The effect of zinc and vitamin A supplementation on immune response in an older population.
OBJECTIVE
To determine if either supplemental vitamin A, zinc, or both increases cell-mediated immune response in an older population.


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


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


METHODS
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.


METHODS
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.


METHODS
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.
Fortes
C
C
National Institute of Health, Rome, Italy.
Forastiere
F
F
Agabiti
N
N
Fano
V
V
Pacifici
R
R
Virgili
F
F
Piras
G
G
Guidi
L
L
Bartoloni
C
C
Tricerri
A
A
Zuccaro
P
P
Ebrahim
S
S
Perucci
C A
CA
D000368:Aged; D019587:Dietary Supplements; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007111:Immunity, Cellular / Q000187:drug effects*; D007958:Leukocyte Count / Q000187:drug effects; D008214:Lymphocytes / Q000187:drug effects; D008297:Male; D016176:T-Lymphocyte Subsets / Q000187:drug effects; D014801:Vitamin A / Q000008:administration & dosage / Q000276:immunology*; D015032:Zinc / Q000008:administration & dosage / Q000276:immunology*
D014801:Vitamin A; D015032:Zinc