How to strengthen our natural defenses and prepare us for the colder season that inevitably brings colds and flu? Certainly with diet and supplements it is possible to protect the respiratory tract, but let's try to understand better on the basis of scientific studies.
Elderberries
Elderberry, scientific name Sambucus nigra, is considered a valuable ally against colds and flu. In fact, elderberries are a precious source of antioxidant substances, such as quercetin and anthocyanins. Thanks to these substances, elderberries are appreciated for their interesting anti-inflammatory, antiviral and antimicrobial properties with a protective action especially at the level of the upper respiratory tract (Kravitz et al, BMC Complement Altern Med., 2011). It has been observed that the intake of elderberry extracts is able to reduce the symptoms and duration of colds (Tiralongo et al, Nutrients, 2016). Elderberry, both in the form of extracts and juice or syrup, reduces the duration of influenza A and B by an average of 4 days, also decreasing the use of drugs to treat symptoms (Zakay Rones et al, Journal of International Medical Research, 2004).
Vitamin C and D
Vitamin D reduces the levels of chronic inflammation, which, in the long run, weakens the immune system. Not only that, vitamin D stimulates the natural defenses, proving to be protective against influenza and respiratory tract infections (Kearns et al, Am J Med Sci, 2015). Most of the vitamin D present in our body has been synthesized in the skin following exposure to UVB rays. As for other sources, only a fraction of vitamin D is obtained from the diet since few foods contain vitamin D such as fatty fish, some mushrooms such as shiitakes and cheeses. Vitamin C is found in abundance in citrus fruits, kiwis, berries, tomatoes and green leafy vegetables (Abdullah et al, StatPearls Publishing, 2021). Also this vitamin supports the body's defenses. For example, the daily intake of 200 mg of vitamin C has been shown to reduce the severity and duration of colds. Not only that, in patients hospitalized for pneumonia and with low levels of vitamin C, the integration of this vitamin has improved respiratory symptoms in the most severe cases and generally reduced the hospitalization period (Carr et al, Nutrients, 2017).
Rosehip
From rosehip berries a tea with antioxidant, anti-inflammatory and immunostimulating action is obtained thanks to its content in vitamin C and phenolic compounds. In particular, rosehip tea is used to prevent and combat colds and flu. Scientific studies have observed that the greatest benefits can be obtained with an infusion of rose berries in water for 6-8 minutes at 84-86° C (Ilyasoglu et al, J Food Sci Technol, 2017).
Medicinal mushrooms
Some mushrooms, such as shiitake, maitake, cordyceps or reishi, have been shown to carry out a protective action on the immune system, strengthening our natural defenses thanks to the presence of particular polysaccharides called beta glucans (Mallard et al, PLoS One, 2019). For example, a cordyceps-based treatment has been shown to counteract bacterial infection in the lungs, reducing inflammation and increasing the immune response (Li et al, Braz J Med Biol Res., 2017). In general, medicinal mushrooms stimulate the production of T-type immune cells, responsible for recognizing and inhibiting viruses, and NK cells, which are our first line of defense against viruses and tumors (Lull et al, Mediators Inflamm, 2005). Medicinal mushrooms can be taken in the form of supplements. Shiitakes can also be bought fresh or dried in specialty stores.
