# Concentrations of the serum long-chain omega-3 polyunsaturated fatty acids and hair mercury in men in different apolipoprotein E phenotypes

## TL;DR

This study found that APOE4 carriers had slightly higher mercury levels in their hair compared to non-carriers, but no differences in omega-3 fatty acid levels.

## Contribution

The study provides new evidence on mercury accumulation differences in APOE4 carriers without differences in omega-3 levels.

## Key findings

- APOE4 carriers had slightly higher hair mercury concentrations compared to non-carriers.
- No differences in LC n-3 PUFA concentrations were found between APOE4 carriers and non-carriers.
- Fish consumption was associated with higher mercury and omega-3 levels, but associations were similar in APOE4 carriers and non-carriers.

## Abstract

Fish is a source of long-chain omega-3 polyunsaturated fatty acids (LC n-3 PUFA) and methylmercury, a toxic heavy metal, with opposite effects on cardiovascular disease risk and cognitive decline. Besides diet, the apolipoprotein E (APOE) genotype may affect LC n-3 PUFA and mercury concentrations in the body, but the evidence is inconsistent. The subjects were 1159 men aged 42–60 years, examined in 1984–1989. ANCOVA and linear regression were used in the analyses. The mean ± SD concentrations of serum eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA) were 1.57 ± 0.82, 0.55 ± 0.10 and 2.45 ± 0.75%, respectively. There were no differences in LC n-3 PUFA concentrations between APOE4 carriers and non-carriers (P-values ≥ 0.60). The mean ± SD hair mercury concentration was 1.55 ± 1.3 µg/g. The concentrations were slightly higher in APOE4 carriers vs. non-carriers (difference 0.16 µg/g, 95% confidence interval = 0.01–0.32,P = 0.04). Overall, fish consumption was associated with higher hair mercury and serum EPA and DHA concentrations, but no differences in the associations were found between APOE4 carriers and non-carriers (P-interactions ≥ 0.30). Hair mercury, but not serum LC n-3 PUFA concentrations, were higher in APOE4 carriers vs. non-carriers. However, as no differences were found in the associations of fish intake with LC n-3 PUFA and mercury concentrations, the results could be due to differences in mercury accumulation.