High-dose vitamin D - when useful, when dangerous?

What is Vitamin D?

Vitamin D is a generic term for the so-called calciferols - these are fat-soluble vitamins. Its most important representatives are vitamins D3 and D2.

Vitamin D is particularly important in connection with our bone metabolism - because it helps that the important minerals calcium and phosphate can be absorbed from the intestine and built into the bones.

Normally, with sufficient UV-B radiation, our body also produces enough vitamin D. In Germany, however, due to the geographical location, this is only the case from March to October. Then what about the time in between? Well, it is usually possible for us to produce enough vitamin D during the "sunny time" so that we have a decent store for the "shady days".

How does a vitamin D deficiency come about?

However, other factors are responsible for whether we are even able to build up enough reserves. These include a .:

  • climate

  • Altitude

  • Air pollution

  • Duration of sunshine

  • Diseases of the stomach, intestines, liver, kidneys

  • Taking medication (e.g. certain epilepsy and cancer drugs)

  • Dress habits (e.g. veiled for religious reasons)

What is high-dose vitamin D therapy?

There is no general answer to this question, as there is also no consensus in research about when to speak of high-dose therapy. However, what the quantities always have in common is that they do not exceed the maximum daily intake recommended by the Federal Office for Risk Assessment of 800 i. E. (international units) far exceed.

The concept of high-dose therapy with vitamin D became known primarily through the Brazilian doctor Cicero Galli Coimbra and the Coimbra protocol named after him. This comes from a. for multiple sclerosis and sees gifts of 80,000 i. E. Vitamin D a day before. The assumption behind it: People suffering from multiple sclerosis have a vitamin D resistance. In addition to the extreme amounts of vitamin D, those treated receive various micronutrients, have to adhere to a low-calcium diet, drink plenty of water and often do sports. Problematic: Studies have not yet proven the benefit of this form of therapy - the successes have so far only been based on experience reports. Important: This form of therapy is monitored by a doctor and should by no means be carried out on your own.

Generally speaking, such high-dose therapies can be viewed with skepticism. In the following, we briefly examine the benefits of high-dose vitamin D in various diseases.

Cardiovascular diseases and high doses of vitamin D.

Various studies have already indicated a connection between a reduced vitamin D status and an increased risk of cardiovascular diseases. Possible links exist between the vitamin and conditions such as:

  • Heart attack

  • stroke

  • Heart failure

  • high blood pressure

  • Cardiac arrhythmias

  • thrombosis

For this reason, research has examined, for example, how a monthly high dose of 200,000 i. E. Affects the development of diseases of the cardiovascular system. As a result, there was no significant difference between the vitamin D group and the control group. In view of this, the researchers conclude that a high monthly dose shows no real benefit in preventing the development of cardiovascular diseases. However, they also admit that a weekly or even daily high dose still needs to be investigated in this regard.

Researchers found similar results in a comparable study design in connection with only high blood pressure. Here too, after a long-term dose of 100,000 i. E. Per month for 1 ½ years no significant improvement can be found if the patient has not previously had a vitamin D deficiency.

Bone health and high-dose vitamin D.

The aspect most commonly associated with vitamin D is bone health. This connection has also been repeatedly investigated in studies in the recent past. a. in the context of high-dose doses of vitamin D. To date, z. For example, the relationship between vitamin D supplementation and bone density in older people has not been adequately investigated, and some studies provide contradicting results.

In 2019, researchers investigated this fact and supplied three different control groups with vitamin D in different amounts every month. After one year, no significant differences in bone density could be found. Ultimately, however, it turned out that a monthly intake of up to 48,000 i. E. Vitamin D can be classified as safe, because none of the test subjects showed serious side effects.

Potentially negative effects were found in another study on the same subject. There three different control groups received either 400, 4,000 or 10,000 i.v. E. Vitamin D daily. In the higher dose groups, even lower bone densities could be measured in the spoke after the examinations were completed. The researchers therefore conclude that an increased dose of vitamin D does not have a positive effect on bone density and that future studies should show whether more vitamin D may even have a negative effect on bone density.

However, a study of the frailty of older people shows that not all studies are negative. In this study, older adults received up to 4,000 i. E. daily and it was found that their physical performance (running speed, grip strength and other functions) improved as a result. These positive results could only be observed in those people who had already been classified as frail at the beginning.

Multiple sclerosis and high-dose vitamin D.

In this context, the Coimbra Protocol was also used by the experts from the German Multiple Sclerosis Society. V. discussed. They are of the opinion that the study situation is not sufficient for a therapeutic implementation and that further controlled studies must follow. In this context, it is important to note that such an ultra-high dose therapy should never be undertaken on one's own initiative. This is the only way to avoid vitamin D poisoning, albeit rare.

The study situation for MS and vitamin D is contradictory. In animal experiments, an increased disease activity could in some cases even be observed if high-dose vitamin D was given over a long period of time.

On the other hand, there is a large-scale study from 2016, the findings of which should not be underestimated. Study participants with multiple sclerosis who were 14,000 i.v. E. who received vitamin D per day had significantly less disease activity with 0.28 flare-ups per year than the control group with 0.41 flare-ups per year. In addition, it was observed that injuries typical of multiple sclerosis (referred to here as MRT lesions) were significantly lower in the vitamin D group than in the control group. High-dose vitamin D could therefore have a protective effect in MS.

Can you poison yourself with vitamin D?

Yes, it is possible - but very rarely. Cases have been reported of severe overdose (10,000 and 50,000 i.u. per day) in the elderly, leading to renal failure and calcium overdose. An affected 60-year-old man subsequently developed chronic kidney weakness and is now on dialysis.

Yes, such cases rarely occur, but the secondary diseases are nonetheless undoubtedly due to excessive doses of vitamin D. And with the increased awareness of vitamin D, there is also an increase in the number of people who take vitamin D - as a result, the number of poisonings potentially increases. So-called vitamin D toxicity is then associated with various symptoms, including: a .:

  • Nausea & vomiting

  • stomach pain

  • confusion

  • frequent urination

  • constant thirst

  • Dehydration

Vitamin D - supplement in high doses or not?

In view of the current state of studies, we would advise against high-dose self-treatment with vitamin D. Even with the controversial Coimbra Protocol, the therapy is permanently accompanied by a doctor who regularly takes measurements and reassesses whether and, if so, how much vitamin D should be taken.

Of course, there are circumstances that require the administration of vitamin D, not least an established vitamin D deficiency. But who actually has a defect?

Who is Vitamin D Deficient?

According to the Robert Koch Institute, around 30% of people in this country are actually undersupplied; among women, the undersupply increases statistically with age. However, these values ​​vary greatly depending on the measurement period - in summer the deficiency reaches a low of around 8%, in winter a high of 52%. In view of these numbers, the research institute judges that the supply situation in Germany is to be classified as “not optimal”.

The consequences of a permanent deficiency in vitamin D are related to age. Children may have what is known as rickets - this condition disrupts bone growth. In adults, however, what is known as osteomalacia can occur, in which bones soften, so to speak, and are more easily deformable. As a result, the bones can break more easily. The older we are, the more likely is osteoporosis, also known as "bone loss", with a vitamin D deficiency.

All these changes require therapeutic intervention, either through a vitamin D substitution or increased exposure to sunlight.