How Important is Nutrition for Your Immune System?

They say you are what you eat. Which is why eating well can keep you fighting fit.

Cold weather signals the arrival of cold season, the time of year when it seems like every you know is sniffling their way through some bug or other. This year, its arrived harder than ever. After 18 months of masks, relentless hand-washing and social distancing, our immune systems are slightly weakened, which means that infections we'd have fought off a couple of years ago now have us mainlining Lemsip.

As with everything, good health starts from the inside out. While there's no food that 'boosts' your immune system (despite what all those açai berry-shilling pop-up ads might claim) the right diet is vital for keeping your body fighting fit.

What is the immune system?

The immune system is the body's defence against infections. It's made up of a number of different cells, proteins, and structures that work together to protect us against many diseases. It's a complicated beast, and much of the way it functions – and fails to function properly – is still not fully understood.

However, it's known that leading a healthy lifestyle, which includes regular physical activity, avoiding unnecessary stress, and eating a good diet, will support an optimally functioning immune system.

How does nutrition help maintain a healthy immune system?

Eating a varied diet will help to ensure you’re meeting the recommended daily intakes (RDAs) for all essential nutrients. These are the amounts of vitamins, minerals, and macronutrients that need to be consumed on a daily basis. If you're deficient in certain vitamins and minerals then this could lead to a weaker immune system.

For several nutrients, it may be useful to have an intake higher than the RDA to maintain a properly functioning immune system^[1]. Some of the most important nutrients in relation to the immune system are:

Vitamin C

Vitamin C helps support the production and function of certain types of white blood cells that attack bacteria and viruses. Whilst the notion of vitamin C preventing the common cold has been exaggerated^[2], an adequate vitamin C intake of at least the RDA is essential to an efficient immune system.

Vitamin D

Lots of cells involved in the immune response have vitamin D receptors. Therefore, varying levels of vitamin D affect how these cells function and do their job^[3]. Like vitamin C, it helps support several different white blood cells to protect the body against foreign invaders^[4].

Vitamin E

Vitamin E is one of the main dietary antioxidants which means it helps to prevent damage to cells. One immune cell type (called T-cells) recognises and coordinates the response to viral infection. Vitamin E also helps protect the cell membrane of T-cells, supporting them in fighting off infections.

Zinc

Zinc has been shown to support the cells of the immune system and to have a particularly strong antiviral effect for certain types of viruses^[5]. Zinc also helps regulate multiple parts of the immune system^[6].

Selenium

Selenium is another antioxidant and has been shown to help reduce inflammation when it has become a detriment to health^[7]. Furthermore, inadequate selenium intake has been associated with a slower immune response^[7].

Protein

Protein does more than just provide the building blocks for muscle, it’s incredibly important for immunity. Our immune system is mainly made up of proteins and is necessary to repair damaged tissues^[8]. Take protein out of the immune system and it’s not much of a system anymore.

Essential fats

Omega-3 fats found in oily fish, flaxseed and walnuts and omega-6 fats from vegetable oils, nuts and seeds have important immune-regulatory functions. Omega-3 fats tend to produce less inflammatory signalling molecules than omega-6 fats^[9]. In the West, we tend to get enough omega-6 in our diets but many of us struggle to consume enough omega-3, therefore inflammation could be a health issue^[10]. This is why it’s important to have a good balance of omega-3 to omega-6 fats.

Getting enough fluids

Being adequately hydrated is extremely important when it comes to the immune system. For example, the mucus in the mouth, nose and respiratory tract is on the frontline when it comes to protecting our body against foreign invaders. Being dehydrated can lead to decreased mucus production, thereby reducing protection. Dehydration can also be an added stressor to the body which can impair immune function and increase susceptibility to infection. Therefore, it’s important to drink plenty of fluid throughout the day.

Huel and immune health

All Huel products are rich in essential fats and have a good omega-3:omega-6 ratio. They’re also high in protein from pea and brown rice and contain all the essential vitamins and minerals. Huel products also include vitamin C, D, E, zinc and selenium at levels higher than the RDA.

Can food boost your immune system?

The short answer is no, and you wouldn’t want it to either. The immune system is complex and finely balanced. “Boosting”, or having an overactive immune system, can lead to negative consequences such as a cytokine storm which can occur as a result of some diseases^[11].

Although you can’t “boost” your immune system with food, following general good-health guidelines is the best way to keep your immune system strong. A balanced diet with a particular focus on adequate micronutrient intake, ie vitamins and minerals, as well as major macronutrients like protein and essential fatty acids are key to supporting the immune system with nutrition.

What is a gut microbiome?

Inside our gut reside good bacteria which help us digest our food. They have been shown to have a number of other functions, including having a role in supporting a healthy immune system^[12]. This is known as the gut microbiome and a good diet is crucial for a healthy microbiome. It’s an area of research that needs much more work but has had loads of interesting developments in recent years.

Key points:

• A varied diet helps ensure ample intake of key nutrients required for a healthy immune system
• Vitamins C, D and E, zinc, selenium, protein and essential fatty acids are of particular note
• Drink plenty of fluid
• You can’t “boost” your immune system with food
• A healthy gut microbiome supports a healthy immune system
• Huel contains ample amounts of all nutrients required for an optimally functioning immune system

References

1. Gombart AF, et al. A Review of Micronutrients and the Immune System-Working in Harmony to Reduce the Risk of Infection. Nutrients. 2020; 12(1):236.
2. Hemilä H, et al. Vitamin C for preventing and treating the common cold. Cochrane Database of Systematic Reviews. 2013; (1).
3. Aranow C. Vitamin D and the immune system. J Investig Med. 2011; 59(6):881-6.
4. Di Rosa M, et al. Vitamin D3: a helpful immuno-modulator. Immunology. 2011; 134(2):123-39.
5. Read SA, et al. The Role of Zinc in Antiviral Immunity. Advances in Nutrition. 2019; 10(4):696-710.
6. Wessels I, et al. Zinc as a Gatekeeper of Immune Function. Nutrients. 2017; 9(12).
7. Hoffmann PR, et al. The influence of selenium on immune responses. Molecular nutrition & food research. 2008; 52(11):1273-80.
8. Li P, et al. Amino acids and immune function. The British journal of nutrition. 2007; 98(2):237-52.
9. Radzikowska U, et al. The Influence of Dietary Fatty Acids on Immune Responses. Nutrients. 2019; 11(12):2990.
10. Patterson E, et al. Health implications of high dietary omega-6 polyunsaturated Fatty acids. J Nutr Metab. 2012; 2012:539426-.
11. Tisoncik JR, et al. Into the eye of the cytokine storm. Microbiol Mol Biol Rev. 2012; 76(1):16-32.
12. Belkaid Y, et al. Role of the microbiota in immunity and inflammation. Cell. 2014; 157(1):121-41.
13. Rinninella E, et al. Food Components and Dietary Habits: Keys for a Healthy Gut Microbiota Composition. Nutrients. 2019; 11(10):2393.