Mercury Exposure From Seafood Not Significantly Linked to CVD, All-Cause Mortality

Fears of mercury exposure may influence consumption limits of seafood, despite previous studies reporting an association between increased consumption and reduced cardiovascular disease (CVD) related death.

A team of investigators led by Wei Bao, MD, PhD, University of Science and Technology of China examined the association of seafood consumption and mercury exposure with all-cause and cardiovascular disease (CVD)-related mortality in the US general population.

They found no association of the current low to moderate level of environmentally mercury exposure with the risk of all-cause of CVD-related mortality.

Methods

The cohort study used data from the large-scale National Health and Nutrition Examination Survey (NHANES). Data is collected consecutively and released every 2-years, with a cycle containing approximately 10,000 participants.

Further, the data in the study included the 2003 - 2016 cycles from NHANES for trends in blood mercury concentration, while data cycles from 2003 - 2012 of NHANES were used for the estimation of risk of mortality associated with blood mercury concentration. All participants were adults aged 20 years or older.

Additionally, they assessed dietary intake through two 24-hour dietary recalls, with the first at the mobile examination center examination and the second collected by telephone 3 - 10 days after the first examination.

For the mercury exposure, investigators collected blood specimens and measured mercury levels through inductively coupled plasma mass spectrometry. They noted a limit of detection of 0.14 or 0.2 μg/L for 2003 - 2004, 0.2 or 0.32 μg/L for 2005 - 2006, 0.28 μg/L for 2007 - 2008, 0.33 μg/L for 2009 - 2010, and 0.16 μg/L for 2011 - 2012.

Outcomes were considered all-cause and CVD-related mortality. Data was linked to mortality records through December 2015. The analysis took place from January - March 2021.

Findings

A study population of 17,294 participants with a mean blood mercury concentration of 1.62 (2.46) μg/L were included in the analysis, with a mean age of 45.9 years and 53.3% female (n = 9217). Over 131,276 years of follow-up, a total of 1076 deaths occurred, with 181 deaths linked to CVD.

The data show blood mercury concentration had a weak correlation with fish consumption (r = 0.23, P < .001), dietary intake of EPA and DHA (r = 0.21, P < .001), and dietary selenium intake (r = 0.12, P < .001).

Through the multivariable-adjusted HR, investigators observed an increase in seafood consumption of 1 oz equivalent per day and all-cause mortality was 0.84 (95% CI, 0.66 - 1.07) and for CVD-related mortality was 0.89 (95% CI, 0.54 - 1.47).

They noted this indicated “no association between an increase in seafood consumption of 1 oz equivalent per day and all-cause and CVD-related mortality.”

Additionally, blood mercury concentrations were not associated with the risk of all-cause or CVD-related mortality. When comparing the highest to the lower quartile of blood mercury concentration, the multivariable-adjusted HRs were 0.82 (95% CI, 0.66 - 1.05) for all-cause mortality and 0.90 (95% CI, 0.53 - 1.52) for CVD-related mortality.

Takeaways

“At the current mercury exposure levels in US adults, this study does not suggest a need to change the current dietary guidelines that recommend seafood consumption as part of a healthy diet for US adults in terms of concerns about the cardiovascular effects of mercury,” investigators wrote.

The study, “Association of Seafood Consumption and Mercury Exposure With Cardiovascular and All-Cause Mortality Among US Adults,” was published online in JAMA Network Open.