Vitamin D is the key

There are a lot of circulating articles at the moment which recommend taking vitamin D supplements, but what does all this mean and is it really necessary? Well, I am here to talk you through the research and shed some light on why we need vitamin D.

What is vitamin D and why do we need it?

So, let’s start with the basics. Vitamin D is needed in the body to manage the amount of calcium and phosphate in the body. First and foremost, we need calcium in order to maintain and grow strong bones, but calcium also allows organs in the body to function, such as the heart. Phosphate also promotes bone health, but is also involved in the body’s energy functions, as well as muscle and nerve function. Vitamin D is fat soluble meaning it is stored and transported within fat molecules. We get vitamin D naturally from sunlight, as well as from foods in the diet. Food sources which are high in vitamin D include: oily fish (herring, salmon, mackerel etc.), cod liver oil, tuna, oysters, prawns, egg yolks, fortified dairy products, butter and margarine. It’s also not just the type of food that affects the vitamin D content, but also how the food itself is cooked. This is because vitamin D is fat soluble, therefore you should try to avoid oils and other fats when cooking food that is high in vitamin D to ensure no vitamin D content is lost.

Vitamin D in the UK

As mentioned previously, we get vitamin D from sunlight but as the UK is not as sunny as other countries, we are only able to make vitamin D from the sun in months April to September, we struggle to get the needed vitamin D in the winter (Webb et al. 2010).

Covid-19 Impact

In particular, this year it is expected that people are in need of further vitamin D supplementation, because many of us were stuck inside due to lockdown for many of the optimal months for sun. There are circulating reports that vitamin D provides a protective benefit for Covid-19, but there is no concrete evidence to support this so don’t panic if you have a known deficiency in vitamin D.

Variation between people

Research has found that people vary in their capacity to make vitamin D from the sunlight (Lucas et al. 2011). A known group that are prone to deficiencies in vitamin D, and therefore need to get more vitamin D from food sources of supplements, are people with darker skin (Libon et al. 2013; Clemens et al. 1982; ). As well as people who notably get less exposure to sun, for example those working night shifts or the elderly in care homes.

What does a deficiency in vitamin D look like?

There are various symptoms of vitamin D deficiencies. One symptom of deficiency is getting ill or infected often, which I guess may be where the link to Covid-19 has come from. Other symptoms are fatigue and tiredness, back/bone pain, impaired wound healing, bone and hair loss and muscle pain. Depression is also associated with vitamin D deficiency, but it appears unclear whether depression is a symptom of the vitamin D deficiency, or the vitamin D deficiency is a symptom of depression. It may be simply that people with depression are less likely to be exposed to the sun. If you do have one of the aforementioned symptoms, it doesn’t necessarily mean you have a deficiency as there is a big overlap with other deficiencies, such as iron deficiency.

What can you do to increase vitamin D?

So, other than eating the food sources mentioned and getting enough sunlight, you can get vitamin D from supplements. Vitamin D supplements can be found in chemists and this is the best place to buy them as chemists can offer advice on their consumption. It is recommended for most people to take supplements of 10 micrograms per day. Contrary to some claims, tanning beds are definitely not a good way to supplement vitamin D and are actually very damaging (Gilchrest et al. 2008)

Is there such a thing as too much vitamin D?

Most people shouldn’t consume more than 100 micrograms a day of vitamin D as too much vitamin D can lead to hypercalcaemia, an excess of calcium in the body. Don’t get too hung up on the possibility of too much vitamin D as its unlikely you will exceed the recommended amount. This recommendation of 100 micrograms a day is general the same for people above the age of 10, pregnant women, breastfeeding women and the elderly population. There is no such thing as too much sun exposure in terms of vitamin D intake, however you need to be mindful to wear suncream and not stay out in the sun too long due to the potential for skin damage. Different ages do have different recommendations for vitamin D such as:

  • Infants under the age of one should not consume more than 25 micrograms a day.
  • Children between the ages of 1-10 should not consume more than 50 micrograms a day.
  • Certain people will be notified by their doctor that their recommended level of vitamin D will differ from the general recommendations.
So what does this all mean?

Doctors recommend you to be taking vitamin D as a supplement in these winter months in the UK, and it is advised that you should increase your consumption of foods which are high in vitamin D. This is especially needed in the UK, this year more than ever, due to the lack of sun exposure. Just make sure that your vitamin D intake is within the recommended intake for your age and needs. So what can you take away from this information? Get consuming vitamin D!


Clemens, T.L., Henderson, S.L., Adams, J.S. and Holick, M.F., 1982. Increased skin pigment reduces the capacity of skin to synthesise vitamin D3. The Lancet319(8263), pp.74-76.

Gilchrest, B.A., 2008. Sun exposure and vitamin D sufficiency. The American journal of clinical nutrition88(2), pp.570S-577S.

Libon, F., Cavalier, E. and Nikkels, A.F., 2013. Skin color is relevant to vitamin D synthesis. Dermatology227(3), pp.250-254.

Lucas, R.M., Ponsonby, A.L., Dear, K., Valery, P.C., Pender, M.P., Taylor, B.V., Kilpatrick, T.J., Dwyer, T., Coulthard, A., Chapman, C. and Van der Mei, I., 2011. Sun exposure and vitamin D are independent risk factors for CNS demyelination. Neurology76(6), pp.540-548.

Webb, A.R., Kift, R., Durkin, M.T., O’brien, S.J., Vail, A., Berry, J.L. and Rhodes, L.E., 2010. The role of sunlight exposure in determining the vitamin D status of the UK white adult population. British Journal of Dermatology163(5), pp.1050-1055.

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