As the nights draw in and colds and flu start doing the rounds, many of us start thinking about how to look after ourselves through the winter months. Getting enough of the nutrients that support normal immune function is a good place to start, but recent figures suggest plenty of us could be falling short. The latest National Diet and Nutrition Survey (NDNS) data has highlighted potential gaps in folate, iron and magnesium among women and some adults aged over 65[i].
The figures underline the scale of the issue, with 83% of UK women aged 16–49 having folate levels below World Health Organisation recommendations[ii], around a quarter of women potentially not getting enough iron, and 16% of adults aged over 65 falling short on magnesium[i]. The data also show 96% of UK adults aren't getting enough fibre[i]. These nutrients play different roles in supporting our health: folate helps produce new cells[iii], iron supports normal immune function and red blood cell formation[iv], and magnesium is involved in processes linked to the body's immune response[v]. Fibre also supports digestive health and beneficial gut bacteria, which play a role in digestion, immunity and overall wellbeing[vi].
Jo Travers, nutritionist for Discover Great Veg, said: “These findings are a reminder that even when we think we're eating well, we may be missing out on certain nutrients. Eating a varied, balanced diet can help, with foods such as beans, lentils, nuts, seeds, wholegrains and dark leafy vegetables providing a range of vitamins and minerals that support our health and wellbeing.
“Green and red kale and cavolo nero, for example, provide fibre and contain some iron, while spinach is particularly useful for magnesium, vitamin A and folate. Although no single food can ‘boost’ the immune system, stirring these vegetables into everyday meals such as soups, curries or pasta dishes is a simple way to increase our intake of these key nutrients.”
Five nutrients to focus on this winter
Folate
Folate helps the body make new cells, including those involved in the immune response. With 83% of UK women aged 16–49 below WHO recommendations[vii], it's a nutrient worth paying attention to. An 80g portion of raw spinach provides around a third of the daily requirement, while beans, lentils and chickpeas are also useful sources[ii].
Fibre and gut health
Fibre helps keep the digestive system working normally and supports beneficial bacteria in the gut microbiome, which also plays a role in immune health[v]. With 96% of UK adults not getting enough fibre[i], cavolo nero and green and red kale can help contribute to overall intake, along with lentils, beans and wholegrains.
Iron
Iron supports normal immune function and helps the body make red blood cells and haemoglobin[iv] . Women have higher requirements than men, and around a quarter may not be getting enough[i]. Cavolo nero and green and red kale contain the mineral and can contribute to overall intake. While plant-based iron is less readily absorbed than iron from meat, kale also provides vitamin C, which helps the body absorb it. Serving kale with vitamin C-rich foods, such as red peppers, can further improve absorption. Other sources include red meat, beans, nuts, lentils and seeds.
Vitamin A
Vitamin A helps support normal immune function and maintain protective barriers in the body, including the lining of the respiratory system[vi]. Spinach is a particularly useful source, while eggs and dairy products can also contribute.
Magnesium
Magnesium is involved in processes linked to the body's immune response[v]. Around 16% of adults aged over 65 are not getting enough magnesium[i], while an 80g serving of cooked spinach can provide around 20% of daily magnesium needs. Other sources include nuts, seeds, wholegrains and beans.
You don’t need to overhaul your diet to make a difference. A handful of spinach stirred into a curry, some shredded kale added to a soup, or cavolo nero tossed through pasta are all easy ways to get more of these nutrients into everyday meals, and they’re in season and at their best right now.
Looking for inspiration? Browse our kale, cavolo nero and spinach recipes for warming winter dishes the whole family will enjoy.
References
[i] Office for Health Improvement and Disparities and Food Standards Agency (2025). National Diet and Nutrition Survey: Results from Years 11 to 14 (2019/20 to 2022/23). London: GOV.UK. Available at: NDNS report. (Accessed: 14 October 2026).
[ii] Office for Health Improvement and Disparities and Food Standards Agency (2025). National Diet and Nutrition Survey: Results from Years 11 to 14 (2019/20 to 2022/23). London: GOV.UK. Available at: NDNS report. (Accessed: 14 October 2026).
World Health Organization (2015). Guideline: Optimal serum and red blood cell folate concentrations in women of reproductive age for prevention of neural tube defects. Geneva: World Health Organization.
[iii] Courtemanche, C. et al. (2004). ‘Folate deficiency inhibits the proliferation of primary human CD8+ T lymphocytes in vitro.’ Journal of Immunology, 173(5), pp. 3186–3192. PMID: 15322179.
[iv] Brock, J.H. and Mulero, V. (2000). ‘Cellular and molecular aspects of iron and immune function.’ Proceedings of the Nutrition Society, 59(4), pp. 537–540. PMID: 11115788.
Ni, S. et al. (2022). ‘Iron Metabolism and Immune Regulation.’ Frontiers in Immunology, 13, 816282. DOI: 10.3389/fimmu.2022.816282.
[v] Lötscher, J. et al. (2022). ‘Magnesium sensing via LFA-1 regulates CD8+ T cell effector function.’ Cell, 185(4), pp. 585–602. DOI: 10.1016/j.cell.2021.12.039.
[7] Nielsen, F.H. (2018). ‘Magnesium deficiency and increased inflammation: current perspectives.’ Journal of Inflammation Research, 11, pp. 25–34. PMID: 29403302.
[vi] Zheng, D., Liwinski, T. and Elinav, E. (2020). ‘Interaction between microbiota and immunity in health and disease.’ Cell Research, 30(6), pp. 492–506. DOI: 10.1038/s41422-020-0332-7.
[9] Kim, C.H. (2021). ‘Control of lymphocyte functions by gut microbiota-derived short-chain fatty acids.’ Cellular & Molecular Immunology. PMCID: PMC8093302.