Some substances, such as vitamins A, C and D, mineral salts such as selenium and zinc but also probiotics, beta carotene and omega 3 fatty acids have been shown to be able to modulate the immune system. This means that, once introduced into the body, they can make changes to the immune response in order to optimize it and effectively counteract any infections. But do different ways of taking these substances, that is through supplements or with the diet, bring the same effects? It seems they don't. In fact, as emerges from a very recent scientific research, apart from a few exceptions as we will see below, only the nutrients taken with the diet have been shown to strengthen the immune system in the fight against infections (Polak et al, Nutrients, 2021).
The experiment, do diet and supplements have the same effects?
Scientists recruited 120 people between the ages of 17 and 35 and asked them to fill out a questionnaire. In particular, the volunteers had to indicate their usual diet, whether or not they took supplements and their state of health, specifying any infections by viruses, bacteria or fungi that had affected them in the last year and indicating the duration and severity of the disease. From the indications on diet and supplements, the researchers were able to assess the intake of nutrients and to link it to the state of health. What emerged was that supplements were generally not linked to an improvement in health conditions as they did not change the frequency, severity and duration of any infections. The only exception was vitamin D. In fact, the intake of vitamin D supplements is related to a decrease of the cases of infection. Instead, when vitamins, minerals and antioxidants were taken with the diet, in particular by eating unrefined foods, fruits and vegetables, it was observed that the immune defenses were strengthened with a lower incidence of infections that had in any case a milder course.
Diet is better
The explanation given by the scientists is as follows. The diet guarantees the intake of nutrients in the right quantity, without excesses or deficiencies. The same cannot be said about supplements, which are only beneficial when there is a proven deficiency of a particular nutrient. In fact, if the deficiency of a certain vitamin, mineral or antioxidant can weaken the immune system, an excess is also to be avoided. For example, an adequate intake of omega 3 fatty acids, guaranteed by a varied diet, has an anti-inflammatory action, useful to avoid an excessive inflammatory response on the part of the body in case of external threat and at the same time to speed up the recovery from viral infections of the respiratory tract. On the contrary, however, an excess of these substances, often linked to supplements taken without real need, can interfere with the immune response. Then, a lack of iron weakens the immune system while an adequate intake of this mineral through the diet allows the body to perform important functions such as the differentiation and development of T cells of the immune system, used to recognize cells infected by viruses. However, if, without a proven need, you take supplements containing iron, the risk is to excessively increase this substance and also the risk of infections. Selenium strengthens the body and makes it less susceptible to infections. Selenium is taken with the diet or, if there is a real deficiency, with supplements. In fact, if you use supplements without having a selenium deficiency, this could worsen allergic phenomena such as asthma or may weaken the immune system against parasites.
Therefore, a varied diet is the best ally to strengthen the immune system. By eating in a balanced way, in fact, we can guarantee in the right quantity vitamins, minerals, antioxidants, probiotics and omega 3 useful to modulate the immune system. Supplements are a great help in case of a proven deficiency of a certain substance but, if this is not, the risk is to take an excess of nutrients that could even weaken the immune system. The only exception is vitamin D, which, if taken through supplements, decreases the incidence of infections, especially that of viral origin and affecting the lungs.