Onions and garlic add zest to many dishes, but they also have health benefits.

What would a kitchen be without the distinctively pungent smell and taste of onions and garlic filling out the flavors of almost every type of cuisine imaginable?

Though long associated with eye irritation, garlic and onions are common ingredients in many recipes. Good thing, too, as they have many health benefits.

It doesn't matter if they are chopped or sliced or added as a spicy garnish, according to researchers at the University of Wisconsin.

Onions have a natural blood-thinning effect that can play an important role in cardiovascular health. The researchers even claim on the university's Website that an onion thins the blood more efficiently than aspirin.

The catch is the blood-thinning effect is more pronounced in stronger-tasting onions that often cause heartburn. Consequently, consumers may shy away from eating raw onions even though they are healthier when uncooked. The cooking process destroys the blood-thinning effect.

Onions are also recommended for hypertension. UW scientists gave two to three tablespoons of onion essential oil per day to people with moderately high blood pressure. They found that 67 percent of these people had lower blood pressure, systolic levels dropped an average of 25 points and diastolic readings dropped 15 points after consuming the onion essential oil.

Onions also stimulate insulin production in the body, thus are effective in lowering blood sugar. The higher the onion intake, the lower the level of glucose found during clinical tests.

Why? Onions are a very good source of chromium, which helps cells respond appropriately to insulin. One cup of raw onion contains more than 20 percent of the daily recommended intake of chromium.

Onions and garlic are close relatives in the big onion family.

A large percent of the world's garlic is grown in China. No wonder it's such a common ingredient in Chinese cuisine. Just like the onion, it has medicinal benefits.

Both help reduce the risk of osteoporosis - the crippling bone disease that affects one in three women, usually after menopause.

In experiments conducted on rats by researchers at the University of Bern in Switzerland, 1 gram of onion a day can help prevent the process where calcium seeps from the bones making them brittle, the scientists wrote on the university's Website.

People who include onions and garlic as dietary staples have a lower risk of getting several common cancers, according to a research report on the Cornell University's Website.

Based on a study conducted by Liu Ruihai, an associate professor of food science at Cornell University, onions and garlic are higher in anti-cancer chemicals than other varieties tested. Furthermore, they are found particularly effective against liver and colon cancer cells. "Although milder onions are becoming more popular, the bitter and more pungent onions appear to be healthier," Liu wrote in the report.

So forget those teary eyes and bad breath. Add onions and garlic to your diet.

(Shanghai Daily February 10, 2009)