How Much Vitamin D3 and K2 Should I Take Daily?

The official number and the number on the tub

They differ by up to a factor of ten, and both are legal. SACN set 10 micrograms of vitamin D a day as the reference nutrient intake for everyone aged 4 and over in 2016.^[6] The NHS carries the same figure down to age one, and 10 micrograms is 400 IU.^[1]

Product doses are set by the ceiling instead of the target. The NHS says not to take more than 100 micrograms — 4,000 IU — of vitamin D a day, so manufacturers price the whole range between the advice and the limit.^[1] Neither number is a treatment dose, and no supplement may be sold as one.^[10] The only wording a UK label may carry is the authorised nutrient claims on the Great Britain register.^[7]

IU and micrograms: what each label figure actually means

One microgram of vitamin D equals 40 IU, so every label figure converts cleanly.^[1] The conversion is the fastest way to check a recommended dosage against the two numbers that matter: the 10 microgram advice and the 100 microgram ceiling.

Conversions are ours, at the NHS's 1 µg = 40 IU. The 10 µg advice and the 100 µg adult limit are both the NHS's.^[1] The limit applies to the daily total across every product, not to one label.

Vitamin D3 and K2 dosage for adults: where the limits sit

The adult ceiling of 100 micrograms a day covers pregnant and breastfeeding women, older adults and children aged 11 to 17. Children aged 1 to 10 should not have more than 50 micrograms a day, and infants under 12 months no more than 25.^[1] Some medical conditions lower those figures further, which is a GP question.

Vitamin K has no UK upper limit of the same kind. The NHS says taking 1 mg or less of vitamin K supplements a day is unlikely to cause harm, and that there is not enough evidence about more.^[4] It also says vitamin K supplements should not be taken at all with warfarin.^[5]

Products use 100 to 200 micrograms of MK-7 on the industry's reading of one small comparison. Ten healthy women aged 20 to 21 were randomised into two groups of five. In the five given a single 420 microgram dose of MK-4, none was detectable in serum at any time point. In the other five, MK-7 peaked at six hours.^[8]

Those doses sit well under the NHS's 1 mg line. They are still vitamin K supplements, and the NHS says not to take those with warfarin at all.^[5]

Should you take vitamin D3 and K2 together? There is no UK rule against it. Both are fat-soluble, so one fat-containing meal serves both, and the K2 amount does not move the vitamin D ceiling.

Is it better to take D3 and K2 at night or morning?

Neither, on the evidence available. No trial has compared morning against night dosing for blood vitamin D status, and the variable that has been shown to matter is the meal rather than the hour.^[9] We have taken that question apart properly in the best time to take vitamin D.

Is it safe to take 10,000 IU of vitamin D3 daily with K2?

Not on UK advice, no. 10,000 IU is 250 micrograms, two and a half times the 100 microgram daily maximum the NHS sets for adults, and adding K2 does not change that ceiling.^[1] The upper limit is set on vitamin D alone.

Doses that high exist because they are prescribed. The NHS lists loading regimens of up to 300,000 IU for severe deficiency, for example 50,000 IU once a week for six weeks, under medical supervision. A maintenance dose of 800 to 2,000 IU a day follows.^[2] That is a treatment decision a doctor makes, not a shelf decision.

Can you take too much vitamin D3 and K2 in a day?

Yes for vitamin D, and the NHS names the mechanism. Taking too many vitamin D supplements over a long period can cause too much calcium to build up in the body. That can weaken the bones and damage the kidneys and the heart.^[1] Sunlight cannot cause it — you cannot overdose on vitamin D through sun exposure.^[1]

For vitamin K the honest answer is that nobody knows. The NHS says there is not enough evidence to know the effects of taking high doses of vitamin K supplements each day, while 1 mg or less is unlikely to cause harm.^[4]

What happens if I take 5000 IU of vitamin D3 every day?

You are 25% over the UK adult limit before counting anything else. 5,000 IU is 125 micrograms against the NHS maximum of 100 micrograms a day, and that maximum is the total across every product you take.^[1]

There is no UK figure that scales K2 to a D3 dose. Combined products pair 100 to 200 micrograms of MK-7 with anything from 1,000 to 4,000 IU of D3, and the K2 figure does not change the vitamin D ceiling.

The practical risk is not one tablet but the stack. A 5,000 IU product plus a multivitamin plus a cod liver oil capsule can double the limit while every individual label still reads sensibly. If a doctor has recommended a different amount, the NHS says to follow their advice rather than the general figure.^[1]

What are 5 physical signs you're taking too much vitamin D?

The NHS's serious-side-effect list for colecalciferol names things worth a call to a doctor or 111, and labels four of them as possible signs of too much calcium in the blood:^[3]

1. Being sick (vomiting)
2. Feeling confused
3. Bone or joint pain
4. An irregular heartbeat

Two more sit on the same list without the calcium label: needing to pee more often than usual, and swelling in any part of the body. A high temperature with a sharp pain in the side or lower back is flagged separately, as a possible early sign of kidney stones.^[3] None of these is specific to vitamin D, which is why the instruction is to phone rather than to self-diagnose.

What is the best time of day to take vitamin D3?

Whichever hour your main meal falls at. The NHS instruction for colecalciferol capsules and tablets is to swallow them whole with water with your main meal of the day, and it names no hour.^[2]

A fat-containing meal raised the 12-hour plasma vitamin D3 peak by 32% against a fat-free one, in 50 older adults given a single large test dose.^[9] The four trials behind that, and the October-to-March rule, are in the best time to take vitamin D.

How much vitamin D3 and K2 you take daily is one number in a cupboard full of them. The daily total is what matters, and the meal is what carries it. Our vitamin D3 and K2 gummies, one a day carry 4,000 IU of D3, 200 micrograms of K2 as MK-7 and 600 mg of calcium.

That puts them at the adult ceiling, which makes them a reason to check the rest of your cupboard rather than to add to it. Every amount in the gummy vitamins range is printed on the label.

Related reading

Why the two are combined in one product is set out in our guide to the benefits of taking vitamin D3 and K2 together, along with what each is allowed to say on a label.