Increased mortality in vitamin D deficiency
Vitamin D deficiency has long been known as a risk factor for osteoporosis. More recent studies have suggested that vitamin D might influence other chronic diseases such as cardiovascular disease, diabetes, cancer and infections due to its hormonal effects. If this were true, insufficient vitamin D supply would also have an effect point to the mortality of the population.
Scientists are investigating this question in the ESTHER * study. The German Cancer Research Center (DKFZ) is carrying out the investigation in cooperation with the Saarland Epidemiological Cancer Register, Saarland Ministry for Social Affairs, Health, Women and Family. The study includes almost 10.000 participants from all over the Saarland. The head of the study is Prof. Hermann Brenner from the DKFZ.
Especially in winter, the concentration of vitamin D in the blood of many study participants was particularly low. In January, for example, 24 percent of the test subjects had a very low and 71 percent a low vitamin D level **. In comparison, the proportion of ESTHER participants with very low vitamin D values in July was only 6 percent, with a low vitamin D value 41 percent.
The particularly low vitamin D levels in winter can be explained by the fact that the body produces most of its vitamin D requirements itself under the influence of UV-B radiation from sunlight. The small amount of UV-B light in Germany in the dark season is often not enough to sufficiently boost vitamin D production.
Mortality was statistically significantly higher in participants in the ESTHER study with very low and low vitamin D levels than in subjects who had higher levels of vitamin D in their blood. After taking into account all confounding factors, the mortality rate within the eight-year observation period was 1,7-fold increased in subjects with very low vitamin D values and 1,2-fold increased in participants with low vitamin D values.
In particular, study participants with very low vitamin D values had an increased risk of dying from a respiratory disease (2,5 times the risk of death). They also succumbed to cardiovascular diseases (1,4-fold) or cancer (1,4-fold) more frequently.
So should everyone take prophylactic vitamin D supplements?
Scientists are discussing this question controversially: Randomized controlled studies that examined the influence of vitamin D intake on mortality showed rather low effects overall. Large studies are currently underway that will require a few years of follow-up time to clarify the question of the effectiveness of vitamin D supplements. "The results of the ESTHER study show, however, that this research effort could be worthwhile, since low vitamin D levels are very common in Germany," says Dr. Ben Schöttker, the first author of the work.
Until there are reliable findings on vitamin D supplementation, the scientist recommends basking in the sun in the warm season in order to ensure a sufficient supply of vitamin D and to create a storage facility for the winter. The need can usually not be met with food alone. The duration of sun exposure should be limited - depending on the skin type - so that the risk of skin cancer does not increase. The German Nutrition Society recommends that for most people in Germany from March to October, depending on skin type, 5 to 25 minutes of sun exposure per day on the face, hands and forearms is sufficient to produce sufficient vitamin D.
* ESTER = epidemiological study on the chances of prevention, early detection and optimized therapy of chronic diseases in the elderly population
** Definition of the vitamin D level:
• very low: <30 nmol / L serum 25-hydroxyvitamin-D
• low: <50 nmol / L serum 25-hydroxyvitamin-D
Schöttker B, Haug U, Schomburg L, Köhrle L, Perna L, Müller H, Holleczek B, Brenner H.
Strong associations of 25-hydroxyvitamin D levels with all-cause, cardiovascular, cancer and respiratory disease mortality in a large cohort study.
American Journal of Clinical Nutrition 2013; DOI: 10.3945 / ajcn.112.047712
Source: Heidelberg [DKFZ]
