As we head into peak cold and flu season it’s now the perfect time to focus on our immune system. Getting enough sleep, minimising stress, and maintaining good hygiene are paramount. So too, is proper nutrition.
Over 70% of your immune system is in your gut, and your gut microbiome can directly influence the way your body responds to pathogens. Did you know certain foods have been shown to contain immune-boosting properties?
To help keep you fit and firing over winter, we’ve rounded up some key nutrients and food sources to strengthen your gut microbiome and boost your immune system.
Probiotics are live ‘good bacteria’ and are naturally occurring in fermented foods. During food fermentation, natural sugars are converted into lactic acid, facilitating the growth of lactobacilli and other probiotics.
People who have high levels of lactobacilli in their bowel usually have fewer Enterobacteriaceae - bacteria associated with inflammation. Chronic inflammation can damage the lining of the gut, allowing bacterial cells to pass through and threaten disease.
Food sources: Kefir, yoghurt, sauerkraut, kimchi, miso, kombucha, probiotic supplement (i.e. Yakult). Note - probiotic supplements containing lactobacilli and other beneficial species (i.e. bifidobacterium) are an option for those who do not regularly consume fermented foods
Prebiotics are dietary fibers that act as ‘food sources’ for good bacteria. Higher consumption of prebiotic foods has been linked to reduced growth of some disease-causing gut bacteria. A word of caution, some foods rich in prebiotics are also sources of dietary FODMAPs. If you have IBS (Irritable Bowel Syndrome), some of these foods may aggravate, rather than relieve your digestive symptoms. But don't worry, there are plenty of FODMAP friendly prebiotic foods!
Food sources (High FODMAP): Garlic, asparagus, artichoke, legumes, apples
Food sources (Low FODMAP): firm bananas (white greenish tinge), flaxseeds, oats, cacao
Our bodies don't make vitamin C, but we need it for immune function. The recommended daily intake is 75mg for women and 90mg for men. Whilst experts are undecided as to whether high doses of Vitamin C can prevent a common cold, long term intakes of 200mg per day (or more) may reduce the duration of cold symptoms. According to a review of 29 clinical trials written in 2013, higher levels of Vitamin C intake translated to about one less day of illness in both adults and children.
We suggest you aim to meet Vitamin C targets with wholefoods, because you will benefit from other important nutrients. For example, blueberries are rich in Vitamin C and ‘pterostilbene’, a phytonutrient which may increase your number of infection-fighting T-cells, and CAMP – a protein that protects against bacterial infection. By consuming 5 servings of vegetables and 2 servings of fruit each day, you are likely to achieve the cold-fighting Vitamin C goal of 200mg.
Food Sources: Citrus fruits, berries, dark green leafy vegetables, legumes
Zinc is an important mineral with many roles to play, including immune function, wound healing, macronutrient metabolism, thyroid function and fertility.
Zinc supplementation has been shown to enhance T cell activation, and reduce both the severity and the duration of ‘common cold’ symptoms. There are plenty of reasons to ensure your diet is rich in this important nutrient all year round. You may wish to opt for an extra 'boost' with zinc supplements, if you feel cold symptoms coming on – the recommended dose is 75mg/day.
Food sources: Lean red meat, poultry, seafood, tofu, pumpkin seeds, cashews.
Vitamin D is known to play a protective role against viral and bacterial infections. In fact, studies have shown that deficiency in Vitamin D can increase risk your of infection, and your risk of developing an autoimmune condition.
Sun exposure is the best option for obtaining Vitamin D, however, this can be difficult in winter, when we need it most, which is why Vitamin D rich foods are so important.
Food sources: Oily fish (i.e. salmon, sardines), egg yolks (particularly free range), mushrooms, fortified milk (i.e. Rev, Vitasoy Calci-plus), fortified cereals (i.e. Special K).