Simultaneous ingestion of dietary proteins reduces the bioavailability of galloylated catechins from green tea in humans

• Published in: European journal of nutrition 2013-02, Vol.52 (1), p.281-288
• Main Authors: Egert, Sarah, Tereszczuk, Jane, Wein, Silvia, Müller, Manfred James, Frank, Jan, Rimbach, Gerald, Wolffram, Siegfried
• Format: Article
• Language: English
• Subjects: Adult; Antioxidants - administration & dosage; Antioxidants - pharmacokinetics; bioavailability; Biological Availability; blood; Body Mass Index; casein; caseinates; Catechin - administration & dosage; Catechin - analogs & derivatives; Catechin - pharmacokinetics; Chemistry; Chemistry and Materials Science; Chromatography, High Pressure Liquid; Cross-Over Studies; Dietary Proteins - administration & dosage; electrochemistry; epicatechin; epigallocatechin gallate; Female; green tea; Humans; ingestion; Nutrition; Original Contribution; pharmacokinetics; skim milk; soy protein; Surveys and Questionnaires; Tea - chemistry; Young Adult
• ISSN: 1436-6207; 1436-6215
• DOI: 10.1007/s00394-012-0330-8

Purpose To investigate the influence of dietary proteins (casein, soy protein) and skimmed milk on the plasma kinetics of green tea (GT) catechins. Methods In a randomized cross-over design with one-week intervals, 24 healthy normal-weight women consumed a test drink containing 1.75 g GT extract with or without the addition of different proteins. Treatments were GT (control), GT with skimmed milk (GT + M), GT with caseinate (GT + CS), or GT with soy protein (GT + S). Venous blood samples were taken before and several times during a period of 4.5 h after consumption of the test drink. Plasma concentrations of catechins were analyzed by HPLC with electrochemical detection. Results Compared to control, consumption of GT with milk, caseinate, or soy protein significantly reduced the bioavailability (mean area under the plasma concentration–time curve) of total catechins (means ± SEM; GT + M, 87 ± 5%; GT + CS, 79 ± 5%; GT + S, 88 ± 4%), epigallocatechin gallate (GT + M, 68 ± 4%; GT + CS, 63 ± 5%; GT + S, 76 ± 5%), and epicatechin gallate (GT + M, 68 ± 5%; GT + CS, 66 ± 6%; GT + S, 77 ± 6%), while the bioavailability of non-galloylated catechins such as epigallocatechin (GT + M, 134 ± 9%; GT + CS, 118 ± 9 %; GT + S, 123 ± 8%) and epicatechin (GT + M, 125 ± 10%; GT + CS, 114 ± 11%; GT + S, 110 ± 8%) significantly increased. No significant differences in bioavailability of GT catechins were observed between the treatments GT + M, GT + CS, or GT + S. Conclusion Simultaneous ingestion of dietary proteins reduces the bioavailability of galloylated catechins from GT in humans.