High-Throughput Quantitation of Proline Betaine in Foods and Suitability as a Valid Biomarker for Citrus Consumption.
Proline betaine has been proposed as a candidate dietary biomarker for citrus intake. To validate its suitability as a dietary biomarker and to gain insight into the range of this per-methylated amino acid in foods and beverages, a quick and accurate stable isotope dilution assay was developed for quantitative high-throughput HILIC-MS/MS screening of proline betaine in foods and urine after solvent-mediated matrix precipitation. Quantitative analysis of a variety of foods confirmed substantial amounts of proline betaine in citrus juices (140-1100 mg/L) and revealed high abundance in tubers of the vegetable Stachys affinis, also known as Chinese artichocke (∼700 mg/kg). Seafood including clams, shrimp, and lobster contained limited amounts (1-95 mg/kg), whereas only traces were detected in fish, cuttlefish, fresh meat, dairy products, fresh vegetable (<3 mg/kg), coffee, tea, beer, and wine (<7 mg/L). The human excretion profiles of proline betaine in urine were comparable when common portions of orange juice or fried Stachys tubers were consumed. Neither mussels nor beer provided enough proline betaine to detect significant differences between morning urine samples collected before and after consumption. As Stachys is a rather rare vegetable and not part of peoples' daily diet, the data reported here will help to monitor the subject's compliance in future nutritional human studies on citrus products or the exclusion of citrus products in the wash-out phase of an intervention study. Moreover, proline betaine measurement can contribute to the establishment of a toolbox of valid dietary biomarkers reflecting wider aspects of diet to assess metabolic profiles as measures of dietary exposure and indicators of dietary patterns, dietary changes, or effectiveness of dietary interventions.
Chair for Food Chemistry and Molecular Sensory Science, Technische Universität München , Lise-Meitner-Straße 34, D-85354 Freising, Germany.
Roman
R
Lang
Chair for Food Chemistry and Molecular Sensory Science, Technische Universität München , Lise-Meitner-Straße 34, D-85354 Freising, Germany.
Tatjana
T
Lang
Chair for Food Chemistry and Molecular Sensory Science, Technische Universität München , Lise-Meitner-Straße 34, D-85354 Freising, Germany.
Matthias
M
Bader
Chair for Food Chemistry and Molecular Sensory Science, Technische Universität München , Lise-Meitner-Straße 34, D-85354 Freising, Germany.
Anja
A
Beusch
Chair for Food Chemistry and Molecular Sensory Science, Technische Universität München , Lise-Meitner-Straße 34, D-85354 Freising, Germany.
Verena
V
Schlagbauer
Chair for Food Chemistry and Molecular Sensory Science, Technische Universität München , Lise-Meitner-Straße 34, D-85354 Freising, Germany.|Bavarian Center for Biomolecular Mass Spectrometry , Gregor-Mendel-Straße 4, D-85354 Freising, Germany.
Thomas
http://orcid.org/0000-0003-4057-7165
T
Hofmann
D000328:Adult; D001622:Betaine / Q000378:metabolism / Q000652:urine*; D001628:Beverages / Q000032:analysis*; D015415:Biomarkers / Q000378:metabolism / Q000652:urine; D002957:Citrus / Q000378:metabolism*; D005260:Female; D005638:Fruit / Q000378:metabolism*; D057166:High-Throughput Screening Assays; D006801:Humans; D008297:Male; D011392:Proline / Q000378:metabolism / Q000652:urine*; D053719:Tandem Mass Spectrometry; D055815:Young Adult
D015415:Biomarkers; D001622:Betaine; D011392:Proline
citrus; dietary biomarker; proline betaine; stable isotope dilution analysis