What is the immune system?
Our immune system protects us against a wide variety of antigens. It fights against external agents (bacteria, fungi, parasites, viruses) and internal ones (damage to body structures and cancer cells) that can cause us harm. After the mentioned agents meet the barriers of our organism, such as the skin, the microbiota, or the defence molecules, the immune response is activated.
We can distinguish two types of immunity: innate and acquired, but the truth is that both act cooperatively.
The first line of defence. It occurs immediately and can last a few hours. It is known that, like acquired immunity cells, they also have non-specific memory and help regulate acquired immunity.
Acquired or specific immunity
Its duration ranges from days to weeks. Lymphocytes are most responsible for this response. They carry out three stages. First, the agent is recognized (bacteria, viruses ...), then there is an activation phase, and finally, it is destroyed. It has a self-regulation system that does not last longer than necessary and also a memory system. This memory allows them to remember if it is the first time they have come across this antigen, or if the "appointment" had already occurred. In this way, when the unwanted guest reappears, the response is faster and more reliable.
According to their genes, environmental factors, and lifestyle, each person will have their immune system. There are also differences between men and women. They develop a more excellent immunity in which hormonal differences also have a lot to do with it, which is why they are more susceptible to autoimmune diseases and infections and tumours.
Food and immune system What can we do?
From nutrition, we can seek control of inflammation and oxidation state.
From nutrition, we can seek control of inflammation and oxidation state.
Inflammation is a typical physiological defence against pathogen infection and tissue damage and ends rapidly under normal circumstances. However, in many chronic conditions, the inflammatory response continues and leads to significant tissue and organ damage. The inflammatory response is known to play an essential role in the development of autoimmune diseases.
Omega 3 and 6 fats are part of cell membranes, giving them flexibility and elasticity. Straightforwardly, omega three fatty acids have a more anti-inflammatory effect than omega 6. Still, it is not that the consumption of omega 6 is terrible, but that a balance between the two will be what promotes that anti-inflammatory response.
OMEGA-3: Flax and chia seeds and oils and walnuts. Fish such as mackerel, horse mackerel, sardine, herring, salmon, tuna or cod, and seaweed.
OMEGA-6: Seeds of plants such as sunflower, corn and borage. Nuts such as peanuts, pine nuts and pistachios. Food of animal origin, mainly if their diet is based on seeds.
Some studies in people with rheumatoid arthritis, it was observed that taking omega three supplementations (minimum 2 grams or more a day of EPA and DHA), for 3-4 months decreased both joint stiffness and the number of joints with pain and Consequently, taking anti-inflammatory medication.
Essential vitamins and minerals in the immune system
The immune cells also need to feed and receive nutrients essential to carry out their duties.
Antioxidant function and necessary to synthesize collagen (essential for the epithelial barrier).
Neutrophils need high concentrations of this vitamin to counteract the oxidative stress they face in destroying pathogens.
It is also essential in the regulation of the inflammatory response, and some studies give it antiviral properties. It can improve the severity of symptoms and the duration of upper respiratory tract infections, such as a cold.
But it will not always be appropriate to resort to its supplementation, since it must be borne in mind that, at higher doses, less absorption may occur.
Foods that provide vitamin C
Strawberry, guava, kiwi (especially golden), lime, lemon, tangerine, mango, peach, melon, orange, papaya, grapefruit, broccoli, Brussels sprouts, red cabbage, kale, cabbage, cauliflower, kohlrabi, parsley, bell pepper, tomato.
Vitamin D3 (cholecalciferol)
Immunomodulatory. This vitamin has receptors in almost all human tissues that can regulate gene expression. In other words, its relevance goes far beyond its participation in calcium absorption and bone health.
Some studies show an association between low concentrations of the vitamin in the blood and the risk of respiratory infections at different stages of life.
More than 90% is synthesized through the skin, with food being responsible for only 10% (maximum).
But if we also consider factors that can affect its bioavailability, we can understand that vitamin D deficiency is widespread.
- Situations related to vitamin D deficiency are Inadequate and low sun exposure to UVB rays (use with ultraviolet radiation filter, indoor physical activity, environmental pollution, latitude).
- Medications (anticonvulsants, antifungals, antiretrovirals against HIV, cholestyramine, glucocorticoids, antacids, laxatives ...) or pathogenic conditions (celiac disease, hyper or hypoparathyroidism, asthma, some lymphomas, chronic kidney failure, type 2 diabetes, atopic dermatitis, COPD, depression).
- Stages of life: advanced age, menopause.
- Inadequate diet.
- Decreased bioavailability.
- 1,25-OH-vitamin D receptor abnormalities.
- Others: institutionalization (e.g., nursing homes).
Obesity and vitamin D deficiency
No wonder is seeing obesity-related to vitamin D deficiency. But is that so? Vitamin D (25OHD) is distributed in serum, fat, muscle, liver, and other tissues increased in a person who is obese. The reality is that people with obesity (or people with larger bodies) may have less exposure to the sun (will social stigma have something to do with it?), And it has been observed that when there is an exposure to UVB rays, they have a skin synthesis similar to that of other people. But the synthesized vitamin is distributed in a larger volume, so the amount that is distributed in the serum is less. The same can happen in response to vitamin D supplementation.
How do I know if I have adequate vitamin D values? *
We would have to look analytically at the values and bear in mind that recent scientific reviews tell us about fair benefits ranging from 30 and 50 ng/ml (75-125 nmol / L).
* But beware, because there are autoimmune diseases (sarcoidosis ... for example) that can significantly increase active vitamin D and lead to hypercalcemia (in this case better 20-30 ng / ml).
The European Food Safety Authority has established a maximum acceptable and, therefore, safe intake level for the general population of 4,000 IU / day of vitamin D3 (cholecalciferol).
Therefore, it is crucial not to self-supplement. It should be the professional who adjusts the dose individually, controls the treatment evaluating different parameters in urine and blood tests, and can readjust a correct maintenance dose to maintain adequate levels over time.
It is key to maintaining proper immune function. It is anti-inflammatory and antioxidant. Its deficit can be caused by low consumption of foods rich in zinc and high in nutrients that can interfere with its absorption, such as calcium and some dietary fibres, making us more susceptible to infections.
Worldwide, zinc deficiency (mild to moderate being more common) accounts for 16% of lower respiratory tract infections (trachea, lungs, and diaphragm), 18% of malaria, and 10% of disease diarrheal.
Foods that provide zinc
The best sources are red meat and poultry, cheese (although calcium can inhibit absorption), shrimp, crabs, and other shellfish.
Other sources: legumes (beans, peas, soybeans, peanuts), seeds (pumpkin, sunflower, sesame), brewer's yeast, nuts (almonds, walnuts, hazelnuts, pistachios), whole or fortified cereals, cooked vegetables and vegetables (spinach, spinach, cruciferous, beets, green beans, mushrooms).
Its supplementation can reduce the markers of oxidative and inflammatory stress and the incidence of infections. Furthermore, they can be useful in the treatment of diarrhoea in children, but not all supplements offer the same effectiveness. The zinc aspartate is one of the chemical forms having a while lower zinc oxide, a bioavailability higher absorption.
Iron deficiency anaemia increases the chance of infection. For many bacteria, parasites, or tumour cells, iron can be used during infection, so the body uses mechanisms to reduce its availability. In infectious or inflammatory processes, the liver hormone hepcidin has also been seen to increase, which regulates iron metabolism, favouring the decrease in iron that we mentioned.
But speaking of anaemia, we cannot look only at iron. Other minerals and vitamins that can interact with it or participate in different phases of its metabolism, such as copper, zinc, magnesium, cadmium, and chromium or vitamin C, must be taken into account.
- Phytochemicals and immune system
Phytochemicals (natural compounds found in plants) such as polyphenols have been shown to influence microbiota and gut immunity. For example, curcumin is a polyphenol derived from Curcuma longa, with a wide variety of biological functions: anti-inflammatory and antioxidant. But the polyphenols in the food we eat may have limited bioavailability, as they are not absorbed efficiently in the small intestine.
The human intestine harbours the most complex microbiota, with a substantial impact on our homeostasis and immunostains. Dysbiosis or imbalance of the intestinal microbiota can make us more susceptible to infections, hypersensitivity reactions, autoimmunity, or chronic inflammation.
Therefore, treating dysbiosis can help us regain immune responsiveness.
Alterations in the lung microbiota can also lead to an impaired immune response, increasing the risk of lung infection. Or imbalances in the skin microbiome, higher reactivity of the immune system.
Not to mention the impact that a poor state of our oral health can have. The oral microbiota can synthesize substances with repercussions on the immune system such as antimicrobial substances, anti-inflammatory compounds, antioxidants ... also inhibiting some species of pathogenic microorganisms. But if the balance of our immune system is disturbed, for example, by an unhealthy diet and poor oral hygiene, the appearance of pathogenic organisms that give rise to diseases such as periodontitis or caries is favoured.
A healthy microbiota should resist the changes we can find ourselves with (such as ageing due to age) and have the ability to recover the basal microbial profile after the alteration.
Non-food factors affecting the immune system
Some psychological states or chronic stressful experiences and emotions (anxiety, sadness, depression) or behaviours could influence our immune system's defensive capacity, and, conversely, the immune system could induce changes in the nervous system.
In other words, some research supports regulation in both directions.
Stress is that which represents a challenge, that supposes a real or perceived threat. It ends up causing a response at the level of different systems, especially the nervous, immune, and endocrine systems. And if it occurs chronically, it can make our body more vulnerable to certain diseases.
In some studies in both humans and animals, you see how it can cause our immune response to decrease or increase. When it occurs chronically, it is associated with higher levels of cortisol and a more excellent production of pro-inflammatory factors. An alteration in the immune response can be seen.
Pro-inflammatory cytokines could even inhibit neurotransmitters' function (responsible for carrying information between neurons) of the central nervous system.
Another example is the alterations of the immune function associated with depressive states that include immunosuppression and an increase in the inflammatory response.
It is common to find that certain diseases related to the immune system, such as autoimmune ones, develop or exacerbate in circumstances in which the organism has been threatened by a high degree of stress.
In the end, it will be true that "sleeping cures everything." And is that when we get into bed, our body continues to work. Some certain compounds and hormones increase (prostaglandins, prolactin, growth hormone, melatonin, anti-inflammatory cytosines ...) and others that decrease (adrenaline, cortisol, anti-inflammatory cytokines, C-reactive protein, thyroid hormones ...), helping our defence system. It seems that, during the hours of sleep, cells of the immune system leave the circulatory system and travel to the lymph nodes, and this allows a first exposure to the foreign agent and activates the specific immune response, being able to recognize it if there is a second meeting. So sleep is essential to achieve balance and maintain our health.
The quality of sleep or the hours we sleep can even affect our food choices, and we can add more factors that weaken our immune system. At the same time, taking care of our diet can promote better rest.
Physical exercise to improve our defences
Moderate physical exercise can reduce the risk of infection compared to people with a more sedentary lifestyle. However, high-performance training or continued overtraining without adequate breaks or not adapted to us can immunosuppress, due to the stress, the body is subjected to.
Therefore, we can obtain many benefits of regularly practising physical activity or exercise, personalizing the training, and adjusting the dietary guidelines to achieve higher performance from our immune system.