Boosting Our Immune System – Katia Frank, DipION BSc MBA mBANT rCNHC

In this New Year blog London based Nutritional Therapist Katia Frank from Nutrition Applied explains how we can do to bolster our immune system during the winter flu and cold season.

At the beginning of the new year, many of us resolve to take steps to improve our health. Besides getting fitter or shedding a few unwanted pounds, top of the list should be supporting our immune system to see us through the winter months and beyond.

Most of us are familiar with the science that viruses live longer at lower temperatures and lower humidity. And given we spend a lot of our time indoors during these winter months, the risk of infection is that much greater. Yet, why do some people get more illnesses than others?

The critical factor is the strength of our immune system. Lowered immunity is not only evident in increased frequency of colds and infections, but also slow wound healing, gut issues including diarrhoea, and increased fatigue and irritability.   


Factors that affect our immune system

Excessive stress, lack of exercise, loneliness, smoking, poor diet and lack of sleep all play a role in lowering our defences.

Stress, smoking and excessive alcohol can deplete our bodies of crucial immune supporting nutrients such as Vitamin C and zinc, leading to chronic inflammation and increased susceptibility to infections. 

In addition, sugary snacks and processed foods are not only nutrient deficient, but also cause chronic inflammation which weaken our defences against pathogens. Lack of exercise and obesity also increase inflammation and compromise the functioning of our immune cells.


So what can we do?

Micronutrients identified for a well-functioning immune system include vitamins A, C, D, E, B2, B6 and B12 as well as folic acid, iron, selenium and zinc. We can replenish these key micronutrients by eating a rainbow diet which comprises a wide variety of coloured plant foods. Limit sugary snacks and highly processed meals because, although they fill you up, they are very low in nutrients.

Choose seasonal vegetables such as turnip, swede, cabbage, cauliflower, leeks, mushrooms, onions and carrots. A benefit to eating this way is that it feeds helpful bacteria in the gut, which play a fundamental part in regulating a healthy immune response, ensuring our bodies can recognise invaders and distinguish them from healthy body tissue.

Infections significantly deplete the body’s vitamin C stores, due to the onset of inflammation as well as the body’s increased metabolic requirements in times of illness. We can’t store this vitamin so must eat it daily. Sugar competes with vitamin C for uptake into cells, so replace sugary sweet treats with citrus fruit. Other foods rich in vitamin C include kiwis, peppers and cruciferous vegetables.  

As well as providing lots of vitamin C in the diet, opting for yellow, orange, red and green, leafy vegetables will also mean a good supply of beta-carotene which is converted to vitamin A. This key vitamin helps support the body as it fights off infection and illness. It’s also important for skin and mucous membrane health, enhancing the body’s initial barriers against infection.

It is thought that vitamin D deficiency may be associated with sub-optimal immune function and an increased risk of infection. This is more likely to be a problem during winter when there are fewer daylight hours. Vitamin D rich foods include salmon, sardines, eggs and mushrooms, as well as some fortified foods such as plant milks or nutritional yeast.

Curcumin, which is found in turmeric, may also have potential benefits for improved immune function. When adding turmeric to soups, stews, stir-fries and warmed plant milks, add a sprinkle of black pepper. This is because piperine, which is found in pepper, helps the body to better absorb the curcumin.

Zinc and selenium are two significant minerals needed for immune cells to function properly. Soil exhaustion means we may be getting less from our food so we need to make a concerted effort to regularly eat foods rich in both. The best sources of zinc are seafood, red meat, egg yolks, lentils, beans, chickpeas, hemp, pumpkin, squash and sesame seeds, cashews and almonds. Sources of selenium include fish and brazil nuts.

Beta glucan, a form of soluble fibre found in oats, wheat and barley, is linked to a long list of potential health benefits including decreasing inflammation and helping to activate immune cells so that they can protect the body against infection. Yet another good reason to start your day with a bowl of oats!


In conclusion

A varied colourful diet, of unprocessed or minimally processed foods, low in sugar should provide you with adequate amounts of vitamins and minerals essential for immune health. However, with our modern lifestyles we may have less than optimal diets so should consider high quality supplements even if only during the winter months. If you have any concerns it is always best to seek advice from a health practitioner or registered nutritional therapist who can advise on brand, dosage and possible drug and nutrient interactions.