Contents
Title Page
List of original publications
General abbreviations
Abstract
1.
Introduction
2.
Review of literature
2.1.
The lactase enzyme and its regulation
2.1.1.
Endogenous regulation
2.1.2.
Exogenous regulation
Milk and lactose
Other dietary components
Stress factors
Drugs
2.2.
Metabolism of lactose in the human body
2.3.
Motility and lactose-induced gastrointestinal symptoms
2.3.1.
Neural and hormonal control of gastrointestinal motility
Visceral hypersensitivity
2.3.2.
Exogenous factors modifying intestinal motility and the digestion of lactose
Dietary components and nutrient content of the diet
Intestinal inflammation
Emotional factors
Drugs
2.4.
Diagnosis of lactose maldigestion and related gastrointestinal symptoms
2.5.
Current methods of reducing lactose-related gastrointestinal symptoms
3.
Aims of the study
4.
Subjects, study designs, materials and methods
4.1.
Human studies (Studies I - IV)
4.1.1.
Subjects and study designs
4.1.2.
Dietary instructions and study diets
4.1.3.
Methods used for diagnosing hypolactasia and lactose intolerance
The Golden Standard diagnosis for hypolactasia and lactose intolerance (I-IV)
Breath hydrogen measurement (I - III)
Blood glucose and urine galactose measurements (I - IV)
Symptom questionnaires (I-IV)
4.1.4.
Gastrointestinal transit time (II)
4.1.5.
Urine and plasma samples for inflammatory markers (IV)
4.2.
Animal experiments (V)
4.2.1.
Experimental animals and study design
4.2.2.
Intestinal samples
4.2.3.
Biochemical determinations
Lactase activity
Lactase expression by immunohistochemical methods
4.3.
Ethics
4.4.
Statistical analyses
5.
Results
5.1.
Comparison of diagnostic methods for detecting lactose maldigesters
5.2.
Modification of gastric emptying and the temperature of the test solution
5.3.
Measurement of inflammatory markers following the ingestion of lactose
5.4.
Induction of lactase with lactose
6.
Discussion
6.1.
Evaluation of study designs and methods
6.1.1.
Human studies
6.1.2.
Experimental studies
6.2.
Possible tools for reducing lactose-induced gastrointestinal symptoms
6.2.1.
The hypothesis of role of gastric emptying and intestinal motility
6.2.2.
The hypothesis of inflammation
6.2.3.
The hypothesis of induction of lactase by lactose
6.3.
How should lactose intolerance be diagnosed?
7.
Conclusions
8.
Acknowledgements
9.
References