The Effect of Zinc and Vitamin A Supplementation on Immune Response in an Older Population

J Am Geriatr Soc. 1998 Jan;46(1):19-26. doi: 10.1111/j.1532-5415.1998.tb01008.x.


Objective: To determine if either supplemental vitamin A, zinc, or both increases cell-mediated immune response in an older population.

Design: A double-blind, randomized, controlled trial of supplementation with vitamin A and zinc.

Setting: Casa Di Riposo Roma III, a public home for older people in Rome, Italy.

Subjects: The health and nutritional status of 178 residents were evaluated. One hundred thirty-six residents agreed to participate in the trial and were randomized into four treatment groups, and 118 of these residents completed the trial.

Intervention: The four treatments consisted of: (1) Vitamin A (800 micrograms retinol palmitate); (2) Zinc (25 mg as zinc sulfate); (3) Vitamin A and Zinc (800 micrograms retinol palmitate and 25 mg as zinc sulfate); (4) Placebo capsules containing starch.

Main outcome measurements: Immune tests-counts of leucocytes, lymphocytes, T-cell subsets, and lymphocyte proliferative response to mitogens-were measured before and after supplementation.

Results: Zinc increased the number of CD4 + DR + T-cells (P = .016) and cytotoxic T-lymphocytes (P = .005). Subjects treated with vitamin A experienced a reduction in the number of CD3 + T-cells (P = .012) and CD4 + T-cells (P = .012).

Conclusions: These data indicate that zinc supplementation improved cell-mediated immune response, whereas vitamin A had a deleterious effect in this older population. Further research is needed to clarify the clinical significance of these findings.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Dietary Supplements*
  • Double-Blind Method
  • Female
  • Humans
  • Immunity, Cellular / drug effects*
  • Leukocyte Count / drug effects
  • Lymphocytes / drug effects
  • Male
  • T-Lymphocyte Subsets / drug effects
  • Vitamin A / administration & dosage
  • Vitamin A / immunology*
  • Zinc / administration & dosage
  • Zinc / immunology*


  • Vitamin A
  • Zinc