Low levels of vitamin D are associated with a markedly higher risk of myocardial infarction and early death, according to a Danish study.

Vitamin D deficiency traditionally has been linked with poor bone health, according to background information in the study. However, the results from several population studies have indicated that low levels also may be linked to a higher risk of ischemic heart disease. Other studies have shown vitamin D deficiency may increase blood pressure.

With the new study, which involved more than 10,000 Danes, "we have now examined the association between a low level of vitamin D and ischemic heart disease and death in the largest study to date," Dr. Peter Brondum-Jacobsen, the study's lead author and a member of the Clinical Biochemical Department at Copenhagen University Hospital, said in a news release.

The researchers found extremely low levels of vitamin D, compared with optimal levels, are linked to a 40% higher risk of ischemic heart disease, 64% higher risk of MI, 57% higher risk of early death and 81% higher risk of death from heart disease.

"With this type of population study, we are unable to say anything definitive about a possible causal relationship," Borge Nordestgaard, clinical professor at the Faculty of Health and Medical Sciences at the University of Copenhagen and senior physician at Copenhagen University Hospital, said in the news release. "But we can ascertain that there is a strong statistical correlation between a low level of vitamin D and high risk of heart disease and early death.

"The explanation may be that a low level of vitamin D directly leads to heart disease and death. However, it is also possible that vitamin deficiency is a marker for poor health generally."

The scientists are working to determine whether the connection between a low level of vitamin D and the risk of heart disease is a genuine causal relationship.

"The cheapest and easiest way to get enough vitamin D is to let the sun shine on your skin at regular intervals," Nordestgaard said. "There is plenty of evidence that sunshine is good, but it is also important to avoid getting sunburned, which increases the risk of skin cancer. Diet with a good supply of vitamin D is also good, but it has not been proven that vitamin D as a dietary supplement prevents heart disease and death."