Vitamin D explained

Vitamin D is an essential part of living well with strong bones, but we often hear from people who have questions about it. 

Do I need a supplement and if so, how much should I be taking? Should I get a blood test before I start taking a supplement? How does vitamin D help with osteoporosis? Here, our Clinical Advisor Sarah, explains some of the basics you need to know about vitamin D. 

How does vitamin D work and why is it important?

Vitamin D is produced in our skin when it’s exposed to sunlight and it’s also absorbed from the food we eat or supplements we take. It then gets converted into a more active form by our liver and kidneys, working more like a hormone than a vitamin. It regulates and controls things going on in other parts of our bodies.

There has been lots of interest in whether vitamin D prevents diseases like breast cancer and multiple sclerosis, and more recently if it has a role to play with COVID-19 - a review has since concluded there is not enough evidence to support taking vitamin D solely to treat or prevent COVID-19 though. It is accepted, however that vitamin D has some effect on our immune systems, as well as muscles and bones, so it’s important to ensure that you are getting enough.

Vitamin D is essential for making our bones strong. Its main job is to help them absorb calcium from our gut and prevent it being lost by our kidneys. It also plays a part in making our muscles work well too. Strong muscles are important to stop us falling over, which is especially important for those living with osteoporosis who have weaker bones that are more likely to break, or those with poor balance as a result of old age.

How much vitamin D do I need and what’s the best way to get it?

We should all aim for 10 micrograms (4OOIU) of vitamin D a day, alongside any that we get from sun exposure. Going outside in the sunshine during the spring and summer months (April to September) is how most of us will get the vitamin D we need. You can also absorb vitamin D from food, although it’s difficult to get enough this way, and supplements.

Some vitamin D gets stored in our fatty tissue, but there may not always be enough to take us through winter. Because of this, it’s important that we all consider taking a vitamin D supplement during the winter months.

If you aren’t getting outside much or avoid exposing your skin to sunlight for health or other reasons, you might not be getting enough and should consider taking a supplement all year round. If you’re older, your skin won’t be producing vitamin D as well, so it’s important to top up with a supplement too.

If you are living with osteoporosis, it’s usually recommended that you take a vitamin D supplement all year round. This is because osteoporosis treatments work better if you have good vitamin D levels. If your healthcare professional thinks you need a vitamin D supplement, they'll advise you on how big a dose to take.

What are your top tips for vitamin D?

• Get outside between the beginning of April and the end of September to absorb vitamin D from the sun.
• Spend about 10 minutes, twice a day, between 11:00 and 15:00, with your face and arms exposed to sunlight.
• Take precautions not to get sunburnt and remember that babies and children need to take special care. Using sunscreen doesn’t seem to cause low vitamin D but sunblock will reduce your exposure.
• Consider taking a supplement in the winter months or all year round if you are not getting outside much or keep your skin covered.
• You can also increase the vitamin D you get from your diet with fortified food, but remember that it’s quite difficult to get enough vitamin D from natural sources, so you may still need to take a supplement.
• If you are vegan, ask for a vitamin D2 supplement – it might work more slowly than vitamin D3 but for most people this won’t matter.
• Don’t take big doses of vitamin D unless they are prescribed for you. 10 micrograms (400IU) is the recommended daily amount. If you have osteoporosis and especially if you are taking an osteoporosis medication, you may be prescribed 20 micrograms (800IU).
• You don’t need a blood test before you take a vitamin D supplement unless this is part of a broader bone health assessment.
• Vitamin D isn’t an osteoporosis drug treatment, but you do need to have sufficient levels for your treatment to work well. Some treatments can lower calcium levels in the blood, which is why it’s important you get enough vitamin D. Talk to your healthcare professional about what’s best for you.

More information and support

Find out more about Vitamin D here. For information and support tailored to you call the free Helpline on 0808 800 0035 or email nurses@theros.org.uk