Health Benefits of Onion

While onion's health promoting abilities have long been recognized, it's only recently that their considerable curative abilities have been conclusively demonstrated and thus their elevation to Superfood status.

Onions are a major source of two phytonutrients that play a significant role in health promotion: flavonoids and the mixture of over fifty sulfur-containing compounds. The two flavonoid subgroups found in onions are the anthocyanins that impart a red/purple colour to some varieties, and the flavanols such as quercetin and its derivatives that are responsible for the yellow flesh and brown skins of many varieties of onions. The flavonols are concentrated in the skin of most onions where they contribute to the colour of the vegetable.

We now know that the health promoting compounds in onion, like those in garlic, are separated by cell walls. Slicing an onion ruptures these walls and releases the compounds which then combine to form a powerful new compound: thiopropanal sulfoxide. In addition to mitigating various diseases, this substance also gives cut onions their pungent aroma and their ability to make us cry.

To get the most health benefits from onions, let them sit for five to ten minutes after cutting and before cooking. Heat will deactivate the thiopropanal sulfoxide and you want to give it time to fully develop and concentrate before heating.

While chopping onions may make you cry, their considerable cardiovascular benefits should bring a smile beneath your tears. Like garlic, onion consumption has been shown to lower high cholesterol levels and high blood pressure. Onions, along with tea, apples and broccoli --the richest dietary sources of flavonoids- have been shown to reduce the risk of heart disease by 20% in a recent meta-analysis that reviewed the dietary patterns and health of over 100,000 individuals.

From a health promotion standpoint, the most pungent onions pack the biggest wallop. In one test of the flavonoid content of onions, shallots had six times the amount found in Vidalia onions, the onion with the lowest phenolic content. Shallots also had the most antioxidant activity. Western Yellow onions had the most flavonoids - 11 times the amount found in Western White, the type with the lowest flavonoids content. All types of onions are good additions to your diet but try to choose the stronger tasting ones when appropriate to your recipe.

Regular consumption of onions has also been associated with a reduced risk of colon cancer. It's believed that the flavonoid quercetin in onions is the protective factor as it's been shown to stop the growth of tumours in animals, and to protect colon cells from the negative effects of some cancer-promoting substances. There's also evidence that onions may lower the risk of cancer of the brain, oesophagus, lung and stomach.

By : Jill Sabato