Can I boost my immune system through food?
The immune system has a variety of nutrient requirements, so eating a varied whole food diet including an assortment of different coloured vegetables and fruit, as well as healthy fats and good quality protein is key to it running smoothly. However, there are specific nutrients that studies have shown play an essential role in enhancing immunity, including beta-glucans, phytonutrients, and foods that promote a healthy digestive system such as prebiotics and probiotics.
Beta-glucans found in baker's yeast and to lesser extent mushrooms, help to heighten the immune systems first line of defence, so eating these often, helps to ensure that the immune system is ready to defend you as soon as it is under attack from an infection.
Phytonutrients in coloured fruits and vegetables, as well as legumes, nuts and teas, have been shown in research to have a positive impact on human health. Some of the notable phytonutrients include resveratrol found in grape skin and cocoa, carotenoids found in yellow, orange and red-coloured vegetables, curcumin found in turmeric and ellagic acid - also referred to as a tannin - in walnuts and pomegranates.
Recent research shows that the microbiome in your gut plays a role in a well-functioning immune system, as 70% of immune cells are in the digestive system. Eating foods such as prebiotics including Jerusalem artichoke, garlic, and asparagus helps to feed the good bacteria in your gut. Nourishing your digestive system with bone broth, stewed apples, and fermented foods such as sauerkraut and kefir is also worthwhile.
What foods should we avoid?
Unsurprisingly, processed foods can impair your immune system as they are often nutrient-depleted and enriched with chemicals such as additives, oxidised vegetable oils and MSG. These types of chemicals put stress on your body, so the immune system can not function properly.
Also, foods that contain a high amount of sugar or refined carbohydrates can promote low-grade systemic inflammation in the body which impacts the immune system's first line of defence. Sugar feeds harmful bacteria and yeasts in the body, such as Candida, which can offset the balance of healthy bacteria in the digestive system. As your body relies on beneficial bacteria to protect it from infection when this is off-balance, you are more venerable to harmful bacteria and viruses.
Highly processed vegetable oils such as sunflower, soybean and canola oil also promote systemic inflammation as they are often oxidised and rancid, and contain a high amount of omega 6 vs, omega 3. The ratio of omega 3 vs omega 6 in your body is a critical factor in immune health. Avoiding these oils and eating foods high in omega 3 such as cold-water fatty fish, flaxseed and chia seed, may help to bring back the balance to support a healthy immune function.
It’s not just what you eat but how you eat
There is lots of evidence to support that eating within a shortened eating window benefits immune health. Often referred to as intermittent fasting, which involves eating within a window of between 6 to 12 hours, and then fasting overnight has been shown to have many health-promoting benefits. This type of fasting aids your body to use fat as fuel rather than glucose, which produces ketone bodies in your body. Being in ketosis may improve immune health through regulating gene expression, which helps to build essential proteins that the immune system requires to function correctly.
Eating within a shortened eating window also gives your digestive system time to recover and heal. As your immune system repairs and restores during sleep, it is best to eat earlier in the day, and eat your last meal at least 3 hours before bed, ideally at around 6 pm, so that the digestive process does not disrupt your well-earned rest.
Want to know more? Read 10 ways to boost your immune system.
And if you liked this, you might enjoy my other articles, Simple daily habits to transform your health and Are anti-inflammatory foods the secret of healthy eating?