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Assessment of lactase activity in humans by measurement of galactitol and galactonate in serum and urine after milk intake.
Am J Clin Nutr. 2019 02 01; 109(2):470-477.AJ

Abstract

Background

Lactase is an enzyme that hydrolyzes lactose into glucose and galactose in the small intestine, where they are absorbed. Hypolactasia is a common condition, primarily caused by genetic programming, that leads to lactose maldigestion and, in certain cases, lactose intolerance. Galactitol and galactonate are 2 products of hepatic galactose metabolism that are candidate markers for the intake of lactose-containing foods.

Objectives

The primary objective of the study was to explore the changes in serum and urine metabolomes during postprandial dairy product tests through the association between lactase persistence genotype and the postprandial dynamics of lactose-derived metabolites.

Methods

We characterized the 6-h postprandial serum kinetics and urinary excretion of lactose, galactose, galactitol, and galactonate in 14 healthy men who had consumed a single dose of acidified milk (800 g) which contained 38.8 g lactose. Genotyping of LCT-13910 C/T (rs4988235) was performed to assess primary lactase persistence.

Results

There were 2 distinct postprandial responses, classified as high and low metabolite responses, observed for galactose, and its metabolites galactitol and galactonate, in serum and urine. In all but 1 subject, there was a concordance between the high metabolite responses and genetic lactase persistence and between the low metabolite responses and genetic lactase nonpersistence (accuracy 0.92), galactitol and galactonate being more discriminative than galactose.

Conclusions

Postprandial galactitol and galactonate after lactose overload appear to be good proxies for genetically determined lactase activity. The development of a noninvasive lactose digestion test based on the measurement of these metabolites in urine could be clinically useful. This trial was registered at clinicaltrials.gov as NCT02230345.

Authors+Show Affiliations

Lausanne University Hospital, Service of Endocrinology, Diabetes and Metabolism, Lausanne, Switzerland.Agroscope, Federal Department of Economic Affairs, Education and Research, Bern, Switzerland.Agroscope, Federal Department of Economic Affairs, Education and Research, Bern, Switzerland.Lausanne University Hospital, Service of Endocrinology, Diabetes and Metabolism, Lausanne, Switzerland.Lausanne University Hospital, Service of Endocrinology, Diabetes and Metabolism, Lausanne, Switzerland. Agroscope, Federal Department of Economic Affairs, Education and Research, Bern, Switzerland.Lausanne University Hospital, Service of Endocrinology, Diabetes and Metabolism, Lausanne, Switzerland.Agroscope, Federal Department of Economic Affairs, Education and Research, Bern, Switzerland.Agroscope, Federal Department of Economic Affairs, Education and Research, Bern, Switzerland.

Pub Type(s)

Journal Article
Validation Study

Language

eng

PubMed ID

30721917

Citation

Vionnet, Nathalie, et al. "Assessment of Lactase Activity in Humans By Measurement of Galactitol and Galactonate in Serum and Urine After Milk Intake." The American Journal of Clinical Nutrition, vol. 109, no. 2, 2019, pp. 470-477.
Vionnet N, Münger LH, Freiburghaus C, et al. Assessment of lactase activity in humans by measurement of galactitol and galactonate in serum and urine after milk intake. Am J Clin Nutr. 2019;109(2):470-477.
Vionnet, N., Münger, L. H., Freiburghaus, C., Burton, K. J., Pimentel, G., Pralong, F. P., Badertscher, R., & Vergères, G. (2019). Assessment of lactase activity in humans by measurement of galactitol and galactonate in serum and urine after milk intake. The American Journal of Clinical Nutrition, 109(2), 470-477. https://doi.org/10.1093/ajcn/nqy296
Vionnet N, et al. Assessment of Lactase Activity in Humans By Measurement of Galactitol and Galactonate in Serum and Urine After Milk Intake. Am J Clin Nutr. 2019 02 1;109(2):470-477. PubMed PMID: 30721917.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Assessment of lactase activity in humans by measurement of galactitol and galactonate in serum and urine after milk intake. AU - Vionnet,Nathalie, AU - Münger,Linda H, AU - Freiburghaus,Carola, AU - Burton,Kathryn J, AU - Pimentel,Grégory, AU - Pralong,François P, AU - Badertscher,René, AU - Vergères,Guy, PY - 2018/04/25/received PY - 2018/10/02/accepted PY - 2019/2/6/pubmed PY - 2019/10/23/medline PY - 2019/2/6/entrez SP - 470 EP - 477 JF - The American journal of clinical nutrition JO - Am J Clin Nutr VL - 109 IS - 2 N2 - Background: Lactase is an enzyme that hydrolyzes lactose into glucose and galactose in the small intestine, where they are absorbed. Hypolactasia is a common condition, primarily caused by genetic programming, that leads to lactose maldigestion and, in certain cases, lactose intolerance. Galactitol and galactonate are 2 products of hepatic galactose metabolism that are candidate markers for the intake of lactose-containing foods. Objectives: The primary objective of the study was to explore the changes in serum and urine metabolomes during postprandial dairy product tests through the association between lactase persistence genotype and the postprandial dynamics of lactose-derived metabolites. Methods: We characterized the 6-h postprandial serum kinetics and urinary excretion of lactose, galactose, galactitol, and galactonate in 14 healthy men who had consumed a single dose of acidified milk (800 g) which contained 38.8 g lactose. Genotyping of LCT-13910 C/T (rs4988235) was performed to assess primary lactase persistence. Results: There were 2 distinct postprandial responses, classified as high and low metabolite responses, observed for galactose, and its metabolites galactitol and galactonate, in serum and urine. In all but 1 subject, there was a concordance between the high metabolite responses and genetic lactase persistence and between the low metabolite responses and genetic lactase nonpersistence (accuracy 0.92), galactitol and galactonate being more discriminative than galactose. Conclusions: Postprandial galactitol and galactonate after lactose overload appear to be good proxies for genetically determined lactase activity. The development of a noninvasive lactose digestion test based on the measurement of these metabolites in urine could be clinically useful. This trial was registered at clinicaltrials.gov as NCT02230345. SN - 1938-3207 UR - https://www.unboundmedicine.com/medline/citation/30721917/Assessment_of_lactase_activity_in_humans_by_measurement_of_galactitol_and_galactonate_in_serum_and_urine_after_milk_intake_ L2 - https://academic.oup.com/ajcn/article-lookup/doi/10.1093/ajcn/nqy296 DB - PRIME DP - Unbound Medicine ER -