The rules to follow for nutrition and the immune system

The prevention of seasonal ailments also passes from the table. Here’s how to protect yourself with taste.

“We are what we eat”, asserted the German philosopher Ludwig Feuerbach more than a century ago and, even without knowing the biochemical basis of this statement, he had fully hit the mark on all fronts.

All the cells, tissues and organs of our body are made up of the same elements that we introduce every day with the diet, with the small addition of some microelements produced at the level of the intestine, skin and mucous membranes by the bacteria that make up the endogenous bacterial flora of the different parts of the organism (whose composition and vitality depends, however, more or less directly, by our nutritional standard).

Of course, fats, proteins, complex carbohydrates taken through food are first broken down, reworked and transformed during the processes of digestion, intestinal absorption, use for energy or biosynthesis purposes or storage in reserve stores, but the basic molecules (amino acids, glucose, glycerol, fatty acids, vitamins, mineral salts, etc.) remain exactly the same as we have ingested.

If we took into account this simple truth, widely overlooked, and if we knew all its implications on health, well-being and psychophysical efficiency, our food choices would probably be much more careful and thoughtful.

The activity of the immune system is also profoundly influenced by the way we eat, both in terms of macronutrients that provide energy and substrates to build new defensive cells (lymphocytes and macrophages) and antibodies, and micronutrients that intervene as cofactors in the activity of many key enzymes of cellular replication and metabolism.

Eating too much or too little, in an unbalanced way or favoring ready/preserved foods rich in calories, but poor in useful substances, can prevent our defensive system from being fully efficient and react in the best way to attacks by viruses and bacteria, exposing us to a greater risk of getting sick at any time of the year and, above all, in the autumn and winter months, when many pathogens are invigorated by the cold and particularly widespread.

Even the prevention of seasonal ailments, such as colds, coughs and flu, just like that of many cardiovascular, degenerative and cancer diseases, therefore also passes from the table and filling the supermarket cart with the right foods can avoid having to enter the pharmacy or doctor’s office too often. Let’s see how.

Nutrition and the immune system

Medical experience and countless studies conducted over decades have shown that many diseases are linked to specific nutritional deficits and can be prevented and treated simply by replenishing, in good time, the deficient micronutrient. Just to mention the most well-known examples, it applies to scurvy in the case of vitamin C, to rickets in the case of vitamin D, to blindness in the case of vitamin A.

More recently, it has been understood that many vitamins and some essential microelements are able to significantly influence, in a more or less direct way, also the activity of the immune system and that their insufficient intake compared to the needs can make the body more susceptible and defenseless against infections by various pathogens.

The vitamins for which evidence of a useful action on the level of immune defenses have been collected are above all C, A, E, D, B6, B9 (folic acid, whose integration is strongly recommended during pregnancy) and B12; Among the microelements, zinc, selenium, iron and copper were found to be advantageous.

More precisely, vitamins A, C and E and zinc support the barrier function of the skin.

Antioxidant principles such as vitamins C and E, selenium, copper and zinc counteract the harmful action of free radicals and other oxidizing compounds constantly produced by energy metabolism and more consistently during infections and inflammations. In addition, they modulate the reactivity of several key cells of the immune system and influence the production of pro-inflammatory substances such as cytokines and prostaglandins.

Vitamins A, B12, C, D, E and folic acid and the minerals iron, zinc, copper and selenium work synergistically to support the activity of immune system cells. In addition, studies show that all of these micronutrients, with the exception of vitamin C and iron, play a role in the production of antibodies.

Strengthening the immune system through nutrition

To be sure to get an adequate supply of all the compounds necessary for the immune system every day, it is important to choose, varying often, and take the right foods in the right quantities (ie neither too much nor too little), also taking into account some important aspects of preparation and storage aimed at preserving the nutritional value of the different foods as much as possible.

In this regard, it should be remembered that water-soluble vitamins, such as vitamin C and all those of group B (for example B6, folate and B12) and carotenoids (precursors of plant origin of vitamin A), are very labile and delicate. Immersion in water, heat during cooking, exposure to light and air, as well as the simple passage of time, degrade them quickly, substantially and irreversibly, greatly depleting the foods that contain them.

To be able to meet the organic needs of these compounds, therefore, it is necessary to consume fresh foods (those of vegetable origin should be used within a few days of harvest), preferably raw or undercooked and, above all, not boiled (this also applies to milk). Fruits and vegetables should be stored whole and unpeeled, in a cool place away from light.

If you buy freshly squeezed orange juice or drinks made from other fruits, fresh compotes or ready-made smoothies, you should prefer products packaged in tetrapack containers or in non-transparent bottles/trays to avoid losing vitamin C, which is rapidly degraded by light. This advice also applies to milk and yogurt, as light destroys much of the vitamin B2 contained in these foods.

Micronutrients such as zinc, selenium, iron and copper are much less damaged by all these factors, but they easily pass into the water during boiling (which should, therefore, be avoided) and can be made little bioavailable (ie difficult to assimilate and usable by the body) due to the interaction with other substances contained in the same foods or in foods taken at the same time.

This is the case, for example, of phytates contained in many foods of plant origin such as spinach, cereal bran, dried fruit and seeds, which bind iron and zinc (as well as calcium and magnesium).

Conversely, it should be remembered that the intestinal absorption of iron is promoted by vitamin C, of which citrus fruits are rich: therefore, an excellent combination to support the immune system comes, for example, from a carpaccio (iron, B vitamins) with rocket (vitamin C, zinc, selenium, iron), seasoned with lemon juice (vitamin C) and extra virgin olive oil (vitamin E).

With regard to cooking methods, those most respectful of the vitamin content and mineral salts of foods are low temperature and / or short-lived and such as to keep all the nutrients inside the food, such as steaming, baking, grilling or quick sautéing in the pan.

Legumes that help the immune system

Legumes are foods with a high nutritional value, both in terms of macronutrient composition and in terms of the content of essential micronutrients capable of supporting the immune system and numerous other fundamental functions of the body.

In general, legumes are an excellent source of protein, even if less “noble” than those of foods of animal origin (red and white meat, fish, eggs and dairy products) and should always be combined with those of cereals (rice and peas, pasta and beans, chickpea soup, etc.) to obtain a complete food from the point of view of amino acid composition. In addition, legumes provide varying proportions of unsaturated fatty acids (more abundant in chickpeas) and slow-assimilating carbohydrates (more abundant in peas and beans).

Legumes also offer more specific help to the immune system thanks to their content in vitamins and minerals. On this front, the most useful varieties are above all beans and chickpeas (both rich in zinc; the former also in copper; the latter in vitamin B6), white beans and lentils (sources of iron) and peas (rich in vitamin B9, less than, zinc and iron).

Fruits and vegetables that help the immune system

Given that vitamin C, E and A are essential allies of the body’s natural defenses, all fruits and vegetables that contain them should become a constant presence in the kitchen and be included in almost all meals and snacks of the day.

Here are the main plant food sources of vitamin C, vitamin E and pro-vitamin A (in the form of carotenoids, especially beta-carotene).

Vitamin	Food sources
Vitamin C	Citrus fruits (oranges, lemons, grapefruits, limes, mandarins, etc.), grapes, strawberries, berries, kiwi, melon, peppers, tomatoes and tomato paste, broccoli, cabbage, cauliflower, sprouts Brussels, peas, spinach, potatoes
Vitamin E	Dried fruit (for example, almonds, hazelnuts, groundnuts), vegetable oils (olive, seed, sunflower, soya and the like)
Pro-vitamin A	Yellow-orange fruits and vegetables (such as apricots, melon, mango, papaya, tangerines, oranges, pumpkins, peppers, tomatoes, carrots), vegetables with dark green leaves or other edible parts (spinach, broccoli, chard, dandelion, parsley, basil, arugula and other salads)

It is also good to remember that taking vegetables rich in vitamin C also allows you to ensure a better level of vitamin E, since the first averages regeneration endogenous of the second, increasing antioxidant protection Overall.

On the B vitamin front, fruits and vegetables cannot help much, since the average vitamin B12 content in vegetables is generally negligible and that of vitamin B6 modest when considering potatoes, bananas, cauliflower, green beans and dried fruit.

The range of choice extends in the case of folate (vitamin B9) which can be obtained in satisfactory quantities from asparagus, spinach, broccoli, cabbage and Brussels sprouts, artichokes, turnip greens, salad, tomatoes and dried fruit. A smaller contribution is also offered by oranges, kiwis and strawberries.

The only appreciable vegetable source of vitamin D is represented by some mushrooms, in particular porcini, morels, ova, chanterelles and pegs; in champignons the vitamin D content is lower and in others even zero.

All fruit and vegetables also ensure a fundamental supply of water (hydration is crucial for the health and well-being of the body) and mineral salts.

Appreciable amounts of zinc, for example, are found only in dried fruit (in particular, in cashews, peanuts, pistachios and almonds), as well as selenium, of which pistachios and Brazil nuts are rich. Selenium can be taken in larger doses through enriched vegetables, such as potatoes or selenium carrots, which must however be cooked correctly and, above all, not boiled.

As known, the vegetable reference point for iron is spinach, followed by tomatoes, potatoes and broccoli, while among the fruits only the dried ones (in particular, cashews, walnuts and pistachios) and contain interesting quantities.

Potatoes, hazelnuts and other dried fruits, along with prunes and vegetables with dark green leaves, are, instead, useful to meet the need for copper

Other foods that help the immune system

Other foods that, by virtue of their content of essential micronutrients, can support the body’s natural defenses are spices and aromatic herbs, also advantageous because they allow you to make foods more appetizing without adding too much salt.

Among these, chili pepper (extraordinary source of vitamin C and vitamin A and endowed with antiviral and antibacterial properties), rosemary and basil (rich in vitamin C, A and iron), pepper (containing iron and copper) and mustard, in the form of seeds or sprouts (source of folate) deserve to be remembered. Useful to strengthen the immune system are also saffron and turmeric, thanks to the content of vitamin A and curcumin, a substance characterized by anti-inflammatory properties.

Ginger, in addition to being a good source of iron, manganese, zinc, copper, selenium and vitamin B6, would seem, instead, to have antioxidant, anti-inflammatory and antipyretic properties advantageous in case of colds and colds, although the basis and extent of these benefits remain to be clarified (as for many other spices).

More certain and investigated are the benefits, in terms of prevention of seasonal ailments, of fish, in particular the fatty fish of the North Seas such as cod, mackerel, salmon, herring and tuna (but also sardines and eels) and some molluscs (above all, oysters for zinc and copper) and crustaceans (crab, lobster, shrimp and Norway lobster).

In this case, the favorable protective effects against respiratory tract infections, such as colds and flu, would be due both to the high content of vitamin A and D (present mainly in liver and fish oil), selenium, zinc and copper and to the essential fatty acids of the omega-3 series.

In this regard, a study that examined, in over 20 thousand children from six European countries, the protective effects of a diet more or less rich in fish, fruit and vegetables against diseases of the respiratory tract, showed that a greater consumption of both fish and fruit was associated with a lower incidence of cough during the winter, with the same exposure to pollutants present in the environment, climate and atmospheric conditions.

When to resort to targeted supplements

When the presence of food intolerances, allergies or other gastrointestinal diseases (gastroesophageal reflux, chronic inflammatory bowel diseases, malabsorption, etc.) or systemic (diabetes, cardiovascular diseases, gout, reduced liver or kidney function, etc.) require you to avoid specific foods or entire categories of foods, preventing you from following a varied and balanced diet and obtaining all the micronutrients Needed to support immune system activity, resorting to targeted supplements can help avoid deficiencies.

The periodic intake of targeted supplements may be advisable in the elderly (especially if affected by difficulties in chewing, digestion or intestinal absorption or in therapy with drugs that reduce the absorption or metabolism of certain micronutrients), in children with no appetite or food intolerances, in children and adults who follow restrictive diets or with eating disorders, in those who follow a very active / stressful lifestyle and / or practice intense physical activity, in smokers and in those who habitually consume excessive amounts of alcohol.

Supplementation can also be useful after a flu, seasonal illnesses of various kinds or an infectious disease of a certain importance, especially if to treat it it was necessary to take antibiotics that weakened the body and temporarily destabilized the intestinal flora. In the latter case, to promote a better and faster physical recovery, it can also be useful to take probiotics, with proven beneficial effects on the gastrointestinal balance and the immune system.

In all cases, but especially when an elderly person with specific pathologies or a child has to take a supplement, the ideal is to first ask for the doctor’s opinion, even if food supplements can be freely purchased in pharmacies and parapharmacies without a prescription.