As the clocks go back and the days get shorter, most of us spend less time outdoors and more time under artificial light. That has a direct effect on one nutrient in particular: vitamin D. In the UK, the winter sun simply isn’t strong enough for your body to make it, which is why the NHS advises almost everyone to consider a daily supplement from autumn onwards.
This guide explains why vitamin D matters, who needs it most, how much to take and how to choose the right supplement for you and your family.
What Does Vitamin D Do?
Vitamin D helps your body absorb and use calcium and phosphorus, two minerals your body needs for strong bones and teeth. In the UK, vitamin D has several authorised health claims. It contributes to the maintenance of normal bones, teeth and muscle function, and to the normal function of the immune system. You can see the full list in the Great Britain nutrition and health claims register.
Why the UK Winter Makes Vitamin D Hard to Get
Your skin makes vitamin D when it’s exposed to direct sunlight. From late March or early April to the end of September, most people in the UK can make enough by spending short periods outside.
Between October and early March, the sun sits too low in the sky for your skin to make any meaningful amount. On top of that, we tend to stay indoors, cover up and spend more time commuting in the dark. Food alone rarely fills the gap, because only a handful of foods contain vitamin D.
Food Sources of Vitamin D
These foods contain some vitamin D, although it’s difficult to get enough from diet alone:
- Oily fish such as salmon, mackerel, sardines and herring
- Egg yolks
- Red meat and liver
- Fortified breakfast cereals, fat spreads and some plant milks
If you’re pregnant, avoid liver and liver products, as they contain high levels of vitamin A.
Who Should Take Vitamin D?
Everyone During Autumn and Winter
The NHS advises that adults and children over the age of 4 should consider taking a daily supplement containing 10 micrograms (400 IU) of vitamin D from October to March.
People Who Should Take It All Year
Some people are at higher risk of low vitamin D and are advised to take a daily supplement throughout the year. This includes people who:
- Rarely go outdoors, such as those who are frail or housebound
- Live in a care home
- Usually wear clothes that cover most of their skin when outside
- Have dark skin, such as people of African, African Caribbean or south Asian origin, as their skin may not make enough vitamin D even in summer
Babies and Young Children
The NHS recommends that breastfed babies from birth to 1 year should be given a daily supplement of 8.5 to 10 micrograms of vitamin D. Babies having more than 500ml of infant formula a day don’t need one, as formula is already fortified. Children aged 1 to 4 should have a daily 10 microgram supplement all year round. Always choose a product made for children and follow the label.
How Much Vitamin D Is Safe?
For most adults, 10 micrograms (400 IU) a day is enough. The NHS advises adults not to take more than 100 micrograms (4,000 IU) a day, as taking too much over a long period can cause calcium to build up in the body, which can weaken bones and affect the kidneys and heart. Lower upper limits apply to children, so never give children adult supplements.
You can’t overdose on vitamin D from sunlight, but always protect your skin and avoid burning.
Some people are advised by their doctor to take a higher dose for a period of time, for example after a blood test shows low levels. In that case, follow your doctor’s advice rather than general guidance.
Which Type of Vitamin D Is Best?
Vitamin D3 or D2?
Vitamin D3 (cholecalciferol) is the form your skin makes from sunlight, and it’s found in animal foods. Vitamin D2 (ergocalciferol) comes from plants and fungi. Research suggests D3 is generally more effective at raising and maintaining vitamin D levels in the blood, which is why most supplements use it.
Most D3 comes from lanolin, found in sheep’s wool, so it isn’t vegan. If you follow a plant based diet, look for vegan D3 made from lichen or choose D2. You’ll find suitable options in our vegan products collection.
Tablets, Softgels, Sprays or Drops?
Vitamin D comes in many formats, so choose the one you’ll take most consistently:
- Softgels and capsules are simple and affordable. Vitamin D3 1000 IU offers a gentle everyday amount, while Vitamin D3 2000 IU suits adults who prefer a slightly higher daily serving.
- Oral sprays are ideal if you dislike swallowing tablets. The range from BetterYou is a popular choice.
- Liquid drops let you add vitamin D to food or drinks. Liquid D3 + MK 7 has a fresh mint flavour.
Should You Take Vitamin D With K2?
Many people choose vitamin D combined with vitamin K2. Vitamin K contributes to the maintenance of normal bones, and both nutrients are involved in how the body uses calcium. A combined formula such as Vitamin D3 + K2 MK 7 is a practical everyday option. If you take blood thinning medicine such as warfarin, speak to your GP before taking any supplement containing vitamin K.
Some people also like vitamin D with magnesium, and Vitamin D3 + Magnesium combines both in one capsule.
Tips for Taking Vitamin D
- Take it with a meal. Vitamin D is fat soluble, so it’s absorbed better alongside food that contains some fat.
- Make it a habit. Keep it next to the kettle or your toothbrush so you remember every day.
- Check your other supplements. Many multivitamins already contain vitamin D, so add up the total before taking a separate product.
- Start in October. Begin when the clocks go back and continue until spring.
Signs You May Be Low in Vitamin D
Low vitamin D doesn’t always cause obvious symptoms, but some people notice tiredness, aches and pains, muscle weakness or low mood. These signs can have many other causes, including low iron or vitamin B12. Our guide on which vitamin deficiencies can make you feel cold covers some of them. If symptoms last, ask your GP about a blood test.
Who Should Speak to a Doctor First?
Speak to your GP or pharmacist before taking vitamin D if you have kidney disease, high calcium levels, sarcoidosis or another long term health condition, or if you take regular medication. If you’re pregnant or breastfeeding, the NHS recommends 10 micrograms a day, but check with your midwife before taking any other supplements.
Frequently Asked Questions
When should I start taking vitamin D in the UK?
Most people should start in October and continue until March, when the sun becomes strong enough again for your skin to make vitamin D.
Can I get enough vitamin D through a window?
No. Glass blocks the UVB rays your skin needs to make vitamin D, so sitting by a sunny window won’t help.
Is it better to take vitamin D in the morning or at night?
There’s no best time. Taking it with your largest meal of the day may help absorption, and taking it at the same time each day helps you remember.
Should I keep taking vitamin D in summer?
Most people can stop between April and September if they spend time outdoors. People in higher risk groups are advised to take it all year.
Does a multivitamin contain enough vitamin D?
Many do, but amounts vary. Check the label to see whether it provides at least 10 micrograms. If you’re unsure where to start with supplements, our beginner’s guide is a helpful read.
Final Thoughts
Vitamin D is one of the simplest supplements to add to your routine, and one of the most useful during a UK winter. For most adults, 10 micrograms a day from October to March is enough, while people in higher risk groups should take it all year. Choose the form you’ll take most consistently, check your other supplements so you don’t double up, and speak to your GP if you’re unsure.
Get ready for the darker months with vitamin D tablets, softgels, sprays and drops in our vitamins and minerals collection, or explore genuine supplements from trusted brands at Modflex, delivered fast across the UK.