Vitamin D deficiency causes an increased risk of death

Deficiency of the sun hormone leads to increased mortality

21/11/2014

Vitamin D plays a crucial role in various processes in the organism and a deficiency of the so-called sun hormone is associated with numerous health complaints. While the effects of vitamin D deficiency on bone formation are undisputed, other ailments, such as cardiovascular disease, remain in doubt as to the extent to which a causal relationship can actually be assumed.

For the first time, scientists from the University of Copenhagen have now been able to show a causal relationship between a low vitamin D level and a generally increased mortality in the context of a recent study. Their results were obtained by Shoaib Afzal from the Copenhagen University Hospital „British Medical Journal“ (BMJ). The new findings seem to be a clear argument in favor of taking vitamin D supplements when vitamin D deficiency threatens, but some important questions remain open.

Effects of vitamin D deficiency on the risk of death
In many cases, statistical correlations between various diseases and a lack of vitamin D have already been established in the past, but until now it has remained unclear whether a causal relationship actually exists. For example, both cardiovascular disease and vitamin D deficiency can be traced back to an unhealthy lifestyle without the vitamin D deficiency affecting the cardiovascular system. The current Danish study has circumvented such weaknesses in previous analyzes by investigating the effects of genetic vitamin D deficiency on overall life expectancy and mortality, respectively.

Genetic vitamin D deficiency
The Danish study is based on data from 96,000 study participants from the United States „Copenhagen City Heart Study“ and the „Copenhagen General Population Study“. In the investigations, the vitamin D levels of the subjects were measured on the basis of blood samples and then checked for connections with genetic defects. In their current study, the Danish researchers now analyzed the „Correlation between genes associated with persistently low vitamin D levels and mortality“, so the message of the University of Copenhagen. „We have observed that genes associated with low vitamin D levels cause a 30 percent increase in mortality and a 40 percent higher risk of cancer deaths“, explains Shoaib Afzal. Here was clearly a causal relationship to determine. The more pronounced the vitamin D deficiency was, the higher the risk of death.

No impact on the risk of fatal cardiovascular disease
A link between genetically determined vitamin D deficiency and the risk of death from cardiovascular disease has not been identified in the current analysis, the Danish scientists report „BMJ“. „Genetically low levels of 25-hydroxyvitamin D were associated with increased overall mortality, cancer mortality and other mortality but not with increased cardiovascular mortality“, writes co-author Børge Nordestgaard, a professor at the University of Copenhagen and chief physician at Copenhagen University Hospital. Here, the observed association in previous studies is probably due to the fact that certain risk factors for diseases of the cardiovascular system, such as high cholesterol or obesity (obesity) cause a reduction in vitamin D levels in the blood. Thus, the vitamin D deficiency would not cause heart disease, but the result of common risk factors.

Causal link clearly proven
Although has already been in previous studies „found a close statistical link between low vitamin D levels and increased mortality“, however, the results may have been distorted by the fact, „Vitamin D deficiency is a marker of unhealthy lifestyle and poor health in general“, reports Professor Børge Nordestgaard. In the current study, however, assume a causal relationship, since the analysis „based on a study of genes - genes that can not be explained by unhealthy lifestyles“, Nordestgaard continues. According to their own assessment, the Danish researchers have clearly demonstrated that a low vitamin D level causes increased mortality. Here, therefore, the obvious conclusion is to compensate for the vitamin D deficiency, if necessary, by taking appropriate preparations. However, the best way to increase vitamin D levels remains unclear, the study authors write.

Many questions
First, for example, the amount of vitamin D must be determined, which should be taken in case of doubt, writes Professor Børge. In addition, it should be determined how and when the vitamin D intake is most effective. The body produces vitamin D on its own when the sun shines on our skin. In this way, humans usually cover about 90 percent of their daily vitamin D needs, and the remaining 10 percent can be absorbed through the diet. However, the skin needs about 30 minutes of contact with sunlight per day to produce enough vitamin D. This is not guaranteed for many people, so they tend to develop a vitamin D deficiency. Here is the option to counteract this by vitamin D supplements. However, prolonged outdoor stays would usually remedy the deficit. Which is the right way, according to the statement of the Danish researchers so far remains open. The question here is whether we should make the best possible use of the sun by means of the sun, take in the diet or supplement it as vitamin supplements, the Danish researchers report. It is also unclear whether the delivery should be best in childhood or adulthood.

Enlightenment through further studies
More detailed information on the health effects of vitamin D intake and the benefits of chronic diseases hope for the British heart specialists Paul Welsh and Naveed Sattar in a commentary to the „BMJ“-Articles from other ongoing studies with names like „Vital“ (USA, 20,000 participants) or „Find“ (Finland, 18,000 participants)“, reports the „daily newspaper“. In 2017, first results regarding the effects of the vitamin on the risk of diseases such as cancer, diabetes or cardiovascular disease are expected. Thus, the risks of a vitamin D deficiency will be significantly better assessed in the future (fp)