IMMUNITY AND NUTRITION

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Our immune system protects us against infection as it has the ability to fight off unwanted invasions. But does what we eat hold the answer to improving how well this functions?

The idea of boosting our immune system seems to be plastered upon health post after health post. But how much truth is behind these claims?

Our body has two ways it protects us from infection - the innate immune response and the adaptive immune response. The Innate immune response is not specific to a threat and includes things such as skin which acts as a physical barrier. 

The adaptive immune response is a response that is specific to the threat. This develops over time and remembers how to respond if that same infection attacks again. It is able to quickly reproduce an army that can fight off that specific threat. 

The immune system mounts a response which results in what we know as symptoms. So, what would happen if we actually boosted this immune system? Well it would mean our body would overreact, which isn’t what we want!

Everyone’s immune response is individual to them. We know if our immune system is better than others if we get ill less frequently, the duration of illness is shorter and we aren’t as poorly as others.  Your immune system is affected by genetics, age, gender, exposure to previous infections, vaccinations, stress and exercise. In addition to this your weight, alcohol, gut flora, nutrient status and your overall diet also effect how you respond to infection.

Different nutrients can help the immune system work in different ways. They each play a role in keeping our immune system working and responding appropriately. 

Every day our immune system is at rest. If the body’s immune system goes from its resting position to being activated there is an increased demand of energy. Therefore, it is important that we are able to provide our body with enough energy to meet its new higher demands.  Keeping a healthy weight is important as being either underweight or overweight can impact upon your overall health. 

Omega 3 fatty acids have long been known to support heart health but what about immune function? It is thought that omega 3 fatty acids can help when destroying unwanted invaders, can become part of signals and also protect our cells from damage. Omega 3 can be found in chai seeds oily fish, walnuts and flax seeds. 

Vitamin A and Zinc are both involved in the regulation of cell division which produce new cells. Our immune system needs to be able to quickly produce lots of immune cells to fight off infection. A vitamin A deficiency has been linked to higher risks of infection and less effective immune systems. Vitamin A sources include milk, yoghurt and oily fish. The body can produce vitamin A from beta-carotene which can be found in yellow fruits. The best sources of Zinc are red meat.

It is thought that as well as supporting bone health vitamin D can influence the innate and adaptive immune responses. Vitamin D is a hormone and our body cannot make it, instead it is made under the skin when you’re in sunlight. If you are deficient in vitamin D it is possible you have an increased susceptibility to infection. Vitamin D has been associated with autoimmune disorders, but the mechanism is not clear and more research is needed. You can get vitamin D from food with oily fish containing reasonable amounts but look out for foods that are fortified in vitamin D. 

A popular home remedy for the common cold is often increasing vitamin C in the diet to try and reduced symptoms. Although research suggests that vitamin C cannot reduced risk of developing a cold it was thought that a dose of 1 – 2g could reduce length and severity of the cold, but vitamin C was taken before the cold developed. However, there are associated risk with taking this level of vitamin C and side effects can include stomach pain, diarrhoea and flatulence. Vitamin C is found in such a wide variety of fruit and vegetables but it can’t be stored in the body so it is advised that people have vitamin C containing foods every day. 

Let’s go back to the original question - does what we eat hold the answer to improving our immune system? Nutrition can play a part in supporting our immune function but there is no one miracle food. The more recent thoughts that we have to “boost” our immune system are a myth.  What we can do is give our bodies the best tools to be able to deal and respond appropriately when we can catch an infection. By having a balanced diet as part of a healthy lifestyle you will be able to provide your body with the appropriate nutrients to aid your immune system. 

NOTE: High consumption of vitamins and minerals can be toxic and there are safe upper limits. In addition, supplementation can interfere with some medications. Always consult your GP or Dietitian before changing your diet.

References

 

Aranow, C. 2011. Vitamin D and the immune system. Journal of investigative medicine, 59(6), pp.881-886.

Baeke, F., Takiishi, T., Korf, H., Gysemans, C. and Mathieu, C. 2010. Vitamin D: modulator of the immune system. Current opinion in pharmacology, 10(4), pp.482-496.

Clarke, S.T. 2016. Influence of dietary interventions on the immune system: An investigation of the impact of omega-3 fatty acids, dietary fermentable materials and high energy diets.

Chavali, S. and Forse, R.A. 2018. The role of omega-3 polyunsaturated fatty acids on immune responses during infection and inflammation. Diet, Nutrition, and Immunity, pp.179-186.

Hemilä, H and Chalker, E. 2013. Vitamin C for preventing and treating the common cold. Accessed June 2020. Available via : https://www.cochrane.org/CD000980/ARI_vitamin-c-for-preventing-and-treating-the-common-cold] [

Kubena, K.S. and McMurray, D.N., 1996. Nutrition and the immune system: a review of nutrient–nutrient interactions. Journal of the American Dietetic Association, 96(11), pp.1156-1164.

Prasad, A.S. 2008. “Zinc in Human Health: Effect of Zinc on Immune Cells” Accessed June 2020. Available via :  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2277319/]

SACN. 2016. “Vitamin D & Health”. Accessed June 2020. Available via: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/537616/SACN_Vitamin_D_and_Health_report.pdf]

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