Improving your Immunity

Autumn is almost upon us and with children now back at school and the colder weather not too far away, it is this time of the year that we need to make sure our immune systems are working effectively so we can ward off the plethora of bugs, germs and illnesses that the change in weather and the new school term can bring. 

So what can we do to help strengthen our immune system naturally and how can diet and nutrition help improve our defences against illness and get us in shape for the months ahead?

What is the Immune System?

Before we talk about how to improve immunity, it might be useful to know what we mean by the immune system, so here’s a quick science bit for you. The immune system is our body’s defence system and it comprises of cells, tissues and organs which all work together to try and protect our body from germs and microorganisms that can cause us to become ill. When our immune system is healthy and working effectively we are less susceptible to disease and illness, but if our immune system is weakened or compromised through things such as stress, tiredness, or poor diet, we leave ourselves exposed to the elements and we become more vulnerable to picking up illnesses.

Diet and Immunity

What we eat has a huge impact on how well our body functions and the link between immunity and nutrition has long been known. If we don’t provide our body with good nutritious foods, how can we expect it to work at an optimum level and maintain our health?  There are certain foods, vitamins and minerals which have been shown to have a positive impact on our immune system and it’s these foods we need to incorporate into our daily diet in order to stay healthy, especially at this time of the year. Even slight deficiencies in certain vitamins and minerals such as zinc and vitamin C have been shown to impair immune function and leave us more susceptible to infection. There are also foods which have been shown to reduce immune function and interfere with the body’s immune response, so these should be reduced in the diet where possible.


Now, we are not just talking about any old mushrooms here because when it comes to boosting immunity only Shiitake mushrooms will do the job!! These mushrooms have the biggest immune boosting properties and have also been shown to discourage inflammation in the body. Shiitake mushrooms have been used for centuries in ancient medicine for their health boosting properties, including anti-aging ability, so forget 'an apple a day keeps the doctor away', try a mushroom instead!


Garlic really is a bit of a wonder food and is often referred to as one of nature’s best antibiotics, so it is definitely worth putting up with garlic breath to reap its health benefits! Not only does garlic have antibacterial properties, but it also has antiviral and antifungal properties too, which helps explain why, when it comes to improving immunity, garlic is a real winner. Consumption of garlic has been shown to enhance immune cell function and reduce susceptibility to colds and flu so definitely a food you want to be eating at this time of the year! To get the best health benefits from garlic, it really should be eaten raw several times a week, try it in salad dressings, smoothies or add it to your cooking at the last minute rather than at the start. You could also consider consuming it in supplement form too. You certainly won’t have to worry about vampires anymore!!!!

(Note: if you are taking blood thinning medication, consult your GP before increasing garlic or starting a garlic supplement.)

Green Tea

Green tea is a popular drink nowadays and with all its health boosting properties it’s no wonder people have turned to it for their hot drink fix. Most of green tea’s health benefits stem from a compound called Epigallocatechin 3-gallate (EGCG for short), which is a powerful antioxidant. This has been shown to help fight infection and boost immunity by stimulating white blood cell function (white blood cells are our main defence against infection) and helping reduce inflammation. Its taste may be an acquired one, however it’s well worth it and if you add a piece of citrus fruit to your green tea it’s even better, as this addition can increase the antioxidant absorption by the body by 13 fold!


This is a soluble fibre found in a variety of foods, including barley, oats, rye, shiitake mushrooms, seaweed and yeasts (oats are the highest source). Some research has shown that Beta-Glucan can help strengthen the immune system, as it has antimicrobial and antioxidant properties which can enhance the function of some white blood cells needed to fight infection. It is also very useful in helping to lower cholesterol levels too.


In the same family as garlic, onions are just as important in the fight against infection so deserve their own little spot in this article. The immune boosting benefits of onions can mostly be attributed to an antioxidant called Quercetin (which has been shown to prevent cancer cell growth & reduce mucus production in the airways). They are also a high source of vitamin C and selenium, which are both important in immune function. In fact, onions are one of the highest sources of selenium in the vegetable world! Onions also contain a natural prebiotic called Fructan. Prebiotics help to keep your gut healthy by stimulating the growth and activity of ‘good’ bacteria in the digestive tract. This is especially important when it comes to immunity as, believe it or not, 70-80% of your immune function is found in the digestive system, so keeping your gut healthy is essential if you want a strong immune system!

Vitamins and minerals for boosting immunity

All vitamins and minerals are important for good health and have their own unique jobs to do in the body. However, there are a few that are specifically vital for healthy immune function.  Zinc is one such mineral and is essential for proper immune system development and correct functioning. Even a mild zinc deficiency can increase your risk of infection and illness so make sure you consume a variety of foods high in zinc such as red meat, seeds, oats, shrimp and turkey.

Selenium is another mineral essential for improving immunity and its deficiency, amongst other things, can cause immune impairment. Dietary intake of selenium in many countries (including the UK) has been found to be lower than government recommendations, so it’s important that foods naturally high in selenium are eaten regularly. Good food sources of selenium include Brazil nuts, shellfish, oily fish (salmon, mackerel, sardines, herring and fresh tuna), sunflower seeds, chicken, brown rice and eggs. Goat’s milk is also a very good source of selenium, containing 27% more of this essential mineral than cow’s milk. Delamere Dairy’s goats’ milk products are therefore a good choice for those wishing to increase selenium levels naturally and easily!

Goat’s milk is also a very good source of selenium, containing 27% more of this essential mineral than cow’s milk.

Vitamin C is probably the best known vitamin in relation to immunity, and deficiency of it reduces our body’s resistance against infection, whereas a higher availability of vitamin C in the body, enhances our immune system in a variety of ways. Both vitamin C and zinc are especially important in children as a lack of these nutrients during the growth and development stage has been shown to impair immune defences. Vitamin C can be found in foods such as citrus fruits, blueberries, broccoli, kiwis, peppers and fresh chilies.

Foods containing B vitamins are also required for a healthy immune system, with B12 involved in the production and function of special cells in the body that fight infection and B5 promoting the production of antibodies. High sources of B vitamins include green leafy vegetables, bananas, chicken, fortified cereals, milk, eggs and nuts.

Foods which negatively affect immunity

Some foods are known to have a negative impact on immune function and if consumed regularly or in large amounts, can leave you more susceptible to illness. Alcohol is one such food that not only reduces the body’s ability to absorb vital nutrients required for strong immunity, but it also interferes with the function and production of white blood cells which are vital to fighting infection. Consuming too much sugar and sugary foods may also weaken immunity by inhibiting a process called phagocytosis. This is the process by which some white blood cells engulf bacteria and viruses and thus keep us healthy, so if this process is inhibited, our immune defences are weakened. Despite many people relying on foods and drinks containing caffeine to get them through the working day, its effects on the immune system are not that positive if consumed in large amounts. Excess caffeine raises cortisol levels in the body. This is the body’s stress hormone and raised cortisol levels may reduce immune function.

Aging, nutrition & immunity

Many research studies have shown that as we age our immune response reduces, meaning that the elderly are more susceptible to infections and diseases. Although there are many physiological reasons for this, some research has shown a link between micronutrient deficiency in the elderly and decreased immune function. Micronutrients are nutrients required in small amounts in our diet and are essential for good health. They include all the main vitamins and minerals such as the B vitamins, vitamin C, iron, zinc and magnesium to name a few.

The elderly tend to eat less and do not eat as varied a diet hence why micronutrient deficiency is more common in the elderly and why immune function can be impaired. To reduce the risk of micronutrient deficiency:

  • Don’t eat the same things all the time. Eat a variety of foods of different colours, especially fruit and vegetables. 

  • If your appetite has lessened, don’t just stop eating. Instead eat little and often, rather than over face yourself with large meals.

  • According to the World Health Organisation, iron deficiency is the most common deficiency in the world. So try snacking on iron rich foods such as nuts, seeds, dark chocolate, pulses and beans to maintain those iron levels.

  • If you know your diet is lacking or you don’t eat certain food groups such as whole grains or fruit and vegetables, you could consider taking a multivitamin.

There is no one thing that can make you immune to all infections and illnesses, but you can help yourself stay as healthy as possible by making sure you eat the right things in the right amounts. Incorporating the foods discussed above will give you a fighting chance of staying well in the coming months, even if it may mean having a slight ‘eau de garlic’ scent!!


  • Journal of the American College of Nutrition, 2015. Consuming lentinula edodes (Shiitake) mushrooms daily improves human immunity: A randomized dietary intervention in healthy young adults

  • Molecular Nutrition & Food Research, 2008. The influence of selenium on immune responses

  • The Journal of Nutrition, 1987. Selenium content and distribution of human, cow and goat milk

  • British Journal of Nutrition, 2013. Nutrition, immunity and human health

  • The American Society for Clinical Nutrition, 1973. Role of sugars in human neutrophilic phagocytosis

  • The Journal of International Medical research, 2012. A Combination of High-Dose Vitamin C plus Zinc for the Common Cold

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