Best Time to Take Vitamin D: Morning or Night, With Food, and With K2? (UK)

What to do: time, food, dose and form

For why winter matters, see our guide to vitamin D in winter.

Should you take vitamin D with food?

Yes. Vitamin D dissolves in fat, so a meal with some fat helps you absorb more. The NHS guide to colecalciferol (vitamin D3) says to take tablets and capsules with your main meal of the day. The studies:

• Fat vs no fat: in 50 healthy older adults given one large dose with breakfast, blood vitamin D3 peaked 32% higher after a meal containing fat than after a fat-free meal. The type of fat made no difference.
• How much fat: in a placebo-controlled trial of 64 young adults, levels rose more after two weeks when the dose came with a meal containing at least 15g of fat.
• Largest meal: in 17 bone clinic patients whose levels weren’t improving, taking their dose with their largest meal raised levels by about half over two to three months. It was small and had no comparison group.

One exception is worth knowing. In a cross-over trial of 88 adults given a single large dose of D3 already dissolved in oil, blood levels rose the same whether they took it fasting or with a high-fat breakfast. So the formula can matter as much as the meal.

You don’t need a fry-up: eggs, yoghurt, cheese, nuts, avocado, oily fish or olive oil all count. Oil-based drops already contain fat, but a meal is still a good habit.

Vitamin D morning or night: can you take it at night?

There’s no good evidence that morning works better than night, or the other way round. Tie it to something you do daily, such as breakfast or your evening meal. Building a better start to the day? See our morning routine for energy.

Claims that vitamin D at night keeps you awake, or helps you sleep, rest on limited and mixed evidence:

• A 2021 review in healthy people found 11 observational studies on sleep with mixed results, and named supplement timing as an open question.
• A 2022 meta-analysis found vitamin D improved a sleep quality score in three small trials, with moderate certainty. Effects on sleep length and sleep disorders were unclear.

So there’s no clear reason to avoid an evening dose. If you feel it affects your sleep, move it to breakfast. For sleep itself, the basics matter more: see sleep hygiene and your circadian rhythm.

Does vitamin D at night lower melatonin?

This is a common reason given online for taking vitamin D in the morning. The main study usually behind it is small, and it didn’t test timing at all:

• Researchers in Israel gave 40 people with multiple sclerosis either 800 IU (20 micrograms) or 4,370 IU (about 109 micrograms) of D3 a day for a year.
• After three months, the high-dose group had lower levels of a night-time melatonin marker in their urine. The 800 IU group, on double the NHS amount, showed no significant change.
• The study compared doses, not times of day, and the people in it had MS and were on medication.

So the evidence is neutral. There’s nothing to show that 10 micrograms with your evening meal changes melatonin or sleep in healthy adults. If you’re curious about melatonin itself, see melatonin in the UK.

Can I take vitamin D at night?

Yes. If your evening meal is the biggest, fattiest meal of your day, it may even be the better slot, because that’s what helps absorption. The one thing that matters more than the hour is taking it every day.

Does vitamin D help you sleep?

Not directly. Observational studies link low vitamin D with poorer sleep, but trials of supplements on sleep are small and mixed, so vitamin D isn’t a sleep aid. The NHS advice is 10 micrograms a day from October to March, mainly for bones and muscles. Morning or night is fine for most people, so take it when you’ll remember.

• The link: a 2018 meta-analysis of nine observational studies (9,397 people) found vitamin D deficiency was linked to about 50% higher odds of sleep problems. A link, not proof of cause.
• The trials: the 2022 meta-analysis above found a better sleep quality score with supplements, but from just three small trials.

So take vitamin D for the reasons the NHS gives, not to fix your sleep. Vitamin D contributes to the maintenance of normal bones and the maintenance of normal muscle function. Think you might be low? See signs of vitamin D deficiency. For sleep, see magnesium for sleep and taking magnesium and vitamin D at night. For timing, see morning or night.

Do vitamin D supplements work?

Yes, for topping up vitamin D when the sun can’t. The NHS says we don’t make enough from sunlight between October and early March, and a lack can lead to bone pain from osteomalacia in adults. They aren’t a cure-all: the NHS says there isn’t enough evidence to take vitamin D solely to prevent or treat COVID-19.

Vitamin D3 or D2?

Most supplements contain vitamin D3 (colecalciferol, also spelt cholecalciferol), the natural form of vitamin D in the body. If you see cholecalciferol on a label, it simply means vitamin D3. Vitamin D2 (ergocalciferol) is the other main form.

A 2012 meta-analysis led by the University of Surrey found D3 raised blood levels more than D2. The difference was clear with large, infrequent doses but disappeared with daily doses. D3 is a sensible default, and a daily D2 product still gives you vitamin D.

A later Surrey trial in 335 women tested a daily 15 micrograms over 12 winter weeks, in juice or biscuits, and D3 still raised blood levels more than D2. For the full comparison, including whether vitamin D and D3 are the same, see our guide.

Some D3 is animal-derived, and the NHS notes vitamin D capsules may contain gelatine. Vegan? Look for D3 from algae or lichen. See is CBD oil vegan?

Should you take vitamin D with K2?

There’s no NHS advice to take vitamin D with K2. The NHS says most people get all the vitamin K they need from a varied diet, such as green leafy vegetables, vegetable oils and cereal grains, and that 1mg or less a day from supplements is unlikely to cause harm.

Research on the pairing is limited. A 2024 review of 31 studies in postmenopausal women found the combination may have positive effects on bone and heart health markers, but trials varied a lot and the findings don’t apply to everyone.

iImportant: vitamin K affects blood clotting, and the NHS says not to take vitamin K supplements while on warfarin. If you take any blood thinner, ask your pharmacist first. Otherwise a D3 and K2 product is a personal choice, not a necessity.

Vitamin D with magnesium, calcium and other supplements

Magnesium and vitamin D can be taken together, and a 2018 review found the enzymes that activate vitamin D in the liver and kidneys appear to need magnesium. They don’t have to be taken at the same time. See magnesium and vitamin D together and the best time to take magnesium.

If you take magnesium in the evening, as many people do, you can take vitamin D with your evening meal at the same time. There’s no need to split them.

Calcium. Vitamin D and calcium are often sold together, and vitamin D contributes to normal absorption/utilisation of calcium and phosphorus. Most adults get the 700mg of calcium a day they need from food. The NHS says taking 1,500mg or less a day from supplements is unlikely to cause harm, and more than that could lead to stomach pain and diarrhoea. See calcium supplements and magnesium and calcium together.

iCount every product containing vitamin D, including multivitamins. If your doctor has prescribed vitamin D, the NHS says to check before taking other supplements containing calcium or vitamin D.

If you already take a multivitamin, check its label first: it may already contain vitamin D. See are multivitamins worth taking for the bigger picture.

Can I take vitamin D and iron together?

Yes. The NHS guides to vitamin D (colecalciferol) and iron (ferrous sulfate) don’t list each other as an interaction, so you can take both on the same day. The timing differs. Iron is absorbed best on an empty stomach, 30 minutes before eating or 2 hours after, and a doctor or pharmacist may suggest taking it with orange juice or vitamin C. The NHS says to take vitamin D tablets with your main meal.

Leave a 2-hour gap between iron and tea, coffee, dairy or eggs. Calcium can reduce how well iron works, so ask your pharmacist how long to leave between iron and calcium, magnesium or zinc supplements, including combined calcium and vitamin D tablets. See how to take iron tablets.

Daily or weekly vitamin D?

For a shop-bought supplement, daily is the simplest and the way NHS advice is written: 10 micrograms a day. Weekly doses are mostly something a GP prescribes; the NHS says a course to correct a deficiency is usually taken daily or weekly for 6 to 10 weeks.

What the research shows on spacing doses out:

• Daily, weekly or monthly can match. In 48 women recovering from a hip fracture, the same total amount of D3 given daily, weekly or every four weeks produced similar blood levels after two months.
• Very large, rare doses are a different story. In an Australian trial of 2,256 women aged 70 and over, a single yearly dose of 500,000 IU led to 15% more falls and 26% more fractures than a placebo, with the extra falls concentrated in the first three months after each dose.

The practical answer: take a small amount every day, and only take large weekly or monthly doses if a doctor prescribes them.

Sprays vs tablets vs drops

The best way to take vitamin D is the format you’ll actually use every day. The vitamin is the same; what changes is convenience.

Are sprays absorbed better? A 2020 systematic review found four trials comparing D3 sprays with other formats. Only one, with several limitations, found the spray raised blood levels more; the other three found no difference. So a spray is a fine choice if you dislike tablets, but it isn’t a stronger option.

Prescribed colecalciferol also comes as liquid, drops, chewable and dissolvable tablets. The NHS says capsules and tablets should be taken with your main meal of the day.

How much vitamin D to take

The recommended vitamin D intake in the UK is 10 micrograms (400 IU) a day for everyone aged 1 and over, including pregnant and breastfeeding women.

• Adults: 10 micrograms (400 IU) a day, which the NHS says is enough for most people.
• Upper limit: no more than 100 micrograms (4,000 IU) a day unless a doctor advises it, including in pregnancy, breastfeeding and for ages 11 to 17.
• Converting: 1 microgram = 40 IU, so 25 micrograms = 1,000 IU.
• All year: the NHS advises 10 micrograms daily all year if you’re rarely outdoors (for example frail or housebound), live in a care home, or usually cover most of your skin outdoors. If you have dark skin, for example an African, African-Caribbean or south Asian background, consider it all year too.
• If you’re deficient: a GP may prescribe a higher short-term dose after a blood test. Only take high doses on medical advice.

More in our vitamin D in winter guide. Think you might be low? See vitamin D deficiency symptoms and why you feel tired in winter.

October to March: vitamin D and the sun in the UK

The NHS advises everyone to consider a daily vitamin D supplement during autumn and winter, which in practice means from October to March. With the clocks going back on 25 October and daylight getting shorter, now is a good time to start; see how to protect your sleep when the clocks go back.

The NHS says that from about late March or early April to the end of September, most people can make all the vitamin D they need from sunlight on their skin. Between October and early March, the sun isn’t strong enough.

There’s no set time or number of minutes. The NHS advises striking a balance with sun safety:

• Never burn. You can burn in the UK, even when it’s cloudy.
• Spend time in the shade between 11am and 3pm from March to October, when the sun is strongest.
• At a UV index of 3 or more, consider protecting your skin with at least SPF30 and 4-star UVA protection.

Dark winter days take a toll in other ways too. See seasonal affective disorder, our winter wellness guide, how to boost your immune system and cold or flu?

Who should check with a GP or pharmacist first

The NHS advises telling your doctor before taking vitamin D (colecalciferol) if you have high calcium in your blood or pee, kidney problems or kidney stones, high vitamin D levels, sarcoidosis, or a peanut or soya allergy.

iSome medicines interact with it, including digoxin, some diuretics (such as bendroflumethiazide and indapamide), epilepsy medicines, steroids such as prednisolone, cholestyramine and some antifungals. Ask your pharmacist if any apply.

Babies and children

• Breastfed babies should have 8.5 to 10 micrograms of vitamin D daily from birth, whether or not the mother takes it.
• Babies having more than 500ml (about a pint) of formula a day don’t need a supplement, as formula is fortified.
• Children aged 1 to 4 should have 10 micrograms every day, all year.

There’s no official best time for baby drops: give them at the same time each day and follow the label. If you qualify for Healthy Start, you can get free vitamin drops for children. Never give two vitamin D supplements at once.

Our products are for adults only, and we don’t recommend them during pregnancy or breastfeeding. The NHS advises pregnant and breastfeeding women to consider a separate 10 microgram vitamin D supplement.

Vitamin D3 in your CBD drops

For most people, a separate vitamin D supplement is the simplest way to get the NHS 10 micrograms. If you already use CBD oil, our Evolabs Mint CBD Oil adds vegan, algae-based vitamin D3 to its CBD: 10 micrograms (400 IU) per half pipette, the NHS daily amount (200% NRV). Count it towards your daily total, and keep to no more than 100 micrograms a day from all sources. Read why we added algae-based D3 and when to take CBD oil.

Vitamin D contributes to the normal function of the immune system, the maintenance of normal bones and the maintenance of normal muscle function.

The FSA’s 10mg a day figure is precautionary advice rather than a legal limit, set while longer-term safety research continues. At Evopure we think it is a very cautious figure, and many adults use more. If you go above it, increase slowly, and check with your GP or pharmacist first if you take any medication.

Related guides

• Can you take magnesium and calcium together?
• See also our honest guide to vitamins for men over 40.
• When to take calcium supplements.
• Avocado is an easy way to add some fat to a meal. See avocado benefits and nutrition.
• We compare the forms in more depth, including what the trials show on K2, in D2 vs D3 and vitamin D3 with K2.
• Not sure which product to buy? See which vitamin D supplement is best in the UK.
• If you’d rather start with your diet, see foods high in vitamin D, with micrograms per portion.