The active ingredients that are good for the body: vitamin C and D, zinc, selenium, iron

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Louise Hay

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Vitamins and Minerals for the immune system

Knowing which micronutrients are good for our body and, consequently, choosing which foods to favor is the first step to having efficient defenses.

Among the elements most relevant to the physiology of the immune system are vitamins C and D, selenium, iron and zinc. Often in a synergistic way, these contribute to maintaining the physiological activities of the immune cells, whose key role is to control and defend our organism.

For this reason, it is essential to assimilate, every day, adequate quantities with the diet: know these "active principles"allows you to give preference to foods that are rich in it and, in case of deficiencies, to resort to food supplements a support of the immune system.

They must never be missing

Vitamins and minerals are defined as "micronutrients" because they are present in minimal quantities in food and micro-doses are enough to exert their beneficial functions on the body.

Vitamin C:

La Vitamin C it boasts many properties and performs numerous functions, making it indispensable for the overall well-being of our organism.

The function for which it is best known is that antioxidant: Vitamin C in fact counteracts the action of free radicals, harmful molecules that can weaken the body, protecting it from oxidative stress.

Vitamin C also participates in the synthesis of collagen in the skin and cartilage, facilitates the absorption of iron, counteracts cell aging and is energizing in moments of physical and mental fatigue. Vitamin C is also valuable for maintaining the normal function of blood vessels, accelerates wound healing, keeps the skin healthy and improves the body's reaction in times of high stress.

Immune system: what is Vitamin C for?

Vitamin C acts to support various functions of the immune system:

  • Modulates the immune response: Vitamin C is recognized as having an immunomodulating action as it activates and supports an adequate response to pathogens, but, at the same time, it avoids excessive damage to the organism related to the immune reaction. Numerous studies have shown that vitamin C is able to reduce the risk and improve the course of respiratory and systemic infections, acting both in terms of prevention and speed of healing.
  • Promotes microbial killing: Vitamin C stimulates the migration of neutrophils to the site of infection and improves the phagocytosis and toxicity capabilities of immune cells against pathogens.
  • Reduces the risk of colds: ensuring an adequate intake of vitamin C through diet or supplementation, especially in the elderly or in those exposed to risk factors, is necessary for proper immune function and resistance to infections. Studies on the effects of vitamin C have shown that colds can last fewer days and symptoms may be less severe in people who regularly consume adequate levels of vitamin C. Even in athletes exposed to short periods of strenuous physical activity - a condition that causes immunodeficiency and greater risk of getting sick - vitamin C is useful in preventing contagion.

Where it is

The main sources of vitamin C they are fresh fruits and vegetables. Especially citrus fruits (such as oranges, grapefruits), strawberries, currants and kiwis are rich in it. As for vegetables, vitamin C is present in significant quantities in peppers, tomatoes, broccoli, cabbage, Brussels sprouts, lettuce, spinach, rocket, radicchio and potatoes.

How much you need

According to the indications contained in the Reference Intake Levels of Nutrition and Energy for the population your country (LARN) of the Society your country of Human Nutrition (SINU), therecommended intake of vitamin C it stands at 80 mg for women and 90 mg for men. As for the immunomodulatory activity and prevention against infections, the recommended dose of vitamin C is at least 500 mg per day.

Vitamin D

La vitamin D is known above all for being an ally of bone health: in fact, vitamin D plays a fundamental role in bone formation and mineralization. Furthermore, vitamin D is involved in the regulation of calcium homeostasis (in particular, it allows its absorption and fixation in the skeleton) and participates in the balance of other minerals such as phosphorus, sodium and magnesium. The functions of vitamin D, however, are not limited to maintaining healthy bones.

Immune system: what vitamin D is for

Vitamin D contributes to normal functioning, as it is capable of influencing both innate and adaptive immunity.

In particular, the active form of vitamin D:

  • Increase the antimicrobial capabilities of immune cells.
  • It plays a vital role in the check for infections, especially acute respiratory ones, and in reducing the excessive inflammatory response by white blood cells.

Numerous studies have shown that low levels of vitamin D are directly associated with an increased likelihood of running a cold or other upper respiratory tract infections. Vitamin D supplementation is important for immune health throughout the year, but especially during the peak of the cold season when vitamin D levels are at their lowest.

In 2017, a meta-analysis published in the British Medical Journal collected and evaluated the evidence of clinical studies carried out to date on the use of the vitamin, demonstrating how its supplementation is able to reduce the risk of acute respiratory infections. This effect has been particularly evident in those who are very lacking in it.

The results of the publication have raised a lot of debate in the scientific community and the question of whether it is really useful to recommend supplementation with vitamin D in healthy people in order to strengthen their immune systems and prevent respiratory infections remains. On the other hand, the opinion is shared that in subjects with vitamin D deficiency this indication is sustainable. In this case, the aforementioned study showed how effective daily vitamin D supplementation is, rather than a weekly or monthly intake. Regarding the dosage, there is no certainty, and it would seem to depend on the degree of deficiency or on the person's health conditions. The daily requirement of vitamin D, in fact, varies according to age.

Where it is

Almost all of vitamin D (about 90% of the requirement) is produced in the skin, starting from a derivative of cholesterol, by the action of ultraviolet light from the sun. For this reason, we often hear the advice to stay outdoors as much as possible.

Vitamin D is also found in alimony, such as cod liver oil, egg yolk, cheese, butter, some fatty fish (eel, mackerel, sardine, tuna and salmon), liver, green vegetables and mushrooms.

In the winter period, nutrition becomes the main source of vitamin D and, when deficient, it is possible to consider the opportunity to supplement it to ensure an adequate intake, always under medical advice and supervision.

How much you need

As for bone health, in general, the daily requirement of vitamin D. is equal to 400 international units (IU). The doses can vary and go up to 1000 IU per day in the presence of risk factors or more marked deficiency.

Based on the studies carried out, to support the immune system and protect against flu and other acute respiratory infections, it is reasonable to take a vitamin D supplement of 1000 IU per day.

Sali Minerals

Together with that of vitamins, the group of nutrients that cannot be missing in the diet to support the immune system is that of mineral salts. In fact, these are elements that directly participate in the activation and maintenance of defenses and, if the organism is deficient, they can increase the vulnerability towards infections and various other diseases.

The organism needs it in minimal quantities, but that "little" must be there because the mineral salts are essential for maintaining the well-being of the organism: the daily nutritional requirement, as well as for other micronutrients, can be satisfied within the framework of a healthy and balanced nutrition. If the diet is not sufficient to guarantee the right amount every day, it is possible to resort to food supplements, with medical advice.


Il selenium it is an essential mineral that belongs to the group of microelements; plays an important protective action on cell membranes. In particular, this mineral helps to counteract it oxidative stress which causes aging: selenium is one of the main elements of protection against free radical damage, especially if it is associated with vitamin E.

Selenium supports normal defense function by stimulating the production of antibodies, the activity of T and natural killer lymphocytes and the functions of innate immune cells.

Selenium is also involved in the metabolism of thyroid hormones and protects the cardiovascular system.

The selenium content in foods is variable because it depends on its presence in the soil from which the foods come. Good food sources of this mineral are: Brazilian nuts, offal, stockfish, shellfish, tuna, sardines and rice.


Lo zinc it is an indispensable mineral for the well-being of the organism, as it is part of the molecular structure of many enzymes. Zinc has antioxidant properties and plays a key role in macronutrient metabolism, neurological functioning and reproduction.

Zinc is as important as immunostimulatory since it has a central role in the maturation and differentiation of immune cells, promoting the development of lymphocytes and the production of antibodies.

Especially in the change of seasons or when the body is subjected to excessive stress, zinc helps to relieve the sense of fatigue, increasing energy. Furthermore, this element helps to keep the mucous membranes and skin intact, that is, the first barriers to the penetration of infectious agents into our body.

Zinc is present in foods such as meat, fish, eggs, milk and derivatives, wheat bran, legumes and nuts.


Il iron participates in the activity of numerous enzymes: contributes to the normal formation of red blood cells and hemoglobin, thus helping to carry oxygen around the body. This mineral also serves for the production of collagen (a substance that makes up many tissues, including skin) and neurotransmitters. Furthermore, iron contributes to strengthening the immune defenses and, being involved in energy metabolism, increases resistance to fatigue.

In foods, iron is found in two forms: the emic (more available) is contained in foods of animal origin (beef, offal, egg yolk), while the non-emic (absorbed in lower quantities) is characteristic of vegetables, such as legumes, spinach, dried fruit and apricots.

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