Is 1000 IU of vitamin D enough?

Written by Cassie, registered pharmacist
Founder of Clean Green Safe

1000 IU is one of the most common vitamin D doses on the shelf, so if you’ve picked one up and wondered whether it’s the right amount, you’re in very good company. It’s one of the questions I hear most often.

The honest answer is that it depends on you. Let’s go through what 1000 IU actually means, how it compares with the Australian guidelines, and when it’s worth getting a little more advice.

What does 1000 IU of vitamin D mean?

IU stands for International Unit. For vitamin D, 1000 IU is exactly the same as 25 micrograms (mcg). Australian labels usually show micrograms, while products made for overseas often show IU, which is why the same dose can look so different from one bottle to the next.

You can check any amount with our vitamin unit converter.

How much vitamin D do Australian guidelines suggest?

The NHMRC daily targets for adults are:

• 19 to 50 years: 5 mcg (200 IU)
• 51 to 70 years: 10 mcg (400 IU)
• Over 70: 15 mcg (600 IU)
• Pregnancy and breastfeeding: 5 mcg (200 IU)

So 1000 IU (25 mcg) is above the daily target for every adult group. These targets were set assuming you get very little sun, though, and many people have lower vitamin D levels than they realise.

Where does most of our vitamin D come from?

For most Australians, it’s the sun. Our skin makes vitamin D when it’s exposed to sunlight, and only a small amount comes from food, such as oily fish, eggs and some fortified foods. Because we rightly protect our skin from the sun, getting the balance right can be tricky, especially in winter and in the southern states.

Who might need more than 1000 IU?

Some people are more likely to have low vitamin D, including those who:

• spend most of their day indoors, or work night shifts
• cover most of their skin for cultural or religious reasons
• have naturally darker skin
• are older, or live in residential care
• have certain medical conditions, or take medicines that affect vitamin D

If any of these sound like you, your GP can check your level with a simple blood test. If it’s low, they may suggest a higher dose for a while, and then a maintenance dose. It’s best to let the test guide you, rather than guessing.

Can you take too much vitamin D?

Yes. In Australia, the upper limit for adults is 80 mcg (3,200 IU) a day from all sources. Vitamin D is stored in the body, so very high doses taken for a long time can build up and raise calcium levels in your blood.

This is where imported products need a careful look. Some follow higher overseas limits and contain 5000 IU (125 mcg) or more per capsule. And if you also take a multivitamin or a calcium and vitamin D tablet, the amounts add together.

Three simple checks you can do today

• Note whether each label uses mcg or IU, and convert if you need to. 40 IU equals 1 mcg.
• Add up every product that contains vitamin D, including multivitamins and calcium supplements.
• Keep your total at or under 80 mcg (3,200 IU) a day, unless your doctor has advised a higher dose for a set time.

If you’re unsure, or you take other medicines, please have a chat with your pharmacist or GP. We’re always happy to help you make sense of your labels.

ABOUT THE AUTHOR

Cassie, registered pharmacist

Cassie is a registered pharmacist, a parent and the founder of Clean Green Safe. With a background in Australian supplement regulation across the TGA, FSANZ and NHMRC, she built Clean Green Safe to help people understand what’s really in their supplements, and how it all adds up across everything they take.