Generales

By: Natalia Piedrahita Tamayo - Journalist

They say we are what we eat. How true is this popular saying? Nutrients —vitamins, proteins, carbohydrates or lipids— are the raw material for the immune system to generate defensive responses or surveillance barriers against any foreign body that tries to enter the body.

There is an organic patrol that resides in the human body and is on the lookout for any foreign bacteria or viruses that enter the system. These are cells that circulate in the body and ensure not only the lifespan of a body on Earth but also its quality in terms of health. This defense mechanism is known as the immune system.

However, the same system that has the power to turn a hostile germ into a beneficial one can work the other way around. "It houses the molecules that make it possible to identify the cells and microorganisms that reach the body. It can set up an immune defense against them and react effectively. This is how it neutralizes the threats. However, it does not always work. When the immune system is unbalanced, it can be the cause of diseases", said Luis Fernando García Moreno, physician and professor emeritus of the Faculty of Medicine of Universidad de Antioquia.

How much does food affect the functioning of the body's defenses? For the founder of the Cellular Immunology and Immunogenetics Group and the Institute of Medical Research, food is not medicine but a precursor of what the body needs. Therefore, a balanced diet that includes vitamins, proteins, fats, lipids and carbohydrates is essential to balance this system (see table).

When ingested, food does not immediately reach the tissues in the form of these nutrients. They must first pass through the digestive tract, where they are broken down by the bacteria that inhabit the intestine —also known as the microbiome— which aid the body's defense.

When there is an active infection in the body, the organism experiences an excess demand for nutrients to manufacture the cells that defend it. In the case of COVID-19, which for many elderly patients has been lethal, García Moreno explained that the reason is that the immune system also "ages". When it does, it is not the same as that of a child or young person. Instead, the adult has been exposed to many more antigens (see box), and they wear it out. Therefore, it has less memory for new stimuli.

What are immunogens or antigens? They are cells that generate an immune response. There are innate responses, which are the first line of defense, such as the skin barriers and the body's secretions. There are also adaptive immune responses that come later with the production of antibodies. They can neutralize the virus or attack the cells that contain it. Finally, there are more effective cells such as t-lymphocytes, which attack cells that are already affected.

Food: Source of Energy and Health

Among the essential nutrients that the body receives through a good diet are fiber and vitamins. Beatriz López Marín, teacher and researcher of the Impact of Food Components on Health Research Group (ICAS), which belongs to UdeA’s School of Nutrition and Dietetics, stated, "The body needs vitamin B₉ —folic acid— iron, zinc, vitamins B6, B12, D and A. These are fundamental in the correct response of the immune system, as are macronutrients such as proteins, fats —polyunsaturated fatty acids such as Omegas 3 and 6— and carbohydrates".

López Marín emphasized, "Proteins, which are fundamental for the human defensive system, for example, are found in dairy products, meats, fish, fruit and grains such as beans. The body's energy sources are related to carbohydrates, which are found in fruit and cereals. Vitamin D is key for the body's defenses and can be obtained from citrus fruits, among others".

Although it has not been proven that food can cure a disease, several studies show that food is the key to strengthening the immune system. Beyond the popular sayings that point out the benefits of food such as ginger, turmeric and citrus fruits, there is research such as Chicken soup inhibits neutrophil chemotaxis in vitro (2000), by B. O. Rennard, R. F. Ertl, G. L. Gossman, R. A. Robbins and S. I. Rennard, which shows that eating meat broth reduces the propensity to upper respiratory tract infections.

It should be considered that the energy requirements of children are different from those of elderly people, and a specialist physician or nutritionist should always be consulted to make dietary decisions.

However, some recommendations that apply to the entire population. "The beneficial effect of vegetables and fruit cannot be replaced by a processed food. Whatever you are going to spend on a supplement, spend it on healthy food", suggested García Moreno.

Vegetables as a source of nutrients Vegans or vegetarians require a balanced diet in which vegetable protein is received in adequate amounts since it guarantees the entrance of antioxidant substances into the body. Dairy products can be useful for this purpose. Likewise, probiotics help to normalize the intestinal flora, stimulate defenses and process food, stated Luis Fernando García Moreno. A diet that guarantees the variety of nutrients the body needs is the best alternative. These are some sources of nutrients: .