Nutrients for immune health

At this time of year many of us feel that we’re picking up colds and infections every time we leave the house. So what can you do to become more resilient to seasonal colds and infections? We suggest you start by thinking about the foods you eat and check your diet is giving you the vital nutrients for immune health. The human body has very effective systems for fighting germs, but it can't do it's job effectively without a good supply of protein and specific vitamins and minerals, such as vitamins A, C, E, D, Zinc, and iron.

In this guide we highlight some of the most important vitamins, minerals and other nutrients needed for immune health and give you suggestions on food sources for each of these key nutrients.

 

How to strengthen your immune system

The immune system is the body's defence mechanism against infections, viruses, and harmful pathogens. It consists of a complex network of cells, tissues, and organs, including white blood cells, the lymphatic system, and antibodies. This system identifies and neutralises threats while also remembering past infections to provide quicker responses in the future.

A strong immune system relies on proper nutrition, rest, and overall health to function effectively.

Some of the key vitamins, minerals and other nutrients needed to support your immune function are listed below, together with details of the best food sources for these nutrients

1.Protein – the building block of immune health!

A low intake of protein increases risk of infection. Eating plenty of good quality protein on a daily basis is a fundamental building block for a strong immune system. Protein is needed to make immune cells and antibodies, and a lower protein intake can lower production of these cells. Protein helps the body repair tissues and supports overall immune function.

Protein provides essential amino acids that enable the body to make enzymes and signalling molecules that are critical for immune responses. Adequate protein intake is also needed to make cytokines, which help the body to regulate immune reactions and inflammation.

Most people benefit from 1- 1.5g of protein per kilogram of bodyweight to meet their daily requirements.

For more details on protein see here

Best sources: Meat, including poultry, fish, eggs, beans, nuts, dairy foods, soybeans and tofu.

2.   Omega 3 fatty acids

Omega 3 fatty acids, which are particularly found in fatty fish, have long been known for their important role in immune health. These fatty acids support immune health in a number of ways: 

-       by reducing inflammation,

-       by enhancing immune cell function,

-       by promoting a balanced immune response

-       by helping to regulate white blood cell activity,

-       by improving communication between immune cells

-       by supporting the integrity of cell membranes.

Omega-3s also play a role in resolving inflammation after an immune response, preventing excessive immune reactions that can lead to chronic conditions.

Best sources - fatty fish, such as salmon, mackerel and sardines, flaxseeds, chia seeds, and walnuts.

3.   Vitamin C

Vitamin C is one of the most well known nutrients for fighting infections. It helps stimulate the production of white blood cells, which are essential for fighting infections. Vitamin C is also a powerful antioxidant that protects immune cells from damage caused by harmful molecules called free radicals.

Best sources -  Bell peppers are one of the best sources of vitamin C, and other good sources are kiwi fruit, broccoli, strawberries, and citrus fruits (oranges, lemons, grapefruits).

4.Vitamin D

Vitamin D is critical for immune health  and low vitamin D levels are linked to a higher risk of respiratory infections, colds, flu, and COVID-19 complications.

Sources of Vitamin D

• Sunlight – the UVB rays from the sun trigger vitamin D production in the skin, and this is the best source of vitamin D

• Foods -  fatty fish, such as salmon and mackerel, fortified dairy, egg yolks, and mushrooms

• Supplements – are recommended in the winter months for those living in the Northern hemisphere,( i.e in the UK!) or all year around for those with limited sun exposure.

You can out find more on vitamin D here

5.Zinc

Zinc is essential for immune cell development and communication. It also helps reduce the severity and duration of infections, including the common cold. Zinc also supports wound healing and plays a role in reducing inflammation.

Best food sources -  Shellfish especially oysters and beef. Seeds such as pumpkin, sesame, hemp and poppy seeds are also particularly good sources of zinc, so including seeds in your diet on a regular basis will be very helpful for ensuring a regular supply of zinc.

6.Vitamin A

Vitamin A was originally called the ‘anti-infective vitamin’ because of its important role in the immune system. It supports immune health through its role in making white blood cells. It is also important for maintaining the integrity of mucosal barriers (such as the gut and respiratory lining), which act as the first line of defence against pathogens.

Vitamin A from animal sources is called retinol, while vitamin A from plant sources is called carotene. The body absorbs retinol more efficiently than carotene. Carotenes are converted into vitamin A in the intestines. However, the conversion rate is variable between individuals, and may be subject to genetic variability. Eating foods such as carrots with a source of fat helps the conversion of carotene to vitamin A.

Best food sources

Retinol – oily fish, especially tuna, eggs, dairy products such as butter and cheese, and organ meats 

Carotene -  carrots, sweet potatoes, spinach, pumpkin and squash

7. Vitamin E

Unfortunately, the immune system declines with age, making us more susceptible to infection. Vitamin E has been shown to specifically  enhance the crucial T-cell mediated immune response which declines with age. Vitamin E is also another powerful antioxidant that helps protect immune cells from oxidative stress. So it is really important we have a good supply of vitamin E in our diets, particularly as we get older.

Best sources – Eating nuts and seeds is a very effective way of ensuring you have plenty of vitamin E in your diet - almonds, hazelnuts and sunflower seeds are all particularly good. Olive oil is also an excellent source as are olives, salmon, trout, spinach, blueberries, avocados and eggs.

8. Iron

Having enough iron in your diet is also really important for a healthy immune system, as iron is needed for the growth and activity of immune cells. It supports oxygen transport in the blood, which is essential for overall energy and immune function.

Best sources -  red meat, poultry, lentils, and spinach. Spirulina is a great source of iron for vegetarians.

9. Selenium

Selenium helps regulate immune responses and reduce inflammation. It also plays a role in protecting cells from oxidative stress.

Best sources - eating a handful of Brazil nuts every week is probably the easiest way to make sure you get enough selenium, as Brazil nuts are particularly rich in selenium. But don’t overdo it as higher intakes of selenium are potentially toxic.

Other good sources include fish, seafood, seeds such as sunflower, chia and sesame, meat and eggs.

Gut health and the immune system

The health of the gut is considered critical for immune health, as many immune cells are situated in the gut. Bacteria in the gut have a direct influence on the immune system and act as a first line of defence, as they:

• regulate immune responses,

• prevent excessive inflammation,

• help the body identify and fight pathogens.

  
  

A healthy gut microbiome, with a good range of bacteria, contributes to a strong immune system. However, an imbalance in gut bacteria (dysbiosis) can lead to a weakened immune system, with increased susceptibility to infections and autoimmune disorders. 

If you have digestive health issues it is best to try to address these issues, as it is likely that this will also strengthen your immune health.

You can improve the health of your gut by increasing the range and diversity of bacteria in the gut. Probiotics (beneficial bacteria) and prebiotics (food for these bacteria) help maintain a balanced gut microbiome. Including probiotic and prebiotic-rich foods in your diet can help maintain gut health and enhance immune function.

Best foods for gut health

Probiotics –  fermented foods such as kefir, kimchi, sauerkraut, live yoghurt, some cheeses, miso. It’s good to include some fermented foods in your diet every day if possible.

Prebiotics – found in many fruits and vegetables, but particularly good sources include, garlic, onions, chicory root, bananas, Jerusalem artichokes, apples and whole oats.

Final Thoughts

Eating a nutrient-rich diet is one of the best ways to strengthen your immune system and maintain good health. Try to include good quality protein, fermented foods and foods containing the essential vitamins and minerals into your diet. This should help to protect your body against infections. Ensuring you have a balanced diet along with taking regular exercise, good sleep, and stress management will ensure your immune system is functioning at its best.

By making conscious choices in your nutrition, you empower your body to defend itself naturally. Stay healthy and strong!