Lactose Intolerance: Causes, Symptoms and Treatment

Lactose Intolerance: Causes, Symptoms and Treatment

Lactose intolerance is a condition in which a human body is unable to digest lactose due to insufficient amount of lactase enzyme production.

If lactose containing food gets consumed by lactose intolerant patient, then it can cause some health issues like bloating, diarrhea & abdominal cramps etc.

Lactose is the main carb in dairy products & also found in breast milk.  It is made of glucose & galactose. The lactase enzyme is needed to breakdown the lactose into glucose and galactose for the absorption in bloodstream which is then used for energy.

Without lactase enzyme, lactose move through our gut undigested & causes digestive issues.


Types of Lactose Intolerance;

Primary Lactose intolerance:

A common cause of lactose intolerance and lactose mal-absorption, in which lactase production gets too much low with age, making hard for adults to digest lactose. It is also known as lactose non-persistence, adult-type hypolactasia & hereditary lactose intolerance. It develops in childhood at various ages in different racial groups.  This type of tolerance usually seen in large amounts in Asian, African and Hispanic Ancestory. The condition is also common among those people who belong to Mediterranean & South European descent.

Secondary lactose intolerance:

This type of lactose intolerance results from small bowel injury, such as acute gastro-enteritis, persistent diarrhea, small bowl over growth, cancer chemotherapy or other cause of injury in the mucosal layer of small intestine. It can present at any age but mostly common in infancy. The treatment includes restoring lactase levels & improves signs & symptoms though it can take some time.

Congenital or developmental lactose intolerance:

This form of lactose intolerance is extremely rare, yet potentially hazardous. It occurs in newborn infants, caused by a complete absence of lactase activity.  This disorder is pass from generation-generation through inheritance referring as autosomal recessive which means that both the mother & father must pass on the same gene variant for a child to be affected.

It’s been known that infants with congenital lactase deficiency would not expect to survive before the 20th century. Because, before this century lactose free milk substitute was unavailable.

 Lactose Malabsorption:

It is a physiologic condition that appears as lactose intolerance. In this process there is the imbalance between the amount of ingested lactose and the capacity for lactase to hydrolyze to disaccharide.

Developmental Lactase deficiency:

This type of lactase deficiency been observed among preterm infants of less than 34 weeks. It also known as relative lactase deficiency.


The sign and symptoms of lactose intolerance usually appears 30min – 2h after eating & drinking lactose containing foods. The common signs and symptoms are;-

  • Diarrhea
  • Nausea
  • Abdominal cramps & pain
  • Gas
  • Bloating
symptoms of Lactolose intolerance

When to consult with doctor

If you are suffering with symptoms which particularly get too much worse, then you must consult with doctor.

GIT distress occurs due to the undigested lactose which attracts water to move into your digestive tract. Once it reaches your colon, the lactose is fermented by intestinal bacteria, forming short chain fatty acids & gas.

What is the cause or risk factor behind lactose intolerance?

As it is mentioned earlier lactase activity commonly declines with age. Lactase deficiency may also develop when the intestinal villi damaged by any disease, certain medicines, malnutrition & prolonged diarrhea. Depending on the extent of the intestinal damage, lactose intolerance may be temporary or permanent. In extremely rare cases, infant is born with lactase deficiency due to the mutation in MCM6 gene which regulates lactase enzyme production.

Now let me tell you something about MCM6 gene

Do you know every person has a gene called MCM6, which helps in regulating the production of enzyme lactase? Variation in this gene can cause lactose intolerance. Some people have the ability to digest lactose throughout life but some have the greater chance of developing lactose intolerance as an adult. This happens because specific version of this gene is responsible for either increase or decrease likelihood for lactose intolerance.

Risk factors:

There are some risk factors that can make you or your child more prone to lactose intolerance include;-

Increasing age:

Lactose intolerance usually appears in adulthood. The condition is uncommon in babies & young children.


As mentioned earlier lactose intolerance is more common in ethnic groups like African, Asian, Hispanic & American Indian descent.

Premature birth:

Premature infants may have reduced level of lactase because the small intestine doesn’t develop lactase producing cells until late in the 3rd semester.

Disease affecting small intestine:

Some diseases associated with small intestine can also cause lactose intolerance including Crohn’s disease, celiac disease & bacterial over-growth.

Certain cancer treatments:

If you have received radiation therapy for cancer treatment at your abdominal area or have intestinal complications from chemotherapy, then you have an increased risk of lactose intolerance.


The prevalence of lactose intolerance varies among ethnic groups such as African & Asian etc.

In which countries it is too much common?

 About 65% of global population is lactose intolerant. The risk varies greatly between countries. It is highly common in Asia, Africa & Northern Europe.  95% population is Lactose intolerant in Asia & Africa and 10% in Northern Europe.

Which dairy product to prevent it from?

Prevention does not mean that you avoid dairy products it means to eat foods which are low in lactose. But you can also try lactose free milk, yogurt & sour cream etc.

Lactose intolerance may affect your health especially if it keeps you from getting enough nutrients such as calcium & vitamin D.

So don’t stress about it eat foods which are rich in calcium and vitamin D but should be low in lactose or either lactose-free?

Here are 6 foods that are in lactose (Click Here)

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