Vitamin D plays an important role in keeping your bones, muscles and immune system healthy.
A lack of vitamin D can lead to:
- bone conditions such as rickets in children
- bone pain and bone weakness caused by a condition called osteomalacia in adults
In Ireland, many adults have low levels of vitamin D, especially during the winter months.
Good sources of vitamin D
The body can create vitamin D from direct sunlight on the skin when outdoors. But between October and early March, sunlight is not strong enough to make vitamin D.
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
Often the amount of vitamin D in foods is quite small. Everyone should take a vitamin D supplement, even if they eat some foods containing vitamin D.
Another source of vitamin D is dietary supplements.
How much vitamin D you need
Everyone in Ireland needs to take a vitamin D supplement.
The amount you need depends on your age, skin tone, your situation and the time of year.
If you have dark skin – for example you have an African, African-Caribbean or south Asian background – you may also not make enough vitamin D from sunlight.
The amount of vitamin D you need is often described in micrograms.
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).
What is IU?
Sometimes the amount of vitamin D is expressed as International Units (IU).
- 1 microgram of vitamin D is equal to 40 IU.
- 5 micrograms of vitamin D is equal to 200 IU.
- 10 micrograms is equal to 400 IU.
- 15 micrograms is equal to 600 IU.
You can get vitamin D supplements from pharmacies.
They are available as:
- tablets, including a chewable tablet and a tablet that dissolves in your mouth
- drops
- sprays
Take the supplements with a meal to help your body absorb the vitamin D.
People at risk of vitamin D deficiency
Everyone in Ireland is at risk of vitamin D deficiency in winter.
Some people are at risk of deficiency all year round.
You need to take a daily vitamin D supplement all year round if you:
- are not often outdoors - for example, people who are housebound, in a nursing home or find it hard to leave the house
- usually wear clothes that cover up most of your skin when outdoors
- have black or brown skin
- are over 65
- are pregnant
- are a baby
Effects of taking too much vitamin D
Taking too much vitamin D over a long time can cause a build-up of calcium in the body (hypercalcaemia). This can weaken the bones and damage the kidneys and the heart.
The amount of vitamin D that can be harmful depends on your age:
- Babies under 12 months should not have more than 25 micrograms a day.
- Children age 1 to 10 should not have more than 50 micrograms a day.
- Adults and children age 11 and older should not take more than 100 micrograms of vitamin D a day.
Some people have medical conditions that mean they can tolerate even less than these limits.
Follow the advice of your GP if they recommend that you take a higher or lower amount of vitamin D. If in doubt, talk to your GP.
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
