Vitamins to boost your immunity this winter

Chilly weather and shorter daylight hours can leave us feeling groggy, and low in mood, and may even disrupt our sleep-wake cycle. The elements can dry out the skin and cause eczema, arthritis, and asthma to flare up.  

With our immune systems having taken a hit from spending a few years away from other people, this winter, there is bound to be an increase in colds and flu. So, what can we do about it?  

Ensuring you get your necessary boosters and flu jabs is the first recommended step, but did you know that certain vitamins and minerals can help to boost your immunity too?  

In this blog, we look at some key vitamins and minerals that are particularly beneficial in winter, including: 

• Vitamin D  
• Vitamin C 
• Vitamin E  
• Iron  
• B vitamins  
• Zinc  

Vitamin D

Vitamin D helps us absorb phosphate and calcium from our diet, both essential for healthy bones, teeth, and muscles. Vitamin D also plays a role in immunity and can protect against respiratory infections [1], important for the cold and flu season.  

Our main source of vitamin D is sunlight. However, as days shorten (particularly October through to March), we can become deficient. We can get small amounts from our diet, but often not enough, which is why a daily 10µg supplement is recommended over the autumn and winter months [2]. For some people, it is recommended that a supplement is taken all year round.  

You can read more about vitamin D and vitamin D deficiency in our vitamin D guide.  

Is there a link between vitamin D and COVID-19?  

Of recent interest is the potential benefits of vitamin D in the treatment of COVID-19. New evidence and studies are emerging discussing the correlation between vitamin D and COVID-19. In essence, having low vitamin D may make you more likely to catch COVID, and also more likely to experience severe disease [3].  And vitamin D may reduce the need for a ventilator, compared with a placebo. But due to the limited number of studies and inconsistencies in measuring treatment outcomes, further research and clarification are required. Randomised control trials are currently underway [4,5].  

Vitamin C

Vitamin C is another multi-functional micronutrient that supports and strengthens our immune system. Its strong antioxidant properties support the function of white blood cells by helping them get where they need to go – mainly at the site of an infection. Once at the site of infection,  white cells help in the process of breaking down bacteria and other foreign bodies, ultimately killing microbes.  

Vitamin C also helps clear out any useless cells that sometimes can contribute to tissue damage [6]. 

It is perhaps no surprise that a vitamin C deficiency can leave your immune system vulnerable to infection. What’s more, an infection can significantly impact levels of vitamin C due to high levels of inflammation and metabolic activity [6].  

Adults need about 40mg of vitamin C a day as the body can’t store it. You can achieve this through diet alone, or if you’re finding this difficult, supplements (no more than 1000mg) are an easy and effective way to boost your levels and keep illness at bay.  

Sources of vitamin C include:  

• Citrus fruits  
• Tomatoes  
• Avocado  
• Peppers  
• Strawberries and blackcurrants  

Vitamin E

Vitamin E is an antioxidant, combatting the effects of free radicals produced by the breakdown of food and toxins. It is a key player in regulating the body’s immune responses to infection, helping us to fight off seasonal coughs and colds [7].  

Unlike vitamin D, vitamin E deficiency is rare as you can generally get enough through the diet, but occasionally supplementation may be recommended. Vitamin E can also be found in moisturisers and other skincare products, where it nourishes the skin at the source, protecting it from damage and enabling healing [8], making it a good remedy for dry and flaky winter skin.  

Sources of vitamin E include:  

• Wheatgerm  
• Vegetable oil and olive oil  
• Nuts and seeds  
• Avocado  
• Spinach and broccoli  

Iron

Iron is a mineral essential for creating haemoglobin – the protein that carries oxygen to the tissues to release energy.   

Some winter complaints including tiredness, irritability, cold intolerance, and pale skin, may be attributable to an iron deficiency. 

Iron deficiency is perhaps more common than you think, affecting up to two billion people worldwide and up to a quarter of women in the UK aged 19 to 64 [9,10].  

Women, vegetarians, and vegans are among the people most at risk due to menstrual losses and a lack of iron intake respectively.  

Iron has many functions in the body, including physical and cognitive performance. It plays a vital part in thermoregulation - the ability to maintain a constant body temperature in response to cold stress. A lack of iron can also disturb the immune system, increasing the risk of illness and infection [11]. Therefore, checking your iron levels are sufficient this winter can help to keep you warm and well.  

Sources of iron include:  

• Red meat  
• Liver (though avoid in pregnancy)  
• Beans and pulses 
• Nuts  
• Green vegetables such as spinach, broccoli, and kale  

B vitamins

The B vitamins are a family of vitamins, each with different functions. Broadly speaking, they are involved in the body’s metabolic activity (to release energy) and ensure the normal functioning of the nervous system. The vitamin B complex also supports the immune system and contributes to healthy skin, hair, and nails, particularly B2, B3, and B7.  

Vitamin B6 (pyridoxine), B9 (folic acid), and B12 (cyanocobalamin) —are crucial in producing healthy red blood cells. Therefore, as with iron, a deficit can cause anaemia and impact energy levels and mood.   

A lack of these B vitamins can also lead to depression [12], something not uncommon in winter, so check you’re not lacking in these super vitamins to stay energised and in good spirits. 

Sources of B vitamins include:  

• Meat and liver  
• Fish  
• Eggs  
• Milk  
• Nuts  
• Legumes  

Zinc

Zinc is an essential mineral for the normal functioning of many different systems in the body, including the reproductive, nervous, and immune systems. It ensures the healthy production and maturation of white blood cells, which are the guard cells in our bloodstream that fight off infection.  

Zinc is also critical for wound healing [13], making it one of the more important minerals for staying healthy this winter.  

Sources of zinc include:  

• Meat  
• Cheese  
• Bread  
• Wheatgerm  
• Shellfish  

What’s the verdict on vitamins for winter?  

During the cold and flu season, vitamins and minerals form a fundamental part of our natural defences, keeping us well and energised. It is best to get your vitamin and mineral requirements through your diet. But, in some cases, a supplement may be an easier and more effective way to meet your recommended intake—just make sure you are not taking over the recommended dose and that you speak to your doctor before taking any new medication. 

You can check on your vitamin and mineral health through a simple blood test. If you aren’t sure what blood test is best for you, read our Health and Wellness Buying Guide or try our test finder.  

References  

1. Jolliffe D. A. et al. (2020) Vitamin D supplementation to prevent acute respiratory infections: systematic review and meta-analysis of aggregate data from randomised controlled trials. medRxiv [Preprint]. 2020 Nov 25:2020.07.14.20152728. doi: 10.1101/2020.07.14.20152728. Update in: Lancet Diabetes Endocrinol. 2021 Mar 30  
2. Public Health England. (2020) Statement from PHE and NICE on vitamin D supplementation during winter. Available at: https://www.gov.uk/government/publications/vitamin-d-supplementation-during-winter-phe-and-nice-statement/statement-from-phe-and-nice-on-vitamin-d-supplementation-during-winter (Accessed 21 September 2021) .  
3. https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD015043/full  
4. Stroehlein JK et al. (2021) Vitamin D supplementation for the treatment of COVID-19: a living systematic review. Cochrane Database of Systematic Reviews 2021, Issue 5. Art. No.: CD015043. DOI: 10.1002/14651858.CD015043.  
5. https://www.bmj.com/content/378/bmj.o1822  
6. Carr AC, Maggini S. (2017) Vitamin C and Immune Function. Nutrients. 3;9(11):1211. doi: 10.3390/nu9111211. PMID: 29099763; PMCID: PMC5707683.  
7. Lee, Ga Y. and Sung N. Han. (2018) The Role of Vitamin E in Immunity. Nutrients, 10, no. 11: 1614. https://doi.org/10.3390/nu10111614  
8. Santos J. S., Tavares G. D. and Barradas T. N. (2021). Vitamin E and Derivatives in Skin Health Promotion, Vitamin E in Health and Disease - Interactions, Diseases and Health Aspects, Prof. Pınar Erkekoglu and Dr. Júlia Scherer Santos, IntechOpen, DOI: 10.5772/intechopen.99466. Available from: https://www.intechopen.com/chapters/78135  
9. Miller J. L. (2013) Iron deficiency anemia: a common and curable disease. Cold Spring Harbor perspectives in medicine, 3(7), a011866. https://doi.org/10.1101/cshperspect.a011866  
10. National Diet and Nutrition Survey. (2020) National Diet and Nutrition Survey Rolling programme Years 9 to 11 (2016/2017 to 2018/2019). Available at: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/943114/NDNS_UK_Y9-11_report.pdf (Accessed 22 September 2021).  
11. Zimmermann M. B., Hurrell R. F. (2007). Nutritional iron deficiency. Lancet. 370(9586):511-20. doi: 10.1016/S0140-6736(07)61235-5. PMID: 17693180.  
12. Mikkelsen K, Stojanovska L, Apostolopoulos V. (2016) The Effects of Vitamin B in Depression. Curr Med Chem. 23(38):4317-4337. doi: 10.2174/0929867323666160920110810. PMID: 27655070.  
13. Lin, P. H., Sermersheim, M., Li, H., Lee, P. and Steinberg, S. M., & Ma, J. (2017). Zinc in Wound Healing Modulation. Nutrients, 10(1), 16. https://doi.org/10.3390/nu10010016