Essential Nutrients For Immunity
A well-functioning immune system is vital when it comes to protecting yourself against getting sick, and nutrition plays a big role in this. Certain nutrient deficiencies can impair your immune system, increase your susceptibility to infection and increase the severity of illness [1]. A healthy diet helps to improve your immune function by providing essential nutrients, reducing inflammation and oxidative stress, and promoting a more diverse gut microbiome.
Vitamin D
Vitamin D is a powerful immunomodulator that regulates your body’s immune function. It also enhances the expression of antioxidant-related genes and improves cellular immunity. Around 1 in 4 Australian adults are vitamin D deficient. I recommend getting 20 minutes of direct sunlight during the safe hours (2 hours after sunrise or before sunset) on exposed face, shoulders, arms & legs daily. During the winter months, it’s a good idea to take a daily supplement and get your levels checked.
Zinc
Zinc is incredibly important for the immune system as it functions as an essential co-factor in many immune dependent responses. It’s also an antioxidant and protects against oxidative stress as a result of immune activation. Zinc is also a powerful antiviral in itself and exhibits antiviral activity against at least 40 different viruses. Include lots of zinc-rich foods into your diet - quinoa, oats & other whole grains, tofu, tempeh, beans, chickpeas, pumpkin, sunflower & hempseeds, walnuts, cashews & almonds, and tahini. I also recommend getting your zinc levels checked and supplementing with the help of a practitioner if your levels are low.
Vitamin C
Vitamin C has many important immune roles including functioning as an antioxidant to reduce oxidative stress as a result of immune activation; stimulating the production of interferon, which is a protein that inhibits viral replication; stimulating monocyte movement to infection site; influencing lymphocyte proliferation, natural killer cell & neutrophil activities; and regenerating vitamin E [2]. When we are sick or under stress, our vitamin C levels rapidly deplete, meaning we may have an increased requirement for vitamin C. Include plenty of fresh fruit and veggies into your diet, especially oranges, kiwi fruit, capsicum, strawberries, tomatoes, broccoli, cabbage, kale, spinach and parsley. Vitamin C is volatile to light and heat, so the fresher the produce the better. Eating seasonally, growing some of your own veggies and eating raw or minimally cooked veg is ideal. Vitamin C supplementation can be beneficial in times of increased need, such as when you are sick or chronically stressed.
Quercetin
Quercetin is a polyphenol found in plant foods that has antioxidant and anti-inflammatory properties and helps to support healthy immune function. [3]. Include an abundance of quercetin-containing foods into your diet such as citrus fruits, berries, grapes, apples, onions, parsley, tea & olive oil. Supplementing with quercetin may be beneficial in supporting your body’s immune response.
Vitamin A
Vitamin A plays an important role in immunity through it’s immunomodulating properties. Deficiency is associated with reduced function of immune cells and impaired antibody responses [2]. Vitamin A is also required for healthy mucous membranes, which is our first line of defence against pathogens. Include lots of vitamin A foods in your diet. Vitamin A is found in animal foods, however your body can produce vitamin A from carotenoids found in plants. Foods rich in carotenoids are: sweet potato, pumpkin, carrots, kale & capsicum.
Selenium
Selenium is a trace mineral that is found in large amounts within the spleen and lymphatic system. Selenium plays an important role in influencing both innate and acquired immunity, therefore a deficiency can affect both of these. Include plenty of selenium-rich foods into your diet. Brazil nuts are one of the best sources but other great sources include animal products, whole grains, beans, mushrooms, sunflower seeds, oats & spinach.
Essential fatty acids
Omega 3 is a gatekeeper of immune cell regulation and is required for immune cell activation. It’s recommended to include 3 portions of wild-caught oily fish per week to achieve optimal omega 3 levels. If you are plant-based, include lots of walnuts, hempseeds, flax seeds & flax oil. Supplementing with a good quality micro-algae supplement with EPA & DHA is also recommended.
Probiotics
Up to 70% of the immune system lives in the gut, so gut health and immune health are very strongly linked. Probiotics are known to influence a number of immune components including antimicrobial activity - reducing intestinal PH, stimulating secretion of antimicrobial peptides, inhibiting bacterial invasion and decreasing local and systemic inflammation; modulation of immune cells; barrier function & integrity [2]. Include 2-3 servings of fermented foods into your diet everyday such as yoghurt, kefir, sauerkraut and kimchi. Probiotic supplements can be beneficial but are very strain and species specific, so always good to work with a practitioner to find the right one for you.
Other considerations:
A wholefoods diet rich in fresh fruit and veg, wholegrains, legumes, nuts & seeds will ensure that you get a wide array of nutrients required for immunity. The benefit of obtaining nutrients from food rather than supplements is that in nature, nutrients often occur together in correct ratios and work synergistically to benefit your health.
Limit refined foods as these often have their nutrients stripped from them and contain added sugar. Sugar suppresses the immune system and reduces white blood cell function, which may still be evident 5 hours after sugar consumption [2].
Reduce caffeine intake, as excessive caffeine can act as a stressor to an already depleted immune system [2].
The state of the gut has a huge influence on the body’s ability to absorb nutrients. Poor gut health = poor nutrient absorption regardless of how healthy your diet is or how many supplements you take. This is best addressed with a practitioner who will take your individual case into account and formulate a treatment plan specific for you.
Chronic stress is associated with reduced immunity and also impairs your body’s ability to absorb nutrients. Practice daily mindfulness activities such as yoga & meditation.
References:
https://pubmed.ncbi.nlm.nih.gov/34168111/
Clinical Naturopathic Medicine (2019) - Leah Hechtman
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7675685/