The Wonders of Vitamin D

Monday, 28 September 2020

It’s that time of year when the leaves are starting to fall from the trees and articles on the importance of taking Vitamin D supplements seem to be everywhere. This year, Vitamin D has been getting more coverage than normal due to claims that being deficient of the ‘Sunshine Vitamin’ may increase your risk from Covid-19. Whilst the stance of Public Health England (PHE) remains that there is insufficient evidence to support taking vitamin D supplements to prevent or treat Covid-19, there are some interesting observations from other parts of the World.

Why do we need Vitamin D? 

Vitamin D is important for bone and muscle health and there are suggestions it helps to prevent inflammatory diseases, reduce acute respiratory tract infections and lower the risk of some cancers. Vitamin D is different to other vitamins because it is created in our bodies through a series of biochemical processes when our skin is exposed to UVB in sunlight, hence the nickname ‘the Sunshine Vitamin'. It is reported that 20% of people in the UK are vitamin D deficient and this proportion increases significantly for people with darker skin tones which have greater difficult in synthesising the vitamin.

In April this year, as Covid-19 was rampaging through the American population, a homeless shelter in Boston, Massachusetts tested all of its 500 overnight residents for Covid-19. Homeless shelters are notoriously busy, overcrowded and prime breeding grounds for infectious disease, yet daily screening for basic symptoms was showing no sign of the virus. On the evening of the tests, a staggering 40% of residents proved to be Covid-19 positive, despite all being asymptomatic. Similar observations were also being made at other homeless shelters in the USA. Why was the disease not impacting a group of people whose lifestyle was anything but healthy? One of the suggestions is that street life maximises the daily exposure to UVB rays aiding vitamin D synthesis which in turn regulates the immune system. Similar observations were reported during the Spanish Flu Pandemic in 1919 when  patients at the Camp Brooks hospital spent their days outdoors for sunshine and fresh air and they reported a death rate of only 10% compared to 40% in other hospitals. Observations like these are driving research to understand links between Vitamin D and Covid-19. Only this week 'The Independent' reported on research by Dr Holick, a Vitamin D expert in the USA, indicating that vitamin D supplements could reduce the threat of serious complications from Covid-19 by 54%. 

How do we know if we’re getting enough?

There is no consensus on how long we need to spend in the sun, the NHS state that we should expose our face, hands and forearms to UVB daily, for short periods of time to keep our levels topped up. Peak UVB rate is 10am -2pm at the equator and decreases at higher latitudes. However, if you live above 50 degrees latitude in the northern hemisphere there is insufficient UVB for Vitamin D synthesis from October to March due to the tilt of the earth. It doesn’t matter how bright or warm the sun is during these months, all of the UVB is absorbed by the atmosphere. This is significant in the UK, where the mainland lies between 50 and 58 degrees north suggesting that the entire UK population do not get enough UVB to metabolise the Vitamin for half the year. 

How can we keep topped up during the Vitamin D Winter? 

A mid-winter holiday with a good dose of sun can help to top up our stores, but that is expensive and in the current times quite challenging. More importantly our bodies can only retain a certain amount and it quickly declines if it is not regularly replenished. We can boost our levels by eating certain foods like eggs, meat or oily fish or we can take Vitamin D supplements. 

Regardless of whether there is a link between Vitamin D and Covid-19, there is no doubt that having sufficient Vitamin D has significant health benefits. The UK Government advises that all people take a daily supplement containing 10 micrograms of vitamin D during the autumn and winter months since it is difficult for people to meet the daily requirements from food alone. Some groups are advised to consider Vitamin D supplements all year round; those whose skin has little or no exposure to the sun, like those in care homes or who cover their skin when outside and ethnic minority groups who have dark skin. The UK government also advises that during the Covid-19 pandemic, everyone should consider Vitamin D supplementation because they might not be getting enough from sunlight if they're indoors most of the day.