Higher calcium levels in the bloodstream determine a person's increased risk of developing coronary artery disease and heart attack, a new study suggests.
Coronary artery disease (CAD), which often results in a heart attack, is the most common cause of death on a global level. According to the Centers for Disease Control and Prevention (CDC), approximately 735,000 people have a heart attack every year in the United States.
A new study conducted by Dr. Susanna C. Larsson, from the Karolinska Institutet in Stockholm, Sweden, and her colleagues points to a genetic predisposition to higher calcium levels as a possible factor for CAD and heart attack.
Their findings are published in the current issue of JAMA.
Genetic variants may hold key
In their article, the researchers highlight the importance of calcium to the system, mentioning its role in blood clotting, blood pressure regulation, and muscle contraction. They also explain that their study was spurred by previous research that suggested a correlation between calcium levels and CAD.
However, they note that the observational nature of former studies meant that their results were inconclusive, and a causal link between high calcium content in the blood and CAD or heart attack could not be proven.
Dr. Larsson and her colleagues opted for a different approach. They used a technique called mendelian randomization, a method using genetic variants - that is, genetic differences that allow us to tell how susceptible we are to particular conditions and diseases - to test for causal links between calcium levels and CAD or heart attack.
The study was conducted on publicly available data collected from 184,305 individuals. Of these, 60,801 had been diagnosed with CAD, 70 percent of whom had also experienced a heart attack, and 124,504 were deemed free from heart disease.
In the analysis, the researchers took into account six genetic variants related to calcium levels in the system.
As expected, they found that a higher risk of CAD and heart attack was linked to a genetic predisposition to a higher calcium concentration in the blood.
The researchers also took an interest in the effect of calcium supplements on individuals already predisposed to higher levels of calcium.
However, they were unable to confirm whether a supplement intake would also impact the risk of CAD or heart attack in these cases. Dr. Larsson and her colleagues highlight the need for further investigation on this count.
"Whether the risk of CAD associated with lifelong genetic exposure to increased serum calcium levels can be translated to a risk associated with short-term to medium-term calcium supplementation is unknown."
Dr. Larsson and her colleagues also acknowledge some limitations to their study, with the main factor relating to the analysis of genetic variants, citing the prominence of the genetic variant for the calcium-sensing receptor, a protein involved in keeping calcium levels stable in the system.
Among other shortcomings, the researchers also mentioned the occasional lack of information on the biological sex and age of the individuals who provided the data. Both of these characteristics have the potential to influence the results.
Despite these drawbacks, the study is crucial in solidifying the findings of previous research, adding a key element to the list of CAD and heart attack risk factors.