Lactose intolerance

The symptoms of lactose intolerance usually begin 30 minutes to 2 hours after consuming lactose-containing products. The undigested lactose builds up in the intestine and causes:

• Abdominal pain
• Bloating
• Loose stools
• Flatulence
• Borborygmi (a rumbling or gurgling noise made by the movement of fluid and gas in the intestines)
• Fullness

Rarely, the individual may also experience:

• Nausea
• Vomiting
• Headache
• Constipation
• Muscle pain
• Joint pain

The malabsorption of lactose produces several toxic chemicals such as acetone, acetaldehyde, ethanol, and peptides. This can lead to the appearance of some extra-intestinal symptoms, which include:

• Memory deterioration
• Musculoskeletal pain
• Depression
• Anxiety
• Mouth ulcers
• Heart rhythm disorders
• Vertigo

Did you know? The amount of lactose usually required to produce symptoms of lactose intolerance is about 8 to 12 oz (236 to 354 ml). However, the amount may vary from person to person.

What is lactose?

Lactose is a type of sugar found in the milk of humans and mammals, except for sea lions and walruses. It is also present in products derived from milk, such as cheese and yogurt. Breast milk contains approximately 7.2 g of lactose per 100 ml, while cow’s milk contains about 5 g of lactose per 100 ml. During infancy, lactose provides a significant source of energy that supports overall growth and development.

Interesting fact: Lactose is the only sugar that does not increase the risk of dental caries.

How is lactose digested and absorbed in the body?

The enzyme lactase, present in the small intestine, plays a crucial role in the digestion of lactose. Lactose consists of two types of sugar molecules: glucose and galactose. In the small intestine, lactose is broken down into these two simple sugars. Glucose is then absorbed into the body and utilized as an energy source.

How does lactose intolerance occur?

The primary cause of lactose intolerance is the deficiency or inactivity of the lactase enzyme.

What happens if lactose is not digested?

• Accumulation of lactose in the large intestine.
• Bacteria present in the large intestine ferment lactose, producing gases including hydrogen (H₂), carbon dioxide (CO₂), methane (CH₄), and short-chain fatty acids (SCFA).
• These gases affect gastrointestinal function and manifest as the symptoms mentioned above.

What is the difference between lactose intolerance and cow’s milk allergy?

Cow’s milk allergy is an immune-mediated reaction, unlike lactose intolerance, which primarily results from a deficiency in the lactase enzyme. Symptoms of lactose intolerance typically appear around 5-6 years of age, in contrast to milk allergy, which peaks during the first year of life. Distinguishing symptoms of cow’s milk allergy include skin rashes and swelling of the lips, tongue, and palate, which are less likely to occur in lactose intolerance.

Lactose intolerance is a non-preventable condition. However, the following risk factors can initiate lactose intolerance or increase its severity:

• Age: The risk of lactose intolerance typically increases in adulthood.
• Race: Individuals of Asian, American, and Hispanic descent are more prone to lactose intolerance.
• Genes: Genetic factors may predetermine the production of lactase enzymes and the gut microbiome, predisposing some individuals to lactose intolerance. However, it is rare for someone to be born with a lactase deficiency.
• Premature birth: Premature infants have a higher risk of lactose intolerance due to the underdeveloped intestine's inability to digest lactose.
• Composition of gut microbiota: Certain bacteria in the intestine ferment lactose, producing gas that increases the likelihood of developing symptoms of lactose intolerance.
• Amount of lactose consumed: The severity of symptoms can increase with the amount of lactose consumed.
• Food accompanying dairy products: The risk of developing symptoms is elevated when lactose-containing foods are consumed alongside high-protein and fatty foods, such as meat and fish, which remain longer in the large intestine and trigger symptoms.
• Gastrointestinal diseases: Certain diseases can affect the brush border cells of the intestine, damaging lactase enzymes and potentially causing lactose intolerance. These diseases include:
  • Celiac disease
  • Small intestinal bacterial overgrowth (SIBO)
  • Gastroenteritis
  • IBS-D
  • Cystic fibrosis
  • Inflammatory bowel disease (IBD)
  • Enterocolitis
• Anxiety disorders: Anxiety and depression have been associated with an increased likelihood of developing lactose intolerance.
• Cancer treatment: The risk of lactose intolerance may increase following chemotherapy or radiation therapy for stomach or intestinal cancer.

The diagnosis of lactose intolerance requires assessing the medical, family, and dietary history of the patient. Understanding the clinical history helps reveal the association between the ingestion of lactose and the occurrence of symptoms.

Medical history is followed by a physical examination in which signs of abdominal pain, tenderness, and bloating are evaluated.

The commonly used tests for the diagnosis of lactose intolerance include:

• Lactose breath test (hydrogen breath test): This test is most commonly used for diagnosing lactose intolerance. It involves breathing into a balloon-type container every 30 minutes over a few hours to measure the amount of hydrogen in the breath. A high amount of hydrogen gas indicates the presence of undigested lactose, a marker of lactose intolerance. However, certain factors can affect the test result by altering the intestinal bacterial flora:
• Use of specific medications such as oral antibiotics, proton pump inhibitors, and aspirin
• Abuse of laxatives (stool softeners)
• Invasive procedures requiring bowel cleansing with enemas
• Use of probiotics before the test
• Consumption of certain foods such as beans, corn, white wheat, potatoes, and oats
• Lactose tolerance test: This test measures the amount of glucose at regular intervals after consuming 50 g of lactose-containing liquid. Readings are taken at 0, 60, and 120 minutes. A failure of blood glucose levels to rise by 20 mg/dl may indicate lactose intolerance. The test has good sensitivity, except in conditions such as diabetes and small intestinal bacterial overgrowth. However, it is useful in instances where there is an absence of bacteria that do not produce hydrogen and the hydrogen breath test cannot be utilized. Note: The measurement of breath hydrogen after ingestion of 25 to 50 g of lactose is more sensitive and specific than the lactose tolerance test.
• Milk tolerance test: Normally, lactose is digested and absorbed as glucose. Lactose intolerance is characterized by malabsorption of glucose. In this test, 500 ml of milk is given to the individual, followed by testing of blood sugar. A rise in blood sugar of less than 9 mg/dl indicates lactose intolerance.
• Stool acidity test: This test measures the pH of stool. Lactose intolerance is characterized by a decrease in the pH of the stool.
• Bowel biopsy: In this procedure, a small portion of the small intestine is removed for examination. Any damage to the cells of the small intestine that produce the lactase enzyme is checked. This test is invasive and hence rarely performed. It is also used to rule out secondary causes of lactose intolerance.

Lactose intolerance is predominantly a genetic condition with few modifiable factors. However, dietary modification plays a crucial role in avoiding symptoms associated with lactose intolerance. Studies suggest that adults can consume up to 12 g of lactose in a single dose with no or minimal symptoms. Therefore, it is advisable to check the lactose content in food servings before consumption. The following lists include food items to be limited and those that are allowed:

Foods to Limit

• All kinds of milk: whole, low fat, non-fat, cream, powdered, condensed, evaporated, goat, acidophilus, and chocolate
• Milk products such as butter, cottage cheese, ice cream, creamy/cheesy sauces, cream cheeses, soft cheeses (brie, ricotta), mozzarella, whipped cream, and frozen yogurt
• Milk and food items made from milk are not the only sources of lactose. Lactose is also added to several foods to incorporate sweetness and softness. Individuals with severe intolerance should be aware of these products. Such food items with 'Hidden Lactose' include:
• Milk bread
• Baked goods like muffins, biscuits, waffles, pancakes
• Processed breakfast cereals
• Mixes for cakes, pancakes, biscuits, and cookies
• Instant potatoes, soups, and breakfast drinks
• Margarine
• Salad dressings
• Candies and other snacks

Foods Allowed

• Lactose-free milk, soy milk
• Lactose-free dairy, hard cheeses (Parmigiano Reggiano, Pecorino, Grana Padano, fontina, taleggio, provolone, Swiss), gorgonzola
• Fruits and vegetables
• Legumes
• Cereals
• Meat, fish, and eggs

Learn more about healthy food substitutes for people with lactose intolerance.

The treatment approach for lactose intolerance should be aimed at providing symptomatic relief while improving the metabolism of lactose.

Objective of Treatment

• To provide symptomatic relief
• To increase the absorption of lactose
• To avoid nutritional deficiencies from a restricted diet
• To treat the underlying condition in individuals with secondary lactase deficiency

Treatment Approaches

• Minimizing lactose intake
• Using alternative nutrient substitutes
• Using enzymatic or lactase supplements
• Retaining adequate amounts of calcium and Vitamin D

Dietary Modification

The maximum tolerable dose of lactose is identified by avoiding lactose-containing dairy products for 2-4 weeks. This is followed by a gradual reintroduction of low-lactose dairy products. The dose is increased gradually to determine the amount that can be safely consumed without symptoms.

Foods to be limited and those that are allowed have been discussed in the prevention section.

Lactase Enzyme Supplements

Patients with mild lactose malabsorption may benefit from lactase enzyme supplements, which are taken whenever food containing lactose is consumed.

The main advantage of this treatment approach is that individuals can still consume dairy products, thus retaining the nutritional benefits of milk and avoiding the risk of osteoporosis and other bone-related disorders.

Probiotics

Probiotics contain lactase-producing bacteria that assist in the digestion of lactose.

A significant reduction in the symptoms of lactose intolerance is observed with probiotics.

Nutritional Supplements

Dairy foods are a rich source of calcium, proteins, magnesium, and several other minerals. While lactose-free diets help manage symptoms, they may also deprive individuals of the nutritional benefits of dairy products. Therefore, it is important to augment the diet with other rich sources or supplements.

A few home remedies help in reducing the severity of symptoms associated with lactose intolerance. These include:

• Cocoa powder: Research suggests that cocoa powder aids in the digestion of lactose by reducing the emptying time of the stomach, helping to ease symptoms such as abdominal pain, nausea, and vomiting.
• Apple cider vinegar: It aids in the digestion of lactose and helps to curb digestive problems associated with lactose intolerance due to its acid-neutralizing effect.
• Ginger (Adrak): A very useful home remedy to alleviate symptoms such as nausea and gas associated with lactose intolerance.
• Chamomile tea: Helps in reducing bloating by neutralizing stomach acid.
• Yogurt: Highly rich in beneficial bacteria, it aids in the digestion of dairy products.

Did you know? Fermented foods such as idli and dosa help in creating beneficial bacteria in the digestive system. The consistent intake of such foods aids in reducing the symptoms of lactose intolerance.

Dairy products, especially milk, are an excellent source of calcium and vitamins (A, B12, and D). Restricting these products can lead to several complications, including:

• Osteopenia (weakening of the bones)
• Osteoporosis (severe case of bone loss)
• Malnutrition
• Weight loss
• Rickets (condition that affects bone development in children)
• Growth failure or delay

Homeopathy

Homeopathy has shown promise in managing symptoms related to lactose intolerance. Some of the homeopathic medications include:

• Magnesia muriaticum
• Aethusa cynapium
• Apis mellifica
• China officinalis

The cases of lactose intolerance are on the rise. The following adjustments in daily life may prove to be beneficial:

• Restrict instead of avoid: Studies suggest that lactose-intolerant individuals can tolerate the following amounts of lactose:
  • Up to 12 g of lactose at once (about 250 ml of milk).
  • Up to 24 g of lactose spread out across the day (about 500 ml of milk).
  Most guidelines recommend the intake of tolerable amounts of lactose instead of completely eliminating it from the diet. This helps in maintaining optimum levels of calcium and Vitamin D. The following measures can be taken while consuming lactose-based products:
  • Add low-dose lactose-based foods such as cheeses and lactose-hydrolyzed milk products.
  • Incorporate fermented products into your diet, as they are a good source of probiotics, which exert beneficial effects on gastrointestinal microflora.
• Identify the tolerable dose: The tolerable dose of lactose varies for each individual. The following steps can be followed to identify the dose:
  • Go on a temporary lactose-free diet to achieve remission of symptoms.
  • Introduce foods that have low lactose content and gradually increase the dose to determine the tolerable level.
• Find the right alternatives: Some low-lactose foods, such as yogurt, can also cause symptoms in certain patients due to the varying amounts of lactose in different types of yogurt. Greek yogurt has the least amount of lactose and can usually be safely consumed. Plant-based alternatives are also available and can be consumed based on individual palatability and nutritional balance. Lactose-free vegan diets are increasingly popular, with several milk substitutes such as soy, almond, and rice milk being completely lactose-free.
• Eat in conjunction with other food: Lactose-intolerant individuals are advised to consume dairy products alongside other food items to reduce symptoms. This is because other food items can slow down the digestion process in the stomach.
• Split the dairy foods: Low-dose lactose-containing foods should be divided into meals rather than consumed all at once. This approach helps alleviate symptoms even after consuming lactose.
• Read the labels: Most individuals are aware of the milk and dairy products that contain lactose. However, lactose powder is also used in several packaged foods to enhance flavor. Therefore, it is crucial to read the labels of all packaged food items.
• Check on your vitamin and mineral intake: While dairy products are not essential, they are rich in calcium and other minerals. Calcium is vital for the proper growth and development of bones and teeth. Children, adolescents, pregnant women, and older adults require higher amounts of calcium. It is important to include other foods and drinks rich in calcium, such as spinach or calcium-enriched soy milk.
• Quality of life: Lactose intolerance can impact the quality of life and nutritional status of individuals due to restrictive diets. The fear that certain foods will trigger symptoms can lead to long-term anxiety. This anxiety may cause individuals to believe that most foods will induce symptoms, leading to avoidant/restrictive food intake disorder, which can result in weight loss. This can be mitigated by becoming aware of your maximum tolerable dose. In severe cases, seeking help from a professional is recommended.