Beta-carotene-induced enhancement of natural killer cell activity in elderly men: an investigation of the role of cytokines

Am J Clin Nutr. 1998 Jul;68(1):164-70. doi: 10.1093/ajcn/68.1.164.


We showed previously that natural killer (NK) cell activity is significantly greater in elderly men supplemented with beta-carotene than in those taking placebo. In an attempt to determine the mechanism of beta-carotene's effect, we analyzed the production of NK cell-enhancing cytokines (interferon alpha, interferon gamma, and interleukin 12). Boston-area participants in the Physicians' Health Study (men aged 65-88 y; mean age, 73 y) who had been supplemented with beta-carotene (50 mg on alternate days) for an average of 12 y were enrolled in a randomized, placebo-controlled, double-blind study. Elderly subjects taking beta-carotene supplements had significantly greater plasma beta-carotene concentrations than those taking placebo. Beta-carotene-supplemented elderly men had significantly greater NK cell activity than did elderly men receiving placebo. Percentages of NK cells (CD16+CD56+) were not significantly different between the beta-carotene and placebo groups. Production of interleukin 12, interferon alpha, or concanavalin A-stimulated interferon gamma by cultured peripheral blood mononuclear cells was not significantly different between beta-carotene-supplemented elderly and those taking placebo. Our results indicate that beta-carotene-induced enhancement of NK cell activity is not mediated by changes in percentages of CD16+CD56+ NK cells nor through up-regulation of interleukin 12 or interferon alpha.

Publication types

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

MeSH terms

  • Aged
  • Aging / immunology*
  • Cytokines / biosynthesis*
  • Dietary Supplements*
  • Double-Blind Method
  • Humans
  • Interferon-alpha / biosynthesis
  • Interferon-gamma / biosynthesis
  • Interleukin-12 / biosynthesis
  • Killer Cells, Natural / immunology*
  • Male
  • Physicians
  • Placebos
  • beta Carotene / administration & dosage*


  • Cytokines
  • Interferon-alpha
  • Placebos
  • beta Carotene
  • Interleukin-12
  • Interferon-gamma