Humans have two types of immunity: innate and adaptive. Innate immunity is the body’s first-line of defence, primarily consisting of physical barriers (such as skin), and secretions – including mucus, stomach acid and enzymes in saliva and sweat which prevent microorganisms getting inside the body. It also consists of cells that attack all foreign invaders entering the body.
Adaptive immunity is a system that learns to recognise a pathogen. It’s regulated by cells and organs in our body such as the spleen, thymus, bone marrow and lymph nodes. When a foreign substance enters the body, these cells and organs create antibodies and multiply the immune cells specific to that harmful substance in order to attack and destroy it. They also remember the pathogen for future reference.
There are many things we can do to support our immune system and even improve its function. Simple changes to your diet and lifestyle can all play a big role in helping you avoid getting sick.
We are what we eat
The nutrients we get from the foods in our diet play key roles in both building and maintaining our immune system.
Take for example the amino acid arginine. This is essential for generating nitric oxide within immune cells, which is an important defence molecule against organisms. Vitamin A and zinc are crucial in the rapid reproduction of immune cells. Vitamin C contributes to immune defence by supporting the cell functions of both immune systems. Similarly, vitamin E has been shown to enhance immune responses in animals and humans and to provide protection against several infectious diseases, such as flu, COVID and the common cold.
A varied diet including fruits and vegetables, wholegrains, nuts, seeds, dairy products, as well as fish, meat, or plant protein alternatives, will all contain these key nutrients which support our immune health.
The vast combination of microorganisms that live in our gut – known as our microbiome – also have significant effects on our health and wellbeing, despite their tiny size. In fact, the microbiome is often referred to as the “second brain” due to the extensive relationship it has with the body’s organs and systems.
One particular role the microbes in our gut play is supporting immune function. They help to control inflammation, the process the immune system uses to protect us from harmful pathogens. Ensuring the microbiome is healthy can improve immune function.
There are many ways we can support our microbiome through the foods we eat. For example, research has shown a Mediterranean diet, which is rich in vitamins, minerals and dietary fibre, has an anti-inflammatory effect in the gut, which can help boost the body’s immune function.
This effect may be explained by a strain of bacteria known as Faecalibacterium prausnitzii which is key to immune regulation. This bacteria tends to be low in the western diet but abundant in the Mediterranean diet. You should also avoid too many refined cereals, sugars and animal fats, which can all heighten inflammation in the body which weakens the immune response.
Probiotics (supplementary blends of live bacteria) may also have benefits. Research has even shown a probiotic blend of bacterial strains Lactiplantibacillus plantarumand and Pediococcus acidilactici reduced the amount of virus detected in the nose and lungs, as well as the duration of symptoms, in COVID patients.