Abstract
BACKGROUND/AIM: Familial resemblance in dietary patterns has been a subject of interest, with both genetic and environmental factors playing crucial roles. This study aims to investigate trends in macronutrient intake correlations over a 9-year period among different familial pairs, including parent-offspring, siblings, and spouses, using data from the Tehran Lipid and Glucose Study (TLGS). METHODS: This longitudinal study, conducted within the framework of the TLGS, analyzed data from 1,814 families over a 9-year period. Dietary intakes were assessed using a validated 168-item food frequency questionnaire. Macronutrient intakes were calculated and adjusted for age. Familial correlations were estimated using intraclass correlation coefficients for various familial pairs (parent-offspring, siblings, and spouses) across four consecutive surveys. Changes in correlations were analyzed over 3-year, 6-year, and 9-year intervals, as well as across all four surveys, to determine overall trends in macronutrient intake correlations. RESULTS: The results revealed diverse trends in intake correlations for carbohydrates, proteins, fats, and specific fatty acids across familial relationships. Parent-offspring dyads exhibited varied patterns, with some nutrients showing regression to the mean. Sister-sister pairs demonstrated strengthening correlations for energy, carbohydrates, fats, and saturated fatty acids over time. Conversely, brother-sister pairs displayed weakening correlations for most macronutrients, particularly energy, proteins, cholesterol, and fiber. Spouse correlations tended towards regression to the mean for energy, carbohydrates, and fats, and fiber. CONCLUSIONS: The present study illuminates the dynamic nature of familial dietary correlations over time. The contrasting trends between sister-sister and brother-sister dyads suggest a significant influence of gender on shared dietary patterns. These findings underscore the complex interplay of genetic and environmental factors in shaping family dietary behaviors and highlight the importance of considering both gender and relationship type when examining familial nutritional habits.