Quite a few people have been asking me lately what they can do to improve their immunity (it’s a particularly frosty winter over here in the UK!). Some feel they experience it more so than others, but I’m sure many of us go through phases where we feel like we just can’t shake that cough or sniffle. Just about any little stress seems to set off another round of a cold.
This blog post isn’t going to tell you to take a whole bunch of supplements. For some individuals, some supplementation is warranted, however it’s not something that can easily be discussed on a general basis. I’m going to talk about eating to support your immune system from a broader, dietary perspective. Where possible, getting our nutrients from natural, whole foods is usually the best place to start!
In this blog post I’m going to give you an overview of some of the key nutrients that contribute to a healthy immune system, and some of the foods you can find them in.
Your immune system is a complex, multi-layered organisation, like an army with various divisions. It’s got different types of battalions for different stages of attack and defence. Very basically, we can divide the immune system into two main parts; innate immunity (also called non-specific immunity), and adaptive immunity (also called specific immunity).
- The innate immune system encompasses our body’s general defence mechanisms that aim to protect us against anything ‘foreign’. This includes physical barriers like our skin, and chemical barriers like certain components of blood and saliva. Some of our white blood cells (mainly ‘neutrophils’ and ‘macrophages’, and others) are also part of the innate immune system.
- The adaptive immune system is the ‘specialised’ arm. It develops different cells to act against different diseases/infections. The main cells that make up the adaptive immune system include T cells and B cells (which are are type of white blood cell called a lymphocyte). B cells make ‘antibodies’ in response to infections. Antibodies are like unique weapons, designed to target a specific intruder.
I’ve picked out three key minerals and three key vitamins that are involved in nourishing a healthy immune system. Below is a little summary, and some of the food sources where you can find these nutrients in reasonable quantities.*
Zinc: Zinc is a mineral involved in numerous aspects of cell metabolism, protein and DNA synthesis, and it also plays a key role in immune function. Adequate zinc intake facilitates the proper functioning of certain immune system cells – including our innate system T cells and other lymphocytes (including our special “natural killer cells“; yes that’s really their name!). You can find zinc in oysters (very high), shellfish, meat, eggs, and nuts and seeds. Pumpkin seeds are one of the best plant-based sources, but also try sunflower seeds, cashews, almonds, pine nuts and tahini (sesame paste).
Copper: Copper is an essential trace mineral that facilitates bodily processes like energy production, connective tissue formation, and iron metabolism. Our immune system needs copper to help produce immune cells including T cells and neutrophils. Copper deficiency can impede the production and effectiveness of these immune cells. Great news – an excellent source of copper is dark chocolate! Choose a quality dark chocolate and have about 30 grams (so just a few squares). You can also find copper in almonds, lentils, beef liver and dried apricots.
Selenium: Selenium is another essential trace mineral in the body; it’s one that’s particularly important for the function of certain antioxidant enzymes. Selenium deficiency can decrease our ability to resist infection because it can reduce the production of immune system cells and antibodies. One of the easiest sources of selenium is Brazil nuts. You only need 2-3 nuts to meet your recommended daily intake for selenium – amazing! Selenium can also be found in eggs, yoghurt, tuna, sardines and other fish, and sunflower seeds.
Vitamin C: Yes, vitamin C is actually helpful for immunity, among other things! One of those things you always hear with some truth to it. Adequate vitamin C intake is associated with better resistance to, and recovery from, a number of common infections. This is particularly true when vitamin C is paired with adequate zinc intake. Vitamin C supports the innate and adaptive immune response, and it’s also a powerful antioxidant (fights off free radicals). Good sources of vitamin C are your citrus fruits, berries, kiwifruit, peppers/capsicum and broccoli.
Vitamin D: Vitamin D plays so many incredible roles in the body, including in our immune system. A number of immune system cells have vitamin D receptors on them. So, active vitamin D plays a direct role in modulating the immune system response; it beefs up the immune response when needed, but also helps to calm it down when it’s not. Vitamin D deficiency is associated with increased susceptibility to infection. Vitamin D is actually pretty hard to source from food. Mother nature has instead gifted us with a free source – sunshine! The best bet is to get a reasonable, safe amount of time in the sun. If you live in a climate which doesn’t allow this easily, speak to your doctor or nutrition professional about whether a supplement may be right for you. Oily fish, cod liver oil and egg yolks provide some vitamin D.
Vitamin E: Vitamin E is another fat soluble nutrient that is a valuable antioxidant in the body. These antioxidant capabilities make it important to our immune system too. Increased vitamin E intake has been shown in population studies to be associated with better resistance to certain infections, especially in older people. Vitamin E-rich food sources include almonds, sunflower seeds and hazelnuts. Moderate amounts are also found in peanuts/peanut butter, cooked spinach, and avocado.
These are NOT the only nutrients that you need to support a healthy immune system. They’re just some of the big hitters that have been studied and that we know play a role in building and maintaing our immune system. But these nutrients work optimally when they’re supported by a balanced, varied diet that also supplies all of the other nutrients our body needs as a whole. (i.e. Eat enough of the macro-nutrients protein, fat, carbohydrates; and the other micro-nutrients being all of the essential vitamins and minerals).
*The food sources I have suggested are not the only sources of these nutrients in the diet; it’s a non-exhaustive list. If you’d like some more information as to where you can source these nutrients, I quite like the Dietitians of Canada website which has great fact sheets. For vitamin fact sheets click here. For minerals fact sheets click here.
In addition to consuming some (or all!) of the foods above so you get in those important immune-supporting nutrients, here are three quick lifestyle tips to keep you feeling well.
- Eat enough. When you are under-nourished, your immune system will suffer. Enjoy balanced, wholesome meals and have complex carbohydrates, good fats and some protein everyday. Rushing around hungry, having a tiny vegetable juice for breakfast, skipping meals…you’ll be the first to get sick.
- Eat a varied diet. Your immune system doesn’t act independently of other bodily systems. And your body thrives when you feed it an array of macro-nutrients, micro-nutrients and phytochemicals (plant-derived chemicals that can have a beneficial effect on the body). Eating a varied, colourful diet is the smart way to make sure you’re covering everything off. Eat the rainbow!
- Support your diet with enough sleep. Sleep is essential to support your immune system. When you are overtired, your defences will go down. Recent studies have indicated sleep-deprived people are more susceptible to catching a virus or recover from one. Ideally, aim to get 7-8 hours of sleep a night. Try to get into a routine of going to bed at the same time each night, and put away that mobile phone!
What are your favourite immune-boosting practices? Do you have little tips and tricks like a homemade chicken soup? Share your ideas! x