Population characteristics across the four surveys (third to sixth) are presented in Table 1. Over the 9-year follow-up, significant variations were observed in all mineral intakes, with some notable patterns. Energy, Ca, Cu, and Se intakes showed significant differences in most surveys, with only one exception each. Fe and K intakes differed significantly across all surveys. P, Zn, and Mg intakes showed significant differences in surveys 3–4, 3–5, and 3–6. Mn intake showed no significant differences between surveys 4–5 and 4–6, while significant changes were observed across other surveys. Cr showed no significant changes in surveys 3–4, 3–5, and 4–5. Na intake differed significantly only between survey 3 and the others, remaining non-significant in later surveys.

Table 2 presents population characteristics during the three-, six-, and nine-year follow-up periods. During the 3-year follow-up, BMI increased, along with intakes of energy, Ca, P, Fe, Zn, Cu, Mg, Mn, Se, and K, while only Na intake decreased. Over 6 years, BMI continued to rise, as did intakes of Ca, P, Fe, Zn, Cu, Mg, Mn, Cr, Se, and K intake, with Na intake decreasing. By the 9-year follow-up, increases were observed in BMI and most minerals (Ca, P, Fe, Zn, Cu, Mg, Mn, Cr, Se, and K), while energy and Na intake decreased.

To improve the clarity of the results, given the large number of minerals and electrolytes examined across multiple surveys, a 5% threshold was set to define significant changes between surveys. Only alterations exceeding this threshold were considered significant and reported in the findings.

Figure 2 shows the correlation changes in mineral intake over a 9-year follow-up with four consecutive measurements in parent-offspring dyads. For father-son pairs, across the four surveys, a regression toward the mean was observed for Cu, Cr, Mg, Na, and K, while a decrease was noted in the intake of Ca, P, Fe, Zn, Mn, Cr, and Se. In mother-son pairs, a similar regression toward the mean was seen for Ca, Fe, Zn, Cu, Mg, Mn, Cr, Se, and Na. Meanwhile, the correlation for P intake increased, and K decreased over the four surveys. For father-daughter pairs, a regression toward the mean was observed for Ca, P, Fe, Cr, and K, while correlations for Zn, Cu, Mg, Mn, Cr, Se, and Na intake decreased. In mother-daughter dyads, we observed a regression to the mean for Ca, P, Fe, Cr, and K, with a decrease in Zn, Cu, Mg, Mn, Se, and Na intake (Fig. 2).

Trends of mineral intake correlations between parent-child pairs during four surveys of Tehran Lipid and Glucose Study

Supplementary Fig. 1 shows the correlation changes in mineral intake for father-son and mother-son dyads over 3-year, 6-year, and 9-year follow-ups. Among father-son dyads, during the first three years of the study, we observed an increase in the correlation of Na intake and a decrease in the correlations for Ca, Cu, Mn, Cr, Se, and K intake. Over the 6-year follow-up, the correlation of Na intake continued to increase, while the correlations for Ca, Fe, Cu, Mg, Mn, Cr, Se, and K intake decreased. During the 9-year follow-up, an increase was seen in the correlations for Mg and Na intake, with a decrease in the correlations for Ca, P, Fe, Zn, Mn, Cr, Se, and K intake. In mother-son pairs, the first three years showed an increase in the correlations for Zn and K intake, while Cr and Se intake correlations decreased. From surveys 3 to 5, the correlation of Mn intake increased, whereas correlations for Ca, Se, Na, and K intake decreased. Over the 9-year period, the correlation of Fe and Cu intake increased, while the correlations for Ca, P, Mg, Cr, Se, Na, and K intake decreased.

Supplementary Fig. 2 illustrates the correlation changes in mineral intake for father-daughter and mother-daughter pairs over 3-year, 6-year, and 9-year follow-ups. In father-daughter dyads, the correlation of Fe and Cu intake increased, while the correlations for Ca, P, Cr, Se, and Na intake decreased. During surveys 3 to 5, the correlations for Fe and Zn intake increased, whereas Cu, Mg, Mn, Cr, Se, Na, and K intake correlations decreased. Over the 9-year follow-up, the correlations for all mineral intakes decreased significantly, except for Fe and Cu, which remained non-significant. Among mother-daughter pairs, during the first 3 years, the correlations for all dietary intakes decreased significantly, except for Cu, which was non-significant. During the 6-year follow-up, the correlations for Ca, Mg, Mn, Cr, and Na intake decreased significantly. In the 9-year follow-up, all mineral intakes showed a significant decrease except for Cu.

Figure 3 shows the correlation changes in mineral intake over a 9-year follow-up with four consecutive measurements in siblings and spouses. Among brother-brother pairs, a regression toward the mean was observed in the intake of Ca, Zn, Cr, Se, Na, and K, with decreases noted for Mg and Cu. The intake of P, Fe, and Mn initially increased from survey 3 to 5 but then dropped in survey 6. In sister-sister pairs, a regression toward the average was seen for P, K, Fe, Mg, Cr, and Se intake, while the intake of Ca and Mn decreased. Interestingly, Cu and Na intake increased from survey 3 to 5, followed by a decrease in survey 6. In contrast, Zn intake decreased from survey 3 to 5 but increased in survey 6. Among brother-sister pairs, a regression toward the mean was noted in the intake of Mg, Cr, and Se, while the intake of Ca, P, Fe, Zn, Cu, Mn, Na, and K decreased. In spouses, we observed a regression toward the mean in the intake of Ca, Fe, Zn, Cu, Mg, and K. P intake increased, while Mn, Cr, and Se intake decreased. Additionally, Na intake decreased from survey 3 to 5 but increased again in survey 6 (Fig. 3).

Trends of mineral intake correlations between spouses and siblings during four surveys of Tehran Lipid and Glucose Study

The variations in mineral intake correlations for brother-brother and sister-sister pairs throughout the 3-year, 6-year, and 9-year follow-up periods are presented in Supplementary Fig. 3. In brother-brother dyads, during the 3-year-transition, the correlation for Na intake increased, while correlations for Ca, P, Zn, Cu, Mg, Mn, Cr, Se, and K intake decreased. During the 6-year transition, correlations for Ca, P, Zn, Mg, Se, Na, and K intake decreased, while Fe and Mn intake increased. Over the 9-year transition, correlations for Na, Fe, and Zn intake showed a tendency to increase, while correlations for Ca, Cu, Mg, Cr, and K intake decreased significantly. Among sister-sister pairs, during the first 3 years, correlations for P, Cu, Cr, Se, Na, and K intake increased, while correlations for Ca, Fe, Zn, Mg, and Mn intake decreased. During surveys 3 to 5, Zn, Cr, Na, and K intake correlation increased, while P, Fe, Cu, and Mn decreased. Over 9 years, Zn, Mn and Cr, Se, Na, and K intake increased, while Ca, P, and Mg showed a tendency to decrease.

Supplementary Fig. 4 shows the changes in mineral intake correlations among brother-sister dyads and spouses over 3-year, 6-year, and 9-year follow-up periods. In brother-sister dyads, the first 3 years showed a decrease in the correlation of Ca, P, Fe, Zn, Mg, Mn, Cr, and Se intake, while Cu and K intake correlations increased. From the 3rd to the 5th survey, the correlation for all mineral intakes decreased significantly. Over the 9-year period, only P and Se intake correlations exhibited an upward trend, while the correlations for all other minerals decreased. Among spouses, during the first 3 years, the Fe correlation increased, while correlations for Ca, Mg, Cr, Se, and K intake decreased significantly. In the 6-year follow-up, correlations for P and Zn intake increased, whereas correlations for Fe, Cu, Mg, Mn, Cr, Se, and K intake decreased significantly. Over the 9-year period, correlations for all minerals decreased significantly, except for P intake.