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Strengthen your Defenses and the Immune System

Published: 15 June, 2015 - Updated: 31 July, 2020 | 9'

Food plays an important role in the development and preservation of the immune system. It is essential to have a balanced and adequate diet so that the immune system's ability to act is optimal and it can efficiently fight not only infections, but also good immune function has an impact on important functions such as mental health and hormone regulation.

In short, being well nourished helps our health and the processes that take place in our body.

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Do you want to boost your immune system? Take care of your diet

From a nutritional standpoint, a healthy immune system is absolutely critical to good health. An inadequate diet can affect the state of our defenses since our organism obtains the essential substances for the correct functioning of the immune system through food.

The World Health Organization states that "nutrition is one of the pillars of health and development. Improving nutrition involves promoting the health of children, mothers, youths and adults; strengthening our immune system; reducing complications during pregnancy and childbirth; reducing the risk of non-communicable diseases (such as diabetes and cardiovascular disease); and prolonging life".

The relationship between a person's nutritional status and their resistance to infection has been a known fact since 1846, when it was established that malnourished children had a dysfunction of lymphocytes (a type of white blood cell) with the consequent deterioration of an immune system that could not defend the body from attack by pathogens.

What is the immune system and how does it work?

The immune system is a complex defense network of our body, comprising tissues, cells and organs, against potentially pathogenic external agents (viruses, bacteria, fungi, pollen, chemicals, etc.). These external aggressors will be recognized and eliminated by the immune system through an organized sequence of reactions or defense mechanisms.

In general, the defense mechanisms or immune response can be nonspecific and specific:

  • The non-specific immune response is the first line of defense and is important in the fight against infection. It is composed of natural barriers, such as skin, mucous membranes, saliva enzymes, tears and nasal secretions, that have the capacity to prevent or break the integrity of viruses, bacteria or others.
  • The specific or acquired immune response is only developed when there is a previous exposure to the foreign agent (antigens) and in it participates primarily lymphocytes (white blood cells) and the substances released by them, antibodies and cytokines.

The main function of the immune system is therefore to defend us against infections, but it does so in an integrated way, anatomically and functionally, with the nervous system and the endocrine system. A striking example of this integration between the three systems is the proven fact that situations of anxiety, depression and emotional stress are often accompanied by a greater susceptibility to infections and other diseases.

What factors weaken the immune system?

The main factors that can affect our defenses or 'weaken' them are poor diet, seasonal changes, consumption of certain medications such as antibiotics, or some chronic diseases.

Lifestyle habits also have a major influence on the well-being of the immune system, such as prolonged stress or anxiety, lack of physical activity, or the use of alcohol and tobacco.

There are some signs or symptoms that may indicate that the body's defenses are low and it is important to pay attention to them:

    • Excessive tiredness
    • Weak hair or excessive hair loss
    • Recurring infections such as herpes
    • Frequently dry eyes
    • Simple illnesses that take longer than usual to get better such as the flu
    • Diarrhea
    • Wounds that take too long to heal

That's why taking care of your nutrition throughout the year is essential to avoid a marked or prolonged weakening of your defenses.

What does the immune system need to maintain a good functional status?

Food as a whole and the nutrients that make it up play a key role in the proper development and maintenance of the immune system. The role of some nutrients will be discussed in detail later on.

Therefore, the nutrients that are incorporated into your body through your diet influence the activity and condition of your immune system and this is called immunonutrition. Nutrients have immunomodulatory properties, that is, their presence and availability is key to normal immune activity, mainly due to two aspects:

  • For the production of new immune elements for the proper development of immune responses (e.g. amino acids are necessary for the production of proteins during the acute phase of the defense system), and
  • for its use in the phenomena of production of new immune cells, to build "an army" that attacks and eliminates the invading pathogen.

In people with certain nutritional deficiencies, the immune response is diminished and in the face of acute and/or chronic inflammation, energy expenditure and nutritional status are altered.

Guidelines to strengthen the immune system and keep your defenses ready

In short, to keep your defense system in good shape, it is advisable to follow some simple guidelines:

  • Follow a varied and balanced diet, based on foods that are rich in vitamins and minerals.
  • Get at least eight hours of sleep a day and guarantee a good rest.
  • Practice physical exercise.
  • Maintain a more relaxed pace of life as much as possible, avoiding stressful situations.
  • Faced with exceptional situations that can affect the immune system, complement your diet with food supplements.


Foods for the immune system and defenses: what to eat

As we can see, keeping our digestive system in good shape significantly helps our immune system. An inadequate diet, with a shortage of fiber and an excess of fried foods and saturated fats, excessive intake of coffee, sugar and alcohol adversely affects the immune system. Prolonged treatments with antibiotics, corticosteroids and laxatives can also reduce its function.

On the other hand, a balanced diet can help our defenses. For example, the Mediterranean Diet has proven for many years that it is a beneficial factor for the body thanks to its richness in nutrients, vitamins, antioxidant substances and the healthy benefits of olive oil.

What nutrients influence the functioning and development of the immune system?

There are six main classes of nutrients that the body needs: carbohydrates, proteins, fats, vitamins, minerals and water.

According to the World Health Organization, the real challenge today in developed societies is the deficiency of specific micronutrients (vitamins, minerals and essential amino acids) that prevent the body from ensuring growth and maintaining its vital functions.

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Micronutrients: vitamins and minerals for the immune system

Micronutrients are nutrients required by the body in very small amounts, but they are still essential and vital for the proper functioning of the body. According to their chemical nature, they are classified into minerals (inorganic substances) and vitamins (organic substances) and the latter are in turn classified on the basis of their solubility into water-soluble and fat-soluble.

Micronutrients provide elements for an optimal immune system function on three levels: in strengthening physical barriers (skin and mucous membranes), in cellular immunity (which depends on white blood cell types), and in humoral immunity (antibody production).

Let's look at some examples of the properties of these micronutrients and in which foods we can find them:

Vitamin C and Vitamin E:

Among its properties is being antioxidants par excellence. The function of the cells of the immune system is strongly influenced by the balance or equilibrium of antioxidant substances, playing a fundamental role in the protection of immune cells against oxidative stress. In addition, they have been shown in studies to stimulate the production of immunoglobulins and the response of white blood cells.

Foods rich in vitamins C and E are: melon, kiwi, citrus, red fruits, broccoli, nuts (walnuts, almonds, hazelnuts), seeds (sunflower seeds, sesame, and linseed), among others.

Group B vitamins:

These are essential for all processes in the body, and help provide the energy needed for the immune system to function. They also participate in the processes of immune cell formation, such as lymphocytes.

Foods rich in B vitamins are: whole grains, dairy products, meat and fish. Within the B group, vitamin B6 stands out and we can find it in unprocessed vegetable sources such as bran and wheat germ, nuts, legumes, potatoes, raw carrots, green beans, raw broccoli, bananas, orange juice, among others. Garlic (whose main active ingredient is allicin) is rich in vitamins B, A and C, but also contains various enzymes, amino acids and minerals such as selenium that are useful in the proper functioning of the immune system.

Vitamin A:

This plays a fundamental role in the development and maintenance of our body's mucous membranes (eyes, nose, mouth) and skin, which are our first defense barriers against harmful agents such as viruses and bacteria, among others.

Foods rich in vitamin A are: colorful fruits and vegetables such as carrots, spinach, sweet potatoes, tomatoes, broccoli, mango, melon, apricot, as well as pork or beef liver that are also food sources of vitamin A.


This exerts a multitude of effects on numerous types of immune cells and is involved in the defense against oxidative stress caused by free radicals that are produced and released by white blood cells when they defend our body from microbes. A healthy adult human body contains 2 to 3 g of zinc, and needs about 15 mg of dietary zinc per day, which is stored in the bones.

Foods rich in Zinc are: hazelnuts, almonds, oats, red meat, fish, eggs, cereals and dark chocolate, all of which provide good amounts of zinc.


This is an essential element, since it is directly involved in the transport of oxygen through the blood to all our tissues, so a decrease in the amount of iron affects the oxidative capacity of the immune system and the ability to fight infections.

Foods that are rich in iron are: beef or pork liver, red meat, fish, seafood such as clams and cockles, spinach, legumes, pistachios, pumpkin seeds, quinoa, tofu, eggs and, to a lesser extent, dairy products, among others.


The presence of magnesium stimulates the immune system's ability to fight infection by activating all the immune cells.

Foods rich in magnesium are: wheat bran, chives, mint, pumpkin seeds, flax, sesame and sunflower seeds, nuts, soybeans, and cashews, among others.


Copper forms part of the structure of many proteins, and is involved in the metabolism of iron, amino acids, and others. It contributes both to normal immune function and to protection from oxidative damage.

Foods rich in copper are: chocolate, legumes, nuts, cereals, dried fruits, poultry and seeds.

Amino Acids and Proteins

These are elements of special importance for the production of antibodies, immunoglobulins, the formation of white blood cells and the functioning of organs with immune function such as the spleen and thymus.

Amino acids of special importance are:


Arginine stimulates the growth and function of lymphocytes. You can find it in foods of animal origin such as fish, pork, beef, chicken, turkey, and in products of plant origin such as peas, beans, vegetables, etc.


Glutamine in conjunction with glucose is a source of energy for the immune system as it facilitates adequate production of lymphocytes and cytokines. In addition, it has a positive effect on the integrity of the intestinal mucosa and helps to maintain the barrier function intact against possible infections. You can find glutamine in good proportions in red cabbage, milk, eggs, yogurt, parsley, radishes, chard, asparagus, among others.


Cysteine contains sulphur which allows it to form special bonds to maintain the structure of proteins in the body, especially in the skin and mucous membranes. Foods that are good sources of cysteine are fish such as hake, cereals such as rice and wheat, vegetables such as peppers and onions, and meats such as pork, chicken and duck.

Fatty acids

Polyunsaturated fatty acids (Omega series) are an integral part of all cells, tissues and organs of the body, and are involved in numerous immune processes because they are an energy source and because they also help regulate the immune responses.

Include in your diet sardines, tuna, salmon, lean red meat, nuts, soya, and whole grains, among others that can provide you with abundant amounts of Omegas.

Olive oil is a monounsaturated fatty acid type Omega 9, whose properties help the metabolism of the body's lipids.


At the immune level, these nutrients play a key role in the cellular immune response, since all immunoglobulins and many other factors in the immune system are bound to a carbohydrate. In fact, the carbohydrate chains attached to proteins have several important functions, including directing the location of viruses, bacteria or fungi to defensive activity. Potatoes, bananas, oats, honey, royal jelly, rice, and whole grains are good sources of carbohydrates.

Your diet can be complemented with dietary supplements in extraordinary situations, so look for the one that best suits your conditions, as only by staying strong and healthy can you help your immune system.