Absorption, excretion, and distribution of dietary antioxidant betalains in LDLs: potential health effects of betalains in humans

Am J Clin Nutr. 2004 Oct;80(4):941-5. doi: 10.1093/ajcn/80.4.941.


Background: Betalains were recently identified as natural antioxidants. However, little is known about their bioavailability from dietary sources.

Objective: The objective was to evaluate the bioavailability of betalains from dietary sources.

Design: The plasma kinetics and urinary excretion of betalains were studied in healthy volunteers (n = 8) after a single ingestion of 500 g cactus pear fruit pulp, which provided 28 and 16 mg indicaxanthin and betanin, respectively. The incorporation of betalains in LDL and the resistance of the particles to ex vivo-induced oxidation was also researched.

Results: Betanin and indicaxanthin reached their maximum plasma concentrations 3 h after the fruit meal and declined according to first-order kinetics. The half-life of betanin (0.94 +/- 0.07 h) was shorter than that of indicaxanthin (2.36 +/- 0.17 h). Both compounds had disappeared from plasma by 12 h after intake. The urinary excretion of indicaxanthin and betanin over 12 h represented 76 +/- 3.0% and 3.7 +/- 0.2%, respectively, of the ingested compounds. LDL isolated 3 and 5 h after the fruit meal incorporated betalains at concentrations of 100.5 +/- 11 and 50 +/- 7.2 pmol/mg LDL protein, respectively. In addition, the particles appeared more resistant to ex vivo-induced oxidative injury than did the samples isolated before fruit ingestion (P < 0.05)-the higher the amount of betalains incorporated, the higher the resistance. The concentrations of vitamin E and beta-carotene in LDL did not change significantly after fruit ingestion.

Conclusion: Our results show that cactus pear fruit is a source of bioavailable betalains and suggest that indicaxanthin and betanin may be involved in the observed protection of LDL against ex vivo-induced oxidative modifications.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Antioxidants / analysis
  • Antioxidants / pharmacokinetics*
  • Area Under Curve
  • Betacyanins
  • Betalains
  • Betaxanthins
  • Biological Availability
  • Cactaceae / chemistry*
  • Chromatography, High Pressure Liquid
  • Female
  • Humans
  • Indoles / blood
  • Indoles / pharmacokinetics
  • Indoles / urine
  • Lipoproteins, LDL / chemistry*
  • Lipoproteins, LDL / metabolism
  • Male
  • Oxidation-Reduction
  • Pyridines / blood
  • Pyridines / pharmacokinetics
  • Pyridines / urine
  • Quaternary Ammonium Compounds / blood
  • Quaternary Ammonium Compounds / pharmacokinetics*
  • Quaternary Ammonium Compounds / urine
  • Vitamin E / analysis
  • beta Carotene / analysis


  • Antioxidants
  • Betacyanins
  • Betaxanthins
  • Indoles
  • Lipoproteins, LDL
  • Pyridines
  • Quaternary Ammonium Compounds
  • indicaxanthin
  • beta Carotene
  • Vitamin E
  • Betalains
  • betanin