Vitamin D – What’s up with The Hype?
More and more people are taking vitamin D, especially now in the dark season. What’s really going on with the new hype?
What Does The Body Need Vitamin D for?
It ensures, for example, that calcium is built into bones and teeth and that the muscles are also supplied with it. A long-term deficiency therefore softens the bones – in children this is called rickets – and in older people it contributes to bone loss (osteoporosis). Vitamin D receptors are also found in almost all other organs and tissues, from the brain to the intestines.
How Do You Take it Up?
Ten to 20 percent comes from food, especially from fatty sea fish such as herring or salmon, and much less is found in eggs or mushrooms. By far the greater part is formed by the body through the skin under the influence of sunlight. The best time to do this is in the summer months, depending on your skin type and the time of day, to go out in the sun for five to 25 minutes without sun protection with uncovered face, hands and arms – without risking sunburn. As the body soon slows down production of its own accord, the rule of thumb is not: the longer, the more. And: the body stores vitamin D and then calls it up in winter.
How Common is a Deficiency?
If you believe self-proclaimed vitamin D apostles: practically everywhere. Serious studies come to different conclusions: The Robert Koch Institute (RKI) has measured vitamin D levels in around 7000 adults. The result: about 30 percent are below 12 ng/ml or 30 nmol/l (nanograms per millilitre or nanomol per litre; in these units the level of the vitamin D form that is transported in the blood is measured), are therefore insufficiently supplied.
However, once the measuring methods had been standardized, only just over 15 percent showed a deficiency. But where does this defect begin? The RKI specifies a minimum value of 12 ng/ml (30 nmol/l), professional societies in the USA recommend 20 ng/ml (50 nmol/l), other experts such as Prof. Andreas Kurth from the Dachverband Osteologie (Umbrella Association of Osteology) believe that a sufficient level is only reached from 30 ng/ml (75 nmol/l).
Am I Myself Affected by This?
According to Prof. Heide Siggelkow, specialist for endocrinology at the University Medical Center Göttingen, young, healthy people who are regularly outdoors in summer do not need to worry about their vitamin D status. But there are also risk groups such as dark-skinned people, women who only go outdoors in disguise, and patients who are chronically ill with liver, kidney or gastrointestinal tract diseases or suffer from osteoporosis. Older people are also at risk because their ability to produce vitamin D is reduced.
So I Should Take Pills Now?
The administration of vitamin D is clearly recommended for babies. If, on the other hand, you belong to one of the above-mentioned risk groups, it is best to have the level determined by a doctor and discuss with him whether and which preparations make sense. The measurement should also be repeated after a few months. The German Society for Nutrition advises to only take vitamin D if the level cannot be improved either by diet or by the sun.
What Dosage is Recommended?
A daily dose of 800 to 1000 International Units (I.E. is a unit of measurement for the biological activity of a substance and is mentioned on many preparations) is harmless. For babies, the German Society for Child and Youth Medicine provides for 400 to 500 I.U. until the second early summer of their lives. The maximum tolerable daily intake is 4000 I.U. for adults (children: 2000 I.U.). However, there are followers of high-dose therapy who take more. This can have serious consequences: At the end of last year, the Drug Commission reported two patients with acute renal failure. They had taken 10,000 and 50,000 I.U. daily respectively.
Is Vitamin D Really a Miracle Cure?
It has long since ceased to be just about bones, but also about metabolic and cardiovascular diseases, certain types of cancer, multiple sclerosis, Parkinson’s disease and dementia. “Data show that those who have higher vitamin D levels are in better health,” says Heide Siggelkow. But: “Maybe people are healthier because they are more active outdoors. The higher levels would then simply be a consequence of their lifestyle.” Larger studies on how people with and without vitamin D develop are still ongoing. One study involving 25,000 men and women has just yielded sobering results. The conclusion of Stiftung Warentest: “According to current knowledge, taking vitamin D supplements cannot prevent cancer, diabetes or cardiovascular disease.