Now more than ever, it is important that we take good care of our immune systems. By practicing good personal hygiene, getting enough sleep, exercising moderately, controlling stress levels and of course having a nutritious diet, we will be in a good place to fend of pathogens.
One of the reasons that nutritionists and dietitians always recommend a varied and balanced diet is so we get all the nutrients our immune system requires to function optimally. In this article, we are going to look at the most important vitamins, minerals and other compounds for our natural defences and outline which foods contain these.
According to the European Food Safety Authority (EFSA), 6 of the 13 vitamins have a role in immune function:
Known scientifically as retinol, we need Vitamin A to develop a healthy immune system from birth, specifically the ‘innate’ element of immunity. Innate immunity is our primary defence mechanism and consists of barriers such as our skin, mucus membranes and certain types of cells like macrophages (1).
Sources of vitamin A are plentiful in the diet. We can get pre-formed from animal products like meat, fish and dairy, while our body can also make it as required from beta-carotene, alpha-carotene and beta-cryptoxanthin. These carotenoids are found in carrots, spinach, kale, peppers and sweet potatoes.
Vitamin A deficiency in the UK is thankfully rare. In fact, there have been cases where people have actually consumed too much – something that can occur if liver is eaten more than once or twice a week. Because vitamin A is widely available, supplementing with vitamin A is not necessary for the vast majority. It is also not advised in women who are pregnant or trying to conceive (2).
In addition to key roles in metabolism and the nervous system, vitamin B6, folate (B9) and vitamin B12 are all needed for healthy immune function. As we cannot store B vitamins, we need to consume them every day.
In contrast to vitamin A which benefits innate immunity, these B vitamins have roles in our adaptive (or ‘acquired’) immunity. This is an extremely complicated and advanced element of our immune system which identifies the specific makeup of pathogens and then makes cells (such as B and T cells) to attack and neutralise them (3). The body remembers this, meaning we can deal with this pathogen much more effectively if exposed to it again in the future. An example of this in action is when we have a vaccine. A vaccine provides a tiny amount of proteins from a specific virus so we can build defences against it in preparation for future exposure.
Looking at B6 specifically, this nutrient is needed for the production of antibodies (4). So to support your immune system, consuming B6 from foods such as meat, fish, nuts, potatoes and bananas is important. Fortunately a lack of B6 in the British diet is not all that common, but if you have a poor diet a supplement would be beneficial.
With regards to folate, we need this to create DNA and RNA, the genetic coding that dictates cell function. Research has shown that a low level of folate leads to a reduction in circulating T cells, meaning the body has a harder time in fighting off viral infections (5). The best sources of folate are plant-based, with legumes, potatoes, green leafy vegetables and citrus fruits all provide high amounts. Similarly, folate is not a nutrient of concern in the UK diet generally speaking. However, supplementation of 400 micrograms per day is very important for women during conception and pregnancy to reduce the risk of neural tube defects in the fetus (6).
Despite only needing very small amounts, vitamin B12 is essential to a strong immune system. Specifically, B12 helps to activate natural killer cells and also ensures that B cells can rapidly identify and target viruses. Just like folate, B12 also has a role in DNA creation (7). A lack of vitamin B12 is commonly seen in vegetarians and vegans. However omnivores can lack B12 too, usually because of problems absorbing it. This is often seen in older adults where a deficiency is fairly common. For these reasons, B12 is a very popular supplement.
Even those with a very basic knowledge of nutrition know that we need to consume fruit and vegetables for their vitamin C content in an effort to fend off illnesses.
Vitamin C is actually involved in both innate and adaptive immunity. Vitamin C is integral in collagen synthesis - the protein which acts as a natural barrier in our skin. Vitamin C is also a powerful antioxidant and helps to control inflammation throughout the body. Looking at adaptive immunity, vitamin C enhances B and T cell function and the production of antibodies (8). There is also research showing that an adequate intake of vitamin C lowers the risk of illness and that taking high amounts of vitamin C upon developing symptoms decreases the severity and duration of the illness (9).
When good sources of vitamin C are mentioned, the obvious answer is oranges. Although abundant in vitamin C, there are a number of foods which are actually better sources. Peppers, broccoli, kale, sprouts, kiwi’s, blackcurrants and rosehips all contain your daily vitamin C requirements per 100g serving. We also cannot store vitamin C, meaning a daily supply is crucial. For this reason, vitamin C supplements are widely used.
Years before vitamin D was even discovered, scientists were noticing that sunlight and cod liver oil (a natural vitamin D source) were beneficial to our bones as well as our immune system.
There is now plenty of research studies that show those with lower levels of vitamin D are more susceptible to illnesses like the common cold (10,11). It is perhaps no coincidence that colds and the flu are much more prominent in the winter months - the time of year where vitamin D levels are at their lowest. Although it’s not universally accepted how vitamin D benefits the immune system, it is acknowledged that it’s extremely important to our natural defences.
The latest government research has shown that 37% of adolescents and 29% of adults in the UK are deficient in Vitamin D during the winter months (12). Due to this, the Department of Health recommend that everyone takes a supplement from September to April. Certain individuals are also advised to take a vitamin D supplement year-round (13).
Like vitamins, there are certain minerals which work to keep our immune system functioning how it should:
Iron also has a crucial role in both innate and adaptive immunity. Studies have shown that those with low levels of iron have a lower number of B, T and natural killer cells (14). They also experience a decreased activity of IgA (immunoglobulin A). IgA is an antibody that works in the respiratory tract and digestive system and is a key element of innate immunity. It binds to pathogens, preventing them entering further into our system (15).
Low levels of iron are also fairly common in the UK, especially in young women. For those with an insufficient amount, supplementation can be very important. It is however possible to get all the iron we need through food. Iron comes in two forms, haem and non-haem. Haem iron is found in animal-based foods whereas non-haem iron comes from plants.
Recent research has outlined potential health issues from too much haem iron, so it’s advised to meet most of our iron needs from non-animal sources (16). Non-haem iron may not be as well absorbed when compared to haem, but by consuming alongside a source of vitamin C we can markedly boost absorption. It is also recommended that we avoid having a source of iron alongside tea and coffee as these can affect how much gets into our system (17).
Zinc has a long list of health benefits, but it is arguably best known for its role in immune function. Remarkably, it is also one of the very few things that can decrease the length and severity of the common cold. A recent study has shown that having a zinc lozenge within the first 24 hours of developing symptoms decreased the duration of the illness by a third (18).
With regards to food, seafood, meat, legumes, nuts, dairy and wholegrains are the best sources of zinc. However due to the immune-boosting properties of zinc as well as all of its other benefits, supplementation is popular to ensure a sufficient intake. Supplementation is a viable option for many given that the British Nutrition Foundation have stated that a significant proportion of young adults, both male and female, have a low zinc intake.
Selenium is one of the lesser-known minerals but its importance in our health and wellbeing is unquestionable.
Although it is not fully understood how selenium impacts our immune system, what is known is that a lack of selenium delays the adaptive immune response to pathogens. In simple terms, selenium deficient people will take longer to fight off an illness (19).
Unfortunately, many Britons are not consuming enough selenium-rich foods such as fish, seafood, wholegrains and nuts. This issue has been compounded by modern agricultural methods that have depleted a lot of selenium from the soil. This is one of the many reasons why organic produce is growing in popularity.
Evidence to back this up can be seen in the cultivation of Brazil nuts – the best source of selenium. One study has shown that the selenium content can vary massively depending on the quality of soil that the tree was grown in. While one region’s Brazil nuts provided almost three times the recommended amount per nut, a neighbouring region was growing nuts that provided just over 10% of selenium requirements per nut (20).
As many struggle to get enough selenium, there is an increasing number of people taking a supplement containing selenium to support their immune system and overall health.
As well as vitamins and minerals, there are some special phytochemicals in certain plants that can strengthen our immune systems and help us overcome illness. Some of the best known include echinacea, rosehip, garlic, ginger and cranberries. These ingredients have traditionally been used to strengthen our natural defences and there is also some good research to validate their use. For example, Echinacea has been shown to help with symptoms of cold and flu whereas regular intake of garlic lowers the risk of becoming ill in the first place (21,22).
At Brainpower Supplements, we fully understand and appreciate the power that botanicals naturally hold. For this reason, we have included a number of high strength plant extracts in our innovative Immune Synergy capsules. These natural powerhouses really compliment the array of essential vitamins and minerals we have included. Also present is acidophilus, a strand of probiotic. As research is emerging on a monthly basis indicating how important our gut microbiome is to our immune function and overall health, this was something we insisted on including (23).
Hopefully our article has outlined which nutrients are important and from which foods you can obtain them. If you need any help with your diet, supplementation or overall lifestyle, please reach out to one of our team members who are always willing and able to help.