The group, led by Dr Peter Brøndum-Jacobsen, took plasma 25-hydroxyvitamin D – 25(OH)D –samples from 10 170 women and men from the Danish general population and followed them for an average of 29 years to assess any associations with the incidence of heart disease and premature death. In addition the team performed a meta-analysis 18 studies investigating the risk of ischemic heart disease and 17 studies looking at vitamin D and early death.
"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,” said Peter Brøndum-Jacobsen from the Copenhagen University Hospital, Denmark.
“We observed that low levels of vitamin D compared to optimal levels are linked to 40% higher risk of ischemic heart disease, 64% higher risk of heart attack, 57% higher risk of early death, and to no less than 81% higher risk of death from heart disease," added Brøndum-Jacobsen.
Sunshine vitamin
Vitamin D – often referred to as the sunshine vitamin – deficiency has traditionally been linked with poor bone health and osteoporosis. However research has begun to suggest that the vitamin plays a key role in many immune-related systems. As a result many researchers have begun to investigate possible links between vitamin D deficiency and a host of health conditions – including heart health.
Results from several population studies have indicated, for example, that a low level of this important vitamin may also be linked to a higher risk of ischemic heart disease, while other studies show vitamin D deficiency may increase blood pressure.
Study details
In the new study, Brøndum-Jacobsen and his team compared the lowest 25(OH)D levels of vitamin D (those with less than 15 nanomol vitamin per litre serum) accounting for 5% of the population with those who had adequate levels of vitamin D (defined as more than 50 nanomol vitamin per litre serum) – accounting for approximately 50% of the study population.
The team reported that decreasing 25(OH)D levels were associated with increasing risk of ischemic heart disease, myocardial infarction, and early death.
“Comparing individuals with plasma 25-hydroxyvitamin D levels at the 1st to 4th percentile with individuals with levels at the 50th to 100th percentile, the multivariable adjusted risk was increased by 40% for ischemic heart disease, by 64% for myocardial infarction, by 57% for early death, and by 81% for fatal ischemic heart disease/myocardial infarction,” wrote the authors.
In a further meta-analysis covering a total of 35 studies the team found the risk of ischemic heart disease and early death were increased by 39% and 46% for lowest versus highest quartile of 25(OH)D levels.
"With this type of population study, we are unable to say anything definitive about a possible causal relationship,” noted Professor Børge Nordestgaard, of the University of Copenhagen – senior author of the paper. “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," he said.
