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Overview - Vitamins and minerals

Vitamins and minerals are nutrients your body needs in small amounts to work properly and stay healthy.

Most people should get all the nutrients they need by having a varied and balanced diet. But some people may need to take extra supplements.

What this guide covers

This guide has information about:

You can find out:

  • what these nutrients do
  • how much of them you need
  • how to make sure you get enough
  • what the risks are if you take too many


There are 3 types of units used to measure amounts of minerals and vitamins:

  • Milligrams – a milligram is 1 thousandth of a gram and is usually written as mg.
  • Micrograms – a microgram is 1 millionth of a gram and is usually written as μg or mcg. 1,000 micrograms is equal to 1 milligram.
  • International Units - these are sometimes used to measure vitamins A, D and E, and are usually written as IU. The conversion of milligrams (mg) and micrograms (μg) into IU depends on the type of vitamin.

More information on vitamins for babies and children

There are separate pages on:

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