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Vitamin D – I want to start vitamin D, which one and how much?

Dr Roger Henderson
Reviewed by Dr Roger HendersonReviewed on 13.10.2023 | 3 minutes read

So you are thinking of starting vitamin D supplements? Here’s the lowdown on everything you need to know, based on the questions we are asked in our work as practising GPs.

How much vitamin D should I take?

Most people need a maintenance dose of vitamin D – enough to top you up during the dark winter months in the UK. The recommended dose is 10 micrograms daily, or it may be measured in International Units (IU), in which case 400 IU is the equivalent. This dose is enough for most, and is also the recommended amount for those at risk of vitamin D deficiency, such as certain ethnic groups or those spending lots of time inside, in which case we suggest you take this all year round.

Similarly, if you are trying to get pregnant, no matter the time of year, you should start maintenance dose vitamin D supplements (and folic acid) to ensure you are in the best of health for your pregnancy, and continue through breastfeeding.

Unless your doctor has recommended a higher dose, or you’ve had a test that indicates a deficiency, you will not get any further benefits from taking a higher dose of vitamin D. If you are already taking multivitamin supplements, check the label as these may also contain vitamin D - the dose may even be the recommended daily amount.

Which type of vitamin D supplement should I take?

There are many vitamin D supplements that you can buy over the counter at pharmacies or supermarkets and these include tablets, sprays, gummies and dissolving effervescent tablets. They come in different strengths, so be sure to check on the packet what amount of micrograms or IU each supplement contains.

Vitamin D tablets and sprays have been shown to be equally effective. The gummies tend to be sugary and the effervescents contain additional salt so we recommend sticking to the tablets or spray to get your vitamin D boost.

What if the supplement I’ve chosen is more than 10 micrograms (400 IU) per tablet or spray?

You can safely take vitamin D weekly or at different intervals such as every other day or every 2 weeks as long as the amount you are taking is equal to 10 micrograms (400 IU) a day. This means that if the supplement dose is higher than 10 micrograms (400 IU), you will need to space out the doses so that you are getting no more than a total dose of 70 micrograms (2800 IU) a week.

What if I’ve been told to take more?

The recommended 10 micrograms a day is to maintain vitamin D levels. If a blood test has shown you have a vitamin D deficiency, your doctor may prescribe a higher dose of vitamin D for a set amount of time until your vitamin D levels are in range. This usually takes two to three months. You can switch to the maintenance dose after this.

Long term use of high dose vitamin D is not recommended but prescribed high doses for a set amount of time is used to treat vitamin D deficiency effectively.

The dose also may seem high if instead of taking it daily you are on a weekly dose.

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Dr Roger Henderson
Reviewed by Dr Roger Henderson
Reviewed on 13.10.2023
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