Nutrition & Immunity

The immune system is functioning day-to-day but we only tend to think about it when the winter comes, get a cold or flu or in unprecedented times such as the current pandemic.

With health being firmly placed at the forefront of our minds during these times of uncertainty the immune system has received much attention.

As people rush out to get as many winter supplements as they can and Google countless ways to boost immunity, many of which tend to be based on false claims, you may ask the question, is there an ultimate way to boost our Immunity through food?

Our food choices and nutrient status are contributing factors that can support our immune system. A healthy balanced diet consisting of whole foods will ensure we have the variety of vitamins, minerals and macronutrients needed to maintain our immune status.

A food-first approach should be taken when considering supplementation, with the exception of vitamin D and those with a deficiency, following a specific lifestyle or in a particular life stage.

Our Immune system

The immune system works hard to protect us, differentiating between our own cells and invader cells and pathogens. It also plays a vital role in cancer surveillance. There are a multitude of factors that can impact our immune function (see figure 1), our nutrient status and diet are just two examples of factors that we have control over.

Figure 1

Vitamins and Minerals

All essential vitamins and minerals are a requirement for a healthy immune system. There are a number that have been highlighted to have a role in maintaining immune function (see figure 2). For example, vitamin A, found in dairy, dark green leafy vegetables and orange coloured fruits and vegetables plays a role in cell division and support. Deficiencies in these nutrients could impair your immune response and therefore make you more susceptible to infection.

Supplementation is a big topic at the moment and many of us will be considering taking a supplement over the winter. However, if you are healthy and do not have a deficiency, the benefits of taking a supplement are limited, more is not always better.

Taking too much of a supplement can be dangerous, many have ingredients that could present with side effects and negatively interact with medications that you may be taking. The best approach would be to consider food before supplementation. Food not only provides vitamins and minerals but also a variety of other nutrients such as protein, fibre and essential fats which can provide a vast number of additional benefits. 

There is one exception, that is vitamin D. The advice from Public Health England states that we should be taking a daily lOµg supplement in the winter months. This is due to the reduced amount of time we may be subject to sunlight (the main contributing source of vitamin D3). Supplementation requirements may also differ according to different life stages and choices such as pregnancy and those following a strict vegan diet.

Figure 2

Gut Health

The gut has many different functions for our body and health, especially when we focus on immunity. Our gut houses 70% of our immune system, mainly consisting of microbes (microbiota) which are the ‘good’ bacteria involved in the development and health of immune cells. To maintain the health of our microbiota, we have to provide them with an energy source, this is where prebiotics come into play. Prebiotics are essentially the food for our microbes, when they ferment prebiotics they produce substances which are essential for the general health of our immune system.

It has been suggested that we should aim to consume 30 different plant- based foods a week to ensure we have adequate amounts of prebiotics in our diet, diversity and variety is key!


The cells in our immune system also utilise macronutrients (Carbohydrates, Protein and Fats), providing fuel and building blocks for antibodies. Carbohydrates are essential for energy production, it is recommended that we consume wholegrain carbohydrates (wholegrain bread, rice and pasta) as they provide us with a steady supply of energy without causing a spike in blood glucose levels. They also contain fibre, an important probiotic.

Protein acts as the building block of immune cells and therefore we should ensure we consume it daily. Sources include meat and dairy products, nuts, beans and pulses and meat alternatives such as soya, tofu and Quorn. Essential fats (Omega 3 and 6) have additional anti-inflammatory effects and may play a role in the prevention of stroke, eye disease and Alzheimer’s.