Your immune system requires vitamins and minerals at certain levels for optimal function. A poor diet lacking in these nutrients puts you at risk. “The immune response is compromised when nutrition is poor,” write the authors of a 2018 literature review.
Not only does a poor diet dependent on processed foods fail to meet micronutrient needs, but it also includes trans fats and sugars that are known to cause oxidative stress which further depletes the micronutrients on this list that also act as antioxidants. Processed foods are also linked to excess body fat, which causes oxidative stress and depletes critical immune system vitamins and minerals like Vitamin C.
Keep in mind that the recommended daily allowances are only enough to avoid outright deficiency. For example, the Vitamin C RDA is not what is recommended for optimal function; it is what is recommended to avoid scurvy, which can cause your teeth to fall out.
Vitamin C for optimal immune health
Vitamin C is essential for the health and production of white blood cells and antibodies. It’s required to produce collagen, which strengthens the barriers in your gut and skin that are important parts of your innate immune system. The water-soluble vitamin is also a powerful antioxidant that mitigates damage inflicted by oxidative stress that can suppress the immune system.
Vitamin C is one of the most commonly supplemented nutrients, however, most common oral forms are difficult to absorb. The sugar added to numerous supplements, particularly gummies, directly interferes with Vitamin C absorption and exacerbates the need for Vitamin C.
The RDA is 75mg/day for women and 90mg/day for men. A single orange meets this demand. However, many experts warn that this RDA is outdated and not nearly enough for optimal function. The National Institutes of Health lists smokers, people with “limited food variety” (including, “some elderly, indigent individuals who prepare their own food; people who abuse alcohol or drugs; food faddists; people with mental illness; and, occasionally, children”) and people with severe malabsorption.
Vitamin C is heavily concentrated in many fruits and vegetables, so if you eat several servings of produce you have little risk of scurvy. Bell peppers, broccoli, guava, strawberries, kiwis, papaya, and oranges contain substantial Vitamin C.
Supplementing Vitamin C can be tricky due to absorption challenges, which is why we made the first liposomal vitamin C. While Vitamin C is the most well-known nutrient for immune health and is available in large doses in supplements marketed for immune system support, your body cannot efficiently absorb the amounts listed on the labels. These supplements often contain more sugar than they do Vitamin C. Liposomal Vitamin C or using sodium ascorbate powder to bowel tolerance are better options.
Vitamin D: Low levels correlated with autoimmune disease and respiratory infections
Vitamin D is critical to immune function, including stimulating production of certain immune cells and regulating certain antimicrobial proteins. Numerous reports indicate that lower circulating levels of the vitamin correlate with incidence of respiratory infection.
“One report studied almost 19,000 subjects between 1988 and 1994. Individuals with lower vitamin D levels (<30 ng/ml) were more likely to self-report a recent upper respiratory tract infection than those with sufficient levels,” writes Cynthia Aranow, MD, in her 2012 investigation Vitamin D and the Immune System. “Another cross-sectional study of 800 military recruits in Finland stratified men by serum vitamin D levels. Those recruits with lower vitamin D levels lost significantly more days from active duty secondary to upper respiratory infections than recruits with higher vitamin D levels,”
Vitamin D deficiency is also linked to occurrence of autoimmune disease.
A NHANES study examining 4,962 who had been hospitalized in 2011-2012 found that 40% of their subjects were Vitamin D deficient. The groups that had the highest rates of Vitamin D deficiency were obese, smokers, and African-Americans. Because much of our Vitamin D is produced in the skin by exposure to sunlight and “pigmentation reduces vitamin D production in the skin,” people with darker complexions are also more prone to Vitamin D deficiency.
In the NHANES study, subjects who reported daily consumption of fortified milk products had lower rates of Vitamin D deficiency, indicating that the effort to combat rickets beginning in the 1930s is effective in helping to avoid deficiency. The fortification of dairy is helpful for those who can consume these products without allergic or digestive reactions. You can find Vitamin D in significant amounts in cod liver oil, sardines, salmon, mackerel, eggs, and tuna and in small amounts in mushrooms. Functional medicine doctor Will Cole emphasizes that since Vitamin D is fat-soluble, it should be paired with healthy fats for maximum bioavailability.
Even with the fortification, suboptimal levels of Vitamin D are widespread. “Vitamin D intake is usually inadequate in most age groups worldwide, even in countries with mandatory food fortification,” writes Dr. Aranow. According to Dr. Cole, “Because of our society’s fear of fat and the fact that the amount of vitamin D your body actually needs is a lot, it can be nearly impossible to get enough from food alone. Couple that with the fact that most of us don’t spend enough time in the sun, supplementation of vitamin D is almost always necessary.”
Vitamin D is easy to find as a supplement. The D3 form is biologically active. Some recommend using a D3 supplement that also contains Vitamin K2.
Vitamin A for immune system cell production
While best known for its support of vision, Vitamin A is critical for the formation of cells in the epithelium that lines the outer and inner surfaces of our body, thereby, serving as the “front line of defense against pathogen invasion.” As an integral part of the mucus in the respiratory and intestine, “it improves the antigen non-specific immunity function of these tissues.” Vitamin A supports the production and maturation of various critical immune cells, and “research has shown that crucial immune organs need constant dietary intake.”
Vitamin A deficiency is rare in the United States and most developed countries, but is common in developing nations. It is one of the leading causes of preventable blindness in children around the world. Vitamin A occurs in a wide variety of foods, not even just the most nutrient-dense healthy options. You can get over 50% of your daily value from a slice of pumpkin pie. Vitamin A is found in just about everything, including carrots, mangos, butter, cheese, beef liver, salmon, and eggs. Because it occurs in so many dietary staples, people in developed countries with access to these foods are unlikely to develop Vitamin A deficiency.
Vitamin E to support white blood cells and act as an antioxidant
Vitamin E is a critical fat-soluble antioxidant. While Vitamin C scavenges free radicals in water-based tissue, Vitamin E works in fat-based regions of the body to prevent oxidative stress and the cascading damage that it causes. Several studies indicate that Vitamin E supports certain types of white blood cells as well as the dendritic cells that act as messengers in the immune system.
According to the NIH, frank Vitamin E deficiency is rare. However, people adhering to low-fat diets may have suboptimal levels. Vitamin E occurs in high levels in vegetable oils, nuts, and seeds. You can also find it in fruits like avocado, mango, and kiwi, and vegetables including red bell peppers, butternut squash, and broccoli.
Vitamin B6 for antibody production
B6, which turns into pyridoxine and pyridoxal 5’-phosphate (PLP) in the body, supports the production of antibodies. And when you’re deficient, that production as well as growth and activity of certain white blood cells is compromised. B6 is also a requirement to absorb another critical immune system nutrient, B12.
A NHANES study from 2004 found a 40% deficiency rate among young adult women sampled in the United States. Other commonly deficient groups included male smokers, African-American men, and people over 65.
Using certain medications — including antibiotics, loop diuretics, oral contraceptives, and hormone replacement therapy — are known to deplete B6. Physical inactivity and poverty are correlated with low B6 levels.
The most B6-dense whole foods include salmon, chicken, pork chops, beef, sweet potatoes, bananas, avocados and pistachios.
Because so many medications deplete Vitamin B6, some people may benefit from supplementation. Look for the Pyridoxine HCI form, preferably in a liposomal formulation for maximum bioavailability.
Folate for optimal immune response
Researchers have found that clinical folate deficiency “results in impaired immune responses.” Part of this impairment could be due to the reduction in circulating levels of certain types of immune cells that require folate for proliferation.
You need folate to regulate levels of homocysteine, a product of protein metabolism that can become dangerous and cause oxidative stress that suppresses the immune system.
Frank folate deficiency is rare due to mandatory fortification that’s been in place for decades since the importance of the nutrient in pregnant women was confirmed. However, marginal folate status is still a concern as several lifestyle factors can deplete folate even when you consume adequate amounts.
Numerous medications — including acid blockers, antacids, antibiotics, anti-convulsants, anti-inflammatories, potassium-sparing diuretics, hypoglycemics, oral contraceptives, hormone replacement therapy — deplete folate. Conditions like celiac disease and the MTHFR gene mutation interfere with folate absorption. Obesity, alcohol consumption, and smoking are all associated with depleted folate.
Folate is found in many plant foods, including edamame, lentils, asparagus, spinach, broccoli, avocados, mangos, lettuce, sweet corn, and oranges. It’s also included in just about every pre-natal supplement and is part of the fortification in grains. The factors that cause depletion and malabsorption may make food sources fall short, and supplementation could be necessary. Look for a B complex supplement — since folate depletion is often accompanied by low levels of B12 and other B vitamins — that includes a methylated folate, preferably in a liposomal form for superior absorption.
B12 for active immune system cells
In addition to its work in tandem with folate to control homocysteine levels, studies show that B12 deficiency leads to fewer and less active immune cells. B12 injections have successfully restored those cells.
B12 deficiency occurs in 1.5–15% of the general population, according to the National Institutes of Health. Stomach acid extracts B12 from proteins in food, so older adults (as stomach acid declines with age) and anyone taking acid blockers (proton pump inhibitors, etc.) is prone to deficiency by malabsorption. Gastrointestinal surgery that removes part of the stomach interferes with B12 absorption pathways, as do gastrointestinal conditions and pernicious anemia. Most of the common medications that deplete folate also deplete B12. Perhaps the most publicized at-risk group for B12 deficiency is vegans due to the lack of naturally occurring B12 in foods that are not derived from animals.
Like folate, B12 is commonly supplemented. Because its best known role is supporting cellular energy production, B12 is found in ludicrous quantities in energy drinks. While a B12 overdose is not possible, taking 3000% of your daily value in a sugary beverage is not going to give you a megadose of B12 since it won’t be absorbed. Sub-lingual or liposomal B complex supplements that include B12 are better options.
Zinc for white blood cells and more
According to a 2003 article in The Journal of Nutrition, even mild deficiency depresses immune system capabilities. Low zinc levels impair certain types of white blood cells and bacteria-fighting cells. However, too much zinc can also suppress immune system capabilities, even causing the death of some immune cells in the same manner as too little zinc. The mineral functions as an antioxidant, and clinical research shows that supplementation decreases the biomarkers of oxidative stress.
Zinc deficiency is common in the developing world due to lack of dietary intake and the co-ingestion of phytates in legumes, nuts, and seeds that interfere with zinc absorption. This interference, along with the lack of ingestion of meat that has the most bioavailable zinc, is why the NIH says that “vegetarians sometimes require as much as 50% more of the RDA for zinc.” They recommend preparing food using techniques that increase bioavailability (ability for your body to absorb and use the nutrient) of zinc in plant foods like soaking beans, grains, and seeds in water for hours before cooking, as well as eating leavened bread products.
Digestive conditions that lead to malabsorption are also risk factors. According to pharmacist Suzy Cohen, zinc and Vitamin A deficiencies can often lead to one another, so keeping both nutrients at optimal levels is key. She also lists numerous common medication classes that deplete zinc, including acid blockers, antacids, antivirals, blood pressure drugs, cholesterol agents, corticosteroids, hormone replacement therapy, and oral contraceptives. Other lifestyle factors like caffeine consumption, excessive calcium supplementation, and smoking deplete zinc.1
Zinc levels decline with age and researchers report that even in developed countries, nearly 30% of elderly people are deficient in zinc.
The best food sources of zinc are those that make the mineral bioavailable, and do not include the phytates that bind to zinc and prohibit absorption. Oysters have by far the highest concentration of zinc. More practical sources include shellfish, red meat, chicken, pork chops, lentils, hemp seeds, and chickpeas. Just remember that you may need more of plant-based sources to make up for the phytate interference.
Zinc is found in numerous immune supporting supplements, as well as multivitamins and complexes like our liposomal B Complex Plus.
Selenium for normal immune response
Some of the most important white blood cells in the immune system require selenium to proliferate in response to threats. Some studies suggest that deficiencies in selenium — as well as zinc and other nutrients — exacerbate the immune system suppression from stress due to chronic disease. “Adequate levels of Se are important for initiating immunity, but they are also involved in regulating excessive immune responses,” write the authors of a review on the topic.
Selenium is a powerful antioxidant that can mitigate the damage of excessive free radicals that leads to oxidative stress, which is associated with premature aging. “Adequate dietary selenium is essential for the activity of virtually all arms of the immune system. It is particularly significant that supplemental selenium can improve immune function in British individuals who consume diets that are considered adequate by World Health Organization (WHO) criteria but do not meet the British Recommended Daily Intake,” write the authors of an article in the Journal of Nutrition.
Worldwide, researchers say that selenium deficiency affects 500 million to 1 billion people due to low dietary intake. Selenium content from plant sources is dictated by selenium content in the soil, which varies by region. In the United States, even people in the regions with the lowest soil selenium do not often have deficiency as food transport serves these lower selenium regions. Indeed, the NIH says that even North Americans living in areas where soil is low in selenium consume the RDA of this mineral. Selenium deficiency is common in China where diet is mostly vegetarian and consists of plants grown in selenium-deficient soil.
Brazil nuts, eggs, sunflower seeds, beef liver, tuna, chicken, salmon, chia seeds, and mushrooms are solid sources of selenium and eating moderate portions of these foods will cover your selenium needs.
1Cohen, Suzy, RPh. Drug Muggers: Which Medications Are Robbing Your Body of Essential Nutrients—and Natural Ways to Restore Them. Rodale, 2011.