Can your diet choices boost your immune system?

The immune system is composed of cells, tissues, organs and proteins; which all help fight pathogens that cause diseases and infection in the body. Our diet cannot prevent us from coming across those pathogens and getting ill. However, it may strengthen our immune response and help our bodies recuperate quicker.

A typical western diet unfortunately tends to encompass ultra-processed foods, high amounts of sugar and red meats, and a low variety of nutrients. These can all adversely affect our immune system and make us more prone to infection and chronic inflammation, as well as decrease our body’s ability to fight diseases quickly and effectively. Conversely, certain nutrients are particularly important when it comes to the development and healthy functioning of our immune cells. Therefore, including plenty of those in our diets can help us boost our immune system. These include:

Vitamin A

Vitamin A supports the white blood cells responsible for identifying pathogens. These are called T cells. Your body can convert beta carotenes into vitamin A, therefore produce containing beta carotenes constitute a great source of vitamin A. These are generally orange or dark green in colour and include the following:

Vegetables containing beta carotene Fruit containing beta carotene
Collard greens




Sweet potatoes


Butternut squash

Red bell peppers




Pink grapefruit


Vitamin C

Vitamin C has been found to improve the overall functioning of our immune system as it is thought to promote the production of white blood cells. Vitamin C may in fact help shorten the duration of a cold as white blood cells are key to fighting infection. The best sources of vitamin C include:

  • Citrus fruit such as oranges, tangerines, clementines, lemons, limes and grapefruit
  • Spinach
  • Red bell peppers
  • Broccoli
  • Kiwis

As the body cannot produce or store vitamin C, it is recommended to include some of these in your daily diet.

Vitamin E

Vitamin E also supports our immune system as it is an antioxidant that helps fight free radicals that can damage cells. The best sources of vitamin E include:

  • Sunflower seeds
  • Almonds
  • Avocados
  • Dark leafy greens
  • Spinach


Research has shown that there is a connection between the bacteria in our gut and our immune system. The more varied and diverse our diet is, the more friendly live bacteria we have in our gut. This healthy bacteria aids digestion and can also help fight unwanted bacteria, reduce inflammation and promote antioxidant activity.

Having a diverse array of gut-friendly bacteria comes from eating a healthy and varied diet with at least 30 different types of fruit and vegetables each week. This may be a difficult goal for some to reach, however, you can also increase your gut bacteria by including fermented foods containing probiotics in your diet. These include fermented yoghurts, kimchi,  sauerkraut, kefir and kombucha.

Vitamin D

Vitamin D plays an essential role and maintaining the immune system’s efficiency and has also been found to enhance our natural defences against diseases. A deficiency in this vitamin can therefore lead to a reduced immune response. Additionally, it helps us maintain healthy bones and muscles.

Vitamin D can be found in foods such as:

  • Fatty, oily fish (salmon, sardines, mackerel and fresh tuna)
  • Egg yolks
  • Liver
  • Red meat
  • Foods fortified in vitamin D (these can include spreads, orange juice, and breakfast cereals)

Green tea

Green tea has high levels of epigallocatechin gallate (EGCG), which is a powerful antioxidant that has been found to increase immune function.  Green tea also contains L-theanine, which is an amino acid that promotes the development and health of our germ-fighting T-cells.