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Measuring Lactase Enzymatic Activity in the Teaching Lab
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Lactase persistence versus lactose intolerance: Is there an intermediate phenotype?

Zbigniew Dzialanski1, Michael Barany2, Peter Engfeldt1

  • 1University Health Care Research Center, School of Health and Medical Sciences, Örebro University, SE 701 82 Örebro, Sweden.

Clinical Biochemistry
|November 26, 2015
PubMed
Summary

Individuals with CT and TT genotypes, previously considered lactase-persistent, show differing physiological responses to lactose. This suggests distinct phenotypes within the lactase-persistent group may exist.

Keywords:
13910 C/T alleleAbdominal painHydrogen breath testOral lactose load test

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Area of Science:

  • Genetics
  • Gastroenterology
  • Human Physiology

Background:

  • The prevailing theory categorizes individuals into lactase persistent (CT, TT genotypes) or non-persistent (CC genotype) phenotypes.
  • However, varying lactase activity levels observed in intestinal biopsies suggest a potential intermediate physiological phenotype.

Purpose of the Study:

  • To investigate potential differences in lactase activity biomarkers and physical symptoms between genotypes during an oral lactose load.
  • To assess disparities in physiological responses among individuals with CT and TT genotypes.

Main Methods:

  • A retrospective analysis of 487 individuals undergoing an oral lactose load test.
  • Measurements included exhaled hydrogen, blood glucose, genotyping from oral mucosa, and symptom questionnaires.
  • Data from 274 participants (56% participation rate) were analyzed.

Main Results:

  • Mean exhaled hydrogen levels at 120 minutes were significantly higher in the CT genotype compared to the TT genotype.
  • No significant differences in blood glucose levels were observed between the CT and TT groups.
  • Symptom prevalence, excluding abdominal pain, was similar between the CT and TT genotypes.

Conclusions:

  • Individuals with CT and TT genotypes, previously grouped as lactase-persistent, exhibit distinct physiological responses to lactose.
  • These genotypic differences indicate potentially significant variations in lactase phenotype with clinical implications.