Lactose Intolerance – Symptoms, Diagnosis and Management
Lactose intolerance is distinct from milk allergy, an immune response to cow’s milk proteins. They may be distinguished in diagnosis by giving lactose-free milk, producing no symptoms in the case of lactose intolerance, but the same reaction as to normal milk in the presence of a milk allergy.
Lactose is a sugar found in dairy products. It is a disaccharide because it has 2 molecules of simple sugar – glucose and galactose. Lactose intolerance is a common condition affecting about 40-60% of the population to varying degrees. Lactose intolerance is due to lack of an enzyme Lactase which is present in the small intestine.
Lactase breaks lactose down to glucose and galactose. Glucose and galactose are then absorbed in the small intestines and assimilated by the body. Lactose cannot be digested by the small intestine. Lactose intolerance is not a life-threatening condition, but the symptoms are uncomfortable.
Lactose intolerance is distinct from milk allergy, an immune response to cow’s milk proteins. They may be distinguished in diagnosis by giving lactose-free milk, producing no symptoms in the case of lactose intolerance, but the same reaction as to normal milk in the presence of a milk allergy. A person can have both conditions.
- Abdominal pain
- Bloating, diarrhea
- Gas, flatulence
Symptoms typically start thirty minutes to two hours after eating or drinking milk-based food. Severity typically depends on the amount a person eats or drinks and the level of lactase deficiency. Lactose intolerance does not cause damage to the gastrointestinal tract.
- Primary – amount of lactase declines with age
- Secondary – due to infection (bacterial or parasitic), inflammation (eg. celiac disease), or trauma (post intestinal surgery)
- Developmental – seen in premature babies. It improves over time
- Congenital – this is a rare condition
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- Increasing age. Lactose intolerance usually appears in adulthood. The condition is uncommon in babies and young children.
- Ethnicity. Lactose intolerance is most common in people of African, Asian, Hispanic, and American Indian descent. Less common in people of temperate climes descent.
- Premature birth. Infants born prematurely might have reduced levels of lactase because the small intestine doesn’t develop lactase-producing cells until late in the third trimester.
- Diseases affecting the small intestine. Small intestine problems that can cause lactose intolerance include bacterial overgrowth, celiac disease and Crohn’s disease.
- Certain cancer treatments. Radiation therapy for stomach cancer or intestinal complications from chemotherapy, the risk of developing lactose intolerance increases.
Clinical diagnosis is made when symptoms are eliminated with cessation of dairy products. Following supporting tests are recommended for effective diagnosis.
- Hydrogen breath test. After consuming a liquid that contains high levels of lactose, the amount of hydrogen in patient’s breath is measured at regular intervals. High levels of hydrogen indicate patients are not fully digesting and absorbing lactose.
- Lactose tolerance test. Two hours after drinking a liquid that contains high levels of lactose, patients undergo blood tests to measure the amount of glucose in the bloodstream. If glucose level doesn’t rise, the body is not properly digesting and absorbing the lactose-filled drink.
- Stool acidity test. Stool is normally alkaline but with lactose intolerance and infections it becomes acidic.
- Evaluate the presence of undiagnosed coeliac disease, Crohn disease, or other enteropathies when secondary lactase deficiency is suspected, and infectious gastroenteritis has been ruled out.
In secondary lactose intolerance, treatment of underlying conditions restores the ability to digest lactose over time. For example, in patients with celiac disease, lactose intolerance improves with gluten free diet.
Management of primary lactose intolerance is based on 4 principles – dietary avoidance, substitution to maintain nutrient intake, regulation of calcium intake, and use of enzyme substitute.
Dairy milk is substituted with plant-based milk such as soy milk, rice milk, almond milk, coconut milk, hazelnut milk, oat milk, hemp milk, macadamia nut milk, and peanut milk which are inherently lactose-free.
Lactase enzyme (β-galactosidase) pills commonly known as Lactaid are commercially available over the counter in most countries. If patient anticipates high lactose diet pills can be taken prior to the meal.
Probiotics are living organisms present intestines that help maintain a healthy digestive system. Probiotics are also available as active or “live” cultures in some yogurts and as supplements in capsule form.