Cited by 516Trace Elements in HealthIron Metabolism and DisordersExercise and Physiological Responses

The DOI matches its Crossref record; 45 of the 48 references it cites were found in a registry or an index; none of the 67 sources its claims cite is checked for support yet.

Zinc supplementation decreases incidence of infections in the elderly: effect of zinc on generation of cytokines and oxidative stress

Open access
Prasad, Ananda S, Beck, Frances WJ, Bao, Bin, Fitzgerald, James T, Snell, Diane C, Steinberg, Joel D, Cardozo, Lavoisier J·2007·The American Journal of Clinical Nutrition

Abstract

Background Zinc deficiency, cell-mediated immune dysfunction, susceptibility to infections, and increased oxidative stress have been observed in elderly subjects (ie, those >55 y old). Zinc is an effective antiinflammatory and antioxidant agent.Objectives The primary objective was to determine the effect of zinc on the incidence of total infections in healthy elderly subjects. The secondary objective was to determine the effect of zinc on cytokines and oxidative stress markers.Design A randomized, double-blind, placebo-controlled trial of zinc supplementation was conducted in elderly subjects. Fifty healthy subjects of both sexes aged 55-87 y and inclusive of all ethnic groups were recruited for this study from a senior center. The zinc-supplemented group received zinc gluconate (45 mg elemental Zn/d) orally for 12 mo. Incidence of infections during the supplementation period was documented. The generation of inflammatory cytokines, T helper 1 and T helper 2 cytokines, and oxidative stress markers and the plasma concentrations of zinc were measured at baseline and after supplementation.Results Compared with a group of younger adults, at baseline the older subjects had significantly lower plasma zinc, higher ex vivo generation of inflammatory cytokines and interleukin 10, and higher plasma oxidative stress markers and endothelial cell adhesion molecules. The incidence of infections and ex vivo generation of tumor necrosis factor alpha and plasma oxidative stress markers were significantly lower in the zinc-supplemented than in the placebo group. Plasma zinc and phytohemagglutin-induced interleukin 2 mRNA in isolated mononuclear cells were significantly higher in the zinc-supplemented than in the placebo group.Conclusions After zinc supplementation, the incidence of infections was significantly lower, plasma zinc was significantly higher, and generation of tumor necrosis factor alpha and oxidative stress markers was significantly lower in the zinc-supplemented than in the placebo group.

Overview

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Written from the paper’s full text.

TL;DR

In a 12-month randomized, double-blind, placebo-controlled trial, daily zinc gluconate (45 mg elemental zinc) lowered infection incidence and reduced ex vivo TNF-α and plasma oxidative stress markers in healthy older adults. Zinc also raised plasma zinc and PHA-induced IL-2 mRNA in zinc-deficient elderly participants.

Key findings

  • Infection incidence over 12 months was lower with zinc than placebo: 0.29 ± 0.46 vs 1.4 ± 0.95 infections per subject (P < 0.01; effect size 1.46); 29% vs 88% of subjects affected (P = 0.001), and 17 zinc recipients vs 3 placebo recipients had no infection.
  • Plasma zinc rose in the zinc group (92.9 ± 9.45 to 104 ± 16.69 µg/dL at 12 mo) while the placebo group trended down (95.7 ± 13.09 to 88.5 ± 9.66; P = 0.0002).
  • Ex vivo TNF-α generation fell significantly in the zinc group and rose in the placebo group, with maximal reduction at 6 mo; oxidative stress markers also improved: MDA+HAE 1.66 ± 0.34 to 1.35 ± 0.18 vs 1.70 ± 0.30 to 1.71 ± 0.35 µmol/L (P = 0.0002), and 8-OHdG 0.63 ± 0.16 to 0.50 ± 0.14 vs 0.66 ± 0.13 to 0.68 ± 0.13 ng/mL (P = 0.030).
  • In a separate 6-month substudy of zinc-deficient elderly, PHA-induced IL-2 mRNA increased with zinc (0.38 ± 0.07 to 0.63 ± 0.03) but not placebo (0.40 ± 0.05 to 0.39 ± 0.04; P = 0.001); plasma zinc also increased (84.0 ± 3.03 to 97.6 ± 5.98 vs 86.8 ± 2.04 to 89.2 ± 3.06 µg/dL; P = 0.0088).

Methods

  • Randomized, double-blind, placebo-controlled 12-month trial in 50 healthy elderly adults aged 55–87 recruited from a senior center; one zinc-group participant dropped out on day 2, leaving complete data for 49 (tables report 24 zinc, 25 placebo). The zinc group received 45 mg elemental zinc/d as zinc gluconate; the primary endpoint was infection incidence, with secondary cytokine and oxidative stress measures.
  • Baseline comparisons were made with 31 younger adults aged 18–54 for plasma zinc, adhesion molecules, nitric oxide, MDA, and ex vivo inflammatory cytokines.
  • A separate substudy randomized 12 zinc-deficient elderly subjects to zinc or placebo for 6 months to measure plasma zinc and PHA-stimulated IL-2 mRNA by RT-PCR in mononuclear cells; analyses used t tests, Wilcoxon rank-sum, chi-square/Fisher exact, paired t tests, and multivariate repeated-measures models.

Limitations

  • The authors state that the trial’s main limitation was its small number of subjects and call for larger zinc trials in the elderly.
  • Evident from the text: the IL-2 mRNA substudy had only 6 subjects per group, and oxidative stress markers were measured at 6 months but not repeated at 12 months.
  • Evident from the text: participants came from one senior center and were described as healthier than nursing-home residents, which may limit generalizability; some baseline imbalances were noted (higher IL-10 in the zinc group; lower plasma zinc in the zinc substudy group despite randomization).

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1093/ajcn/85.3.837

Cites

45 of 45 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

0 of 67 cited sources checked · 0 supported · 0 flagged

Show all 84 claims

  • Probably not a substantial claim. 22
  • It may state two separate claims as one. 11
30 of 30
  • The paper relies on this without support.

    Before this study, zinc had not been reported for managing oxidative stress in elderly people.

    “The use of zinc in the management of oxidative stress in the elderly has not, however, been reported.”
  • The paper relies on this without support.

    The elderly participants in the study are representative of the general elderly population.

    “Our study showed that zinc supplementation administered to the elderly population resulted in a significant decrease in the incidence of infection.”
  • The paper relies on this without support.

    Ex vivo IL-2 mRNA expression in mononuclear cells reflects in vivo IL-2 production.

    “We conclude that zinc is involved in increasing IL-2 production in zinc-deficient elderly subjects by increasing the gene expression of IL-2.”
  • The paper relies on this without support.

    Inflammatory cytokines generate oxidative stress.

    “These inflammatory cytokines, in turn, are known to generate oxidative stress.”
  • The paper relies on this without support.

    The plasma zinc criteria used by the authors validly classify elderly subjects as zinc-deficient.

    “According to our plasma zinc criteria, Ȃ35% of the elderly subjects in the current study were considered zinc-deficient.”
5 of 5

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Baseline zinc comparison is called both significant and nonsignificant

    Major

    The results say baseline plasma zinc did not differ significantly between the separate study's groups, whereas the Table 7 note calls the difference significant at P = 0.016.

  • White participant counts differ between groups

    Minor

    The text says the two groups had equal numbers of white participants, but Table 1 lists 17 in the zinc group and 19 in the placebo group.

  • E-selectin sample exceeds the reported study cohort

    Minor

    Table 2 lists 69 older subjects for the E-selectin measurement, although the study reports complete data on only 49 participants. The text does not account for the additional subjects in that comparison.

  • IL-2 interaction has conflicting P values

    Minor

    The results give P = 0.0001 for the IL-2 mRNA group-by-time interaction, but Table 7 gives P = 0.001 for that interaction.

  • Baseline zinc values disagree for the separate cohort

    Minor

    For the six-person groups in the separate study, the narrative reports baseline plasma zinc means of 86.38 and 88, while Table 7 reports 84.0 and 86.8.

5 of 5

Citations

Cites

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Show all 48 references

3 of the 48 references couldn’t be matched to a known paper.

Research works printed but not linked: 2

  1. Castle, 1993, Lowering the temperature criterion improves detection of infections in nursing home residents, Aging Immunol Infect Dis, 4, 67
  2. Beck, 1997, Changes in cytokines production and T cell subpopulations in experimentally induced zinc deficient humans, Am J Physiol, E1002

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Metadata

Authors
Prasad, A. S., Beck, F. W., Bao, B., Fitzgerald, J. T., Snell, D. C., Steinberg, J. D., & Cardozo, L. J.
Affiliations
Wayne State University (US)
Corresponding author
Prasad, Ananda S
Venue
The American Journal of Clinical Nutrition
Publisher
Elsevier BV
Published
2007-03
Volume
85
Issue
3
Pages
837-844
ISSN
0002-9165 (ISSN-L)
OpenAlex
W1925247835
Cited by
516
References
48
Citations by year
2026: 14 · 2025: 12 · 2024: 30 · 2023: 24 · 2022: 42 · 2021: 58 · 2020: 50 · 2019: 24 · 2018: 24 · 2017: 28 · 2016: 14 · 2015: 22 · 2014: 31 · 2013: 25 · 2012: 25
FWCI
20.75
Type
journal article
Language
en
Open access
Locations
  • American Journal of Clinical Nutrition (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • National Institutes of Health
  • U.S. Public Health Service (5 R01 A150698-04)
Topics
  • Health Sciences › Nursing › Nutrition and Dietetics › Trace Elements in Health
  • Health Sciences › Medicine › Hematology › Iron Metabolism and Disorders
  • Health Sciences › Medicine › Physiology (medical) › Exercise and Physiological Responses
Keywords
zinc supplementation, zinc deficiency, older adults, infection incidence, cytokines, oxidative stress, TNF-α, IL-10, interleukin-2, T helper cells, plasma zinc, endothelial adhesion molecules, zinc gluconate, immune function
MeSH terms
Adolescent, Adult, Aged, Double-Blind Method, Female, Humans, Infections, Male, Middle Aged, Zinc, Incidence, Cytokines, Oxidative Stress, Th1 Cells, Th2 Cells, Dietary Supplements

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