8 tips to boost your immune system

October 5th, 2018 - By fooddoctor
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As the leaves begin to fall from the trees, the nights draw in and the temperatures drop, we know autumn is upon us. Which for many of us means cold and flu season is here, and lots of sore throats and runny noses. Fortunately there are a few things you can do to boost your immune system as we head into autumn.

But first it’s important to understand how the immune system works. Our immune system is a complex system that is made up of a network of different cells, tissues and organs that work together to protect us against infections and foreign substances. There are three lines of defence, the first is designed to keep invaders out and involves the skin, nose hairs, mucous membranes, and stomach gastric juices. If the pathogen gets into the body the second line of defence takes over, where an inflammatory response is produced and the white blood cells ingest the pathogens. These two defence symptoms are known as innate immunity which is a non-specific disease mechanism. The third line of defence is known as adaptive immunity which occurs against specific pathogens that are causing disease and involves the B and T cells (lymphocytes).

With that in mind, I’ve put together my top tips for boosting your immune system.

1. Eat more gut friendly foods

Our guts are home to trillions of beneficial bacteria which control many of our bodily processes including our hormones, digestion and most of our immune system. In fact, our gut wall houses up to 70% of the cells that make up the immune system. Having a healthy gut with lots of beneficial bacteria is therefore crucial to your immune system. The diversity of the bacteria in your gut is considered the key to good health and this can be achieved through what you eat.

Including some prebiotics and probiotics in your diet is a great way to improve the beneficial bacteria in your gut.1 Prebiotics are foods that promote the growth of good bacteria which includes any foods rich in fibre such as oats, flaxseed and apples, as well as foods that contain inulin such as onions, leeks, garlic, artichokes, asparagus and bananas. On the other hand probiotics are living bacteria which are found mostly in fermented foods such as yogurt, sauerkraut, kimchi, kombucha, kefir and pickles.

2. Increase your vitamin C intake

For a long time there has been controversy over whether vitamin C can help prevent the common cold. Research shows that during a viral infection the concentrations of vitamin C in the blood rapidly decline and deficiency in this vitamin can therefore impair the immune response. 2 Vitamin C is needed for several cells of the immune system and as an antioxidant it helps protect the cells against oxidative stress and inflammation.2 Evidence shoes that vitamin C does not reduce the occurrence of the common cold but does reduce the severity and duration of it.3

Whilst there are plenty of vitamin C supplements available, it’s best to keep your levels topped up through food. Foods rich in vitamin C include red peppers, kiwi fruits, oranges, grapefruit, limes, lemons, blackcurrants, broccoli, tomatoes, green peas, papaya and sweet potato. At the first signs of a cold, up your vitamin C intake or take a supplement and continue taking until your symptoms have gone.

3. Consider taking a vitamin D supplement

Vitamin D is known for its fundamental role in bone and muscle health. Recent evidence suggests that it may have an important role in the body’s immune system. When our skin is exposed to sunlight (15-20 minutes) the UV rays convert the cholesterol in our skin into vitamin D. However, from October to April in the UK the sun isn’t strong enough to stimulate this process.

Vitamin D is found in small amounts in foods such as oily fish, liver, eggs and fortified foods (like cereal, almond milks and grains). Last year the government updated the guidelines and now recommends adults and children over the age of one to have 10 micrograms (mcg) of vitamin D per day. Since it is difficult to achieve this intake through food alone, it may be worth considering supplements.

4. Eat foods rich in zinc

Zinc is a mineral important for numerous physiological processes including DNA synthesis, macronutrient (carbohydrate, fat and protein) metabolism and the immune system. Numerous cells of the immune system require zinc to function properly and deficiency in the mineral has been shown to lead to excessive inflammation.4

In the UK between the ages of 19-64 we are recommended to have 9.5mg a day for men and 7mg for women. We get most of our zinc intake from meat but it is also found in shellfish, dairy, wholegrains, nuts and seeds.

5. Eat foods rich in vitamin A

Alongside its role in vision, reproduction and cellular communications, vitamin A is involved in the immune system. Deficiency in the mineral has been shown to impair the immune systems first line of defence and reduce the function of immune cells.5

In the UK 19-64 year olds are recommended to get 0.7mg of vitamin A a day for men and 0.6mg for women. There are two forms of vitamin A in the diet; preformed vitamin A (retinol and retinyl ester) found in animal products like liver, cod-liver oil, butter, eggs and dairy products, and provitamin A (carotenoids) found in leafy green vegetables like spinach, and orange and yellow fruits and vegetables like sweet potato, carrots and tomatoes.

6. Eat chicken soup/bone broth

Ever wondered why your mum gave you chicken soup when you were ill? Well the ability of chicken soup or bone broth to treat the common cold has long been touted as ancient folklore. It dates back thousands of years and remains a staple in many traditional cultures. Although there aren’t many studies that have investigated the effect of chicken soup on the common cold, many experts swear by it. One study found that chicken soup acted as an anti-inflammatory that could potentially reduce the symptoms of the common cold.6

The bones used to make the soup are rich in minerals such as calcium, magnesium and phosphorus and a variety of amino acids including collagen and gelatine. I would recommend making your own soup or broth at home rather than buying one as shop bought ones may contain less nutrients. You could use leftover bones from a Sunday roast or freeze the bones for a later date.

7. Get at least 8 hours sleep

Our busy and sociable lives mean that many of us don’t get enough sleep. The benefits of a good night’s sleep are extremely underestimated and should be considered a vital part of our immune system. Studies have shown that sleep is a strong regulator of the immunological process. Many immune functions display prominent rhythms in sync with our sleep-wake cycle, demonstrating the importance of sleep on these parameters.7

Most us need around eight hours of sleep a night to function at our best and the quality of sleep can sometimes be more important than the amount of sleep. Some of us need more sleep than others so it’s worth trying to find out how much you need to function at your best. If your finding it difficult to sleep try not to use your phone for an hour before you go to bed, don’t eat too late, take a bath with lavender, eucalyptus or tea tree oil, or drink a chamomile tea.

8. Consider elderberry supplements

There are lots of herbal remedies that are thought to boost the immune system but many of them lack any hard evidence. One herbal remedy which does have some research behind it is elderberries. Elderberries are small, dark berries that grow in clusters on elder trees. A number of studies have investigated the effect of elderberries on the immune system and found that the berries do not necessarily reduce the occurrence of common colds but reduce the duration and severity of colds. 8 They’ve also been shown to reduce inflammation in the body.9


If you want to reduce your risk of catching something as you head into autumn try to incorporate the above tips into your routine. Make sure you eats lots of fruit and vegetables, some gut friendly foods, get enough sleep and be aware of your stress levels (as stress can reduce the function of the immune system). Consider taking a vitamin D supplement throughout October to April and when the first signs of a cold appear, take a vitamin C, zinc and elderberry supplement to reduce the duration and severity of the cold.

Speak again soon,

The Food Doctor



  1. Vieira, A., Teixeira, M. and Martins, F. (2013). The Role of Probiotics and Prebiotics in Inducing Gut Immunity. Frontiers in Immunology, 4.
  2. Beveridge, S., Wintergerst, E., Maggini, S. and Hornig, D. (2008). Immune-enhancing role of vitamin C and zinc and effect on clinical conditions. Proceedings of the Nutrition Society, 67(OCE).
  3. Strohle, A. and Hahn, A. (2009). Vitamin C and immune function. Medizinische Monatsschrift fur Pharmazeuten, 32(2);49-54.
  4. Shankar, A H. and Prasad, A S. (1998). Zinc and immune function: the biological basis of altered resistance to infection. The American Journal of Clinical Nutrition, 68(2);447-463.
  5. Stephensen, C B. (2001). Vitamin A, infection, and immune function. Annual Review of Nutrition, 21: 167-192.
  6. Rennard, B O., Ertl, R F., Gossman, G L., Robbins R A. and Rennard, S I. (2000). Chicken soup inhibits neutrophil chemotaxi in vitro. Chest, 118(4);1150-1157.
  7. Besedovsky, L., Lange, T. and Born, J. (2012). Sleep and immune function. Pflugers Arch, 463(1);121-137.
  8. Tiralongo, E., Shirley, W. and Lea, R. (2016). Elderberry Supplementation Reduces Cold Duration and Symptoms in Air-Travellers: A Randomized, Double-Blind Placebo-Controlled Clinical Trial, 8(4);182.
  9. Barak, V., Halperin, T. and Kalickman, I. (2001). The effect of Sambucol, a black elderberry-based, natural product, on the production of human cytokines: I. Inflammatory cytokines, 12(2);290-296.

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