Quercetin is a substance belonging to the flavonoid family. Quercetin occurs naturally in some fruits, vegetables and grains or can be taken as a supplement. The fame of quercetin has grown a lot in recent times as this substance has been indicated as a possible ally against the new coronavirus given its antiviral action. Science immediately became interested in quercetin, bringing out its beneficial properties that, as we will see, are not limited to its action to support our immune system. So let's try to learn more about what quercetin can do for our health.
Quercetin and the immune system, viruses and inflammation
Quercetin helps counteract chronic inflammation, even when this is caused by an unbalanced high-fat diet (Li et al, Nutrients, 2016). A constant level of inflammation over the long term weakens the immune system. So, in this way, quercetin helps strengthen our defenses. Not only that, quercetin also modulates the immune system, helping to avoid excessive responses, which, as seen in the case of the new coronavirus, can be very harmful by causing a cytokine storm with an increased risk of blood clots and lung damage (Saeedi -Boroujeni et al, J Inflamm, 2021). Finally, quercetin showed antiviral properties. In fact, studies carried out both in vivo and in vitro have made it possible to observe that quercetin counteracts the proliferation of various respiratory viruses, including influenza viruses, rhinoviruses, adenoviruses and, according to very recent research, also the new coronavirus (Di Pierro et al, Int J Gen Med, 2021).
Quercetin and type 2 diabetes
Studies in laboratories had already had the opportunity to underline that quercetin has an action similar to that of metformin, a hypoglycemic drug used in the treatment of type 2 diabetes, the diabetes typical of adulthood (Dhanya et al, Biomed Pharmacother, 2021). These properties have been confirmed in vivo and the explanation for what is reported is that quercetin is able to stimulate the use of glucose by the muscles. But quercetin has also been shown to be able to protect against the damage of diabetes. In fact, pancreatic cells have a low level of antioxidant enzymes and this makes them more at risk of apoptosis, that is, death, caused by oxidative stress induced by hyperglycemia. Well, quercetin, thanks to its antioxidant action, has been shown to counteract oxidative stress and protect the pancreas, also stimulating its functionality (Dhanya et al, Biomed Pharmacother, 2021). Not only that, quercetin protects the kidneys, retina and heart from the damage of excess circulating sugars (Salehi et al, ACS Omega, 2020). A constant intake of quercetin, even in low quantities such as 20 mg per day, is able to reduce the incidence of type 2 diabetes (Dhanya et al, Biomed Pharmacother, 2021).
Quercetin and obesity
Quercetin is widely present in fruits, vegetables and cereals and therefore its benefits and its ability to fight obesity are truly noteworthy (Nabavi et al, Food Chemistry, 2015). In fact, quercetin, by acting on some proteins in our body connected with the regulation of metabolism, is able to increase the energy needs of the muscles, thus counteracting the accumulation of fat and body weight (Benett et al, J Cell Signal, 2020). Quercetin has also been shown to reduce accumulations of visceral fat, the most dangerous type of fat as it is capable of increasing inflammation levels (Li et al, Nutrients, 2016).
Quercetin with anti-inflammatory and antitumor action
Quercetin is a powerful antioxidant, therefore it fights free radicals and aging processes and is, precisely for this reason, also neuroprotective. Not only that, studies have shown its anticancer action against different types of cancer. Quercetin is believed to be capable of inducing apoptosis, that is, the programmed death, of diseased cells (Salehi et al, ACS Omega, 2020).
Quercetin, where it is found and side effects
As mentioned in the opening paragraph, quercetin is found naturally in some foods, such as berries, grapefruit, onion, capers, black tea, buckwheat and apples. Alternatively, quercetin can be taken as a supplement. The problem is that often the amount at which quercetin is found in supplements is very high, sometimes exceeding 1000 mg per day, much higher than what is found in food. The problem is that at present there are no studies on the safety of taking high doses of quercetin, more than 1000 mg, for long periods of time, over 12 months. In addition, even for short periods, supplements containing quercetin have been shown to interact with some drugs (Andres et al, Mol Nutr Food Res, 2018). Therefore, given the scarcity of studies in this regard, before starting any quercetin-based treatment it is certainly advisable to ask your doctor for advice who will be able to assess your personal situation. What has been said does not apply to nutrition. In fact, a varied diet that also includes foods containing quercetin is certainly a good choice to counteract the aging processes and overweight and to strengthen your immune system.
