Postprandial Micronutrient Variability and Bioavailability: An Interventional Meal Study in Young vs. Old Participants

Abstract

This study explores age- and time-dependent variations in postprandial micronutrient absorption after a micronutrient-rich intervention meal within the Biomiel (bioavailability of micronutrients in elderly) study. Comprising 43 healthy participants, the study compares young (n = 21; mean age 26.90 years) and old (n = 22; mean age 66.77 years) men and women, analyzing baseline concentrations and six-hour postprandial dynamics of iron (Fe), copper (Cu), zinc (Zn), selenium (Se), iodine (I), free zinc (fZn), vitamin C, retinol, lycopene, β-carotene, α-tocopherol, and γ-tocopherol, along with 25(OH) vitamin D (quantified only at baseline). Methodologically, quantifications in serum or plasma were performed at baseline and also at 90, 180, 270, and 360 min postprandially. Results reveal higher baseline serum Zn and plasma lycopene concentrations in the young group, whereas Cu, Se, Cu/Zn ratio, 25(OH) vitamin D, α-tocopherol, and γ-tocopherol were higher in old participants. Postprandial variability of Zn, vitamin C, and lycopene showed a strong time-dependency. Age-related differences in postprandial metabolism were observed for Se, Cu, and I. Nevertheless, most of the variance was explained by individuality. Despite some limitations, this study provides insights into postprandial micronutrient metabolism (in serum/plasma), emphasizing the need for further research for a comprehensive understanding of this complex field. Our discoveries offer valuable insights for designing targeted interventions to address and mitigate micronutrient deficiencies in older adults, fostering optimal health and well-being across the lifespan.

Keywords: carotenoids; interventional meal study; old; postprandial assessment; trace elements; vitamins; young.

Figure 1

Baseline concentrations of various TEs and TE-associated biomarkers for the young (white) and old (gray) study groups. Data for serum (A) Fe, (B) Cu, (C) Zn, (D) Se, (E) I, (F) Cu/Zn ratio, (G) Se/Cu ratio, and (H) fZn are plotted as a box-and-whiskers plot with straight lines: median; +: mean; •: identified outlier. The dashed lines represent the reference ranges (if available). Significant differences are marked with p < 0.05 (*); p < 0.01 (**) and were calculated by unpaired t-test.

Figure 2

Baseline concentrations of various vitamins and carotenoids for the young (white) and old (gray) study groups. Data for plasma (A) retinol, (B) 25(OH) vitamin D, (C) vitamin C, (D) normalized lycopene, (E) normalized β-carotene, (F) α-tocopherol, and (G) γ-tocopherol is plotted as box-and-whiskers plot with straight lines: median; +: mean; •: identified outlier. The dashed lines represent the reference ranges (if available). Significant differences are marked with p < 0.001 (***) and were calculated by unpaired t-test.

Figure 3

Postprandial progression curves of serum (A) Fe, (B) Cu, (C) Zn, (D) Se, (E) I, and (F) fZn concentrations throughout 360 min after consumption of the micronutrient-rich meal within the young (dashed blue) and old (black) study groups. Shown are the mean (±SEM) ratios of the serum concentrations between each observed timepoint and baseline to reflect postprandial variability. Significant time-dependent differences are marked with p < 0.05 (*); p < 0.01 (**); p < 0.001 (***). Significant differences that were age-related are marked with p < 0.05 (#); p < 0.01 (##); p < 0.001 (###). Calculations for significance were performed using repeated measurement two-way ANOVA followed by Fisher’s LSD post hoc test.

Figure 4

Postprandial progression curves of plasma (A) retinol, (B) vitamin C, (C) normalized lycopene, (D) normalized β-carotene, (E) α-tocopherol, and (F) γ-tocopherol throughout 360 min after consumption of the micronutrient-rich meal within the young (dashed blue) and old (black) study groups. Shown are the mean (±SEM) ratios of the plasma concentrations between each observed timepoint and baseline to reflect postprandial variability. Significant time-dependent differences are marked with p < 0.05 (*); p < 0.01 (**); p < 0.001 (***). Calculations for significance were performed using repeated measurement two-way ANOVA followed by Fisher’s LSD post hoc test.

Figure 5

Correlations between baseline serum/plasma concentrations and ratios of sampling timepoints to investigate the impact of the baseline status on the postprandial variability of (A) Zn, (B) fZn, (C) retinol, and (D) vitamin C in serum/plasma throughout a 360 min investigation period. The blue diamonds indicate young participants, while the gray circles represent old participants. Correlation was determined by Pearson correlation coefficient (r), provided with the corresponding p-values. Additionally, 95% confidence intervals are provided.