It’s not surprising that the only vegetable powerful enough to make you cry is also powerful enough to make you well. Onions are rich in quercetin, a powerful type of antioxidant called a flavonoid that may reduce the risk of cancer. Onions are a member of the same botanical family as garlic, and like garlic they contain allicin, which transforms into organosulfurs—which can lower cholesterol, thin your blood, keep arteries flexible, and kill cancer cells. Red and purple onions deliver anthocyanins, the same antioxidants that make berries a nutritional superstar. Altogether, these nutrients (and many other compounds) add up to a uniquely healing spice.

Onions Are Anti-Cancer

Quercetin and cancer don’t mix. Research shows that quercetin can: slow the growth of cancer cells; stop cancer cells from migrating to other parts of the body (metastasis); and force cancer cells to die in a variety of ways, such as cutting off their blood supply or activating cancer-killing genes. The organosulfur compounds in onions have many of the same effects. And all that cellular activity has a real impact on a daily activity—staying alive! Study after study links a higher intake of onions with lower rates of deadly cancers.

In a study in the American Journal of Clinical Nutrition, Italian researchers analyzed diet and health data from thousands of people. They found a consistent pattern of protection—the more onions in the diet, the less cancer. Specifically, they found that, compared to those who ate the fewest onions, those who ate the most onions had lower risks for developing:

 Colon cancer: 56 percent lower risk

• Breast cancer: 25 percent lower risk

• Prostate cancer: 71 percent lower risk

• Ovarian cancer: 73 percent lower risk

• Esophageal cancer: 82 percent lower risk

• Oral cancer: 84 percent lower risk

• Kidney cancer: 38 percent lower risk

“Our findings confirm a protective role of onions on the risk of several common cancers,” the researchers concluded.

Endometrial cancer. Italian researchers found that women who ate two or more servings of onions a week had a 60 percent lower risk of developing endometrial cancer.

Pancreatic cancer. Researchers at the University of California, San Francisco analyzed health and diet data from more than 2,000 people and found that those who ate the most onions (and garlic) had a 54 percent lower risk of pancreatic cancer, compared to those who ate the least.

Stomach cancer. Researchers from the University of Southern California analyzed diet and health data from more than 1,900 people from China and found the more onions people ate, the lower their risk of stomach cancer.

The Outstanding Onion

There are many other ways that onions protect your health.

Heart attacks. Italian researchers analyzed diet and health data from more than 1,400 people. Those who ate one or more serving of onions per week were 22 percent less likely to have a heart attack than people who hardly ever ate onions. “A diet rich in onions may have a favorable effect on the risk of acute myocardial infarction [heart attack],” concluded the researchers in the European Journal of Nutrition.

High cholesterol. Japanese women have much lower rates of heart disease. Why? To find out, researchers analyzed the diets of 115 Japanese women. They found that the more flavonoids they ate (principally from onions), the lower their level of total cholesterol and LDL cholesterol, two risk factors for heart disease. The fact that Japanese women have such a high consumption of flavonoids—mainly quercetin, and mainly from onions—“may contribute to their low incidence of coronary heart disease, compared with women in other countries,” the researchers concluded in the Journal of Nutrition.

Heart disease. In another study, Dutch researchers measured the flavonoid intake—mainly from tea, onions, and apples—in 805 men. Those who had the highest flavonoid intake had a 58 percent lower risk of heart disease, compared to those with the lowest. The results were in the journal Lancet.

High blood pressure. Researchers from the University of Utah treated 41 people with high blood pressure, dividing them into two groups. One group took 730 mg of quercetin a day and one group didn’t. After one month, those taking the supplement had a drop in blood pressure of 7 points systolic (the upper reading) and 5 points diastolic (the lower reading).

Osteoporosis. Researchers from the Medical University of South Carolina analyzed data from the nationwide National Health and Nutrition Examination Survey, involving more than 35 million women. They found that perimenopausal and postmenopausal women who ate one or more onions a day had a bone density 5 percent greater than women who ate onions once a month or less. “Onion consumption seems to have a beneficial effect on bone density,” concluded the researcher. And those denser bones meant fewer fractures: “Older women who consume onions most frequently may decrease their risk of hip fracture by more than 20 percent versus those who never consume onions,” wrote the researchers in the journal Menopause.

Surgical scars. Researchers found that people who used onion extract gel on surgical scars had scars that were softer, less red, with a smoother texture, and an overall better appearance. The findings were in the Journal of Cosmetic Dermatology.

Allergies. In an article on allergies, researchers at the Boston University School of Medicine point out that quercetin blocks the release of histamine—the immune factor that causes allergic symptoms such as watery eyes and runny nose. Quercetin is a “safe, natural therapy” for allergies that can be used either as a “primary therapy or in conjunction with conventional methods,” wrote the researchers.

Benign prostatic hypertrophy. This condition—commonly called “swollen” or “enlarged” prostate—affects tens of millions of middle-aged men, causing urinary difficulties. Italian researchers analyzed diet and health data from more than 1,800 men and found that those who ate the most onions had a 59 percent lower risk of developing the problem.

Diabetes. There have been so many studies on onions lowering blood sugar in experimental animals with type 2 diabetes that one team of scientists from Korea conducted a “meta-analysis”—they combined the data from all the studies to see if there was one big result. And there was: onions lower blood sugar. The findings were in the Journal of Medicinal Food.

Getting to Know Onion

Onions are cultivated everywhere, including the backyard vegetable garden.

They come in hundreds of varieties of colors, shapes, textures, and strengths. There are yellow, red, purple, green, white, and brown onions. They range in size from that of a fingernail (cocktail onion) to a baseball (storage onion). There are Italian onions, Bermuda onions, pearl onions, leeks, scallions, and shallots.

Onions come in hundreds of varieties of colors, shapes, textures, and strengths.

Shallots: The Healthiest Onion of Them All

Don’t underestimate the healing power of the little shallot. When researchers at Cornell University measured the nutritional content of 13 varieties of onions sold in the United States, they found that, ounce for ounce, shallots have more antioxidant activity than the strongest yellow onions and contain six times more antioxidant phenols than the mildest Vidalia onions.

Shallots can be used both cooked and raw. The flavor of shallots is like a strong onion with a hint of garlic. They are strong, so when using them raw make sure to dice them finely.

Store shallots in a cool place where they have room to breathe. Do not buy shallots that are bruised and do not use shallots that are sprouted. Not only will they taste bitter, but they’ll spoil the other shallots.

Roasted shallots are a nice accompaniment to vegetables, especially when serving beef, pork, duck, or chicken. To make roasted shallots, simmer them in their skins, covered in milk, for about 10 minutes. Drain the milk and roast in a small covered casserole until they are tender, about 20 minutes. Season with Mediterranean Vinaigrette.

Onions flavor more dishes than any other spice. They are the foundation of virtually every base for soups, sauces, meat, fish, and vegetable dishes. They are also a prominent spice in virtually every cuisine, where they are eaten raw, fried, batter-fried, baked, creamed, roasted, broiled, boiled, and pickled.

In China, cooks are partial to sweet and mild scallions. They chop or slice them raw, and put them in soups, stir-fries, and pickled dishes. Onions are put on top of cooked noodles called laksas, stirred into rices, mixed into condiments, and crumbled into sauces.

In Indonesia, onions are sliced and mixed raw into hot condiments called sambals and served alongside marinated meat kabobs called satays. They are pounded and added to spice blends and condiments, and cooked in sauces. They are fried in oil for their crunch and caramelized taste, and added as toppings to stir-fried noodles and fried rice.

In India, pungent, brown-skinned globe onions are used in virtually every dish, and are savored not only for their flavor, but for the texture and consistency they lend to curries. They are eaten raw in a popular onion relish called kache piaz and a tomato-based relish called kachoomar. Indians enjoy eating brown onions just so (they are drier than the brown onions found in the United States) with lemon, especially when they feel a cold coming on.

In Turkey, whole shallots traditionally accompany lamb on the kabob. In Tunisia, cooks favor couscous with a fermented onion paste call hrous.

The French are partial to delicate and strong-flavored shallots, which are used as a base in many sauces, such as béarnaise. The French are known the world over for their French onion soup and the Provencal specialty pissaldière, which is a thick layer of caramelized onions on a thick, crusty dough, resembling pizza. Onion tart is a specialty in the Alsace-Lorraine region, where the food influence is both French and German.

Germans are fonder of onions than the French, and sauté them in fat as a topping on many meat and potato dishes. They are also served on their own, creamed or fried, as a vegetable.

The Spanish enjoy a caramelized onion and tomato sauce called sofregit. The British eat stuffed onions. Russians often grate onions into marinades and other dishes rather than chop them to make their flavor stronger.

In the United States, onions are a staple topS ping, either raw or fried, on hot dogs, hamburgers, ballpark franks, and fast foods. The US has made the batter-fried onion ring world famous.

Onion may help prevent and/or treat:


Benign prostatic

hypertrophy (BPH)


Cholesterol problems (high total cholesterol, high “bad” LDL cholesterol)

Diabetes, type 2

Heart attack

Heart disease

High blood pressure (hypertension)