Flavonoids are plant-based polyphenolic compounds that have a wide range of health benefits, including antiviral (to fight flu) and anti-influenza (to fight the common cold) activity. They not only help fight the pathogens but inhibit their replication, regulate the immune system and improves gut microbiome.
Flavonoids are commonly found in many fruits and vegetables; however, some foods have them in abundance. They are also the largest group of secondary metabolites found in foods, followed by phenolic acids and polyphenolic amides. Some of the essential flavonoids found in foods include flavones (apigenin, flavone, luteolin), isoflavones, flavonols (quercetin, kaempferol), flavanone glycoside (hesperidin), flavanols (catechins) and anthocyanins.
Some studies say that flavonoids work with gut microbes to protect us from flu and other viral infections and one needs the right microbes in the intestine to use those flavonoids to control the immune response.
1. Apple and its skin
Apple is rich in flavonoids such as kaempferol and quercetin while apple skin is rich in luteolin. All the three aforementioned flavonoids are known to have antireplicative and anti-infective effects against viruses and influenza viruses.
2. Red grape
The most common flavonoids found in red grape are anthocyanins, flavonols, catechin and proanthocyanidins. Anthocyanins are found only in red grapes compared to other grapes types.
Blackberries have strong antioxidative activity due to the presence of a large number of flavonoids such as flavone (luteolin), flavonols (myricetin and quercetin), flavanols (gallocatechin, epigallocatechin and catechin) and anthocyanidins (cyanidin).
They are rich in flavonoids such as quercetin and anthocyanins. The antioxidant activities of raspberries due to the presence of flavonoids. They may help prevent viral infections and treat cold and flu.
Flavonoids in orange may help improve symptoms of cold and flu such as nausea and cough. It contains flavonoids such as quercetin, apigenin and kaempferol. Orange juice is also rich in flavonoids and may help treat viral infections
6. Red cabbage
Fresh and pickled red cabbages have the highest of flavonoids such as catechins, kaempferol, quercetin and apigenin. Cyanidin, a type of anthocyanins is the predominant flavonoid in red cabbages that helps treat many drug-resistant influenza viruses.
Carrots are packed with vital flavonoids such as quercetin, myricetin, naringenin, kaempferol, rutin, apigenin and luteolin. These bioactive compounds possess antioxidative, anti-inflammatory and anti-viral properties.
Rutabaga is a root vegetable also known by Swedish turnip or just ‘turnip'. It may help treat cold and flu symptoms such as the sore throat. When mixed with honey, rutabaga works as an expectorant and helps remove phlegm and cough.
Celery is rich in flavonoids like apigenin. It may help treat inflammation caused by influenza and rhinovirus and lower the symptoms of cold and flu such as sore throat, body ache and cough.
Fresh onions contain flavonoids such as flavonols, anthocyanins, dihydroflavonols, kaempferol, quercetin and apigenin. Experts suggest eating raw onions or lightly-fried onions to get the maximum of the benefits.
11. Red wine
The main flavonoids found in red wine include flavanols such as catechin; flavonols such as myricetin and quercetin; and anthocyanins such as malvidin-3-glucoside. Moderate consumption of red wine helps boost the immune system to fight against several strains of influenza viruses and other virus types.
12. Black tea
A study says that black tea contains around 200 mg of flavonoids per 100 mL compared to 71-126 mg of green tea per 100 mL. Catechins are the main flavonoids found in black tea along with isoflavones and anthocyanins.
Isoflavones flavonoids are mainly found in soy and soy food products. Genistein, a type of isoflavones in soy is known to reduce the infectivity of a number of virus strains, including influenza virus and rhinovirus.
Legumes include beans, lentils and peas. All are rich in varieties of flavonoids such as isoflavones, including genistein and daidzein. They help boost the immune system and prevent recurrent events of cold and flu.
15. Dark chocolate
A study talks about anti-influenza virus effects of cocoa which are used in the making of dark chocolates. This effect is mainly due to the presence of flavonoids such as catechin, procyanidins and epicatechin which are predominantly found in the food.