Give Me Sunshine…
Known as the sunshine vitamin, vitamin D has grown in status over the years due to scientific study confirming its significance. Known for its importance of bone health and aiding the absorption of calcium, it is also cited as significant in the prevention/and or treatment of disease, most recently relevant in respiratory diseases.
Vitamin D is one of the only vitamins that we actually make ourselves and it is the only vitamin that is also a hormone. When it’s absorbed by the sun or consumed via food, it is transported to the liver and kidneys where it is converted to its active hormone.
Vitamin D is fat soluble and plays a vital role in supporting the immune system, in fact – every tissue in the body has vitamin D receptors, including the brain, heart, muscles, and immune system, meaning that vitamin D is needed for the body to function. The main forms of vitamin D are D2 and D3. We get the D2 from plant sources such as mushrooms and tofu, and D3 mainly from animal sources such as eggs, dairy products, and oily fish (e.g. salmon, anchovies). When bare skin is exposed to UVB rays from the sun our skin ‘absorbs’ something known calcidiol which is then converted to vitamin D.
As much as 25% of the UK population may be deficient so with the nights closing in, sunlight exposure reducing and an increase in illness over the winter months, it is essential that we optimise vitamin D levels. Those more at risk are those who have a sedentary indoor lifestyle including those who work from home – and yes that is most of us this year meaning this winter vitamin D becomes even more important! Other things that can contribute to low vitamin D are pregnancy and breastfeeding, old age, dark or covered skin, obesity and low magnesium status. Some of us also carry a genetic synapse which can interfere with its internal function.
It would be a miss not to mention Seasonal Affective Disorder (SAD) at this time of year. SAD is a mood disorder featuring depressive symptoms and occurs during winter when there is less daylight and therefore sunshine which coincides with a drop in vitamin D levels in the body. Several studies have suggested that the symptoms of SAD may be due to changing levels of vitamin D3, which may affect serotonin levels in the brain. Various studies also confirm the link between low vitamin D and mental illness. These studies show that optimising vitamin D levels may work towards improving psychological well-being.
The EU daily recommendation for vitamin D for an adult is 5µg (200 IU), however this dosage often proves insufficient for most adults due to a lack of sun exposure and some of the risk factors mentioned. For this reason, 1000 IU is generally considered a more optimal daily dosage of vitamin D for an adult.
When there is a demonstrated deficiency, some individuals require higher doses and this is best guided by a health professional. You can get a vitamin D test done with your GP or privately (which isn’t costly) and this would be a good starting point to find out your vitamin D levels and therefore your needs.