Lactose Intolerance - Symptoms and causes

Understanding Lactose Intolerance: Causes, Symptoms, and Management

Lactose intolerance is a common digestive disorder in which the body is unable to fully digest lactose, a sugar found in milk and dairy products. According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)1, around 30-50 million Americans are lactose intolerant. Lactose intolerance can be classified into various types, including primary, secondary, developmental, and congenital lactase deficiency.

II. Causes of Lactose Intolerance

A. Lactase enzyme deficiency

Lactose intolerance is primarily caused by a deficiency in lactase, an enzyme produced by the small intestine that breaks down lactose into glucose and galactose, which can be absorbed by the body. Dr. Amy Foxx-Orenstein, a gastroenterologist, explains that low levels of lactase can lead to the inability to digest lactose properly, resulting in symptoms of lactose intolerance 2.

B. Primary lactase deficiency

This is the most common form of lactose intolerance, where lactase production declines gradually over time, usually starting after childhood. Dr. David Poppers, a gastroenterologist, suggests that this type of lactose intolerance is more common in people of African, Asian, and Hispanic descent 3.

C. Secondary lactase deficiency

Secondary lactase deficiency occurs when the small intestine's ability to produce lactase is reduced due to an injury, illness, or surgery. For example, intestinal infections, such as gastroenteritis, or conditions like celiac disease, can cause temporary lactase deficiency, which may improve once the underlying issue is resolved 4.

D. Developmental lactase deficiency

Some premature babies may have lactase deficiency, as their small intestine may not produce enough lactase immediately after birth. This type of lactose intolerance is typically temporary and improves as the baby's digestive system matures 5.

E. Congenital lactase deficiency

This rare genetic disorder is present from birth, where the small intestine produces little or no lactase. Babies with this condition cannot digest lactose in breast milk or formula and may require a special lactose-free formula 6.

III. Symptoms of Lactose Intolerance

A. Gastrointestinal symptoms

People with lactose intolerance typically experience gastrointestinal symptoms, such as bloating, gas, abdominal pain and cramps, diarrhoea, and nausea and vomiting. These symptoms usually occur within 30 minutes to 2 hours after consuming lactose-containing foods and beverages 7.

B. Non-gastrointestinal symptoms

In some cases, lactose intolerance may also cause non-gastrointestinal symptoms, such as headaches, fatigue, and joint pain 8. It is essential to consult with a healthcare professional to determine if these symptoms are related to lactose intolerance or another underlying condition.

IV. Diagnosis and Testing for Lactose Intolerance

A. Medical history and physical examination

A healthcare provider will usually begin the diagnosis of lactose intolerance by reviewing the patient's medical history, symptoms, and conducting a physical examination. According to Dr. Benjamin Lebwohl, a gastroenterologist, this information can help the healthcare provider determine if further allergy testing is necessary.

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B. Lactose intolerance tests

Several tests can help diagnose lactose intolerance, including the lactose tolerance test, hydrogen breath test, and stool acidity test. These tests measure the body's reaction to lactose consumption or the presence of undigested lactose in the body, providing a clear indication of lactose intolerance 10.

V. Management and Treatment of Lactose Intolerance

A. Dietary modifications

Managing lactose intolerance primarily involves dietary modifications to limit or avoid lactose-containing foods and beverages. A registered dietitian, Katherine Zeratsky, suggests that individuals with lactose intolerance can experiment with different amounts of lactose to determine their tolerance level 11.

B. Lactase supplements

Lactase supplements can help individuals with lactose intolerance digest lactose more effectively. These supplements, available in tablet or liquid form, can be taken before consuming lactose-containing foods to help reduce symptoms 12.

C. Calcium and vitamin D supplementation

Since dairy products are a significant source of calcium and vitamin D, individuals with lactose intolerance may require supplementation to ensure they receive adequate levels of these nutrients. It is essential to consult with a healthcare provider to determine the appropriate supplementation 13.

VI. Prevention Strategies for Lactose Intolerance

A. Gradual introduction of lactose-containing foods

Some people with lactose intolerance may be able to tolerate small amounts of lactose. Gradually introducing lactose-containing foods into the diet, starting with small portions, can help determine an individual's tolerance level and minimize symptoms 14.

IV. Factors Affecting Lactose Intolerance

A. Ethnicity and genetics

Ethnicity and genetics play a significant role in lactose intolerance. Certain populations are more prone to lactose intolerance due to genetic factors. For instance, people of African, Asian, and Hispanic descent have a higher prevalence of lactose intolerance compared to those of Northern European origin 16. This is because the lactase persistence trait, which allows for lactose digestion, is more common in populations with a history of dairying.

B. Age

Age is another factor that influences lactose intolerance. Lactase production tends to decline as individuals age, leading to an increased risk of lactose intolerance 17. The decline in lactase production is more pronounced in some populations, making lactose intolerance more common among older adults. Therefore, it is essential to be aware of the changing dietary needs as one ages.

C. Diet and lactose consumption

Diet and lactose consumption can also affect lactose intolerance. Consuming large amounts of lactose-containing foods may exacerbate symptoms, even in individuals with mild lactose intolerance. On the other hand, people who regularly consume lactose-containing products may experience a gradual increase in their tolerance levels 18. It is crucial to find a balance in lactose consumption that suits an individual's specific needs and tolerance levels.

D. Gut microbiome

The gut microbiome, comprising the trillions of microorganisms inhabiting the digestive system, can impact lactose intolerance. A diverse and balanced gut microbiome can help break down lactose and alleviate symptoms of lactose intolerance 19. Probiotics, which are beneficial bacteria, may also aid in lactose digestion and reduce the severity of symptoms in some individuals.

V. Diagnosis of Lactose Intolerance

A. Medical history and physical examination

A healthcare provider will usually begin the diagnosis of lactose intolerance by reviewing the patient's medical history, symptoms, and conducting a physical examination. This information can help the healthcare provider determine if further testing is necessary 20. The healthcare provider may also ask about the patient's family history, as lactose intolerance can have a genetic component.

B. Hydrogen breath test

The hydrogen breath test is a non-invasive method for diagnosing lactose intolerance. The patient consumes a lactose-containing beverage, and the healthcare provider measures the hydrogen levels in the patient's breath at regular intervals 21. An increase in hydrogen levels indicates that lactose is not being adequately broken down and absorbed, suggesting lactose intolerance.

C. Lactose tolerance test

The lactose tolerance test involves measuring blood sugar levels before and after consuming a lactose-containing beverage. If blood sugar levels do not rise as expected, it may indicate that lactose is not being adequately digested and absorbed, suggesting lactose intolerance 22. This test may be less accurate than the hydrogen breath test, as other factors can influence blood sugar levels.

D. Stool acidity test

The stool acidity test is primarily used for infants and young children who cannot undergo other lactose intolerance tests. This test measures the acidity of a stool sample, as undigested lactose can lead to increased acidity in the stool 23. A higher level of stool acidity may indicate lactose intolerance.

E. Intestinal biopsy

An intestinal biopsy is a more invasive diagnostic procedure, typically reserved for cases where other tests have not provided a definitive diagnosis. The biopsy involves the removal of a small tissue sample from the small intestine to measure lactase levels directly 24. Low lactase levels in the intestinal tissue can confirm lactose intolerance.

VI. Differential Diagnosis

A. Milk allergy

A milk allergy is an immune system reaction to one or more proteins found in milk, which can cause symptoms similar to lactose intolerance 25. However, milk allergy symptoms may also include hwheezing, and difficulty breathing. It is essential to differentiate between lactose intolerance and a milk allergy, as the latter can lead to more severe reactions and requires different management strategies.

B. Irritable bowel syndrome (IBS)

Irritable bowel syndrome (IBS) is a common disorder that affects the large intestine and can cause symptoms similar to those of lactose intolerance, such as abdominal pain, bloating, and diarrhoea [26](https://www.mayoclinic.org/diseases-conditions/irritable-bowel-syndrome/symptoms-causes/syc-20360016). It is important to distinguish between IBS and lactose intolerance, as the management and treatment of these conditions may differ.

C. Inflammatory bowel disease (IBD)

Inflammatory bowel disease (IBD) refers to a group of chronic inflammatory conditions, such as Crohn's disease and ulcerative colitis, that can cause symptoms similar to lactose intolerance [27](https://www.crohnscolitisfoundation.org/what-is-ibd). Accurate diagnosis of IBD is essential, as it typically requires long-term management and medical treatment.

D. Celiac disease

Celiac disease is an autoimmune disorder in which the ingestion of gluten, a protein found in wheat, barley, and rye, leads to damage in the small intestine. This damage can cause symptoms similar to lactose intolerance, such as abdominal pain, bloating, and diarrhoea [28 ](https://www.niddk.nih.gov/health-information/digestive-diseases/celiac-disease). Differentiating between celiac disease and lactose intolerance is critical, as untreated celiac disease can lead to serious health complications, and the treatment involves adherence to a strict gluten-free diet.

VII. Management and Treatment of Lactose Intolerance

A. Dietary modifications

1. Lactose-reduced and lactose-free products

Individuals with lactose intolerance can consume lactose-reduced or lactose-free products as alternatives to regular dairy products. These options can help to manage symptoms while still allowing for the intake of essential nutrients found in dairy products.

2. Dairy alternatives

There are various non-dairy alternatives available, such as almond milk, soy milk, rice milk, and coconut milk. These can be used as substitutes for cow's milk in recipes and beverages, allowing individuals to avoid lactose while maintaining a balanced diet.

3. Consuming small amounts of lactose

Some people with lactose intolerance may be able to tolerate small amounts of lactose in their diet without experiencing symptoms. It is essential to monitor symptoms and adjust lactose intake accordingly to determine the individual's lactose tolerance level.

B. Lactase supplements

Lactase supplements can be taken before consuming lactose-containing foods to help with the digestion of lactose. These supplements are available over-the-counter in various forms, such as tablets or drops, and can be a helpful tool for managing lactose intolerance symptoms.

C. Probiotics and prebiotics

Probiotics are beneficial bacteria that can help improve gut health and potentially alleviate symptoms of lactose intolerance. Prebiotics are non-digestible carbohydrates that help support the growth of these beneficial bacteria. Including probiotics and prebiotics in the diet may improve lactose digestion and reduce symptoms in some individuals.

D. Calcium and vitamin D supplementation

Since dairy products are a primary source of calcium and vitamin D, individuals with lactose intolerance may need to find alternative sources of these nutrients or consider supplementation to maintain adequate intake.

E. Addressing underlying causes of secondary lactase deficiency

In cases where lactose intolerance is caused by an underlying condition, such as celiac disease or inflammatory bowel disease, it is essential to address the root cause. Treating the primary condition may help to improve lactase production and reduce lactose intolerance symptoms. Consultation with a healthcare professional is crucial in determining the appropriate treatment for the underlying condition.

VIII. Eating Out and Socialising with Lactose Intolerance

A. Communicating dietary restrictions to food providers

When eating out or attending social events, it is essential for individuals with lactose intolerance to communicate their dietary restrictions to food providers. This ensures that lactose-containing ingredients can be avoided or substituted, reducing the risk of symptoms.

B. Researching restaurant menus

Before dining out, research the menu of the chosen restaurant to identify lactose-free or lactose-reduced options. Many restaurants now offer allergy-friendly dishes or provide information on the ingredients used in their meals.

C. Preparing for unexpected situations

Carry lactase supplements and snacks that are safe for consumption in case lactose-free options are not available. This preparation can help to prevent symptoms and ensure that individuals can enjoy social events without worrying about their dietary restrictions.

D. Creating a supportive environment

Educate family, friends, and coworkers about lactose intolerance, its causes, and its symptoms. This understanding will help to create a supportive environment that makes managing lactose intolerance easier and less stressful.

E. Seeking support from others with lactose intolerance

Connecting with others who have lactose intolerance can provide emotional support, practical advice, and a sense of community. Online forums, support groups, and social media platforms can be excellent resources for finding others who share similar experiences.

IX. Monitoring and Adjusting Lactose Intolerance Management

A. Regular check-ups with healthcare professionals

Scheduling regular check-ups with healthcare professionals can help to monitor the effectiveness of lactose intolerance management strategies and ensure that any changes in symptoms are addressed promptly.

B. Keeping a food diary

Recording daily food intake, along with any symptoms experienced, can help to identify patterns and potential triggers. This information can be used to adjust the diet accordingly and improve symptom management.

C. Staying informed about lactose intolerance research and developments

New research, treatments, and dietary options for lactose intolerance are continually being developed. Staying informed about these advancements can help individuals to manage their lactose intolerance more effectively.

D. Adapting management strategies as needed

Lactose intolerance symptoms and severity can change over time. It is essential to be prepared to adapt management strategies as needed to maintain optimal symptom control and overall well-being.

E. Prioritising self-care and mental health

Managing lactose intolerance can be challenging and may impact mental health. Prioritising self-care and seeking support when needed can help to ensure that individuals with lactose intolerance maintain a positive outlook and overall well-being.

X. Prevention Strategies for Lactose Intolerance

A. Early introduction of lactose-containing foods

Some research suggests that introducing lactose-containing foods to infants at an early age may help to reduce the risk of lactose intolerance later in life. However, this approach should be discussed with a healthcare professional before implementation.

B. Supporting gut health

Maintaining a healthy gut microbiome by consuming a balanced diet, staying hydrated, and including probiotics and prebiotics can help to support lactase production and potentially reduce the risk of lactose intolerance.

C. Genetic testing

For individuals with a family history of lactose intolerance, genetic testing may be available to identify the likelihood of developing the condition. This information can be helpful for making informed decisions about dietary choices and management strategies.

 

VIII. Conclusion

Lactose intolerance is a common digestive disorder that affects a significant portion of the global population. Understanding the causes, symptoms, and appropriate management strategies can help individuals with lactose intolerance maintain a healthy and balanced diet. Collaboration between healthcare professionals, patients, and caregivers is essential in ensuring successful management of lactose intolerance and improving the quality of life for those affected by the condition.

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