Melatonin in walnuts: Influence on levels of melatonin and total antioxidant capacity of blood

Russel J. Reiter, L. C. Manchester, Dun Xian Tan

Research output: Contribution to journalArticle

245 Scopus citations

Abstract

Objective: We investigated whether melatonin is present in walnuts (Juglans regia L.) and, if so, tested whether eating walnuts influences melatonin levels and the total antioxidant status of the blood. Methods: Melatonin was extracted from walnuts and quantified by high-performance liquid chromatography. After feeding walnuts to rats, serum melatonin concentrations were measured using a radioimmunoassay and the "total antioxidant power" of the serum was estimated by using the trolox equivalent antioxidant capacity and ferric-reducing ability of serum methods. Results: Mean ± standard error melatonin concentrations were 3.5 ± 1.0 ng/g of walnut. After food restriction of rats and then feeding them regular chow or walnuts, blood melatonin concentrations in the animals that ate walnuts were increased over those in the rats fed the control diet. Increases in blood melatonin were also accompanied by increases in trolox equivalent antioxidant capacity and ferric-reducing ability of serum values. Conclusions: Melatonin is present in walnuts and, when eaten, increase blood melatonin concentrations. The increase in blood melatonin levels correlates with an increased antioxidative capacity of this fluid as reflected by augmentation of trolox equivalent antioxidant capacity and ferric-reducing ability of serum values.

Original languageEnglish (US)
Pages (from-to)920-924
Number of pages5
JournalNutrition
Volume21
Issue number9
DOIs
StatePublished - Sep 1 2005

Keywords

  • Antioxidant
  • Cardiovascular system
  • Ferric-reducing ability of serum
  • Melatonin
  • Trolox equivalent antioxidant capacity
  • Walnuts

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Nutrition and Dietetics

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