Tracking the correlation of mineral intakes among family pairs over nine years: a longitudinal study.

Abstract

Background: This study aimed to assess possible changes in mineral intake correlation between family pairs over time. Mineral intake was measured using a food frequency questionnaire.

Methods: FCOR command of the Statistical Analysis for Genetic Epidemiology software was used to determine the correlation coefficients of minerals in relative pairs. Our first analysis was conducted on adults (n = 748) who had four complete dietary and familial data on the third to sixth surveys of the Tehran Lipid and Glucose Study. In addition, we assessed respectively the 3-year, 6-year, and 9-year changes in mineral correlations among populations with n = 1773, n = 1672, and n = 1352 samples with two mineral intake measurements.

Results: Most of the mineral correlations among various pairs were found to be in the same direction in both four and two measurement analyses. Among the mother-daughter and brother-sister pairs, there was a decreasing correlation for all minerals over time. In father-daughter, we observed decreasing or regression to the mean of correlations. For father-son and spouse pairs, the correlations between minerals showed a decreasing trend or regression to the mean over time, whereas increased for sodium in the father-son and phosphorus in the spouse pair. For mother-son and brother-brother pairs, iron intake correlation increased and other minerals correlations generally showed a decreasing trend or regression to the mean. Among sister-sister pairs, the correlation of calcium and phosphorus decreased, however, the correlation of chromium, selenium, sodium, and potassium increased.

Conclusion: Our study revealed a decreasing trend in correlation or regression towards the mean over time for most minerals in family pairs.