Vitamin D - information on requirements, intake, raw materials

Information on vitamin D

80–95 per cent of the body’s vitamin D requirements are produced in the skin, but only when exposed to sunlight.

In summer, 10 minutes of midday sun is sufficient for people with fair skin. People with darker skin are less sensitive and therefore need 20 to 60 minutes.* Around one-third of the skin’s surface should be exposed to the sun.

So, if we assume that healthy, active people who spend a lot of time outdoors regularly produce enough vitamin D, there really shouldn’t be anyone with a vitamin D deficiency. This appears to be the idealised view held by many media outlets, where non-experts (which, unfortunately, also include many so-called medical journalists) claim that vitamin D, like all other vitamins, is completely unnecessary or even harmful.

The catch is this: not everyone is young, fit, eats a healthy diet, is free from chronic illnesses and spends all their time outdoors in the fresh air.

Factors or situations that hinder or prevent vitamin D production in the skin include:

• Older people who no longer get out much
• Working people who spend the whole day indoors until they can only get out into the sun in the evening – by which time it is too weak or, depending on the season, has disappeared altogether
• People who go outside wearing a veil
• People with specific medical conditions who have a significantly increased need for vitamin D or who lose it
• Children and teenagers who spend more time in front of computers and the television and hardly ever go outside at all
• People – mostly parents with children – who immediately reach for sun cream when outdoors, ideally factor 50. A tip: let the children and yourself spend 15 minutes in the sun in swimwear before applying sun cream!

Here are just a few examples. You can work out for yourself whether the ‘vitamin-bashing’ camp is right – claiming that Germany is so prosperous that nobody has a vitamin deficiency – or whether the advocates are correct, whose views, backed up by studies, point to a widespread vitamin D deficiency.

Vitamin D deficiency – common and widespread

More than half of all people in Germany are deficient in vitamin D. The German Nutrition Society (DGE) considers a serum concentration of 20 ng/ml to be sufficient. According to figures from the Robert Koch Institute, this means that 58% of women and 57% of men have a vitamin D deficiency. During the winter months, this figure is significantly higher still.

Today, however, many experts now consider a normal range to be 40–80 ng/ml. Levels of 20–30 ng/ml are regarded as a mild deficiency, whilst levels below 20 ng/ml are considered a severe deficiency.

Vitamin D intake from food

Very few foods contain significant amounts of vitamin D. The German Nutrition Society (DGE) recommends a daily intake of 20 micrograms of vitamin D for children, adolescents and adults. This would roughly correspond to the daily consumption of 16 chicken eggs, 5 kg of cheese, 80 g of herring or 2 tins of sardines.

In this respect, taking a daily vitamin D supplement is advisable to meet one’s vitamin D requirements and ensures an adequate supply – particularly in winter.

Vitamin D levels in the blood

An optimal vitamin D level (measured as the 25-OH vitamin D3 level in serum) lies between 30 and 70 ng/ml. According to the recommendations of the German Nutrition Society (DGE), the serum vitamin D concentration should be at least 20 ng/ml (= 50 nmol/l). However, most experts consider this value to be too low and recommend a minimum level of 30 ng/ml. It is not the actual vitamin D3 that is measured, but its storage form, calcidilol (25-hydroxy-vitamin D). The reason is quite simple: if vitamin D3 were measured, this would only provide a snapshot of the current status. The stored form, on the other hand, provides information about long-term vitamin D status.

The following guidelines provide a good indication:
below 10 ng/ml – severe vitamin D deficiency
10–20 ng/ml – vitamin D deficiency
20–30 ng/ml – mild vitamin D deficiency
30–70 ng/ml – normal range
above 70 ng/ml – vitamin D levels too high
Levels that are significantly above the 70 ng/ml mark (from 100 ng/ml at the latest) may be toxic and can lead to health problems. A level above 150 ng/ml is definitely considered toxic. There is as yet no information available on the long-term effects of such extremely high levels (which can only be achieved by taking excessively high doses of over 20,000 IU per day). Exceptions to this include certain medical conditions (e.g. multiple sclerosis). However, even in cases of illness, high-dose therapy should be carried out under the supervision of a doctor.

Laboratory values

Possible units of measurement in the laboratory are: ng/ml (nanograms per millilitre) or nmol/l (nanomoles per litre). Occasionally, values are also given in yg/l (micrograms per litre). These values correspond to those in ng/ml (i.e. 36 yg/l = 36 ng/ml).

The conversion factor from ng/ml to nmol/l is 2.5.
(Examples: 20 ng/ml = 50 nmol/l or 30 nmol/l = 12 ng/l)

Best forms of administration: soft capsules containing oil or oil in drop form
Vitamin D is a fat-soluble vitamin. Fat-soluble means that it requires fat or oil as a transport medium. Only then can the body utilise it at all.
Natural, oil-based liquid D3 has very high bioavailability – meaning it is best absorbed by the body.
Important to note: Vitamin D3 in the form of tablets or coated tablets does not contain any natural oils. Furthermore, they often contain unnecessary additives.

Always take vitamin D3 together with vitamin K2

Why should high-dose vitamin D always be taken together with vitamin K2?
Vitamin D3 regulates the absorption of calcium from food into the bloodstream. If it remains there, it is deposited in the body as useless and harmful waste products. In the long term, such deposits lead to dangerous calcification of blood vessels and organs. The body must therefore be able to utilise the calcium in the blood effectively.

And this is where vitamin K2 comes into play. Vitamin K2 activates the proteins osteocalcin and MGP (matrix Gla protein), which are responsible for calcium utilisation in the blood. These proteins ensure the transport and storage of calcium from the blood into the hard tissue of bones and teeth. It is only in this way, with the help of vitamin K2, that calcium reaches where it belongs and where it is needed.

Vitamin K2 therefore prevents calcium in the blood from forming plaque (deposits) on the walls of the arteries, thereby keeping our blood vessels clear.

Vitamin D therefore always requires vitamin K2 to utilise the calcium effectively. When taken as a dietary supplement, vitamin D should therefore always be taken alongside vitamin K2, as the two vitamins complement each other’s functions within the body.

The big misconception

It is often claimed that vitamin D stores calcium in the bones. This is not strictly correct. Together with parathyroid hormone, vitamin D ensures the absorption of calcium from the gut into the blood, thereby raising blood calcium levels. The ‘transport’ of calcium to the bones and teeth – in other words, to where it is needed – is then carried out by the proteins osteocalcin and MGP, provided they are activated by vitamin K2. The ‘reason’ for this ‘misconception’: vitamin K2 in the form of MK-7 is very expensive. It is therefore omitted from almost all vitamin D products. The lack of effect is then, quite pragmatically, simply attributed to vitamin D…

Vitamin K2 as 100% natural all-trans MK-7
However, there are also significant differences when it comes to vitamin K2.

The MK-7 (all-trans) form used in proSan Vitamin D3+K2 (MK-7) is derived 100% from natural plant sources and has a so-called trans content of over 98%. 

You should avoid these forms of vitamin K2: MK4 (very poor bioavailability, so it must be taken in extremely high doses), MK7-cis (practically ineffective), MK9 (little research has been done on it, mostly synthetic, not authorised in Germany). You should also avoid most very low-cost MK7 products (often imported from abroad), where the trans content is very low.

Be cautious with low-cost vitamin K2 products – often from abroad

A carefully manufactured all-trans MK7 active ingredient is still very expensive at present. Many supposedly cheap products, which are mainly sold online from abroad, use cheap imported active ingredients with a low all-trans content (and therefore a high cis content!!!) and are thus largely ineffective. Our advice: You should therefore put your trust in reputable manufacturers (with whom you can communicate easily and verify quality) rather than in supposedly cheap online bargains. Quality comes at a price.

When taken in combination with vitamin D3, the long-acting form of vitamin K2 (MK-7 all-trans) is therefore the best way to ensure an adequate supply to all organs and tissues.

Vitamin D – Overdose

The German Federal Institute for Risk Assessment (BfR) refers to a ‘vitamin D excess’ when the serum level exceeds 160 ng/ml or 400 nmol/l. The BfR identifies hypercalcaemia – that is, too much calcium in the blood – as the main risk associated with such an overdose. Typical symptoms of hypercalcaemia include kidney stones and calcification of blood vessels, the heart and the lungs.

How can a vitamin overdose occur?

It is not possible to overdose through UV radiation or food. The most common cause is the intake of excessive amounts of vitamin D. Particularly online, products from abroad are advertised containing 50,000 IU or even 100,000 IU. Cult-like groups, particularly on social media, promote their sale. These products always originate from abroad. As a rule, nothing is disclosed about quality standards in their manufacture. The ingredients are often inadequately declared or not declared at all – so you frequently have no idea what is actually in them. It is not without reason that such dietary supplements are banned in Germany – yet they can still be easily obtained via the internet.

The safe dose

The Federal Institute for Risk Assessment (BfR) defines a daily intake of 100yg = 4,000 i.E. of vitamin D as the so-called Upper Intake Level – that is, the maximum safe dose that should be taken daily.