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Updated: Jun 18, 2026
04:41
Measuring Lactase Enzymatic Activity in the Teaching Lab
Published on: August 6, 2018
The molecular basis of lactose intolerance
Anthony K Campbell1, Jonathan P Waud, Stephanie B Matthews
1Department of Medical Biochemistry and Immunology, Wales College of Medicine, Cardiff University, Cardiff, CF14 XN, UK. campbellak@cf.ac.uk
Science Progress
|December 8, 2009
Summary
Millions suffer from lactose intolerance due to an inability to digest lactose, the sugar in milk. This common condition, linked to lactase enzyme deficiency, causes various symptoms and may be connected to other diseases.
Area of Science:
- Human Physiology
- Biochemistry
- Genetics
Background:
- Lactose intolerance affects approximately 4000 million people globally.
- Most mammals lose lactase enzyme activity after weaning, leading to lactose maldigestion.
- Symptoms vary significantly across ethnic groups and individuals.
Purpose of the Study:
- To explore the molecular basis of inherited hypolactasia.
- To understand the role of bacterial toxins in lactose intolerance symptoms.
- To investigate the evolutionary significance of lactose and lactase.
Main Methods:
- Analysis of genetic polymorphisms near the lactase gene.
- Investigation of bacterial fermentation products in the large intestine.
- Review of evolutionary history related to milk consumption.
Main Results:
- Two polymorphisms in introns of an upstream helicase gene correlate with hypolactasia.
- Gases and toxins from anaerobic bacteria in the large intestine cause symptoms.
- The evolution of lactose and lactase provided a selective advantage.
Conclusions:
- The genetic basis for inherited hypolactasia is linked to specific gene polymorphisms.
- Bacterial activity in the gut is the primary cause of lactose intolerance symptoms.
- Lactose digestion evolved as a significant factor in human evolution.
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