Zinc absorption in healthy elderly humans and the effect of diet.
Level 3 - non-randomized controlled study
Non-randomized comparative physiological cohort study comparing two age groups
PubMed 8237876 · doi:10.1093/ajcn/58.5.690
What was done
Zinc absorption was evaluated in nine young healthy men (aged 24–40 years) and eight elderly healthy men (aged 70–83 years) using a stable isotope tracer (0.8 mg 70Zn). Absorption was measured on two consecutive occasions after administering test meals with either high or low zinc bioavailability, varied primarily by phytic acid content.
What was found
Zinc absorption from the high-bioavailability meal was 38.9 ± 9.8% (mean ± SD) in young men and 35.0 ± 10.9% in elderly men, showing no statistically significant difference (P > 0.05). For the low-bioavailability meal, absorption dropped by 40% and 43% to 23.4 ± 10.2% and 19.8 ± 6.1% in young and elderly men, respectively, with no significant effect of age.
Why it matters
This study indicates that intestinal zinc absorption and susceptibility to dietary phytate inhibition are preserved in healthy aging at least through age 80.
Limits
The sample size was very small (n = 17 total), and the cohort was restricted to healthy males, limiting generalizability to women or frail elderly individuals with chronic conditions. Only single-meal absorption kinetics were measured.
Cited by
- contradicts Intestinal absorption of zinc declines significantly with age, dropping by approximately half.