Vitamin D helps regulate the amount of calcium and phosphate in the body.
These nutrients help keep bones, teeth and muscles healthy.
A lack of vitamin D can lead to:
- bone deformities such as rickets in children
- bone pain caused by a condition called osteomalacia in adults
In Ireland, studies have shown that adults have low levels of vitamin D.
Good sources of vitamin D
From about late March to the end of September, most people should be able to get all the vitamin D they need from sunlight.
The body creates vitamin D from direct sunlight on the skin when outdoors.
But between October and early March, we do not get enough vitamin D from sunlight.
Vitamin D is also found in a small number of foods.
Sources include:
- oily fish – such as salmon, sardines, herring and mackerel
- red meat
- liver
- egg yolks
- fortified foods – such as some fat spreads and breakfast cereals
Another source of vitamin D is dietary supplements.
How much vitamin D you need
Some people will need to take vitamin D supplements, especially during the winter months when there is less sunlight.
What is a microgram?
A microgram is 1,000 times smaller than a milligram (mg). The word microgram is sometimes written with the Greek symbol μ followed by the letter g (μg).
People at risk of vitamin D deficiency
Some people will not get enough vitamin D from sunlight because they have very little or no sunshine exposure. Or, they do not get enough vitamin D from sunlight.
You may need to take a daily supplement of vitamin D throughout the year if you:
- are not often outdoors – for example, if you're frail or housebound
- are in an institution like a care home
- usually wear clothes that cover up most of your skin when outdoors
- have black or brown skin
Effects of taking too much vitamin D
Taking too many vitamin D supplements over a long time can cause too much calcium to build up in the body (hypercalcaemia). This can weaken the bones and damage the kidneys and the heart.
Do not take more than 100 micrograms of vitamin D a day as it could be harmful. This applies to adults, the elderly, and children aged 11 to 17 years.
Children aged 1 to 10 years should not have more than 50 micrograms a day. Infants under 12 months should not have more than 25 micrograms a day.
Some people have medical conditions that mean they may not be able to safely take as much. If in doubt, talk to your GP.
Follow the advice of your GP if they recommend that you take a different amount of vitamin D.
You cannot overdose on vitamin D through exposure to sunlight. But always remember to cover up or protect your skin if you're out in the sun for long periods. This is to reduce the risk of skin damage and skin cancer.
Content supplied by the NHS and adapted for Ireland by the HSE
