Diet and Immune System - What's the link?

There is a lot of talk about how our diet can prevent illness, and I think it is important for me to start this article by saying that there is no way to “boost” our immune system. No miracle supplements or food can affect our risk of getting ill. Nevertheless, a well-balanced diet provides us with a mix of all the nutrients and micronutrients we need, and can support our immune system ensuring it is functioning properly (1, 2).

What is the Immune System?

The human body is a perfect machine. Our immune system is a large network of cells, organs, protein (antibodies) and biological processes that protect us from illness (3) and has 3 main jobs to do (4):

To fight germs (such as bacteria, viruses, parasites and fungi) and remove them from our body;
To recognise and neutralise harmful substances;
To fight disease-causing changes in our body, such as cancer cells.

There are two sub-systems: the innate immune system and the adaptive immune system. Both these subtypes work together whenever we get in contact with a germ or harmful substance. The innate immune system is a fast non-specific response, providing general protection against dangerous germs or substances that enter the body through the skin or digestive system. On the contrary, the adaptive immune system is a specific response that produces a protein called antibodies, used to identify and neutralise unknown substances or pathogens. This system develops a memory of the pathogens that the body has previously come into contact with so that its response is faster upon a second confrontation with the same pathogen (3, 4, 5)

How can our diet affect the Immune System?

Unfortunately, we can’t “boost” the immune system, this is a fact. However, eating a balanced diet can support good immune functioning (5, 6). Please, note that the information in this article is based on recent evidence and will be updated if needed.

The Mediterranean diet

Inflammation and oxidative stress, which can have a negative effect on our immune system, has been linked to a lack of nutrients and variety in our diet (2). Therefore, following a dietary pattern that provides us with what our body needs, such as the Mediterranean diet may help support the immune system’s functioning. This type of diet is rich in plant foods, whole grains and extra virgin olive oil, with moderate amounts of fish, dairy and poultry and limited red and processed meat. The consumption and frequency of consumption of these food groups have been shown to have antioxidant and anti-inflammatory properties (3, 6).

Sources of protein

You may have heard about the numerous benefits of consuming an adequate daily amount of protein. However, you may not know that not consuming enough protein has been associated with impaired immune function and protection. What is the reason behind this? To put it simply, the amino acids (which are the building blocks of protein) play a crucial role in the activation and growth of specific immune cells and help in the production of antibodies that help neutralise and remove germs (7).

Oily fish, nuts & seeds

Oily fish provide us with Polyunsaturated Fatty Acids (also known as PUFAs), which impact our immune system has been widely recognised. In particular, omega-3 fatty acids have been shown to have anti-inflammatory properties, specific effects on certain immune cells (5, 8) and the ability to modulate our immune system. Omega-3 can be divided into:

α-linolenic acid (ALA), found in nuts and seeds
eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) found in oily fish.

The recommendation for most adults is to aim to consume 2 portions of fish per week, one of which is oily. The presence in oily fish of other micronutrients such as vitamin A, D, the B vitamins, iodine, iron, selenium and zinc (9) may contribute to the optimal functioning of our immune system (2, 3, 10).

The gut microbiota

Something that is often overlooked is that our gut microbiome has a key role in regulating the immune system (11, 12, 13) – about 70% of our immune system can be found in our gut (14), which is pretty shocking. Therefore, we should try to look after our gut by:

Aiming to eat at least 30g of fibre per day. This can be achieved by including a variety of plant-based foods (fruits and vegetables) but also whole grains, beans, legumes, seeds, nuts, herbs and spices. They all count;
Including fermented foods into our diets, if you like them;
Adding probiotics and prebiotics foods.

There is no need to aim for the perfect diet, as this is something that does not exist and in real life is not achievable. Instead, try to focus on making small changes or additions to your current eating habits.

Micronutrients

Different micronutrients are involved in ensuring the normal functioning of our immune system, such as vitamin D, C, A, B6 and B12, along with minerals like iron, folate, copper and selenium. If you consume a balanced diet with a variety of food it is likely you won’t have any micronutrient deficiencies and there is no need to take any supplements. However, if you live in the UK, during winter months, the sun is weaker, and therefore it is recommended to take a 10-microgram supplement of vitamin D a day. This is because our primary source of vitamin D is sunlight as the little amount can be found in food such as oily fish, cod liver oil, meat, egg yolk and some fortified breakfast cereals (2, 3, 10).

Our lifestyle matters too!

We know that food is important, however, many other factors contribute to our overall health wellbeing (15, 16), such as:

Keeping hydrated – aim for at least 6-8 glasses (1.5-2L) of fluid a day, focusing on water;
Limiting alcohol consumption;
Implementing good sleep hygiene;
Keeping active – try to find what you really enjoy, it could dancing, walking, gardening or hiking.
Managing your stress levels.

Summary and helpful tips

Try to eat a balanced and varied diet;
Include foods that support your gut microbiome composition;
To see whether or not you are following a varied-balanced diet, try to write down your weekly meals for a couple of weeks;

If you have a specific nutritional need, follow the recommendations of your healthcare professional (Nutritionist, Dietitian or GP). If you need support understanding how to implement these recommendations within your diet, you can book a discovery call with me here.

Diet and Immune System – What’s the link?

What is the Immune System?

How can our diet affect the Immune System?

The Mediterranean diet

Sources of protein

Oily fish, nuts & seeds

The gut microbiota

Micronutrients

Our lifestyle matters too!

Summary and helpful tips

Like this:

Related

What is the Immune System?

How can our diet affect the Immune System?

The Mediterranean diet

Sources of protein

Oily fish, nuts & seeds

The gut microbiota

Micronutrients

Our lifestyle matters too!

Summary and helpful tips

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Like this:

Related

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