Nutrition and Immunity

Your immune system is one of the best defenses you have against becoming ill. It is a complex and integrated system of cells, tissues, and organs. These include your tonsils (if you have them), lymph nodes and vessels, your thymus, spleen, Peyer’s patches (a type of lymph tissue in your digestive tract), even your bone marrow and, of course, white blood cells.

The three levels of defense provided by your immune system include:

Barrier protection to prevent the entry of disease-causing organisms. These include:

Skin and mucous barriers including the lining of your mouth, sinuses, throat, and digestive tract
Stomach acid and digestive enzymes that neutralize and breakdown pathogens
Beneficial bacteria that live in the lower part of your small intestines and colon (a.k.a. gut microbiota)

Innate immunity which provides general defense

Specific types of white blood cells seek out and destroy foreign invaders

Acquired immunity for specific defense. Also called adaptive immunity as this part of your immune system tailors its plan of attack using antibodies specific to the pathogen its targeting

T lymphocytes that are a type of white blood cell that destroy pathogen-infected cells, as well as pre-cancerous and cancerous cells
White blood cells called B lymphocytes that produce antibodies

Your immune system never takes a break. It works 24/7 to protect your body from infection, injury, and disease. To do this, it relies on a steady supply of nutrients for its baseline functions and more so when it ramps up disease-activity when necessary.

It’s well understood that malnutrition and/or poor nutrition, including not getting adequate high-quality protein, as well as insufficiencies in one or more micronutrients can impair immune function and response (1, 2, 3, 4).

While many vitamins and minerals are involved in maintaining a healthy immune system, the heavy hitters are vitamins A, B6, B12, folate, C, D3, and the minerals copper, iron, selenium, and zinc.

Immune-supporting nutrients

Vitamin A

Vitamin A supports mucous membranes, reinforces the barriers found in the sinuses, lungs and digestive tract that protect against pathogens where it helps to maintain the structural and functional integrity of those mucosal cells. Vitamin A also supports the production of antibodies and other immune cells, and is involved in both innate and adaptive immunity (5, 6).

Vitamin B6

Vitamin B6 supports the natural, rapid reproduction rate of immune cells. As you can imagine, your body is unceasingly fighting pathogens, seeking out and destroy damaged tissues and fighting off precancerous and cancerous cells. For this to happen, your body needs to produce immune cells at an impressively accelerated rate, and this requires lots of vitamin B6 (7).

Vitamin B6 is also needed to ensure your immune system can launch a proper immune response when prompted; pathogens can invade at any time and your immunity needs to respond in a moment’s notice.

Vitamin B12

Vitamin B12’s role in immunity is by reducing the risk for anemia. Vitamin B12 is needed for optimal hemoglobin production, the oxygen carrying pigment found in red blood cells. Those with diagnosed vitamin B12 deficiency (pernicious anemia or megaloblastic anemia) have been shown to have reduced levels of key immune cells such as natural killer cells and lymphocytes (8, 9).

Folate

Folate, or vitamin B9, is needed for DNA synthesis and the formation of new cells including red blood cells and those of the immune system. Folate deficiency can lead to megaloblastic anemia which is associated with an increased risk of infection (10). Also, an inadequate intake of folate can also result in an impaired immune response (11).

Vitamin C

Vitamin C is a potent antioxidant that helps to neutralize any excess free radicals that are produced as part of your immune system’s response to fighting viruses, bacteria, etc. Vitamin C is also needed for the production and optimal function of antibodies and white blood cells (12, 13, 14). Vitamin C’s role in helping white blood cells do their job is so important that they concentrate vitamin C between 25 and 80 times that found in the blood stream.

Vitamin D3

Vitamin D3 is finally getting the attention it deserves where immunity is concerned. Vitamin D3 is converted into a hormone called calcitriol which literally activates disease-fighting genes in your DNA. Vitamin D3 is used in the production of over 200 anti-microbial proteins such as cathelicidins (15, 16, 17).

For this reason, vitamin D3 supports your immune system’s role in reducing the risk for several cancers, as well as reducing the risk for viral-related respiratory infections. As a bonus, vitamin D3 helps to temper the over-activation of the immune system; some inflammation is good and necessary in the fight against pathogens, but too much inflammation backfires. Vitamin D3 brings balance (18).

Copper

Copper appears to play an important role although its exact mechanisms still need to be determined. It plays an important role in the development and maintenance of immune system function. Copper has antimicrobial properties, accumulates at sites of inflammation, and may play a role in the innate immune response to bacterial infections (19). Getting adequate copper is needed to balance zinc as well.

Iron

Iron is involved in hundreds of protein and enzyme activities and is required in order to mount effective immune responses to pathogens and it is well understood that iron deficiency impairs immune responses (20). Sufficient iron is crucial to several immune functions including how immune cells develop and specialize as T lymphocytes.

Selenium

Selenium has long been known to have anti-viral properties by interfering with viral reproduction. Selenium is also part of a potent-antioxidant, glutathione, that helps to lower any potential immune-related excess inflammation that’s part of the immune response. Selenium deficiency impairs features of innate and adaptive immunity affecting both antibody production immune cell-to-cell communications (21, 22, 23).

Zinc

Zinc is tricky in that there are no reliable bodily stores of zinc like there are with other minerals such as calcium, iron, phosphorus, etc., so getting a daily supply is important to maintain the integrity and function of the immune system. Therefore, an inadequate intake will easily lead to a functional zinc deficiency and impair immunity including response, antibody production and function. Zinc is needed for the growth and development of immune cells in both the innate and acquired immunity and is also needed for antibody production (24, 25, 26, 27).

Protein

The body’s essential functions, including immunity, rely on both adequate amounts of protein and energy. If protein and calories are in short supply, susceptibility to infections increase (28).

Various forms of protein-energy malnutrition is a common nutritional problem in vulnerable populations such as young children and the elderly (29). Inadequate protein can impair immune function and negatively affect immune-related barriers increasing the risk of infections of the respiratory, gastrointestinal, and urinary tracts (30).

Not only that, an inadequate intake of energy and high-quality protein impairs other key parts of the immune system such as the lymphoid tissues, including your spleen and lymph nodes (31).

Getting more immune-loving nutrients into your diet

Getting the necessary nutrients needed for optimal immunity is the first step and that can only happen on a foundation of nutrient-dense foods.

By focusing on minimally-processed foods such as meats, fish, eggs, dairy, nuts, seeds, legumes, and 100% whole and/or intact grains will ensure you’re getting good quality protein, energy and the key nutrients outlined in this article.

Eggs in particular are a great source of several of these nutrients such as vitamins A, folate, vitamin B12, iron, selenium, zinc and high-quality protein

Your immune system protects you against infection and disease. To be there for you, you need to feed and nourish the very cells, tissues and organs that rely on a steady supply of nutrients to be their best.

What you eat and drink does matter. Eating more nutrient-dense foods is the foundation to nourishing your immune system and overall health; by doing so, you’ll help build your resistance against infection and disease.