Having an efficient immune system is essential to protect us from illness and infection. This is always true, but especially so during a public health emergency like the one caused by COVID-19.

What can we do to improve our immune defenses?

The immune system’s activity is strongly influenced by our diet. To function properly, it requires an adequate intake of both macro- and micronutrients. Ensuring a varied and balanced diet is key to receiving all the essential compounds needed for optimal immune performance every day.

A healthy gut also plays a vital role in maintaining strong immune defenses. To support gut balance, it is important to consume at least 30g of fiber per day, sourced from legumes, vegetables, and fresh fruits (aim for five servings daily), as well as include probiotics in the diet—naturally found in yogurt and kefir.

Our Dietitian Ilaria Carandente’s Insights

Tell us about the role of micronutrients:

Certain vitamins and minerals are particularly important for the immune system’s effectiveness:

  • Vitamin C: A powerful antioxidant with immune-boosting properties. Deficiency increases susceptibility to infections. Common sources include citrus fruits, but also bell peppers, tomatoes, kiwi, and leafy greens. This vitamin is sensitive to light, heat, and oxygen, which reduce its levels in food. To preserve it, eat or cook vitamin C-rich foods right after cutting them (like fresh orange juice, which should be consumed immediately). Avoid soaking vegetables for too long, as it is a water-soluble vitamin. Cooking methods also matter: boiling, steaming, and baking lead to significant losses, while vacuum cooking or pressure cooking preserve it better.
  • Vitamin D: An immune modulator mainly produced by the skin when exposed to sunlight. Food is a lesser source and includes only a few animal-based products, such as salmon, sardines, herring, tuna, swordfish, eggs (especially the yolk), and cheese. The only plant-based sources with notable vitamin D content are some mushrooms—porcini, chanterelles, and honey mushrooms.
  • Vitamin E: Has antioxidant properties and helps maintain immune cell health. It’s found in nuts (almonds, hazelnuts, peanuts), vegetable oils (olive, seed, sunflower), avocados, and leafy green vegetables.
  • Zinc and selenium: Both have strong antioxidant effects. They are abundant in nuts (pistachios, almonds, cashews, walnuts), with smaller amounts in legumes and whole grains.

What about Omega-3s?

Omega-3 fatty acids are also powerful allies of the immune system, helping to regulate immune responses and inflammation. They are primarily found in fatty fish (especially sardines, mackerel, herring, but also salmon, tuna, and cod), nuts (particularly walnuts, hazelnuts, almonds), leafy greens, soy, and avocados.

Is there a recommended diet?

In general, the Mediterranean diet remains an excellent model to follow. It provides a balanced intake of all macro- and micronutrients needed for strong immune function and overall health.

Can we use vitamin supplements during winter?

Vitamin and mineral supplements may be necessary only in cases of restrictive diets, food intolerances or allergies, or medical conditions that require avoiding specific foods or food groups. Even then, supplementation should be personalized and preferably prescribed by a physician. It’s important to remember that no supplement can replace a fundamentally unbalanced diet.