Exposure to heavy metal may augment the risk of developing cardiovascular diseases, according to research.
Exposure to metals, like from cigarette smoking, drinking water, pollution, certain foods or products, is connected to increased calcium accumulation in the coronary arteries, as suggested by a research published on Wednesday in the Journal of the American College of Cardiology.
The correlations detected are remarkable, as they match those observed for traditional risk factors such as smoking and diabetes, noted Drs. Sadeer Al-Kindi, Khurram Nasir from Houston Methodist, and Dr. Sanjay Rajagopalan from University Hospitals Harrington Heart & Vascular Institute in an accompanying commentary. The experts were not involved in the study.
Calcium buildup in the coronary arteries leads to atherosclerosis, a persistent and inflammatory cardiovascular disease characterized by narrowed arterial walls and reduced blood flow. Partial or complete blockages of the arteries might result in conditions like stroke and coronary heart disease, which can trigger arrhythmia, cardiac arrest, or heart failure.
"Our results underscore the significance of considering metal exposure as a substantial risk factor for atherosclerosis and cardiovascular disease," stated Dr. Katlyn E. McGraw, the lead study author and a postdoctoral research scientist in environmental health sciences at Columbia University’s Mailman School of Public Health, in a press release.
Environmental pollutants are commonly viewed as risk factors for cardiovascular diseases, but the association between metals and coronary artery calcification was mainly unknown, mentioned the study authors. They predicted that elevated urinary levels of nonessential metals – like cadmium, tungsten, and uranium – and essential metals – like cobalt, copper, and zinc – linked to cardiovascular diseases could be linked to calcification.
The relationship between metals and heart health
The researchers analyzed data from 6,418 adults between the ages of 45 and 84, who had participated in the Multi-Ethnic Study of Atherosclerosis. Between July 2000 and August 2002, participants provided urine samples, and their arterial calcium was measured then and four more times over a 10-year period. Participants didn’t have clinical cardiovascular disease and were recruited from several cities.
A normal coronary artery calcium score is zero, which indicates no calcification in the arteries, whiles scores between one and 99 suggest mild proof of coronary artery disease. At the study’s inception, the median coronary artery calcium level was 6.3.
Participants with the most urinary cadmium had 51% higher calcification levels initially and 75% higher levels over the 10-year period, according to the authors. High urinary tungsten, uranium, and cobalt levels were associated with 45%, 39%, and 47% higher coronary calcification levels during the follow-up period, respectively. The calcification levels for those with the highest urinary copper and zinc increased by 33% and 57% over 10 years, respectively.
All these findings remained even after adjusting for sociodemographic characteristics, lifestyle aspects, and cardiovascular risk factors like diabetes, high cholesterol, blood pressure, and blood pressure medications.
The study may help cardiologists tackle a new avenue in assessing and treating patients' heart health, according to cardiologist Dr. Andrew Freeman, director of cardiovascular prevention and wellness at National Jewish Health in Denver, who was not involved in the research.
"When you see your doctor, they'll think of your blood pressure, age, weight, cholesterol (and) diabetes," Freeman said. "It's not usually like your doctor will check your copper or manganese or cadmium level, right? So that might become what we do in the future."
Despite the study demonstrating an association, it does not establish causation, noted Al-Kindi, Nasir, and Rajagopalan in the editorial comment.
"The potential mechanisms ensuring these metals propel atherosclerosis progression thus calls for further research," they added. However, the study authors suspect that the presence of heavy metals could contribute to the hardening of arteries partly via increased inflammation.
Measuring urinary metal levels may present challenges
The study has a few limitations. Urinary metal assessments were conducted mostly at the study's inception, which might not fully capture long-term exposure patterns, mentioned Al-Kindi, Nasir, and Rajagopalan.
However, urinary cadmium is generally considered a reliable measure of long-term exposure with low variability over time, the authors said.
"The study team received a grant to measure urinary metals among all participants at baseline and among 10% of participants at visit 5 in the Multi-Ethnic Study of Atherosclerosis," McGraw said via email. The main findings depend on urine measured only at the beginning, while a secondary analysis on that small subset of participants yielded consistent yet insignificant findings.
"Unfortunately, exposure biomonitoring is expensive and we don't currently have funding to measure exposure biomarkers over the 10-year period," McGraw added. Testing the urine samples required shipping them frozen both to a biobank and then to a laboratory at Columbia as well as types of preparation and measurements on different days for precision.
"The team has sought for more research funding to measure the metals over the 10-year period," McGraw added. "However, this will take a few years if the grant application is successful."
Limiting your exposure to heavy metals
The study emphasizes the necessity for large-scale public health actions, Al-Kindi, Nasir, and Rajagopalan suggested.
Lowering "tolerable thresholds of metals in the atmosphere and water" and increasing the enforcement of metal pollution reduction, especially in areas with disproportionate exposures, are necessary steps, they suggested. These health measures have been linked to decreases in cardiovascular disease mortality due to reduced metal exposure.
The study highlighted numerous sources of metal pollution, such as agricultural and industrial activities like fertilizers, batteries, oil extraction, mining, and nuclear energy production, which contributes to the widespread presence of cadmium, tungsten, uranium, cobalt, copper, and zinc.
Freeman posed an intriguing question: "Is it the metals causing the problem, or is it the substances the metals are found in?" It could be a mix of both, he added, hinting at complexity in the issue.
Reducing metal exposure largely falls upon policy makers, but individuals can also take action, McGraw suggested. This includes quitting smoking or vaping, testing your water supply, and using water filters if necessary.
Adopting a balanced diet, rich in nutrients, and regular exercise can help minimize or lessen the impact of metal exposure, experts recommended.
The effectiveness of chelation therapy, which eliminates certain metals from the body, in relation to heart disease and other cardiovascular issues, is a topic of ongoing debate, according to Freeman and McGraw.
If your occupation involves metal exposure, it's crucial to wear appropriate protective equipment, Freeman emphasized. This may include masks, specialized clothing, and safety glasses to shield your skin and eyes.
The relationship between metals and heart health is a significant concern, as the study indicates that elevated urinary levels of nonessential metals like cadmium and essential metals such as cobalt are linked to higher coronary calcification levels, which can lead to cardiovascular diseases. To improve overall wellness and maintain heart health, individuals can take steps like quitting smoking or vaping, testing their water supply, and using water filters if necessary. Additionally, adopting a balanced diet and regular exercise can help minimize the impact of metal exposure.
