Lactose intolerance affects millions worldwide, occurring when the body cannot fully digest lactose – the natural sugar in milk and dairy products. Reliable genetic tests enable individuals to determine their predisposition to lactose intolerance, supporting accurate diagnosis.
Lactose intolerance is a chronic condition caused by a deficiency of the lactase enzyme, which is necessary for digesting lactose. In individuals with lactase persistence, the enzyme remains active into adulthood, allowing them to digest lactose without issues. However, those with lactase non-persistence experience fermentation of undigested lactose in the colon, leading to symptoms such as bloating, diarrhea, abdominal pain, and gas, with severe cases potentially causing nutrient malabsorption.
The LCT gene regulates lactase production, with 13910C/T and 22018G/A polymorphisms being associated with lactase persistence. This trait is more prevalent in populations of European descent, whereas lactase non-persistence is more common among Asian, African, and Native American populations. Diagnosing lactose intolerance can be challenging, as traditional methods like blood glucose tests, serological tests, and hydrogen breath tests may yield false negatives due to variations in symptom presentation and diagnostic accuracy. Genetic testing can estimate the risk of having lactose intolerance based on the detected combination of alleles.
Causes and Types
Primary Lactose Intolerance
This most common type is caused by a gradual decrease in lactase production after childhood.
Secondary Lactose Intolerance
Develops when intestinal diseases or infections damage the lining of the small intestine, reducing lactase activity.
Congenital Lactase Deficiency
A rare genetic disorder where babies are born without the ability to produce lactase.
Developmental Lactose Intolerance
Seen temporarily in premature infants due to immature digestive systems.
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 & Daily Management
Typical symptoms include bloating, gas, cramps, diarrhea, and nausea — varying by lactose amount and individual tolerance. Management strategies may include:
- Choosing lactose-free products,
- Taking lactase enzyme supplements,
- Consuming yogurt or hard cheeses,
- Trying non-dairy alternatives.
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:
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- 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.
Diagnostics & Molecular Testing
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 for in vitro diagnostics that detects and characterizes the 13910C/T and 22018G/A alleles in the LCT (Lactase) gene from human whole blood and buccal swab samples. Fluorescence detection is performed using FAM, HEX, Texas RED, and Cy5 filters.
Certain variants in the LCT (Lactase) gene are associated with lactose intolerance, affecting the ability to digest lactose in adulthood. The 13910C/T and 22018G/A polymorphisms in the regulatory region of the LCT gene are key markers for lactase persistence or deficiency.
Bosphore Lactose Intolerance Screening Kit v1 detects the following alleles:
- 13910C/T polymorphism: Located upstream of the LCT gene, associated with lactase persistence (T allele) or lactase non-persistence (C allele).
- 22018G/A polymorphism: Another regulatory variant linked to lactase expression levels. Located upstream of the LCT gene, associated with lactase persistence (A allele) or lactase non-persistence (G allele).
Bosphore Lactose Intolerance Screening Kit v1 is a genetic diagnostic test that identifies key polymorphisms associated with lactose intolerance. However, lactose intolerance can also be influenced by epigenetic modifications and environmental factors, such as gut microbiota, diet, and intestinal health.
