Lactose intolerance occurs when the body cannot fully digest lactose, the natural sugar found in milk and dairy products. Normally, the enzyme lactase, produced in the small intestine, breaks down lactose into glucose and galactose so it can be absorbed. When lactase levels are low, undigested lactose passes into the colon, where it is fermented by bacteria. This process produces gas and other by-products, leading to digestive symptoms.
Importantly, lactose intolerance is not the same as a milk allergy. While allergies involve the immune system, lactose intolerance results from reduced enzymatic activity.
Causes and Types
There are several forms of lactose intolerance:
Genetic factors play a central role in the persistence or decline of lactase. Variants in the LCT gene regulate whether lactase production continues into adulthood or diminishes after infancy.
How Common Is It?
Globally, it is estimated that 65–70% of adults have some degree of lactose intolerance. Prevalence differs widely across regions:
- Low intolerance: Northern European populations, where lactase persistence (the continued activity of the enzyme into adulthood) is common.
- High intolerance: East Asian, West African, Native American, and many Middle Eastern populations, lactose intolerance is high with rates often above 70–90%.
This geographic distribution reflects evolutionary adaptation to dairy consumption in different cultures.
Symptoms
When lactose is not digested properly, common symptoms occur within a few hours of consuming dairy products:
- Bloating
- Gas and abdominal cramps
- Diarrhea
- Nausea
Severity varies depending on the amount of lactose consumed and individual tolerance.
Managing Lactose Intolerance in Daily Life
Although there is no cure, lactose intolerance can be managed through dietary and lifestyle adjustments:
- Choosing lactose-free dairy products
- Using lactase enzyme supplements
- Consuming fermented dairy like yogurt and hard cheeses, which contain less lactose
- Spreading lactose intake throughout the day in small amounts
- Exploring non-dairy alternatives such as soy, almond, or oat milk
These measures allow most individuals to maintain a balanced diet without severe discomfort.
Diagnostic Methods
Diagnosing lactose intolerance involves both clinical evaluation and laboratory tests:
- Hydrogen breath test: Measures hydrogen levels in the breath after consuming lactose.
- Lactose tolerance test: Monitors blood sugar levels following lactose intake.
- Stool acidity test: Common in children, checks for lactic acid in stool.
- Genetic testing: Identifies variants in the LCT gene associated with lactase persistence or non-persistence.
The Role of Real-Time PCR in Diagnosis
While traditional tests focus on symptoms and metabolic changes, genetic analysis offers a direct and reliable approach to identifying predisposition to lactose intolerance.
Bosphore Lactose Intolerance Screening Kit v1 is a Real-Time PCR kit developed for in vitro diagnostic use. It detects and characterizes two key polymorphisms in the LCT gene: 13910C/T and 22018G/A. These allelic variants are strongly associated with lactase persistence or deficiency. The kit works with DNA extracted from whole blood or buccal swab samples and provides rapid, sensitive, and specific results through fluorescence detection.
By offering a precise genetic profile, the kit helps clinicians estimate the risk of lactose intolerance and interpret findings alongside patient symptoms.
