Vitamin D is often referred to as the ‘sunshine vitamin’, because our body produces it when it is exposed to sunlight. Most people can produce enough vitamin D from sunlight from late March or early April to the end of September. But it's often difficult to get enough from the sun alone for the rest of the year.
The human body needs 10mcg of vitamin D a day to support the maintenance of healthy bones, teeth and muscle function by helping the body effectively absorb calcium. It also regulates the amount of calcium and phosphate in the body. Plus, getting enough vitamin D is essential to keep your immune system running smoothly.
Lack of vitamin D may lead to an illness called rickets in children and bone pain and muscle weakness in adults – which means you’re more likely to have a fall.
Our bodies can’t make vitamin D from the sunshine during the colder autumn and winter months, it’s important to understand how to increase your intake in the colder months through other sources like food.
Dr Emily Prpa, nutritionist and science manager at Yakult (which is rich in vitamin D ), has shared some facts you may not know about vitamin D.
You can’t make vitamin D through a window
Although it may feel like it’s possible on some days, your body can’t make vitamin D through a window. This is because the UV rays your body needs to make the vitamin can’t pass through the windowpane.
It’s therefore important to spend time outdoors and make sure your skin is (safely ) exposed directly to sunlight for short periods, to help ensure your body makes enough of the vitamin.
Your body can’t produce adequate vitamin D all year round
Even on a very sunny day in autumn or winter, you can’t make vitamin D from the sun because UV rays needs to be a specific wavelength [280-315 nm] for you to produce vitamin D. Unfortunately, the sun isn’t high enough in the sky between late September and early April in Ireland for these wavelengths to be available.
The length of your shadow can tell you if it’s sunny enough for your body to create vitamin D
Did you know that on a sunny day you can look at your shadow to find out if your body can produce vitamin D? If your shadow is shorter than your height, then your body will be able to make the sunshine vitamin, but if it is longer, this means that the sun is too low in the sky and the wavelengths of UVB light needed will not be available. If you’re struggling to find your own shadow, look at another object nearby to see if its shadow is taller than them, for example, a plant pot or tree.
Your body may need as little as nine minutes of sunshine a day to get your daily fix
We don’t need to spend hours in the sun to get our daily fix of vitamin D. In fact, as little as nine minutes of sun exposure can be enough to make the vitamin D needed for a whole day. This does of course vary for everyone, however, and is influenced by factors including skin tone.
Vitamin D can be found in some foods
Vitamin D can also be found in foods like oily fish such as trout and mackerel, and eggs. Other dietary sources include fortified foods and drinks like breads, breakfast cereals, some plant milks and Yakult Balance. Like humans, mushrooms can make vitamin D too when exposed to UV light – so popping them out in the sunlight may help to boost their vitamin D content before consumption.
What is Vitamin D?
Vitamin D is technically not a ‘vitamin’ at all. It’s classified as a prohormone because it’s produced by the body with the help of sunshine, unlike other vitamins which come from our diet. Vitamin D is produced in the skin and converted to an active form in the liver and kidneys.
