Vitamin D, or the "sunshine vitamin" is essential for us as it can help ensure our bones, teeth and muscles stay healthy. However, there are a growing number of people who simply aren't getting enough of it on a daily basis throughout the year, but especially during the winter months.
As a result, Public Health England has recently produced new guidelines recommending adults and children over the age of one should have 10 micrograms (mcg) of vitamin D each day. To get this much into our bodies over the winter, many of us would benefit from taking a vitamin D supplement.
Vitamin D deficiencies can be very serious as they can lead to deformities such as rickets in children, while adults may develop pain and tenderness in their bones due to a condition called osteomalacia.
It has also been linked to a wide range of other medical conditions, includingmultiple sclerosis, depression and heart disease, although more work still needs to be done on whether it directly causes these problems
How does our body make vitamin D?
Exposure of our skin to UVB sunlight leads to a natural build-up of vitamin D, which can happen very quickly in the summer sun. This process takes around half the time it would take for your skin to burn (perhaps 10 minutes for a very fair skinned person, or an hour or more for somebody with darker skin).
If you expose large areas of your body, such as your back, you will develop all the vitamin D you need in a much quicker period of time than if you had exposed just your forearms. Vitamin D build-up is also a quicker process during the middle of the day, when the sun is higher in the sky.
During the spring and summer, we should be able to get all the vitamin D we need from sunlight on our skin. How long we need in the sun to get the required amount of vitamin D varies from person to person, but it is important you avoid burning.
However, during the autumn and winter, sunlight in the UK doesn't have enough UVB radiation for our skin to make the vitamin D we need. This could potentially put millions of us at risk of vitamin D deficiency for up to six months of the year.
We can get small amounts of vitamin D from foods such as eggs, oily fish and red meat and some cereals. Vitamin D is also added to formula milk for infants.
Vitamin D is a fat-soluble vitamin, so you do not need to take a supplement every day to receive the recommended dose. Many people prefer to take a much higher dose supplement once a month, which provides the same overall amount. For instance, 300 mcg taken once a month provides the same overall amount of vitamin D as 10 mcg a day and is perfectly safe.
Some areas of the UK may not actively recommend the practice of taking monthly supplementation and some areas also have problems obtaining some products from manufacturers.
There are some medical conditions which make taking vitamin D supplements problematic. Taking too much vitamin D leads to excess calcium in the blood, and can cause kidney problems. If you're in doubt over whether vitamin D supplements are suitable for you, you should speak to your doctor before you take them.
Vitamin D deficiency symptoms
Vitamin D deficiency doesn't have a clear pattern of symptoms, but some people may experience fatigue, muscle cramps, joint pain or weakness, weight gain, restless sleep, poor concentration, raised blood pressure and bowel movement problems.