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Vitamin D - Vitamins and minerals

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).

Babies under 12 months

Babies under 12 months need 5 micrograms of vitamin D3 as a supplement every day from birth if they are:

  • breastfed
  • have less than 300mls or 10 fluid oz (ounces) of infant formula a day

Vitamin D for babies 0 to 12 months

Children aged 1 to 4 years

Children aged 1 to 4 need 5 micrograms of vitamin D as a supplement every day for a few months each year.

Give this from Halloween (October 31) to St Patrick’s Day (March 17).

Vitamin D supplements for children aged 1 to 4 years

People age 5 to 64

If you choose to take a vitamin D supplement, try:

  • 10 micrograms for healthy children age 5 to 11
  • 15 micrograms for healthy teenagers and adults age 12 to 64

If you were prescribed a vitamin D supplement of more than 15 micrograms, continue to take it.

You can get vitamin D supplements from pharmacies. They are available as a tablet, including a chewable tablet and a tablet that dissolves in your mouth.

Take the supplements with a large meal to help your body absorb the vitamin D.

Adults age 65 and older

People age 65 and older need to get enough vitamin D all year round for bone and muscle health.

They should take a 15 microgram vitamin D supplement every day.

This supplement can be:

  • A multi-vitamin supplement that contains 15 micrograms of vitamin D
  • A calcium and vitamin D supplement that contains 15 micrograms of vitamin D
  • A vitamin D-only supplement that contains 15 micrograms of vitamin D

If you were prescribed a vitamin D supplement of more than 15 micrograms, continue to take it.

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.

Causes of skin cancer and tips to reduce your risk

Content supplied by the NHS and adapted for Ireland by the HSE

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This project has received funding from the Government of Ireland’s Sláintecare Integration Fund 2019 under Grant Agreement Number 123.

Page last reviewed: 17 May 2021
Next review due: 17 May 2024