First things first: vitamin D contributes to the normal absorption and utilisation of calcium from food. Vitamin K contributes to the maintenance of normal bones. That is why the two are found together in almost every good product, and why the question of the right amount has to be answered differently for each of them.
What vitamin D does in the body
Vitamin D is the only nutrient the body can produce itself under sunlight. At our latitudes that barely works from October to March, because the sun sits too low. That is exactly what makes vitamin D the nutrient people talk about most in autumn.
A number of effects are established for vitamin D:
Vitamin D contributes to the normal absorption and utilisation of calcium and phosphorus, to normal blood calcium levels, to the maintenance of normal bones, to the maintenance of normal muscle function, to the maintenance of normal teeth and to the normal function of the immune system. It also has a role in the process of cell division.
So why vitamin K2 as well?
Vitamin K is needed in the body at a different point of the same topic:
Vitamin K contributes to the maintenance of normal bones and to normal blood clotting.
So the two act at different points of the same metabolism: vitamin D on the absorption of calcium, vitamin K on the bones. That is the factual reason for the combination, and the reason why pure D3 products have become less common on the market.
MK-7 and the all-trans form
Labels rarely say just vitamin K2, they usually add something like MK-7. That describes the form of the molecule, menaquinone-7. It is the variant commonly used in food supplements.
A second piece of information is worth a look: all-trans. Menaquinone-7 can occur in two spatial arrangements, and only one of them is the biologically active one. A product that states 100 % all-trans is therefore making a statement about the purity of the raw material. A product that says nothing about it says nothing, either because there is nothing to say or because the proportion is not known.
What a depot dosage means
This is where products differ a lot, and that makes comparing them confusing. Vitamin D is fat-soluble, the body builds up a store. That is why two approaches work: a small amount daily, or a larger amount at longer intervals.
Our Vitamin D3 Depot 5000 IU with K2 is built around the second approach: one tablet every five days. It contains 125 µg vitamin D3, which corresponds to 5,000 international units, plus 100 µg vitamin K2 as MK-7 in all-trans form.
To compare it with daily dosed products you therefore have to convert. 5,000 IU spread over five days corresponds to 1,000 IU per day. So if you compare that with a product providing 1,000 IU daily, you are comparing the same amount, just packaged differently.
The practical difference lies elsewhere: at this rhythm, 180 tablets last well over two years on paper. That is unusually long for a food supplement and makes the price per day a very small number.
What to keep in mind when comparing
- Always convert to the daily amount, not the tablet. Only then are products comparable.
- Watch the unit. Vitamin D is sometimes given in micrograms, sometimes in international units. 25 µg corresponds to 1,000 IU.
- Check whether the vitamin K2 is present as MK-7 and whether the all-trans proportion is stated.
- If you eat a vegan diet, look at where the D3 comes from. Traditionally it comes from lanolin, that is wool grease. Vegan variants are obtained from lichen, as ours is.
In short
- Vitamin D contributes to the normal absorption of calcium, vitamin K to the maintenance of normal bones. Hence the combination.
- MK-7 in all-trans form is the detail that matters with K2.
- Depot dosages are not stronger, they are spread differently. Convert to daily amounts for comparison.
- Our formula provides 5,000 IU D3 and 100 µg K2 every five days, from a vegan lichen source.
