Association of dietary intake and whole blood essential trace elements with frailty in older adults: a cross-sectional study.

Background: Both insufficient and excessive essential trace elements (ETEs) intake can have adverse effects on health.

Aims: We aimed to evaluate the association between dietary intake and whole blood ETEs with frailty, and further explore the joint association of ETEs mixture.

Methods: The analyses included 4,009 participants for dietary intake and 2,635 for whole blood ETEs analyses. Frailty was assessed by FRAIL scale, while dietary intake ETEs were measured by a food frequency questionnaire, and whole blood ETEs were measured using inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP-OES). We used ordinal logistic regression and restricted cubic spline (RCS) models for individual association, and weighted quantile sum (WQS) regression and quantile g-computation for joint association.

Results: Increased dietary intake chromium (Cr), manganese (Mn), copper (Cu), zinc (Zn), selenium (Se) and iron (Fe) were associated with a decreased likelihood of frailty. Blood Fe (Q4 versus Q1: OR = 0.76, 95% CI: 0.61, 0.95) was negatively associated with frailty. L-shaped dose-response associations were found for dietary intake ETEs with FRAIL score, while blood Mn had a U-shaped curve, and Fe showed a negatively linear trend. In the WQS analyses, both dietary intake (β = -0.076, 95% CI: -0.122, -0.030) and blood (β = -0.078, 95% CI: -0.136, -0.020) ETEs mixtures were associated with the FRAIL score. Quantile g-computation also showed similar results.

Conclusions: Our study suggests that different ETEs play distinct roles in frailty, and supplementation needs to consider the type of ETEs and appropriate dosage.