Health & Wellness

What Are The Signs Of A Strong Immune System?

Signs of a strong immune system

The immune system is a complex network, composed of cells, tissues and organs. This network acts as the defence system to invading organisms, and responds to infection to help us feel well. But how do we know if we’re fighting disease properly and what are the signs of a strong immune system? Read on to find out.

What Are The Signs Of A Strong Immune System?

A good indicator of immunity is your overall health. If you are eating well, sleeping well and have fast-healing wounds, the chances are that your immune system is working well. On the other hand, you might find yourself prone to illness and infection if your immune system is weakened.

Tips To Improve Immunity

1. Get Enough Vitamin D

Vitamin D supports the immune defences in both our lungs and our gut and helps us to protect against infection. 1

Vitamin D is produced in our body through exposure to sunlight. In the UK between October and April, our exposure to sunlight is too low to produce sufficient amounts. Therefore it is recommended we take a 10ug supplement of vitamin D everyday during this period. Some foods contain vitamin D such as fortified cereals and eggs, but there aren’t sufficient amounts to protect us from deficiency.

2. Stop Smoking

If you smoke, stopping smoking is one of the best ways to help your immune system to function properly. Aside from the carcinogens that are known to cause cancer, there are many other pro-inflammatory compounds found in tobacco smoke. When the immune system is fighting infection it produces an inflammatory response. Having constantly high levels of inflammation however can impair immune function and lead to further chronic diseases.

The pro-inflammatory compounds in smoke and nicotine serve to put our immune system function out of balance. (2) The good news is that if you stop smoking, you can to some extent reverse the effects that smoking has on immune cells supporting its proper functioning. 3

3. Manage Stress

When we are stressed our bodies release more of a hormone called cortisol. In short bursts, cortisol can help our immune system by being an anti-inflammatory. However, having chronically high levels of cortisol can lead to higher levels of inflammation which limits our ability to fight off infections. 4

Having strategies in place to manage stressful situations or strategies to lower your stress levels such as practicing mindfulness, exercising, and taking some time out to do the things you love, can help you to reduce your levels of stress and improve your immunity.

4. Maintain A Healthy Diet

Signs of a strong immune system

An unbalanced diet which lacks sufficient nutrients can result in weakened immunity. (5) Fruits and vegetables contain antioxidants and key immune-protective nutrients such as fibre, folate, vitamins C & E, zinc, selenium, which all have a strong effect upon cell growth and are necessary for an optimal functioning immune system. 6

Eating a lot of foods that are high in saturated fat and sugar is associated with increased levels of inflammation in the body and can impair the immune system. A healthy diet comprises a balance of different food groups including sources of lean meat or plant-based protein,  wholegrains, dairy/dairy-alternatives, healthy fats (such as olive oil, nuts and seeds) and lots of fruits and vegetables.


Having a well functioning immune system is essential to keeping us healthy. Taking steps to reduce stress, eat a balanced diet and stopping smoking can all help to boost general immunity. Alongside the tips above, exercising regularly and getting enough sleep can help us to see the signs of a strong immune system. However, if you do have any concerns about your immune system, it is important to consult your GP.

Ro Huntriss

Ro Huntriss

Writer and expert

Ro Huntriss is a Registered Dietitian with 10 years of experience working in the NHS, private practice and commercial business. Ro has a Bachelor’s degree in Food Studies and Nutrition, a Master’s degree in Advanced Nutrition, and a second Master’s degree in Clinical Research. Ro is a clinical specialist in several areas to include weight management, diabetes, fertility, women’s health and gut health. Ro is a published academic author and is frequently seen in many national media publications to include BBC, Daily Mail, The Mirror, HELLO! Magazine, Cosmopolitan, Women’s Health and Men’s Health.