Onions and other members of the allium family – such as leeks,shallots, and scallions, contain dozens of compounds that provide protection from cancer, high blood pressure, heart disease, high cholesterol, and asthma. Flavonoids are the first family in onions which promote a healthy heart. I have written about these in my previous articles. Flavonoids are compounds with potent antioxidant powers to prevent the harmful action of free radicals.

One particular flavonoid called quercetin has proved to prevent heart disease in two ways.
Firstly, it helps to keep the dangerous low-density lipoprotein (LDL) type of cholesterol from oxidizing, a process that makes it stick to the lining of artery walls.
Secondly, it helps to prevent platelets in the blood from sticking together and forming harmful clots.

The second group of protective compounds in onions are those that make you cry: they are called the sulfur compounds.
According to experts, these compounds can raise your level of beneficial high-density lipoprotein (HDL) cholesterol, which help plaque from sticking to artery walls. At the same time, they can lower levels of dangerous blood fats, called triglycerides, which help to make blood thinner, while keeping your blood pressure normal.
You don’t need to eat a lot of onions to benefit from these protective compounds. All you need is just one medium onion, raw or cooked, a day.

Protection from Cancer
According to experts, onions may be a key player in cancer protection, especially cancers of the gastrointestinal tract.It’s the flavonoid called quercetin that stops the progression of tumors in the colons of animals, according to Michael J. Wargovich, PhD, professor of pathology and microbiology at the University of South Carolina School of Medicine.
This means that onions perform a double task in surpressing tumors, because the sulfur compounds also fight cancer.

In the Netherlands,researcher in a large study observed the diets of nearly 121,000 men and women.
They found that the more odoriferous bulbs these onion loving Dutch people included in their daily diets,the lower their risk of stomach cancer.

According to scientists, onions prevent cancer not only by putting the brakes on the development of tumors, but also by killing harmful bacteria that may start stomach cancer.

Onions have proved to protect against other forms of cancer as well. Researcher found, after studying a group of 471 men in China, that men who ate the largest number of onions had a much lower risk of prostate cancer.

Also, eating onions has proved to reduce the risk of cancers of the oral cavity and pharynx, esophageal cancer, colorectal cancer, breast cancer, and renal cell cancer in southern Europe.

The sulfur in onions helps protect against cancer by damaging cancer cells and slowing down their growth, according to the National Cancer Institute.

Researchers at the University of Cornell have discovered that four types of onion: shallots, western yellow, pungent yellow, and northern red, are filled with more ant-cancer compounds than other varieties.

Another advantage of the sulfur compounds in onions is that they inhibit the allergic, inflammatory response like that seen in asthma.
Although we need more research about the ability of onions to attack asthma, you can check the anti-inflammatory effect for yourself. The next time you get an insect bite or other type of minor inflammation on your skin, rub a cut onion on it.
This should help reduce the inflammation.

You only need to eat a few servings of onions a day to keep your breathing passages free and clear.Unlike some foods, where it’s just not conceivable that you could eat enough to produce a significant effect, you can with onions. If you like onions, you can consume them in pretty large quantities. And there is good evidence that you should.

A bundle of Benefits
Either you eat onions for good health or good taste, use onions plentiful. Scallions, shallots, and other allium vegetables not only contain the same sulfur compounds and flavonoids as there bigger brother, they also have a few of their own typical nutrients that can help protect against disease and boost your immunity.

Scallions, also called spring or green onions, are basicly just underdeveloped onions. But they contain more nutrients, in particular the B vitamin folate and vitamin C, than the adult ones.
Folate is essential for normal tissue growth and may protect against cancer, heart disease and birth defects.

Shallots, another member of the allium family, have their own benefits. Just one tablespoon of chopped shallots contains 600 IU of vitamin A, or 12% of the DV. This essential nutrient helps to keep your immune system strong and also guards against vision problems associated with aging, like cataracts and night blindness.

In order to get most nutrients from the onions, eat a variety of onions, like red and yellow onions and shallots, which contain more flavonoids than the white onions.

To keep your breath fresh, eat a spring of fresh parsley. This will help to neutralize the sulfur compounds before they turn bad breath.

A kitchen note.
A delicious way to enjoy onions is to put them on the grill. Put chunks of sweet onions on a skewer along with other vegetables, such as eggplant and squash, and grill them till they’re lightly browned and tender. Brush the onions and veggies with heart-healthy olive oil before putting them on the grill.