We are continuing our journey in the skills’ section of the functional nutrition matrix by exploring how tending to core basics has an effect on our immune balance. And today it’s time to talk “Nutrition”!
We’ll do that by touching on the interrelation between nutrition status and immune function as well as microbiota and immune function, looking at some of the most important nutrients for the immune system and finally going through “immune villains” to avoid, and “immune heroes” to load up on!
In these weeks of emergency due to the spread of the Covid-19, together with hand-sanitisers, protective masks, disinfectants and toilet paper, we have seen “immune boosting” supplements, such as vitamin C, disappear from the shelves of supermarkets and health food stores.
And indeed, certain nutrients are fundamental for the health of our immune system. However, as I said in the introductory post Want to support your immune system? Let’s talk basics!, tending to our health in general and that of our immune system in particular through core basic diet and lifestyle behaviours comes first, and you cannot supplement yourself out of a bad diet.
So, before running to supplements (often of dubious quality), let’s look first at what we can do with our diet!
Sometimes though, diet alone is not enough to have a sufficient nutritional status- think nutrient depletion in our soils and consequently foods as well inability to digest or absorb nutrients. Only then, appropriate supplements can play a role.
Let’s look at some theory first!
If you’re not interested in the geeky part, skip to the tips in the last section: Here some tips to support your immune balance through food.
Nutritional status and immune function
The interaction between nutrition, infection and immunity is bidirectional [1]:
poor nutrition predisposes an individual to infections due to compromised immunity,
the immune response to an infection may exacerbate a poor nutritional status.
A healthy immune system is crucial to ensure optimal immune function and adequate nutrition ensures a supply of energy, micro- and macro- nutrients that are required for an optimal immune response. Unfortunately, it is widely recognised that micronutrient deficiencies are common worldwide!
An individual’s nutritional status can predict the clinical course and outcome of infections. To give a couple of examples: deficiency in zinc can increase the risk for bacterial, viral and fungal infections, particularly diarrhea and pneumonia. And low vitamin C status increases susceptibility to infections such as pneumonia, possibly because of the inability to counteract the oxidative stress observed in pneumonia due to the low anti-oxidant status [1].
So what are some of the most needed nutrients to sustain immune-competence?
Vitamins A, D, E, C, several vitamins of the B- group, minerals such as zinc, selenium, iron, essential fatty acids and antioxidants….and more.
Let’s look at a few of them in some more detail.
1) Vitamin A protects us against infection by maintaining the integrity of the epithelial and mucosal cells in our barrier systems (i.e. skin, respiratory tract, digestive tract). It is important for the functioning of cells in our innate immune system as well as for the generation of antibody response to antigen (viruses, for instance!)[1].
2) Vitamin C has powerful antioxidant properties. We are exposed to oxidants all the time, but much more when we are sick. Vitamin C protects us and our white blood cells against the oxidants produced when the immune cells kill pathogens. In addition to that, and among other functions, vitamin C also has a role in the regeneration of other antioxidants, such as glutathione (the “master anti-oxidant” in our body) and vitamin E, it promotes synthesis of collagen, which is needed for the integrity of our skin barriers – also an important part of our defense systems -, it stimulates the production, function and movement of our white blood cells, and can increase levels of antibodies [1].
3) Vitamin D is a hormone, rather than a vitamin, which is mostly synthesised in the skin upon exposure to sunlight and which has important roles in relation to our immune system. It has profound immune-modulating properties, also for as concerns modulating the immune response to infections. Epidemiological studies suggest an association between a deficiency in vitamin D and susceptibility to various pathogens [4] . Among other functions, vitamin D regulates the production of antimicrobial proteins (such as cathelicidins and defensins), which modulate immunity and which have a crucial role in bacterial infections [1,2,3] and potent anti-viral activity [2,3]. It also stimulates immune cell proliferation and helps protect against infections caused by pathogens [1].
4) Vitamin E - Vitamin E is a fat-soluble antioxidant, fundamental in stabilising the cell membrane, protecting its integrity from the damage caused by free radicals. It also enhances the activity of Natural Killer cells (cells in the innate immune system that destru other cells, i.e. cells infected by viruses) and has a role in the adaptive immune response (on the Th1 and Th2 response) [1].
5) Zinc & Selenium - Zinc and Selenium are the top 2 minerals for our immune system. They both have anti-oxidant properties, and protect us from the free radicals that are generated, for example, while we are fighting an infection. Among other functions, Zinc helps maintain our skin and mucosal barrier integrity, has a role in the cellular growth and differentiations of immune cells. Even mild zinc deficiency adversely affects the function of T-cells [5], as well as processes related to the innate immunity [6]. Selenium also influences both the innate and the adaptive immune systems. And Selenium deficiency has been linked to an enhanced viral virulence [5].
6) Essential fatty acids – Essential fatty acids have been found to have immune-regulating properties. Omega-3 fatty acids in particular have a major influence on the activation of immune cells both in the innate and adaptive immune system, because of their role in regulating the properties of the cell membrane as well as for their role as signaling molecules [7].
Microbiome and immune function
Just in recent years, our understanding about the human body and our health has been undergoing a rapid evolution thanks (among others) to discoveries about the microbiota (our gut, skin, mucosal… flora, made up of bacteria—but also fungi, viruses and parasites), and its genome, the microbiome. The microbiome is part of our defense mechanisms and can be considered to be part of our immune system.
Some of the roles of our gut flora that are related to our immune health are:
It performs a structural role in our gut (thus part of our physical barrier towards the external world),
It produces important nutrients for us,
It has a role in the development of the immune system [8,9] (the immune system needs to learn to differentiate commensal bacteria to be tolerated from pathogenic ones – commensal bacteria are part of the bacteria that coexist with the human host without causing harm. They actually play an essential role in human health)
It has a role in the initiation and propagation of infectious diseases (through the colonisation of the mucosal entry sites of pathogens) [8].
Plus, do you know that about 70% of your entire immune system is found in the Gastrointestinal tract (GI)? Time to take care very good care of our GI then!
So, what can we do to support our immune system health through our food choices?
Here are some tips to support our immune balance through food
Avoid the immune system "villains"!
The main ones are:
Nutrient-poor and inflammatory “foods” and anti-nutrients such as refined sugar, processed and refined foods in general
Alcohol
Hydrogenated and trans-fats, mostly present in processed foods
Bad quality fats (i.e. low-quality vegetable oils, fat from/in industrially farmed meats)
Foods you are allergic or sensitive to – this might be tricky: sensitivities might be hidden because they often show as delayed or chronic symptoms and are not easily tested for. If you are aware of some of your sensitivities, avoid eating those foods. This could be something to work on together with a practitioner.
Load up on anti-inflammatory, nutrient-rich, gut-loving food!
When it comes to health in general, and consequently also the health of your immune system, the single most important thing is to eat a varied, whole-, unprocessed- food, nutrient rich diet! Eat the rainbow for a variety of nutrients and bonus anti-oxidants!
NB Always remember to listen to your body and to only do what feels right for you. We are all such incredible but different individual human beings and there is no “one size fits all”. Use the following advice in a way that feels good for you!
Feed and enhance your microbiome by eating prebiotic-, probiotic- and polyphenol- rich foods: veggies, veggies, veggies, as diverse as possible in types and colours and fermented foods such as (fresh, non-pasteurised) sauerkraut, kimchi, pickles, (coconut) kefir.
Add nutrient-dense organ meats such as (chicken, beef, lamb…) liver to your diet. Liver is rich in vitamin A and iron, and can provide some vitamin D.
Eat (pasture-raised if possible, organic) eggs and (grass fed) butter or ghee– for vitamin A and some vitamin D.
Get some vitamin D and essential fatty acids from (fermented) cod liver oil and fatty fish such as wild caught salmon, anchovies and sardines.
Load up on all types of (colourful) plant foods (red, orange, yellow and green veggies) such as carrots, spinach, kohlrabi, mint, parsley, and turnip greens for extra carotenoids (and of course fibres and other micronutrients!) – Please note that carotenoids are forms of pre-vitamin A that need to be converted in the body to retinol and it’s not uncommon – or rather, it’s very common- for people not to be able to do that conversion effectively (in particular elderly, children, people with autoimmune disorders).
More fruits, veggies and spices such as papaya, (yellow, red, green) bell peppers, guavas, coriander, thyme, kale, broccoli, all types of chili peppers, Brussel sprouts, kiwi fruits, oranges, strawberries, grapefruit... for your vitamin C (and of course fibres and other micronutrients!).
You can add in some so-called superfoods for some extra vitamin C: berries such as Goji, Inca, Camu Camu, Rose hips.
Add in nuts and seeds for plant based anti-inflammatory fatty acids, fibres, minerals, some vitamins, polyphenols and as a plant-based source of proteins! Some nuts and seeds such as almonds and sunflower seeds are rich in vitamin E.
Extra-virgin olive oil and veggies such as spinach, Swiss chard, turnip, mustard, and collard greens, papaya, asparagus, bell peppers will also provide you with vitamin E.
Spice it up with kitchen herbs and spices, which may have health promoting, immune-stimulating properties! Turmeric, ginger, cinnamon, garlic, cloves, black pepper, cayenne pepper, sage, rosemary, basil, peppermint, coriander and more!
Drink bone broth or add it to your soups (NB if you can tolerate histamine!) – it has gut healing properties and it is rich in minerals, essential aminoacids, collagen and gelatin.
And never forget…drink plenty of water!
Finally, I’d love to hear from you! Have you been using the extra time at home for some more cooking? Have you been helping your immune system with food? How? I’d love to hear from you in the comments below!
Do you need personal support with your diet and lifestyle during this particularly challenging time? Book your free 20-minute phone consultation here!
References
[1] Maggini, Silvia et al. “Immune Function and Micronutrient Requirements Change over the Life Course.” Nutrients vol. 10,10 1531. (2018)
[2] Sousa, Filipa Henderson et al. “Cathelicidins display conserved direct antiviral activity towards rhinovirus.” Peptides vol. 95: 76-83 (2017)
[3] Gwyer Findlay, E., Currie, S.M. & Davidson, D.J. Cationic Host Defence Peptides: Potential as Antiviral Therapeutics. BioDrugs 27, 479–493 (2013).
[4] Lang, P.O., Aspinall, R. et al. “Vitamin D Status and the Host Resistance to Infections: What It Is Currently (Not) Understood.” Clin Ther. 39(5):930-945 (2017)
[5] Farhan Saeed, Muhammad Nadeem et al, “Studying the impact of nutritional immunology underlying the modulation of immune responses by nutritional compounds – a review”, Food and Agricultural Immunology, 27:2, 205-229 (2016)
[6] Wintergerst ES, Maggini S, Hornig DH “Immune-enhancing role of vitamin C and zinc and effect on clinical conditions.” Ann Nutr Metab;50(2):85-94 (2006).
[7] Gutiérrez, Saray et al. “Effects of Omega-3 Fatty Acids on Immune Cells.” International journal of molecular sciences vol. 20,20 5028. 11 (2019)
[8] Lazar V et al. “Aspects of Gut Microbiota and Immune System Interactions in Infectious Diseases, Immunopathology, and Cancer” Frontiers in Immunology vol. 9, 1830 (2018)
[9] Vighi, G et al. “Allergy and the gastrointestinal system.” Clinical and experimental immunology vol. 153 Suppl 1, 3-6 (2008)
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