Prune Consumption Attenuates Proinflammatory Cytokine Secretion and Alters Monocyte Activation in Postmenopausal Women: Secondary Outcome Analysis of a 12-Mo Randomized Controlled Trial: The Prune Study

J Nutr. 2024 May;154(5):1699-1710. doi: 10.1016/j.tjnut.2023.11.014. Epub 2023 Nov 19.

Abstract

Background: Proinflammatory cytokines are implicated in the pathophysiology of postmenopausal bone loss. Clinical studies demonstrate that prunes prevent bone mineral density loss; however, the mechanism underlying this effect is unknown.

Objective: We investigated the effect of prune supplementation on immune, inflammatory, and oxidative stress markers.

Methods: A secondary analysis was conducted in the Prune Study, a single-center, parallel-arm, 12-mo randomized controlled trial of postmenopausal women (55-75 y old; n = 235 recruited; n = 183 completed) who were assigned to 1 of 3 groups: "no-prune" control, 50 g prune/d and 100 g prune/d groups. At baseline and after 12 mo of intervention, blood samples were collected to measure serum high-sensitivity C-reactive protein (hs-CRP), serum total antioxidant capacity (TAC), plasma 8-isoprostane, proinflammatory cytokines [interleukin (IL)-1β, IL-6, IL-8, monocyte chemoattractant protein-1, and tumor necrosis factor (TNF)-α] concentrations in plasma and lipopolysaccharide (LPS)-stimulated peripheral blood mononuclear cells (PBMCs) culture supernatants, and the percentage and activation of circulating monocytes, as secondary outcomes.

Results: Prune supplementation did not alter hs-CRP, TAC, 8-isoprostane, and plasma cytokine concentrations. However, percent change from baseline in circulating activated monocytes was lower in the 100 g prune/d group compared with the control group (mean ± SD, -1.8% ± 4.0% in 100 g prune/d compared with 0.1% ± 2.9% in control; P < 0.01). Furthermore, in LPS-stimulated PBMC supernatants, the percent change from baseline in TNF-α secretion was lower in the 50 g prune/d group compared with the control group (-4.4% ± 43.0% in 50 g prune/d compared with 24.3% ± 70.7% in control; P < 0.01), and the percent change from baseline in IL-1β, IL-6, and IL-8 secretion was lower in the 100 g prune/d group compared with the control group (-8.9% ± 61.6%, -4.3% ± 75.3%, -14.3% ± 60.8% in 100 g prune/d compared with 46.9% ± 107.4%, 16.9% ± 70.6%, 39.8% ± 90.8% in control for IL-1β, IL-6, and IL-8, respectively; all P < 0.05).

Conclusions: Dietary supplementation with 50-100 g prunes for 12 mo reduced proinflammatory cytokine secretion from PBMCs and suppressed the circulating levels of activated monocytes in postmenopausal women. This trial was registered at clinicaltrials.gov as NCT02822378.

Keywords: dried plums; immunity; inflammatory cytokines; menopause; nutritional intervention; osteoporosis; oxidative stress; peripheral blood mononuclear cells; prunes; randomized controlled trial.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't
  • Research Support, N.I.H., Extramural

MeSH terms

  • Aged
  • Antioxidants / administration & dosage
  • Antioxidants / metabolism
  • Antioxidants / pharmacology
  • Biomarkers / blood
  • C-Reactive Protein / metabolism
  • Cytokines* / blood
  • Cytokines* / metabolism
  • Dietary Supplements
  • Dinoprost / analogs & derivatives
  • Dinoprost / blood
  • Dinoprost / metabolism
  • Female
  • Humans
  • Inflammation
  • Middle Aged
  • Monocytes* / drug effects
  • Monocytes* / metabolism
  • Oxidative Stress / drug effects
  • Postmenopause*

Associated data

  • ClinicalTrials.gov/NCT02822378