# Associations between food group intake and serum levels of selenium and other essential and toxic trace elements in adults

## TL;DR

This study explores how different food groups affect serum levels of essential and toxic trace elements in adults, finding that seafood intake is strongly linked to selenium levels.

## Contribution

The study identifies dietary predictors of trace element status and highlights seafood as a key factor for selenium levels.

## Key findings

- Seafood intake is positively associated with serum selenium and tracks arsenic and mercury concentrations.
- Logistic regression showed higher odds of adequate selenium with increased seafood consumption.
- Dairy was a top predictor in all random forest models for trace elements.

## Abstract

To examine how the habitual consumption of major food groups is related to serum concentrations of essential and toxic trace elements in adults and to identify key dietary predictors of adequate status.

In this cross-sectional analysis, 465 healthy adults (Galicia, Spain; 2020–2022) completed a validated semi-quantitative food frequency questionnaire; foods were categorised in 13 groups. Fasting serum concentrations of 14 trace elements were measured by ICP-MS. Group differences across element tertiles (clinical categories for selenium) were compared using the Kruskal–Wallis test. Random Forest (RF) models were constructed to evaluate multivariate dietary predictors for each element. Age- and sex-adjusted logistic regression were used to identify food group predictors of adequate (> 90 µg/L) vs. non-adequate selenium.

Seafood intake was positively associated with serum selenium concentrations and strongly tracked serum arsenic and mercury concentrations. Dairy, fruit and meat were also included in the RF models. Seafood ranked among the top three RF predictors for 13/14 elements; dairy ranked in all models. Logistic regression indicated higher odds of adequate selenium with greater seafood intake (OR 1.009; 95% CI 1.003–1.015; p = 0.007) and inverse associations with oil (OR 0.947; p = 0.018) and grains (OR 0.992; p = 0.036); positive trends in legume and nut consumption were identified. Individuals with adequate selenium reported consumption of ~ 4 fish servings/week.

Integrating dietary and biomarker data revealed selenium to be the most vulnerable micronutrient. Promoting regular consumption of fish (and possibly nuts) while moderating high-oil/high-grain intake may enhance selenium without exceeding toxic metal reference limits.