Too much vitamin D can damage your heart
High vitamin D concentration in the blood is linked to a greater risk of dying from a heart attack.
In a study involving almost 250,000 people, scientists have found a connection between high levels of vitamin D in the blood and the risk of suffering a stroke or a coronary thrombosis.
The study cannot directly link the two, since it is an observation study, where the scientists have no influence on the doings of the study's subjects.
But the study should not be ignored, says one of the scientists behind.
"It may not provide the definitive truth, but our study does show that we should be aware of the connection," says Peter Schwarz, a professor from the department of clinical medicine at the University of Copenhagen.
Schwarz is backed by Christian Gluud who leads the Copenhagen Trial Unit at the center for clinical intervention research at Copenhagen University Hospital.
"Finding a link in an observational study is not evidence enough but in my mind the study is interesting. When I look at the results I think to myself: "This makes sense, because it perhaps reflects what we’ve previously seen a systematic overview of randomised clinical tests," says Gluud, who was not involved in the new study.
Low vitamin D levels also result in high mortality
The correlation between high levels of vitamin D and increased mortality caused by cardiovascular disease is not the study's only find. In fact, the researchers discovered that it is actually quite difficult to get vitamin D levels balanced right.
Increased mortality also applied to participants with excessively low levels of vitamin D in their blood. Those who fared best were in between.
It is not surprising that vitamin D deficiency is problematic in humans. In fact it is old knowledge which has simply been confirmed by the study.
"In the case of low levels the effect is if possible even more apparent. It just isn't particularly new -- so nobody doubts any longer that vitamin D deficiency is bad for people,” says Schwarz. "What is significant is that the same also applies to high levels."
Calls for more studies on vitamin D
The results are also consistent with those scientists have previously found in randomised clinical tests, says Gluud.
Lars Rejnmark, a professor of clinical medicine from Aarhus University and a leading researcher in the effects of vitamin D on health, says the new study ought to be followed up on.
"It doesn't tell us much about the beneficial or harmful effects of vitamin D because numerous uncertainty factors are involved -- which means that they’re unable to comment on causal relations,” says Rejnmark. “But this could be a launch pad for further research.”
Translated by: Hugh Matthews
- ”A reverse J-shaped association between serum 25- hydroxyvitamin D and cardiovascular disease mortality – the CopD-study”, The Journal of Clinical Endocronology & Metabolism (2015), DOI 10.1210/jc.2014-4551