What is vitamin D?
Vitamin D is a fat-soluble vitamin which means that it dissolves in fats and oils and it can be stored by our bodies for a long time. However, according to the Health and Food Supplements Information Service (HSIS), unlike other vitamins, vitamin D can’t be absorbed in sufficient quantities from food alone. Fortunately, there is a way for our bodies to produce enough vitamin D when our skin is exposed to sunlight, although this is not available throughout the year.
Why do we need Vitamin D?
Vitamin D is essential for several aspects of our health:
- It helps regulate the amount of calcium and phosphorus in our body, which are crucial in keeping our bones, teeth and muscles healthy.
- It can improve our heart function.
- It is important for blood clotting and assists in a healthy immune system.
How do we get Vitamin D?
There are 2 natural ways in which our bodies get vitamin D:
- By creating it in the skin when exposed to UVB light.
- By absorbing it through our diet.
The ‘sunshine’ vitamin
Most of the vitamin D in our bodies comes from the exposure to sunshine. When we are outside in the sun, our skin absorbs ultraviolet B (UVB) radiation which is then used in the skin to produce vitamin D in a process called skin synthesis.
The amount of vitamin D our skin is able to synthesise depends on how much sun we get, making more when the sun is stronger in the spring and summer months, in the middle of the day and when we are in direct sunlight rather than in the shade or on a cloudy day. Most people don’t need much time in the sun to make enough vitamin D when their forearms, hands or lower legs are uncovered. UVB light is blocked by glass so our bodies can't make vitamin D if we're sitting indoors by a sunny window and higher-factor sunscreen could prevent the skin from producing it too.
However, strong sun can also burn our skin, so it’s important to stay safe in the sun by covering up your skin with clothes and sunscreen before you turn red or get burnt.
It’s difficult to say how much time you need to spend in the sun to produce enough vitamin D as it depends on several factors including the colour of your skin (darker skin usually requires more sun exposure to produce the same quantity of vitamin D as lighter skin).
Getting vitamin D from food
- Oily fish (such as salmon, mackerel and sardines)
- Egg yolks and red meat
- Breakfast cereals and fat spreads
How much Vitamin D do we need?
In 2016, Public Health England released new official advice on vitamin D, recommending that all children and adults should get an average daily intake of around 10 micrograms of vitamin D. They also added that during spring and summer, relying on sunlight and a balanced diet should be enough to get the recommended dose. During autumn and winter however, people should consider taking a daily supplement of 10 micrograms of vitamin D to make up for the little or no sun exposure during these months.
Some people could be more at risk of vitamin D deficiency and might need to take supplements all year round. These people might include:
- Babies up to 1 year old.
- Those who spend little times outdoors such as frail individuals and people in care homes.
- Those who wear clothes that cover most of their skin.
- Those with dark skin such as people of African, African-Caribbean and South Asian origin.
What happens if we don’t get enough vitamin D?
- Higher risk of cardiovascular disease, inflammatory and autoimmune diseases and some cancers
- Osteoporosis in older adults
- Hypocalcaemic seizures (due to low blood calcium levels) in young infants as a result of vitamin D deficiency in the mother during pregnancy
- Rickets in children (a condition that affects children’s bone development and it causes bone pain, poor growth and soft, weak bones that can lead to bone deformities)
- Osteomalacia in adults (a condition similar to rickets also known as soft bones)
Recently, pilot and observational studies have suggested that low levels of vitamin D could potentially increase the risk of death due to Covid-19, but more research is needed to support this.
What to take away
Vitamin D is essential for our health and body development and by spending enough time in the sun (while also protecting our skin from sunburn), eating a balanced diet and taking supplements in the winter months, we can provide enough vitamin D for our bodies, keeping them healthy and strong.
However, it is always advised to talk to your GP about your vitamin D concerns because some people might be more at risk from vitamin D deficiency than others.
When taking supplements, also make sure you are not taking in more than it’s recommended, as high doses of vitamin D for long periods of time could weaken your bones and damage your kidneys and heart.
Disclaimer: The content of this website is provided for informational purposes only and does not substitute the medical advice from a healthcare professional.