Onions and other lily plants such as garlic, shallots and chives contain sulfur and sulfide-containing substances that protect against cancer as well as cardiovascular diseases. Stomach cancer is a common type of cancer, the incidence of which is closely related to the food consumed. In onion and garlic growing regions, where the consumption of these lily plants is higher than average, the mortality rate from stomach cancer was significantly lower in each case.
Protection against stomach cancer and colorectal cancer
In a controlled, prospective cohort study, eating more than half an onion per day was shown to significantly reduce the risk of gastric cancer. A reduced risk of colon cancer is also observed with high consumption of garlic and onions. The sulfur-containing ingredients in onions and garlic are probably primarily responsible for this protective effect.
However, the question of whether the lily plants only have this effect when raw or also when cooked or fried has not yet been adequately clarified.
Onions and garlic against aggressive radicals
But onions have other beneficial properties: they have a high content of the flavonoid quercetin. Quercetin has an antioxidant effect, which means it helps the body defend itself against aggressive oxygen free radicals. Quercetin also has anticarcinogenic and antimicrobial effects. Flavonoids are heat stable, so even fried onions still contain high levels of them.
Because of their antimicrobial properties, onions were already valued by the Egyptians around 1500 BC for treating inflamed wounds. The thiosulfinates, which inhibit arachidonic acid metabolism and thus the formation of inflammation mediators, are primarily responsible for this. Various home recipes are also based on this effect, such as onions cooked with sugar for sore throats and coughs.
Alliin as a heart protector
Onions are also true heart protectors: their sulfur-containing compounds inhibit the clumping of blood platelets and thus prevent the formation of blood clots. The blood becomes “thinner” and the overall circulation improves. Ajoen and allicin have proven to be particularly effective substances in this regard. Ajoen has a similarly strong influence on platelet aggregation as aspirin.
So far, ajoene has only been detected in fresh garlic, but not in tablets, oils or other garlic extracts. Anyone who wants to take advantage of the health-promoting properties of ajoene must consume garlic fresh and accept that other people may not always like the special scent that is then emitted through the breath and skin.
Allicin is only formed when the garlic is crushed by the enzymatic cleavage of the substance alliin and is also responsible for the characteristic smell of garlic. By the way, alliin is also responsible for the tears when cutting onions. However, the alliin of onions has a slightly different structure and is converted by a different enzyme. This then produces the onion‘s tear-irritating substance: propanthial sulfoxide.
So you can enjoy the onion tart season and even do something for your health. But be careful: due to the high fat content of onion tart, it can quickly affect your body weight. A good addition is there a colorful salad – with lots of fresh onions.
