Garlic is a common ingredient in cooking, and it is also considered a familiar dietary supplement, used for high cholesterol, heart disease, and high blood pressure. Some people also believe garlic can prevent certain types of cancer, including stomach and colon cancers.
Garlic can be taken in tablets or capsules or can be eaten raw or cooked. Raw garlic cloves are often used to infuse oils or to make liquid extracts. While garlic appears to be safe for most adults, there are side effects, including increased body odor and bad breath, heartburn, allergic reactions, and upset stomach. These side effects are found to occur most commonly with raw garlic.
Garlic has also been found to thin the blood or reduce the clotting ability in blood in some people, similar to aspirin's effect on blood properties. This can create problems for individuals both before and during surgery. Garlic has also been found to interfere with the effectiveness of an HIV drug, saquinavir. The National Center for Complementary Alternative Medicine (NCCAM) has funded research to study whether garlic interacts with certain drugs and how it may thin the blood.
Garlic has been prized as a culinary ingredient and a health remedy for thousands of years. Ancient Egyptians buried it with pharaohs and were said to have fed it to slaves building the pyramids to keep them healthy. It continues to play a major role in the food of that region, where it is added to many foods along with olive oil and garlic's cousin, the onion. The ancient Greeks and Romans were believed to have fed garlic to their athletes, soldiers, and slaves.
For years, China outproduced the rest of the world in garlic exports. However, garlic production was sharply curtailed in 2007 following several other publicized problems with Chinese food exports, including pet food. At that time, the Chinese government demanded that higher safety standards be instituted. Before the crackdown, China had been exporting at least $10 million worth of garlic to the United States every month. This crackdown created a black market for garlic, and shipments of smuggled garlic have been confiscated in Norway and Sweden.
What is it about garlic that leads people to turn to smuggling to get enough of it? Garlic is a member of the onion family, along with shallots, leeks, and chives. All contain the same bioactive sulfur compounds as well as flavonoids, B vitamins, and measurable amounts of manganese and selenium. Its sulfur-containing nutrients offer superior health benefits by increasing the level of hydrogen sulfide, which leads to relaxed arteries and improved blood flow. Sulfur is found in every cell of the human body and helps maintain healthy joints and boosts the immune system. Its anti-inflammatory properties have convinced scientists to study it as a possible anticancer agent.
However, an NCCAM-funded study on the safety and effectiveness of three garlic preparations (fresh garlic, dried powdered garlic tablets, and aged garlic extract tablets) for lowering blood cholesterol levels found no benefit (Gardner et al., 2007). And according to NCCAM, a clinical trial on the long-term use of garlic supplements to prevent stomach cancer found no effect (NCCAM, 2008).
Researchers agree they have a lot to learn about garlic and why, like many other herbs and plants, it is so beneficial. To achieve the greatest health benefits from garlic, the cloves should be crushed or chopped, which activates the enzyme allinase, which in turn stimulates allicin, which breaks down to a variety of healthful compounds. The dicing or crushing allows the allicin to begin working, even though the garlic is cooked.
See also Antioxidants; Blood Pressure; National Center for Complementary and Alternative Medicine (NCCAM).
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