The curious case of lactose intolerance

Having to rush to the toilet in the middle of a movie, with a tummy that is producing audible, rumbling sounds can be an embarrassing experience.

“Not to mention the endless ribbing from friends that you have to put up with,” says Pramod, a marketing executive.

“A group of us friends had met up for dinner and a movie. It could have been the food or the desserts we indulged in, but I distinctly remember the gassy, bloated feeling, the stomach cramps and the mortifying rush in search of the washroom. Even a decade later, the story continues to be regurgitated, with spicier additions, every time we meet up …and my “gluttony” has become legendary,” he laughs.

“But it was much later and after several similar episodes that I came to the conclusion that my gastric issues were being triggered by dairy products. Large amounts of dairy seemed to produce bad symptoms. I was not sure why my body was reacting differently to dairy products in adulthood, nor was I aware that lactose intolerance is something one can develop at any point in life. I have not been to a doctor and have not got any tests done because as long as I avoid or restrict milk products, I feel fine, “ says Pramod

While Pramod can laugh over how his digestive system reacted to milk, 56-year-old Jayamohan, a Govt employee, says he was not sure if his “sensitive stomach” and the frequent episodes of abdominal bloating, continuous belching, pain and occasional diarrhoea are symptoms of lactose intolerance or irritable bowel syndrome (IBS)

“I was convinced that I was “allergic” to milk and milk products. But even after excluding milk products from my diet, I continued to go through these uncomfortable gastric episodes. Stress, lack of sleep or dietary changes and sometimes milk too triggered it. My doctor now tells me that my symptoms are more consistent with that of IBS and that lactose intolerance might be a part of it,” he says.

Doctors do not consider lactose intolerance to be a disorder. They describe it as the digestive system’s reaction to milk sugar (lactose) which it cannot digest. The body needs an enzyme called lactase which is produced by the cells lining the small intestine, to digest lactose. If one is deficient in lactase, the undigested lactose passes on to the colon, where it produces extra gas and water, resulting in bloating, cramps and diarrhoea. Lactose intolerance thus produces symptoms which can be uncomfortable, but it is never dangerous.

“Lactose intolerance is so common that except for the 1-2% people who might experience serious bloating and cramps and nausea immediately after consuming dairy, almost every adult has lactose intolerance in various degrees. The degree of intolerance depends on the amount of lactose their system can tolerate, that’s all,” says C. P. Lakshmi, senior consultant medical gastroenterologist, Gastro Care, Thiruvananthapuram.

As one ages, there is a normal decline in the amount of lactase that the small intestine produces. This is one of the reasons why lactose intolerance might seem to be creeping up on one during adulthood and beyond, leaving one wondering why she can no longer find joy in that milkshake like she used to before.

That said, lactose intolerance seems to be a very subjective term that people use to describe the general digestive issues or symptoms — acidity, burping, gassiness — they feel whenever they consume dairy products.

Lactose intolerance is a specific digestive issue associated with the consumption of dairy products and ceases to be a problem when the person totally avoids or restricts milk products in the diet. But its symptoms can easily overlap with another common and chronic gastric disorders such as IBS, the pathogenesis of which is quite different.

The confusion — as in the case of Mr. Jayamohan — happens because for many people with IBS, dairy products are often one among the many triggers that produce gastric symptoms. It is thus possible to have both lactose intolerance and IBS together, though each are distinct entities.

According to literature, estimates for lactose intolerance vary by ethnicity. The prevalence rate is 75-95% in African American and Asian ethnicities while it is estimated to be 18-26% amongst Europeans.

Lactose intolerance does run in families and the symptoms can become evident during childhood or adolescence, even though in most cases, people seem to complain of lactose intolerance much later in adulthood.

“If you are lactose intolerant, you will develop symptoms within 30 minutes to two hours of consuming dairy products. After a couple of episodes, people generally observe and understand the pattern and come to the conclusion that dairy does not seem to agree with them. But a majority of those with lactose intolerance are still able to consume small amounts of milk products. It is when they go over their personal lactose threshold that they develop digestive symptoms,” says Dr. Lakshmi.

Though there are specific tests like the hydrogen breath test to determine lactose intolerance, these tests do not have much use in clinical practice. People are told to stay away from all dairy products for two weeks and then gradually re-introduce dairy into the diet to see how their body reacts.

Manoj (name changed), a medical oncologist in north Kerala, says that he has experienced lactose intolerance symptoms for the past five years, which he had put down to IBS.

“It took me a while to understand that it was just lactose intolerance and that it was the consumption of large amounts of dairy products that produced all the unpleasant digestive symptoms. I can still have my morning cuppa with milk, but no more. I seem to do well with home-made yoghurt and cheese also,” he says.

“This is a condition that is generally self-diagnosed and self-managed. The usual tests for detecting lactose intolerance are not available here or are expensive but clinical diagnosis seems to suffice. The solution is as simple as avoiding or restricting dairy and people manage very well,” Dr. Manoj says.

It is possible to develop secondary lactose intolerance all of a sudden following surgery or chemotherapy or if one has an infection, ulcerative colitis or Crohn’s disease which affects the small intestine. But this usually goes away once the small intestine regains health.

Dr. Manoj says that while lactose intolerance is quite common among Asians — over 50% of the Indians are deficient in lactase — it is very easy to misdiagnose this condition, especially amongst the elderly.

“In the elderly, some malignancies like colon cancer can present themselves in the initial stages with atypical symptoms similar to that of the symptoms of lactose intolerance. We might end up running an entire battery of tests to rule out malignancies before concluding that it could be a case of lactose intolerance,” he says.

Doctors also caution that lactose intolerance is quite distinct from an allergy to milk.

Lactose intolerance is the digestive system’s response to the milk sugar (lactose), whereas in the event of a milk allergy, the entire immune system will react against the milk protein. The reaction is often immediate and severe in the case of milk allergy, while lactose intolerance will never lead to any serious disease or long-term complications

Can lactose intolerance lead to nutritional deficiencies? Dieticians say that while milk is an important source of nourishment for children, milk is never the primary source of nutrition for adults.

“For persons with lactose intolerance who love to consume milk, there are options such as plant-based milk (soy/almond milk) or lactose-free milk. There are plenty of other food sources — yoghurt, tofu, nuts, spinach, broccoli, orange, lentils and legumes — that a lactose-intolerant person can depend on for calcium supplementation. So you won’t be missing much,” says Lekshmi Manish, a city-based nutritionist.