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

Most people need a maintenance dose of vitamin D – enough to top you up during the dark winter months in the US. 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.

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 the product for the amount of vitamin D each supplement contains.

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

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.

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 are 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.