Introduction

Persons with lactose intolerance have genetic deficiency of the enzyme Lactase that breaks down the lactose in the food into smaller particles that are absorbable in small intestine. Lactose is natural sugar present in the milk and other dairy products.  sizable number of adults believe they are lactose intolerant but do not actually have impaired lactose digestion, and some persons with lactase deficiency can tolerate moderate amounts of ingested lactose. 

Pathophysiology

The lactase enzyme is present in the brush border villi of small intestine. This enzyme breakdown the lactose in glucose and galactose, only these small breakdown products are able to cross the cell membrane in the jejunum and get absorbed in jejunum. These unabsorbed sugars osmotically attract fluid into the bowel lumen. The lactose alone increases the water content three times.

Further, these unabsorbed lactose molecules are acted upon by the colon bacteria that cause fermentation. Fermentation produces gas and results in the cleavage of lactose into monosaccharides. These monosaccharides are also not absorbed in the gut thus further increasing the osmotic pressure and drawing more fluid into the bowel. And these answers can it causes diarrhea?

Prevalence

According to the data from World Population Review 65% of the people have some degree of lactose tolerance. The prevalence vary from region to region` and ethnic groups. Lactose intolerance is generally most common in Asian countries, especially in East Asian, where about 70-100% of people show lactose intolerance; it is least prevented in Northern and Central Europe, where only about 5% of the population has lactose intolerance.

Some people often ask Which are the countries that are 100% lactose intolerant or where is lactose intolerance prevalent? Ghana, Malawi, South Korea, and Yemen are the countries that are considered 100% lactose intolerant.

Causes

There are different causes of the lactose intolerance. And they are classified into different types depending on the cause of intolerance.

1.Primary lactose intolerance

Primary lactose intolerance is associated with natural decline in the enzyme levels which is age related and without any external factors. In infancy and early childhood, the levels of the enzyme are enough in the body to digest lactose but with the time the amount starts declining leading to lactose intolerance in many adults.

2. Secondary Lactose Intolerance

It is secondary to some disease or illness that affects the small intestine where lactase is produced. Most common diseases that affect the small intestine are Gastrointestinal diseases (e.g. Crohn’s disease, Celiac disease) Infections (e.g. gastroenteritis) and surgeries involving small intestine. Symptoms improve if we treat the underlying condition. This is the type of Lactose intolerance that develops later in the life and answers why lactose intolerance develops later in life and in adults.

3. Congenital Lactose Intolerance

There is a rare inherited condition in which there is mutation in the LCT gene. This genetic mutation causes complete absence of the lactase enzyme since birth. And these kids cannot tolerate Brest milk and formula milk containing lactose they require lifelong avoidance of lactose containing foods. And this is why lactose tolerance occurs in babies.

4. Developmental (Transient) Lactose Intolerance

This type of lactose tolerance is present infants that has underdeveloped digestive system due to premature birth or some pathologies. It usually improves as the baby grows, often resolving the intolerance. They usually develop symptoms after consuming milk.

When lactose intolerance develops in life? All these types of Lactose intolerance have different pattern of pathologies and different time of development in life. Congenital and developmental lactose intolerance develops at the time of birth while primary develops later in life whereas secondary type develops at any time in life.

Symptoms

There are different symptoms of lactose intolerance, and they have different amount of severity depending upon the amount of lactose intake and deficiency of Lactase in body. Here is how a person feels like to have lactose intolerance

Abdominal pain: Where is the pain of lactose intolerance? Lactose intolerance cause pain and abdominal cramps in the lower abdomen due to fermentation of lactose in the lower abdomen.

Bloating: Lactose fermenting in the colon produces gas in the abdomen that gives a feeling of fullness and swelling in the abdomen.

Diarrhea: Lactose intolerance, cause diarrhea due to the change the osmotic pressure in the colon.

Flatulence (Gas): Fermentation produces gas in colon that leads to excessive passing of gas.

Nausea and Vomiting: Disturbance in the stomach gives a sick feeling to the stomach which leads to vomiting.

Alot of people lactose intolerant people experience symptoms that are different from what have explained and ask different question like can lactose intolerance cause constipation? Can it cause headache? However, these symptoms have not been established as true symptoms of lactose intolerance and may have other causes that are related to lactose intolerance. Symptoms that are reported but have less scientific support are

• constipation
• headaches
• fatigue
• loss of concentration
• muscle and joint pain
• mouth ulcers
• problems urinating
• eczema

Effective ways to manage Lactose intolerance

The first step towards the effective management of lactose intolerance is the dietary management and sometimes vitamins are given to relief symptoms.

Dietary modifications in lactose intolerance:

Reduce lactose containing foods e.g. milk, soft cheese and ice cream. Use the alternatives available which provide similar nutritional benefits like Almond milk, Soya milk, or Oat milk into your diet.

2. Lactase Supplements

Lactase enzyme supplements can be taken before consuming dairy products to aid digestion. Expert consultation is required to determine the side effects in children and pregnant or breastfeeding women.

3. Acclimatization to lactose

By gradually introducing the lactose in small amounts in diet allows bacteria to adapt that helps bacteria to build tolerance towards it.

4. Nutritional Considerations

Dairy products are the primary source of some nutrients like calcium and vitamin D so the body become deficient of these nutrients so consider fortified foods or supplements to meet daily requirements.

5. Seek guidance

Seek guidance from dietician and health care providers to develop a balanced diet that meets nutritional needs avoiding the symptoms of the disease.

FAQs

How to diagnose lactose intolerance?

Mainly it is diagnosed with history pattern then by eliminating the lactose from diet for 2-3 weeks and observe symptoms. For the confirmation we perform the tests like Hydrogen breath tests, lactose tolerance test and stool acidity test.