In Part 1 of this series, I covered the critical role that nutrition plays in quelling Lyme disease-associated inflammation. In this post, I am going to cover the importance of nutrition for optimal immune function, an essential factor for anyone recovering from Lyme disease.
An overview of the immune system
The immune system is a complex, integrated system of cells, organs, and tissues that protect the body against infection and disease. It must perform the critical role of recognizing foreign invaders, such as bacteria, viruses, and parasites, and destroy them without harming your own body in the process.
The immune system consists of two branches: Innate immunity and adaptive immunity. The innate immune system involves immediate, nonspecific responses to pathogens. It is mediated by the complement system, a biochemical network of proteins that kill invading pathogens; acute-phase proteins and cytokines, which are chemical messengers that regulate the immune response; and phagocytic cells, which “eat” invading pathogens. The innate immune system also includes anatomical barriers to infection (e.g., skin), chemical barriers (e.g., stomach acid), and biological barriers (e.g., the commensal gut microflora).
Adaptive immunity, on the other hand, is the second line of defense against pathogens that involves antigen-specific responses. In adaptive immunity, exposure to a specific pathogen stimulates the production of B lymphocytes and T lymphocytes, which are immune cells that create antibodies. Antibodies are proteins that recognize and bind to foreign proteins or pathogens and target them for destruction. T lymphocytes can also directly attack and destroy cells that have been invaded by pathogens, as well as suppress an overactive immune response.
Specific nutrients are needed to support innate and adaptive immunity and protect the body against infection. These same nutrients can also help the immune system in its fight against existing infections such as Lyme disease. Your immune system requires a handful of nutrients for carrying out its pathogen-fighting activities – vitamin A, vitamin D, vitamin C, vitamin B6, selenium, zinc, iron, and omega-3 fatty acids. In this post, I focus on food sources of each of these nutrients. However, in some cases, supplementation may be required for a period of time to rectify a severe nutrient deficiency. I always recommend doing blood testing before embarking on any treatment protocol that involves nutrient supplements, as high doses of isolated vitamins and minerals can create nutrient imbalances in the body. You can learn more about the laboratory tests I offer through my clinical nutrition practice for assessing nutrient status in the “Work With Me” section at the end of this article.
Nutrients that support immunity
Vitamin A and its metabolites play crucial roles in both innate and adaptive immunity. It helps to maintain the integrity of skin cells and mucosal cells of the gastrointestinal tract, which function as barriers to infection. Vitamin A is also essential for the normal function of natural killer (NK) cells, macrophages, neutrophils, and B and T lymphocytes. Vitamin A deficiency increases susceptibility to infection and promotes dysregulation of T lymphocytes, which causes chronic inflammation. (1)
Pre-formed vitamin A (retinol) is the most bioavailable form of vitamin A. It is found only in animal foods. Carotenoids, while often referred to as "vitamin A," are phytonutrients that must be converted into active vitamin A in the body. The conversion of carotenoids into vitamin A is slow and inefficient in many people, necessitating the intake of vitamin A-containing animal foods.
Food sources of vitamin A and carotenoids:
- Pre-formed vitamin A: Egg yolks, salmon roe, beef liver, grass-fed dairy
- Carotenoids: Pumpkin, carrots, peppers, squash
Vitamin D is a potent modulator of the immune system. It binds to vitamin D receptors on multiple types of immune cells, including monocytes, macrophages, dendritic cells, and T lymphocytes, thus regulating the activities of the immune system. (2)(3)The active form of vitamin D, 1,25 dihydroxy vitamin D3, also regulates two important antimicrobial peptides, cathelicidin and defensin. (4)(5)These proteins are our bodies' own natural "antibiotics." Optimizing vitamin D status is vital for maintaining a robust immune system.
The consensus in the functional medicine community is that we should try to get 4,000 to 5,000 IU of vitamin D3 per day. It is not possible to achieve this intake solely with diet; while you can supplement with oral vitamin D, I recommend that my clients also increase their sun exposure, as sunlight is the most important route by which our bodies obtain vitamin D. See my recommendations below on how to safely increase your sun exposure to optimize your vitamin D level.
How to optimize your vitamin D status:
- Eat foods that contain vitamin D3: Egg yolks, beef liver, fatty cold-water fish
- Get more sun exposure: Sun exposure triggers the production of vitamin D via the skin. It is estimated that our hunter-gatherer ancestors made approximately 4,000 to 5,000 IU of vitamin D3 per day solely through sun exposure. This may not be attainable for many people in the modern-day world, due to our indoors-oriented lifestyles. However, you can still optimize your body's production of vitamin D by being smart about sun exposure. I recommend that my clients use the D Minder app to determine how much sun exposure they should aim for to maintain vitamin D sufficiency. The app uses several data points, including your location, your skin type and body weight, and the amount of time you spend outside, to determine how much vitamin D3 you can make on any given day. If you are falling short of your vitamin D requirement, the app provides you with tips on when to get outside and for how long, so that you can increase your vitamin D level.
Vitamin C is a potent antioxidant that protects the body's cells against reactive oxygen species, which are produced by immune cells to destroy pathogens. An excess of free radicals is detrimental to the immune system, so the reduction of free radicals is important for improving immunity. Vitamin C also stimulates the production and activity of immune cells, including neutrophils, lymphocytes, and phagocytes. (6)
Food sources of vitamin C
Broccoli, Brussels sprouts, peppers, strawberries, citrus fruits
Vitamin E is a fat-soluble vitamin with antioxidant properties. It protects cell membranes from lipid peroxidation, a destructive process that promotes an improper immune response. Vitamin E deficiency impairs B and T lymphocyte function and increases susceptibility to infection. (7)
Food sources of vitamin E
Sunflower seeds, almonds, hazelnuts, avocado, red palm oil, olive oil
Vitamin B6 is involved in the synthesis and metabolism of amino acids in the body. Amino acids serve as the building blocks for many components of the immune system, including cytokines and antibodies. Vitamin B6 deficiency impairs adaptive immunity; (8) correction of B6 deficiency effectively restores immune function.
Food sources of vitamin B6
Beef liver, tuna, summer squash, bananas, plantains, pistachios
Selenium is a unique nutrient that functions as a cofactor for glutathione peroxidase, an antioxidant enzyme that neutralizes harmful free radicals. Selenium also regulates the production of cytokines and eicosanoids (signaling molecules derived from polyunsaturated fatty acids) that orchestrate the immune response. (9) Selenium deficiency impairs innate and adaptive immunity and increases the virulence of some viruses.
Food sources of selenium
Brazil nuts, salmon, tuna shrimp
Zinc is crucial for the normal development and function of cells that regulate innate and adaptive immunity. Zinc deficiency impairs the complement system, reduces the activity of natural killer cells, neutrophils, and macrophages, and impairs the ability of immune cells to generate compounds that kill invading pathogens. (10)T lymphocytes are especially susceptible to zinc deficiency. Replenishment of zinc stores promotes the healthy development and function of immune cells and boosts immunity.
Food sources of zinc
Oysters, liver, beef, lamb, chicken, pumpkin seeds, and cashews.
Iron is an essential component of many proteins and enzymes, including those involved in oxygen transport, cellular energy production, and DNA synthesis. Iron deficiency impairs the immune response. (11) However, too much iron also poses a problem for the immune system because iron is required by many pathogens for replication a survival. In fact, iron sequestration is a response initiated by the immune system in the early stages of infection to reduce the amount of iron available to pathogens; this is most often demonstrated by a decrease in serum iron and an increase in ferritin, the iron storage protein. I recommend that my clients obtain their iron via food, rather than supplements, due to the potential for excess iron to "feed" pathogens and increase free radical damage.
Food sources of iron
- Heme iron: Red meat, poultry, eggs
- Non-heme iron: Legumes, grains, nuts and seeds, spinach
I recommend that my clients eat animal foods because these foods are a source of heme iron, the most bioavailable dietary source of iron. Non-heme iron, found in plant foods such as spinach, nuts, and seeds, is far less bioavailable to the body due to the presence of compounds called phytates, which occur naturally in many plant foods and inhibit iron absorption
Omega-3 fatty acids (EPA and DHA)
Omega-3 fatty acids modulate the immune response by enhancing signaling between immune cells and improving the ability of immune cells to destroy pathogens. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are the most potent omega-3 fatty acids when it comes to enhancing immunity.
Food sources of EPA and DHA
Wild-caught or responsibly-raised seafood; choose low-mercury options such as wild Alaskan salmon, herring, sardines, and oysters.
By eating a whole foods-based, nutrient-dense diet, you can provide your body with the sustenance it needs to maintain a robust immune system; this will help your body better fight infections such as Lyme disease and create a foundation for lifelong health.
Work with Me!
If you are interested in optimizing your nutrient status to assist in Lyme disease recovery, you may want to consider doing the NutrEval Plasma test, an advanced nutritional analysis designed to reveal nutritional imbalances or inadequacies that I offer NutrEval through my nutrition consulting practice. Based on the results of this test, I create a customized nutrient repletion protocol to help you optimize multiple facets of your health, including immunity. For more information about this test and my nutrition consulting services, click here.