A 4-wk intervention with high intake of carotenoid-rich vegetables and fruit reduces plasma C-reactive protein in healthy, nonsmoking men

Am J Clin Nutr. 2005 Nov;82(5):1052-8. doi: 10.1093/ajcn/82.5.1052.


Background: Whether different intakes of vegetables and fruit modulate immunologic markers is currently not known.

Objective: We investigated the effects of low, medium, and high intakes of vegetables and fruit on markers of immune functions, including nonspecific markers of inflammation.

Design: In a randomized controlled trial, nonsmoking men consumed a diet that included < or = 2 servings/d of vegetables and fruit for 4 wk. The subjects were then randomly assigned to 1 of 3 groups to consume 2 servings/d, 5 servings/d, or 8 servings/d of carotenoid-rich vegetables and fruit for another 4-wk period. Plasma concentrations of vitamins C and E and carotenoids were measured. The assessment of immunologic and inflammatory markers included the number and activity of natural killer cells, secretion of cytokines, lymphocyte proliferation, and plasma C-reactive protein concentrations.

Results: The high intake (8 servings/d) of vegetables and fruit significantly increased total carotenoid concentrations in plasma compared with the low intake (2 servings/d; week 4 compared with week 8), whereas concentrations of vitamins C and E did not differ between week 4 and week 8. Immunologic markers were not significantly modulated. In contrast, C-reactive protein was significantly reduced at week 8 in the subjects who consumed 8 servings/d of vegetables and fruit compared with those who consumed 2 servings/d.

Conclusions: In healthy, well-nourished, nonsmoking men, 4 wk of low or high intakes of carotenoid-rich vegetables and fruit did not affect markers of immune function. However, a high intake of vegetables and fruit may reduce inflammatory processes, as indicated by the reduction of plasma C-reactive protein.

Publication types

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

MeSH terms

  • Adult
  • Antioxidants / administration & dosage*
  • Antioxidants / metabolism
  • Ascorbic Acid / blood
  • Biomarkers / analysis
  • Biomarkers / blood
  • C-Reactive Protein / analysis
  • C-Reactive Protein / metabolism*
  • Carotenoids / administration & dosage*
  • Carotenoids / blood
  • Cytokines / analysis
  • Cytokines / metabolism
  • Dose-Response Relationship, Drug
  • Fruit / chemistry*
  • Humans
  • Killer Cells, Natural / immunology
  • Lipids / blood
  • Lymphocytes / immunology
  • Male
  • Vegetables / chemistry*
  • Vitamin E / blood


  • Antioxidants
  • Biomarkers
  • Cytokines
  • Lipids
  • Vitamin E
  • Carotenoids
  • C-Reactive Protein
  • Ascorbic Acid