Clock Gene Variants Are Associated with Energy and Macronutrient Intake in Early Childhood and Adulthood.

Background/Objectives: Obesity remains a global health concern, and personalized prevention strategies that consider genetic predispositions can enhance existing strategies. Research suggests that variation in circadian rhythm-related genes, or clock genes, may influence obesity risk, in part through effects on dietary behaviour. However, associations between single-nucleotide polymorphisms (SNPs) in clock genes and dietary outcomes remain understudied, particularly in children. Therefore, we investigated cross-sectional associations between clock gene SNPs and dietary outcomes using baseline data from 226 adults (138 females, 88 males) aged 26-50 y and 168 children (90 females, 78 males) aged 2-6 y from the Guelph Family Health Study. Methods: DNA was extracted from saliva and genotyped using the Illumina Global Diversity Array, and dietary intake was assessed using the Automated Self-Administered 24 h Dietary Assessment Tool. Nine SNPs representing 8 clock genes were selected based on prior associations with dietary and obesity-related outcomes. Generalized Estimating Equations were used to test associations, adjusted for multiple comparisons with the Benjamini-Hochberg false discovery rate (FDR) procedure. Results: Ten nominal associations were identified (p < 0.05), and 2 remained significant after FDR correction (Padj < 0.05); among children, rs2314339-T (NR1D1) was associated with a lower percentage of energy from protein (β = -2.4%, Padj = 0.003) and rs11605924-A (CRY2) with higher energy intake (β = 118.0 kcal, Padj = 0.044). Conclusions: Findings suggest that clock gene SNPs may influence dietary habits from early childhood. Future longitudinal and functional studies are needed to clarify whether these variants can inform precision nutrition strategies for obesity prevention.