Today we talk about the properties of onion, an edible bulb that we find all year round in supermarkets and greengrocers. The onion enriches every preparation, giving flavor and health. There is probably no better way to describe it than to call it, as a dear friend of ours did during one of our long discussions on nutrition and well-being, a mobile pharmacy. Let's try to understand why.
Onion is rich in antioxidants, among which quercetin, kaempferol and rutin stand out. Anthocyanins are found in the red-skinned onion. Not only that, the onion is a source of fiber, provides vitamins, such as vitamin C, minerals, such as calcium, magnesium, potassium and phosphorus, phytosterols and sulfur compounds, which give antibiotic, anti-inflammatory, antioxidant, anti-tumor, anti-diabetic, anti-obesity and cardioprotective properties (Chung et al, Food Sci Nutr, 2023).
Anti-inflammatory and antioxidant onion
Onion contains antioxidants and sulfur compounds, more stable than those of garlic. These substances make the onion a precious ally in the fight against cellular degeneration, free radical damage and chronic inflammation (Garcia Garcia et al, Nutrients, 2023). Onion is also a food to include in the daily diet to support the immune system and combat respiratory tract diseases (Garcia Garcia et al, Nutrients, 2023). Not only that, eating onion often helps, thanks to its anti-aging effect, to reduce the risk of cataracts and cardiovascular diseases (Dorrigiv et al, Iran J Pharm Res, 2021).
Onion against obesity
Several studies have demonstrated the anti-obesity action of onion. Onion juice, in fact, inhibits the action of the pancreatic enzyme lipase, thus contributing to a reduction in fat absorption. Onion peel extracts, on the other hand, inhibit fat accumulation. Not only that, onion also reduces chronic inflammation, which accompanies overweight and obesity, and triglyceride levels. These properties can be traced back to the quercetin contained in the onion. This antioxidant accumulates above all in the outermost layers and is reduced as we move towards the center of the bulb (Chung et al, Food Sci Nutr, 2023).
Onion for the well-being of the microbiota
Onion carries out a precious prebiotic action, nourishing and promoting good intestinal bacteria (Cordeiro et al, Braz J Biol, 2023). This action can be traced back to the presence of pectin and soluble fibers that balance the microbiota and stimulate the production of short-chain fatty acids, such as butyrate, with a valuable anti-inflammatory action (Cordeiro et al, Braz J Biol, 2023).
Onion, blood sugar and cholesterol
The quercetin in the onion, being an antioxidant, counteracts the oxidation of bad LDL cholesterol, thus helping to prevent and combat diseases such as atherosclerosis. Not only that, the regular intake of onions and derived products, such as onion powder and extracts, helps to reduce triglycerides and total cholesterol and increases good HDL cholesterol (Cordeiro et al, Braz J Biol, 2023). Raw onion is anti-diabetic, helping to reduce blood sugar even in cases of diagnosed diabetes (Taj Eldin et al, Environ Health Insights, 2010).
Onion and liver
Onion and derived products, such as powder and extracts, combat fatty liver, improve levels of steatosis and reduce liver inflammation and ALT and AST values, which increase in case of liver disease (Cordeiro et al, Braz J Biol, 2023). Not only that, onion also helps protect the liver from toxin damage (Dorrigiv et al, Iran J Pharm Res, 2021).
Onion for bone wellbeing
Regular intake of onion also helps protect bones, counteracting the loss of bone density and reducing the risk of osteoporosis (Law et al, Food Funct, 2016). According to studies, post-menopausal women, and therefore at higher risk of osteoporosis, who regularly consume onions have a 20% lower risk of incurring hip fractures (Matheson et al, Menopause, 2009).
Onion, raw or cooked?
Raw onion preserves all its properties and its antioxidant action (Cattivilli et al, Food Funct, 2023). So onion in salad is excellent! But cooking the onion cannot be ruled out. In fact, the antioxidant action is preserved even after cooking in a pan or in the oven, while boiling reduces the antioxidant content by about 30%, especially quercetin, which passes into the water (Ioku et al, J Nutr Sci Vitaminol, 2001). Then, when the onion is cooked together with the meat in a pan, the onion reduces the formation of heterocyclic amines, which are harmful and carcinogenic compounds (Sidhu et al, J Food Sci Technol, 2019). The onion also has a blood thinning action that is even increased following cooking (Cavagnaro et al, J Agric Food Chem, 2012).
Onion, as we have seen, is beneficial and healthy. However, be careful when consuming onion and ask your doctor for advice if you are taking any medications to avoid interactions. Be especially careful if you are taking blood thinners, aspirin, or medications to control your blood sugar (RxList Database).