Lactose Intolerance Test London – Genetic Lactase Deficiency Testing (UK)

What Is Lactose Intolerance?

Lactose intolerance is a common digestive condition caused by reduced activity of the lactase enzyme in the small intestine. Lactase breaks down lactose (milk sugar) into glucose and galactose so it can be absorbed.

Lactase activity is high during infancy, when milk is the primary source of nutrition, and naturally declines after weaning in most mammals.

Chemical structure of lactose breaking down into galactose and glucose
Chemical reaction diagram, illustrating the hydrolysis of lactose into galactose

Approximately 75% of the world’s population loses the ability to digest lactose in adulthood. Prevalence varies significantly by ethnicity:

– Less than 5% in north-western Europe
– Up to nearly 100% in some Asian populations

Symptoms usually begin 30 minutes to 2 hours after consuming lactose-containing foods such as milk, yoghurt, cream or soft cheese.

Symptoms of Lactose Intolerance

The severity of symptoms depends on:

– The amount of lactose consumed
– Individual lactase activity
– Gut microbiota and intestinal sensitivity

lactose digestion in the small intestine with lactase enzyme and lactose intolerance with bacterial fermentation in the large intestine

How lactase breaks down lactose into glucose and galactose, and how lactase deficiency leads to fermentation, gas production and symptoms of lactose intolerance.

Typical Symptoms

– Abdominal bloating
– Abdominal pain
– Diarrhoea
– Flatulence
– Stomach cramps
– Nausea
– Vomiting
– Steatorrhoea (excess fat in stool)
– Failure to thrive (in children)

Conditions With Similar Symptoms

It is important to distinguish lactose intolerance from other gastrointestinal conditions with overlapping symptoms, including:

– Coeliac disease
– Cows’ milk protein allergy (casein and whey)
– Crohn’s disease
– Irritable bowel syndrome (IBS)
– Ulcerative colitis

Correct diagnosis helps avoid unnecessary long-term dietary restrictions.

Genetic Lactose Intolerance Test

What This Test Detects

This genetic test detects the most common variants associated with lactase persistence (continued lactase enzyme activity in adulthood).

Absence of these variants supports a diagnosis of primary lactose intolerance (adult-type lactase deficiency).

Lactose Intolerance Test London, showing low lactase enzyme in the intestine, common symptoms like bloating and diarrhoea, genetic LCT testing, similar conditions, and treatment options including lactose-free diet and lactase supplements.

Genetic lactase deficiency testing in London – symptoms, LCT gene analysis, differential diagnosis and treatment options.

However, secondary lactose intolerance must also be considered. This can occur due to:

– Small bowel conditions
– Coeliac disease
– Inflammatory bowel disease
– Gastroenteritis
– Small intestinal damage

Genetic testing does not diagnose secondary causes.

Test Methodology

Genotyping is performed by melt curve analysis using the TIB MOLBIOL Lactose Intolerance LightMix® IVD kit.

The assay detects the following regulatory variants:

Primary Variant (Common in Europeans)

– –13910C>T (associated with close to 100% lactase persistence in Europeans)

Additional Variants (More Common in Non-European Populations)

– –13907C>G
– –13913T>C
– –13915T>G

HGVS Nomenclature

In HGVS nomenclature, these variants are referenced to the MCM6 gene (NM_005915.5) as:

– c.1917+326C>T (–13910C>T)
– c.1917+329C>G (–13907C>G)
– c.1917+323T>C (–13913T>C)
– c.1917+321T>G (–13915T>G)

Although clinically linked to lactase production, these variants are located within regulatory regions of the MCM6 gene controlling expression of the LCT gene.

Treatment of Lactose Intolerance

Management includes:

– Lactose-restricted diet
– Individualised tolerance assessment
– Use of lactase enzyme supplements (e.g. Lactase tablets)
– Nutritional review to prevent calcium and vitamin D deficiency

The degree of restriction depends on personal tolerance levels. Many individuals can tolerate small amounts of lactose.

Important Considerations About Intolerance Testing

Not all intolerance tests available online are scientifically validated.

Before choosing a test, consider:

Scientific Validity

Select evidence-based tests using validated molecular methods.

Laboratory Accreditation

Use laboratories adhering to recognised quality standards.

Professional Interpretation

Results should be interpreted alongside a detailed medical history by a healthcare professional.

Cost vs Clinical Value

Be cautious of inexpensive “test everything” panels that lack scientific evidence.

Genetic testing is one tool within the broader diagnostic process and should be used alongside clinical evaluation.

Why Choose Genetic Testing for Lactose Intolerance?

– One-time lifetime test
– Not affected by recent diet
– Differentiates primary from non-genetic causes
– Avoids unnecessary long-term dairy restriction
– Supports personalised dietary advice

Start Your Lactose Intolerance Test

– Begin the test
– Read the test instructions
– Read our allergy test FAQ

If you are unsure whether your symptoms are due to lactose intolerance, IBS or another gastrointestinal condition, we recommend booking a consultation for professional assessment.

Consider Allergy Test

If you think your symptoms may be caused by an immune reaction rather than lactose intolerance, you may wish to consider our cow’s milk allergy blood test, available here:

https://foodallergytest.co.uk/product/cows-milk-allergy-test