Red onion is a type of onion, Allium cepa of the Liliaceae family, with a red-purple skin and a white flesh tinged with red.
Red onion, properties
The red onion is rich in antioxidant substances such as thiosulfinates, which give it the classic pungent odor, quercetin, kaempferol but also anthocyanins that are powerful substances that give to the bulb a purple color. These beneficial substances make red onion a food able to fight free radicals and infections, to stimulate the immune system, to protect the liver and to act with anti-inflammatory and antitumor properties (Elberry et al, Mediators Inflamm, 2014 - Fossen et al, Pytochemistry, 2003). Not only that, thanks to the quercetin, the red onion can help in the case of prostatitis by soothing the inflammation (Elberry et al, Mediators Inflamm, 2014). In addition to this, because of their high antioxidant action, red onions are also useful to control blood sugar levels, to improve insulin sensitivity and to counteract overweight since, as has been observed, they increase energy expenditure of the body (Henagan et al, Genes Nutr, 2015). Finally, the intake of raw red onions is associated with a decrease in LDL cholesterol, or bad cholesterol (Ebrahimi-Mamaghani et al, J Obstet Gynaecol Res, 2014).
Red onions and storage, how properties may change
Storing onions too long leads to changes in their nutritional profile. In fact, it has been shown that storing for 6 months at the conditions that can be found in a house, for what concerns temperature and humidity, has caused a decrease by up to 73% in the total anthocyanin content and by up to 36% for what concerns the total antioxidant power. The storage at low temperatures, as a cellar may be, preserves better the quantity of anthocyanins (Gennaro et al, J Agric Food Chem, 2002).
Red onion and cooking methods
In general it is better to serve the red onion raw, for example in a salad, since this will preserve its properties as much as possible. Scientific studies have observed that frying maintains the amount of antioxidants of red onion. Not only that, the fried onion is also able to stimulate the liver and therefore should not be avoided, however, in any case and like any food, also the fried onion should always be eaten with moderation, avoiding excesses and inserting it in a varied diet (Gorinstein et al , J Agric Food Chem, 2008).
Red onion and drugs
Attention also to drug interactions, cooked red onion increases indeed the activity of warfarin, an anticoagulant drug (Bushra et al, Oman Med J, 2011). In addition, the onion in general could interact with antidiabetic drugs (Mateen et al, Indian J Pharmacol., 2011).
