How vitamin D calculators make sense

How vitamin D calculators make sense

We need vitamin D. But how much? Can this be calculated and how? What do you have to pay attention to?

So you can already see that the mere search for a vitamin D calculator is not enough. This allows you to quickly and easily calculate a vitamin D requirement, but is that also yours?

In addition, there are a wide variety of units and setting options. We explain here in summary what you should consider when using such a calculator and whether you can determine your needs without it.

An important note: The vitamin D calculators are nothing more than rule of thumb. This gives you a rough idea of whether you are on the right track, but the right care is not guaranteed. It can be too much or too little. Only blood tests will help here if the suspicion of a vitamin D deficiency is confirmed. We therefore do not recommend self-therapy by computer without blood values.

No matter which vitamin D calculator: The right values and data are necessary

Before we go into the values you need to determine your needs, let’s take a look at the units:

What is it and how do they relate to each other: ng/ml and nmol/l as well as I.E. and μg?

First of all: they are not the same! The three values are not even the same measure. While “International Units” (IU) indicates the dosage of vitamin D, nanograms per milliliter of blood (ng/ml) and nanomoles per liter of blood (nmol/l) are indications of the nutrient concentration in the blood. So they indicate how high your vitamin D level is.

In order to meet your personal needs at all, you first need how much vitamin D is present in your blood. You can get this via a blood test with your doctor of trust.

When you have the lab result, you will see it either in ng/ml or nmol/l. The former is lower than the latter by a factor of 2.5 . An example:

nmol/l in ng/ml:

You have 250 nmol/l of vitamin D in your blood. Divided by a factor of 2.5, this results in 100 ng/ml.


You have 40 ng/ml of vitamin D in your blood. Multiplied by a factor of 2.5, this results in 100 nmol/l.

Most computers work with ng/ml. If you have the value directly from the laboratory, you can expect it. Otherwise, you’ll have to do the first conversion first.

In the above-mentioned IU, there is still the alternative value micrograms (μg). 1 μg corresponds to 40 IU.

Now to the actual vitamin D calculator

Now we have revealed the secret of the units. So now it’s time to calculate the dose you need, right? Yes and no. Because there are two different values that you calculate here:

What is what? Initial dose and maintenance dose.

According to the German Nutrition Society (DGE), the standard value is 100 μg per day for a person aged 11 and over. This is calculated by the fact that roughly 1.5 μg of vitamin D per kg of body weight per day are used. According to the above conversion, 60 IU per kg per day or 4,000 IU per day for an average person. The almost 67 kg used are rather below average. However, the values per kg are also not recommended values, they are only used for the sake of simplicity.

However, our needs are also highly individual apart from body weight. Some are often in the sun with little clothing, others are not – for various reasons. This has a considerable influence on our intake.

Vitamin D is usually taken when you are also deficient. However, if you only take the vitamin D you need, you will never make up for this deficiency. That is why we are talking about an initial dose and a maintenance dose.

In the maintenance dose , you actually consume this approximately 4,000 IU per day . Since vitamin D can be stored well , you can also take a slightly higher dose every few days – here it means not to exaggerate and not to take oversized high doses of vitamin D. Too much is no better.

However, in order to guide the body into the right path, an increased initial dose is often recommended in the first few weeks. This would be, for example.B. an average of about 10,000 IU for 14 days of use. Again, however, it is important to ask your doctor of trust beforehand, because at 20,000 IU is the limit of the highly recommended daily intake according to the EU Commission. High-dose vitamin D also has its side effects.

Roughly speaking, it is always expected that you need 100-140 IU per kilogram of body weight to increase your blood level by 1 ng/ml. So if you want to get from 40 to 60 ng/ml, you need roughly 2,800 IU more than the daily intake.

Compensate for losses – but what do you lose?

In addition, however, you lose a certain amount of vitamin D per day. The stored vitamin D, which you store e.B. in the muscles, is halved every 3-6 weeks, according to studies. This is referred to as the half-life.

However, the vitamin D in your blood is much more volatile. Here, the amount is roughly halved after one day. However, since we supply via the sun, it is usually around 1% loss rate per day – so not even 1 ng/ml per day.

The loss is therefore only very narrow, but is also stated in most computers with less than 1%. Rather, however, it is the very high target values and dosages, contrary to all recommendations, that should give food for thought here. Especially the 60 ng/ml used usually count as “high” vitamin D values. At 40, on the other hand, these are actually normal values.

The recommended procedure: Vitamin D calculator only as an orientation

We therefore recommend using the common vitamin D calculator only as an orientation . Rather, in order to deal with this only halfway seriously, you need a vitamin D blood test anyway. Only then do you know what your status is and can calculate where you want to go.

You can already recognize the sometimes dubious seriousness in information such as gender, as there is no data from studies. Therefore, there is no distinction according to gender in the recommended values of the EU Commission or DGE.

However, it is also important to admit that most computers tend to assume very high vitamin D levels. Already at 30 to 60 ng/ ml one speaks of a sufficient supply. That’s all your body needs in the long run. In the long term, it is recommended to cover the need with dietary supplements with 20 μg. Due to the storage capacity of your body, you can also take slightly higher doses here, e.B. every other day.

If you suffer from a vitamin D deficiency – which is especially the case in the darker seasons in large parts of the population – you can determine your own needs after a blood test without a computer with simple rules of thumb and a later follow-up test . It is too individual to be determined purely mathematically. Your vitamin D levels simply depend too much on whether you can or want to go out in the sun without covering clothing.

Instead of calculating, measuring and checking helps to really take good care of your body.

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