How to Support The Immune System with Diet and Supplements

Our immune system merged throughout our body is there to protect us against infections and other external and internal assaults.

The immune system uses two types of defense mechanisms against threats to our body.

An innate defense mechanism and an adaptive defense mechanism. Each defends against a threat to the body in a different way.

The innate immune defense mechanism protects against anything foreign in a fast way. This defense mechanism fights off pathogens before they can start an active infection. To do this, the immune system uses 

1. Physical protective barriers throughout our body, including the skin, the epithelial lining of the gastrointestinal and respiratory tracts

2. Secretions, mucus, and gastric acid, which form biochemical barriers.

3. Non-specific immune cells, including monocytes, neutrophils, natural killer cells, dendritic cells, and antibodies. 

If the threat manages to avoid these innate defenses, then a more complex, adaptive, antigen-specific immune response is triggered.

This adaptive immune defense mechanism is precise and protects the body by identifying pathogens and differences in molecular structures. Although highly specific, this immune response is slow to react and is activated by first exposure to the pathogens. This immune defense mechanism helps reduce the severity of the threat.

This adaptive immune defense mechanism uses T cells that mature in the thymus and form cell mediated immunity and B cells that develop in the bone marrow and form antibodies which bind to antigens on the pathogen and destroy it. This is called antibody-mediated immunity.

All defense mechanisms of the immune system also protect against non-foreign native cells that may be harmful, such as cancer or pre-cancerous cells.

All parts of the immune system work together to protect the body against pathogens and threats.

As we age, the immune system evolves from the immature and developing immune responses in infants and children to a potentially optimal functioning immune function in adolescents and young adults.

And as we age further, there is a gradual decline in immunity that can be compounded by certain lifestyle choices, including our diet, our environment, and oxidative stress levels.

Optimal immune function is dependent on a healthy immune system. 

And a healthy immune system requires proper nutrition to ensure that the supply of nutrients for the development, maintenance and expression of the immune response are always available. 

The immune response will be inadequate when nutrition is substandard. When the immune system is not healthy, people will suffer from more infections. The severity of infections will also be higher, and they will suffer from more disease overall.

Infections and disease will, in turn, lead to a poor nutritional status, which will in turn, lead to poor immune health, and so a downward spiral of health begins. 

It all starts with the nutritional status, the environment, and the levels of exposure to oxidative stress of the individual. 

Unfortunately, nutrient deficiencies and suboptimal nutrient intake are common all over the world.

It is possible to add foods rich in deficient nutrients regularly into the diet. Still, studies prove that it is not always possible to achieve good nutritional status via a change in diet alone. Adequate and varied food supply is necessary for this but not always an option in different parts of the world and different economic states.

But even in industrialized countries, there are social, economic, educational, ethnic and cultural backgrounds that influence a persons dietary choices, even if a healthy varied diet can be physically attained.

Therefore tailored supplementation in restoring deficient nutrients helps support immune function.

Here is a list of 12 recommended nutrients that support the immune system:

1. Vitamin A – helps support the health of mucosal cells that form part of the immune system’s innate barrier defense mechanism. It is also essential for the functioning of innate immune cells (e.g., NK cells, macrophages, neutrophils). Low levels of vitamin A will lead to a reduction of innate immune cells and their killing activity, as well as increased susceptibility to infections. The top food sources of betacarotene, the provitamin A, include carrots, broccoli, cantaloupe, and squash.
2. Vitamin B-6 – Helps regulate inflammation and has roles in innate immune cell production and activity. Low levels of vitamin B-6 will lead to Lymphocytopenia, a condition of having very low blood levels of lymphocytes (white blood cells with important functions in cell-mediated immunity and antibody responses). The top food sources of vitamin B-6 include potatoes, peanuts, soya beans, oats, and bananas.
3. Vitamin B-12 – Has roles in innate immune cell functions. Low levels of vitamin B-12 will lead to a slow adaptive immune response (e.g., a delayed hypersensitivity response and delayed T-cell production). The top food sources of vitamin B-12 include animal products or methylcobalamin supplements if you avoid animal products.
4. Vitamin C – protects against free radicals produced when pathogens are killed by immune cells. Vitamin C also helps regenerates other important antioxidants, such as glutathione and vitamin E to their active state [9]. And since vitamin C also supports collagen synthesis, it thereby supports the integrity of epithelial barriers, a part of the innate defense mechanism? Vitamin C also stimulates the production, function, and movement of innate immune cells. Low levels of vitamin C will lead to Increased oxidative damage, increased risk of infection and severity of disease, and decreased protection against allergies, wound healing, and cancer. The top food sources of vitamin C include citrus fruits, red peppers, berries, broccoli, potatoes, and brussels sprouts.
5. Vitamin D – Stimulates immune cell production and proliferation and helps protect against infections with antimicrobial proteins, which can directly kill pathogens. Low levels of vitamin D will lead to Increased susceptibility and severity of infections, especially respiratory tract infections, and increased risk of autoimmune diseases like type 1 diabetes, multiple sclerosis, systemic lupus, rheumatoid arthritis, as well as overall mortality. The best vitamin D source is through skin exposure to the sun’s UVB rays at peak sunshine hours or via supplementation with 2000IU of vitamin D daily when there is no regular skin sun exposure.
6. Vitamin E – A crucial fat-soluble antioxidant that protects the cell membranes from free radical damage. Low levels of vitamin E is relatively rare but will lead to impaired immune function. The top food sources of vitamin E on a plant-based diet include seeds, wheat germ, nuts, beets, red peppers, and spinach.
7. Folate – Maintains innate immunity. Low folate levels will lead to a depressed adaptive immune system with delayed response to allergies and infections. The top food sources of folate include all legumes, foods from the broccoli family, and leafy green vegetables.
8. Iron – Involved in the process of killing bacteria through the generation of free radicals that kill pathogens. Low levels of iron will lead to insufficient immune response. The top food sources of iron on a plant-based diet include spinach, legumes, seeds, and quinoa.
9. Selenium – Essential for the function of selenium-dependent enzymes that can act as antioxidants potentially counteracting free radicals. Low levels of selenium will lead to lowered immune function, higher susceptibility to viruses, increased cancer rates and with chronic deficiency, also to cardiomyopathy, a chronic disease of the heart muscle, and in infants, deficient will cause respiratory infections. The top food source of selenium on a plant-based diet is Brazil nuts, and when grown in soils rich in selenium, also broccoli, garlic, and onions.
10. Zinc – is an antioxidant mineral that protects against free radicals [9], and increases adaptive immune cell production, and maintains skin and mucosal membrane health. Low levels of zinc will lead to low lymphocyte number and function, particularly T cells, and contribute to oxidative stress, inflammation, increased infections, and respiratory disease death. The top food sources of zinc include whole grains, legumes, and nuts.
11. Protein – a very important building block for antibodies and immune cells and supports wound healing. The top food sources of protein on a plant based diet include all legumes, whole grains, seeds and nuts. L-lysine has been shown to be particularly supportive of immune function against viruses.
12. Probiotics – when you have any sort of imbalance in your gut microbiome, your immune system is affected, especially since your digestive system can’t extract all the necessary nutrients from all the different types of foods you consume. Therefore, probiotics will enhance immune function. But these should be taken with care when the immune system is fragile or when suffering from cancer.

It is important to note that supplementation recommendations are different for each life stage that the person is in. 

Nutritional needs differ between infants and small children, adolescents and adults, the elderly, pregnant and lactating women, and people with disease states as through different life stages; the immune system undergoes many changes.

Therefore, a specifically tailored supplementation program based on each age group’s specific needs and condition is essential in allowing optimal immune function at any age and reducing the risk and severity of infection, and supporting a quicker recovery from many disease states. 

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References:

[1] Calder PC. Feeding the immune system. Proc Nutr Soc. 2013 Aug;72(3):299-309. doi: 10.1017/S0029665113001286. Epub 2013 May 21. PMID: 23688939.

[2] Maggini S, Pierre A, Calder PC. Immune Function and Micronutrient Requirements Change over the Life Course. Nutrients. 2018;10(10):1531. Published 2018 Oct 17. doi:10.3390/nu10101531