Vitamin D3 + K2 dosage: 1,000 or 5,000 IU?

The short answer: the question cannot be settled at the shelf, because 1,000 and 5,000 IU are not the same kind of number at all. "5,000 IU" describes the content of one tablet, "1,000 IU a day" describes a daily amount — and taken on a five-day rhythm, the 5,000 tablet produces exactly those 1,000 IU. Every official reference value relates to the day: the German Federal Institute for Risk Assessment (BfR) proposes 20 µg (800 IU) per daily portion for food supplements, while EFSA sets the upper limit for long-term intake from all sources at 100 µg (4,000 IU) per day. Both numbers are correct — they simply answer different questions.

Convert first, then compare

For vitamin D a fixed conversion applies: 40 IU = 1 µg. A 5,000 IU tablet therefore contains 125 µg of cholecalciferol, a 4,000 IU tablet 100 µg. That figure describes the tablet itself. What arrives per day is written on the back — and this is where the products part ways:

Product	per tablet/capsule	rhythm on the label	D3 per day
Vitamin D3 4,000 IU + K2 200 µg – 365 tablets	100 µg D3, 200 µg K2	daily or every 2nd day	100 µg (4,000 IU) or 50 µg (2,000 IU)
Vitamin D3 5,000 IU + K2 – 365 tablets	125 µg D3	every 5 days	25 µg (1,000 IU)
Liposomal D3 5,000 IU + K2 100 µg – 180 capsules	125 µg D3, 100 µg K2	every 5 days	25 µg (1,000 IU)

That reverses the order printed on the front of the tins: the smallest number on the shelf — 4,000 — delivers the largest daily amount, because it is the only one intended for daily use. And "1,000 IU per day", the amount many people are looking for, does not exist here as a tablet at all. It is the result of a 5,000 IU tablet taken at five-day intervals.

The reason for the long intervals is storage: vitamin D is fat-soluble, and its storage form, 25-hydroxyvitamin D, has a half-life of roughly two to three weeks. Blood levels therefore follow the average across weeks, not the individual day. How the strengths behave beyond that is worked through in Vitamin D3 K2 20,000 IU: the high dose compared.

Two upper limits, both correct

Anyone looking for the permissible amount runs into two numbers that differ by a factor of five. The contradiction dissolves as soon as you read what each was made for:

Reference value	Vitamin D	Origin and purpose
Nutrient reference value (NRV)	5 µg (200 IU)	Regulation (EU) No 1169/2011, Annex XIII — the basis for the percentage figure on the label
Estimated value in the absence of endogenous synthesis	20 µg (800 IU)/day	D-A-CH / German Nutrition Society (DGE) — what would have to be supplied if the skin contributed nothing
Adequate intake with low endogenous synthesis	15 µg (600 IU)/day	EFSA, Dietary Reference Values for vitamin D (2016)
Proposed maximum level for food supplements	20 µg (800 IU)/daily portion	BfR, opinion 007/2024 — a proposal to risk management, not applicable law
Tolerable Upper Intake Level	100 µg (4,000 IU)/day; children aged 1 to 10 years 50 µg	EFSA (2023) — the amount tolerable long term from all sources combined

The EFSA upper limit is the actual safety figure. It rests on persistently raised calcium excretion in urine as the earliest measurable sign of too much vitamin D; from two controlled studies a value of 250 µg per day was derived as the lowest observed adverse effect level, then secured with an uncertainty factor of 2.5. The 2023 revision did not change the figure — the BfR confirms this explicitly.

The BfR proposal of 20 µg, by contrast, is not a safety threshold but an allocation. The arithmetic is set out in the opinion: from the upper limit for 15- to 17-year-olds (100 µg), what high consumers already take in through ordinary food is subtracted first (7 µg). The remaining 93 µg are split evenly between food supplements and fortified foods — leaving 46.5 µg. An uncertainty factor of 2 halves that again to 23.25 µg, rounded down to 20 µg. So anyone who reads the 20 µg as a line beyond which things become critical is reading a distribution key as a warning sign.

Where the 4,000 IU tablet lands

Right at the top end. Taken daily it delivers 100 µg — the Tolerable Upper Intake Level, exhausted by this single product alone. And that value applies to all sources combined: multivitamins, calcium combinations and fortified foods all count, as does food itself. The German National Nutrition Survey II puts that at around 3 µg per day on average, and a good 11 µg for high consumers.

That is why the label of the 4,000 IU product offers the alternative "or every 2nd day" — that gives 50 µg (2,000 IU) daily and leaves room for everything else. Anyone taking several products alongside one another should add up the vitamin D lines before choosing a strength; the daily amount of a single tin says nothing about the total.

What shifts the number in an individual case

Vitamin D is the only vitamin the body produces itself — at our latitudes, and with regular time outdoors, 80 to 90 % of the supply comes from the skin and only 10 to 20 % from food. That is why there can be no universally valid daily amount for a supplement: the contribution it is meant to make up for varies with the season, time spent outdoors and clothing.

How good the supply actually is, is shown by one measure alone: the serum concentration of 25-hydroxyvitamin D. The usual reference point is 50 nmol/l; according to data from the German Health Interview and Examination Survey for Adults (DEGS), between 33 and 52 % of adults reach that value. Without a laboratory result, the intake recommendation on the pack is a more sensible guide than any rule of thumb found online.

The K2 amount in the same tablet

For vitamin K the situation is different: an upper limit has never been derived, because the data are not sufficient for one. As an adequate intake EFSA gives 1 µg per kilogram of body weight per day, so around 70 µg for adults; the D-A-CH estimated values lie between 60 and 80 µg. Food already supplies considerably more — for adults, the nutrition module of the German National Health Survey found mean intakes of 404 to 431 µg per day, mainly from green vegetables.

The BfR nevertheless proposes a maximum level for food supplements: 80 µg of vitamin K1 or 25 µg of vitamin K2 per recommended daily intake, together with a warning notice. The reason is not toxicity but an interaction: anyone taking coumarin-type anticoagulant medication should use vitamin K-containing products only after consulting a doctor — vitamin K weakens their effect, and what matters is a steady intake. In that situation a plain D3 product such as Vitamin D3 4,000 IU without K2 is the simpler choice.

Where food law ends

There is no binding maximum level for vitamin D in food supplements in Germany; the BfR figures are proposals for a future EU rule. What does exist is a classification by the Joint Expert Commission of the BVL and BfArM: up to a daily dose of 20 µg of vitamin D, a nutritional or physiological effect in the context of the diet can be assumed — such products are food supplements. Above 20 µg per day the commission no longer sees that effect, without this automatically making the product a medicine. What decides the matter is the intended purpose: a product expressly intended to prevent or treat a vitamin D deficiency meets the requirements for a medicinal product.

In practice this means the strength on the tin says nothing about the legal classification. What counts is the daily dose according to the intake recommendation — and for the depot-style products in the range that is 25 µg, only just above the threshold, even though a four-digit number appears on the front.

What may be printed on the tin

Authorised health claims are listed in Regulation (EU) No 432/2012, and only in this wording:

• Vitamin D contributes to normal absorption and utilisation of calcium.
• Vitamin D contributes to the maintenance of normal bones.
• Vitamin D contributes to the normal function of the immune system.
• Vitamin D contributes to the maintenance of normal muscle function.
• Vitamin K contributes to the maintenance of normal bones.
• Vitamin K contributes to normal blood clotting.

None of these claims mentions an amount. They are tied to just one condition: at least 15 % of the nutrient reference value per daily portion — that is 0.75 µg for vitamin D and 11.25 µg for vitamin K. A higher dose does not permit a stronger statement.

Food supplements are not a substitute for a balanced and varied diet and a healthy lifestyle.

Frequently asked questions

Is 5,000 IU too much?

As a tablet strength, the number on its own cannot be assessed. On the intended five-day rhythm a 5,000 IU tablet gives 25 µg (1,000 IU) per day — a quarter of the EFSA upper limit. Taken daily it would be 125 µg and thus more than that upper limit; which is why every pack states that the stated intake amount must not be exceeded.

Why does the BfR say 800 IU and EFSA 4,000?

Because the two numbers measure different things. EFSA's 100 µg (4,000 IU) is the amount that is not expected to cause adverse health effects even long term and from all sources combined. The BfR's 20 µg (800 IU) is the share of that which is arithmetically allotted to a single food supplement, once food, fortified foods and an uncertainty factor have been deducted.

Does an upper limit also apply to the vitamin K2 in the tablet?

No — one has never been derived for vitamin K, because the data are not sufficient. What matters in practice instead is the warning for people taking anticoagulants.

Do I have to take the tablet with a meal?

Both vitamins are fat-soluble, which is why the intake recommendations for these products mention a meal. What matters in practice is described in Taking vitamin D3 K2 5,000 IU correctly. The time of day plays no discernible role for blood levels — the interval between doses, however, does.

Sources: EFSA, "Scientific opinion on the tolerable upper intake level for vitamin D" (EFSA Journal 2023;21:e08145) and "Dietary reference values for vitamin D" (2016); BfR, opinion 007/2024 of 22 February 2024 ("Update 2023: proposed maximum levels for vitamin D in foods including food supplements"); BfR, "Proposed maximum levels for vitamin K in foods including food supplements"; Joint Expert Commission BVL/BfArM, opinion on vitamin D-containing products 01/2016, revision 1.1 (2017); D-A-CH reference values for nutrient intake (2015); EFSA, "Dietary reference values for vitamin K" (2017); Rabenberg M et al., BMC Public Health 18:845 (2018) on vitamin D status in Germany; Regulation (EU) No 432/2012; Regulation (EU) No 1169/2011, Annex XIII.