to the lily (Liliaceae) family, along with onions, aloe, shallots, chives, and saffron. These plants share many chemical similarities, but garlic stands out as being particularly potent.
The Sulfur Solution
All forms of garlic appear to have health-enhancing properties, including both raw and cooked garlic, as well as different types of supplements. In fact, garlic may have the greatest biological activity of any single food that we know.
When a garlic clove is cut, cooked, or crushed, oxidation leads to the formation of more than 200 different compounds, 70 of which contain sulfur. It's likely that sulfur accounts for most of garlic's activity, because this mineral is a constituent of insulin, cartilage, the anticoagulant heparin, and some B vitamins.
Many of garlic's sulfur containing compounds, such as S-allyl-L-cysteine, are chemically similar to N-acetylcysteine, a potent antioxidant and immune booster. The high sulfur content of garlic also makes it an excellent precursor to glutathione, the most potent antioxidant made by the body.
Garlic has been noted to have numerous positive effects on human health. Here are a few highlights:
Infection Fighter.A recent study conducted at the University of Florida, Gainesville, asked 120 men and women to take either 2.5 grams of aged garlic extract or placebos daily for three months. Halfway though the study, the subjects' blood levels of two cold- and flu-fighting compounds-natural killer cells and gamma-delta T cells (a type of immune cell found in the gut)-had increased in number. By the end of the study, people taking the garlic extracts reported a 61 percent reduction in cold or flu duration, a 21 percent decrease in symptoms, and 58 percent fewer missed days at work.
Blood Vessel Tone. The body's red blood cells convert allicin, one of the compounds found in garlic, into hydrogen sulfide. Although the compound is known for its pungent odor, in the body it relaxes blood vessel walls, improving their flexibility and potentially protecting against high blood pressure. A study of 50 people with treated but uncontrolled blood pressure found that aged garlic extract capsules led to an average 10 mm Hg decrease in blood pressure over 12 weeks.
Cholesterol and Triglycerides. In an analysis of 26 published studies, researchers reported that garlic lowered levels of cholesterol and triglycerides, which are risk factors for heart attack. According to the researchers, "Garlic powder and aged garlic extract were more effective in reducing cholesterol levels, while garlic oil was more effective in lowering triglyceride levels."
Coronary Calcification. Garlic supplements can slow the progression of coronary calcification, also known as hardening of the arteries. In a study at the University of California Medical Center, Los Angeles, doctors gave either aged garlic extract or placebos to 19 patients. Over the course of a year, people taking garlic developed two-thirds less coronary calcification compared with those taking placebos. Other studies have found that garlic supplements slow coronary calcification when used with other nutrients, such as the B-complex vitamins or coenzyme Q10.
The lion's share of research on garlic supplements has focused on "aged garlic extract," so you may want to seek out products containing this ingredient. Most studies use 700-2,000 mg per day. If you want to take garlic for a particular health concern, start with around 1,000 mg daily.
There do not appear to be any common side effects caused by taking garlic supplements, and their use isn't contraindicated by any drugs, including warfarin (Coumadin), a common blood thinner. With so many potential benefits and so little risk, it's easy to say that you just can't go wrong with garlic.
If your use of garlic has been limited to cooking, it's time to expand your palate and discover this ancient herb's truly amazing healing powers.
Garlic, Greens, and Rice Soup
Collard greens combined with garlic and sun-dried tomatoes make this delectable soup as healthy as it is delicious. Reprinted with permission from For the Love of Garlic by Victoria Renoux (Square One Publishers, 2005).
2 Tbs. olive oil
1 large Spanish onion, chopped (about 2 cups)
12 cloves garlic, minced
4 bay leaves
2 cups chopped collard greens, firmly packed
5 cups water
1½ cups cooked brown basmati rice
20 sun-dried tomato halves, cut into pieces
¼ cup tamari soy sauce
3 sprigs fresh rosemary, or 1 tsp. dried
1 tsp. dried basil
- Heat oil in large, heavy kettle, such as cast-iron Dutch oven. Add onion, garlic, and bay leaves, and sauté slowly over low heat, at least 30 minutes, stirring occasionally.
- Increase heat to high, and add collards. Sauté until wilted, and add remaining ingredients. Bring soup to a boil, reduce heat, and simmer 30 minutes, or until collards and rice are tender, stirring occasionally. Serve with homemade cornbread.
PER SERVING: 154 cal; 5g pro; 5g total fat (1g sat fat); 24g carb; 0mg chol; 773mg sod; 3g fiber; 5g sugars
Potato and Cauliflower Soup with Roasted Garlic
This soup has a mild but rich flavor, making it an easy first course for a dinner party. Reprinted with permission from For the Love of Garlic by Victoria Renoux (Square One Publishers, 2005).
4 cups peeled and cubed baking potatoes
3½-4 cups cauliflower flowerets (1 small head)
1 cup chopped sweet onion
1 tsp. sea salt
2 cups milk
2 Tbs. mashed, roasted garlic
1 Tbs. chopped, fresh tarragon, or
½ tsp. dried
1/8 tsp. white pepper
- Place potatoes, cauliflower, onion, salt, and 2½ cups water in soup pot or Dutch oven. Cover, and bring to a boil over high heat. Reduce heat to medium, and simmer, 20 minutes, or until vegetables are tender. (Add more water if necessary to prevent vegetables from sticking or burning.)
- Add remaining ingredients. Using handheld blender, regular blender, or food processor, process mixture until smooth and creamy. (If using regular blender or food processor, you may have to process in two or more batches.) If soup is too thick, add more milk. Adjust seasonings to taste, and serve immediately with fresh, whole-grain bread.
PER SERVING: 183 cal; 6g pro; 3g total fat (2g sat fat); 32g carb; 8mg chol; 325mg sod; 4g fiber; 7g sugars