9-cis beta-carotene in human plasma and blood cells after ingestion of beta-carotene

Lipids. 1995 Jun;30(6):493-8. doi: 10.1007/BF02537022.


For 44 wk, thirty male volunteers were given daily either 60 mg of synthesized all-trans beta-carotene, a naturally-occurring beta-carotene derived from Dunaliella bardawil, or a placebo. Basal levels of 9-cis beta-carotene in plasma, platelets, and mononuclear cells were 10, 20, and 25% of those of the all-trans form, respectively. The plasma levels reached a maximum after two weeks of administration and plateaued thereafter in the subjects who took the beta-carotene preparations. The all-trans beta-carotene level in the subjects given the synthesized all-trans form was almost twice that for the Dunaliella preparation. The plasma 9-cis level was found to be higher in the all-trans beta-carotene group than in the Dunaliella group, despite no intake of the 9-cis form in the all-trans group and the higher intake of the 9-cis form in the Dunaliella group. This finding suggests that isomerization of the all-trans form to the 9-cis form may occur in the body either during or after absorption.

Publication types

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

MeSH terms

  • Adult
  • Blood Platelets / metabolism
  • Carotenoids / administration & dosage
  • Carotenoids / blood*
  • Carotenoids / pharmacokinetics*
  • Erythrocytes / metabolism
  • Eukaryota / chemistry*
  • Humans
  • Leukocytes, Mononuclear / metabolism
  • Male
  • Stereoisomerism
  • beta Carotene


  • beta Carotene
  • Carotenoids