The effect of beta-carotene supplementation on the immune function of blood monocytes from healthy male nonsmokers

J Lab Clin Med. 1997 Mar;129(3):309-17. doi: 10.1016/s0022-2143(97)90179-7.


Although there is strong epidemiologic evidence that diets rich in carotenoids such as beta-carotene are associated with a reduced incidence of cancer, the cellular mechanisms underlying this phenomenon remain unknown. This article describes the effect of dietary beta-carotene supplementation on both the expression of functionally associated surface molecules on human monocytes and on the secretion of the cytokine tumor necrosis factor-alpha (TNF-alpha) by monocytes, all of which are involved in the initiation and regulation of immune responses involved in tumor surveillance. A double-blind, placebo-controlled, crossover study was undertaken in which 25 healthy, adult male nonsmokers were randomly assigned to receive beta-carotene (15 mg daily) or placebo for 26 days, followed by the alternative treatment for a further 26 days. The expression of functionally related monocyte surface molecules was quantified by flow cytometry, and ex vivo secretion of TNF-alpha was quantified by an enzyme-linked immunosorbent assay, before and after each treatment period. After dietary supplementation there were significant increases in plasma levels of beta-carotene and in the percentages of monocytes expressing the major histocompatibility complex class II molecule HLA-DR and the adhesion molecules intercellular adhesion molecule-1 and leukocyte function-associated antigen-3. In addition, the ex vivo TNF-alpha secretion by blood monocytes was significantly increased after supplementation. These findings suggest that moderate increases in the dietary intake of beta-carotene can enhance cell-mediated immune responses within a relatively short period of time, providing a potential mechanism for the anticarcinogenic properties attributed to beta-carotene.

Publication types

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

MeSH terms

  • Adult
  • Antigen Presentation / immunology
  • Antigens, Surface / biosynthesis
  • Antigens, Surface / drug effects
  • Antigens, Surface / immunology
  • Antioxidants / metabolism
  • Biological Transport / drug effects
  • Cell Adhesion Molecules / biosynthesis
  • Cell Adhesion Molecules / drug effects
  • Cell Adhesion Molecules / immunology
  • Cross-Over Studies
  • Diet
  • Double-Blind Method
  • Fatty Acids / blood
  • Histocompatibility Antigens Class II / biosynthesis
  • Histocompatibility Antigens Class II / drug effects
  • Histocompatibility Antigens Class II / immunology
  • Humans
  • Male
  • Monocytes / chemistry
  • Monocytes / drug effects*
  • Placebos
  • Smoking
  • Tumor Necrosis Factor-alpha / metabolism
  • beta Carotene / blood
  • beta Carotene / immunology
  • beta Carotene / pharmacology*


  • Antigens, Surface
  • Antioxidants
  • Cell Adhesion Molecules
  • Fatty Acids
  • Histocompatibility Antigens Class II
  • Placebos
  • Tumor Necrosis Factor-alpha
  • beta Carotene