As the colder months approach, you might be curious if your nutrition can play a role in reducing the risk of winter illnesses. We often hear that X or Y can 'boost' your immune system but is this really the case?
Unfortunately, there is no magic food or supplement to 'boost' your immune system. I don't want to bore you with the detailed science behind it but the immune system is very complex and involves many defence mechanisms. Although we can't 'boost' the immune system, we can support our immune function with a balanced diet and lifestyle. There are some nutrients that play a role which I will discuss in this article.
Vitamin C
Vitamin C plays a key role in supporting the immune system, and a deficiency is associated with weaker immunity and increased risk of infections. However, current evidence does not strongly support the use of vitamin C supplements to prevent colds and viruses in the general population (ie. the chance of catching a cold). That said, there is some research to suggest that vitamin C may have favourable effects on reducing the duration of cold symptoms. Although there is not enough evidence to make recommendations on the optimal dose of supplementation. Dietary sources of vitamin C include oranges, kiwis, peppers, tomatoes, broccoli, and strawberries. It may be a good idea to boost your intake of these foods at the first signs of a cold.
Vitamin D
Vitamin D plays a role in supporting immune function, yet suboptimal levels are common, particularly in Ireland and the UK, where sunlight is limited and it's challenging to get enough from diet alone. Dietary sources of vitamin D include fortified cereals, dairy and plant-based milks, as well as fish such as salmon, trout, and sardines. The Food Safety Authority of Ireland (FSAI) recommends that individuals aged 12 and older take a 15µg vitamin D supplement daily from October to March. For adults over 65, a 15µg supplement is advised year-round to maintain adequate levels.
Zinc
Zinc is a mineral that supports the immune system. Dietary sources of zinc includes shellfish, red meat, eggs, nuts, lentils, chickpeas and wholegrains.
Probiotics
A large portion of the immune system is located in the gut. Probiotics are microorganisms like bacteria which have beneficial health effects. Certain probiotics have been shown to positively interact with immune cells in the gut, stimulating immune function and supporting balance within the immune system. As always, a food first approach is important. This is my primary recommendation. Consuming a varied diet supports gut diversity and health. For example, including a variety of different fruit and vegetables, nuts, seeds, wholegrain carbohydrates, peas, beans and lentils. Including some dietary sources of probiotics is a good idea such as kefir, kimchi, kombucha and live yoghurt. There are also probiotic supplements available as a drink or capsules. It’s important to note that research in this field is still emerging, and there are currently no approved health claims linking probiotic intake to immune health.
Some other important things to consider. It's important that you are consuming enough energy from food. In short, if the body does not have enough calories to support basic functions less energy will be available to support immune function. Protein also plays an important role in producing antibodies, wound healing and immune cell function. Fats play a vital role in cell membrane formation and aid the absorption of fat-soluble vitamins A, D, E, and K, as well as essential omega-3 fatty acids, which are crucial for regulating inflammation. Other nutrients that play a role in supporting the immune function include: B-vitamins, iron, vitamin E and selenium.
Overall, consuming a well-balanced diet that includes a variety of meals with carbohydrates, protein and fat and trying to get lots of variety will help you to get a range of nutrients in your diet.
Diet and nutrition is only one aspect to support your immune system. Other factors of a healthy immune system include: genetics, medical conditions, hand hygiene, exercise, stress, sleep, alcohol and smoking. These must not be forgotten!!
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