Many people, especially as they get older, are unable to digest milk and its products. This could be due to lactose intolerance, which can happen at any stage in life. Dr Gaurav Mehta, consultant, gastroenterology/hepatology and transplant hepatology, Kokilaben Dhirubhai Ambani Hospital, Mumbai, says:
“Lactose intolerance occurs when the body does not produce enough of the enzyme lactase, which is required to break down lactose-the natural sugar found in milk and dairy products. Lactase is produced in the lining of the small intestine. When levels are insufficient, lactose passes undigested into the large intestine, where it is fermented by gut bacteria.
This process leads to symptoms such as bloating, gas, abdominal pain, and diarrhea. There are three main types — primary, secondary and congenital lactose intolerance. The most common is primary lactose intolerance, where lactase production gradually declines with age, particularly common in Asian and Indian populations. Secondary lactose intolerance occurs when the intestinal lining is temporarily damaged. Congenital lactose intolerance, is rare and present from birth due to a genetic defect.
Why does lactose intolerance happen sporadically, at any age, and sometimes in phases, during a lifetime, correcting after a few months?
This “on-and-off” pattern is usually explained by secondary lactose intolerance. The small intestine is highly sensitive to injury, and anything that disrupts its lining can temporarily reduce lactase production. Common triggers include intestinal infections, food poisoning, antibiotic use, or inflammatory gut conditions. For instance, after a bout of viral gastroenteritis, the gut lining may be inflamed, leading to reduced lactase activity. During this phase, a person may suddenly develop intolerance to milk. However, as the intestine heals over weeks to months, lactase production can recover. Similarly, changes in gut microbiota-often influenced by diet, stress, or medications-can alter how lactose is processed, contributing to fluctuating symptoms. Hormonal shifts may also indirectly affect gut sensitivity.
Can it be prevented?
Primary lactose intolerance cannot be prevented, as it is genetically determined. However, symptom onset and severity can be managed and, in some cases, delayed. This includes preventing infections through hygiene, avoiding unnecessary antibiotic use, and managing underlying gastrointestinal conditions early. A balanced diet rich in fiber supports healthy gut bacteria, which may improve tolerance to small amounts of lactose. For secondary intolerance, early treatment can reduce the duration of symptoms. Gradual exposure to dairy may also help build tolerance over time. In practical terms, prevention is less about eliminating lactose entirely and more about preserving intestinal health and recognising triggers early.
Is yogurt completely safe to consume in lactose intolerant individuals?
Yogurt is generally better tolerated than milk but is not universally “completely safe.” The reason lies in how it is made. During fermentation, beneficial bacteria such as Lactobacillus partially break down lactose into simpler sugars, reducing the lactose content. Additionally, these live cultures can aid digestion in the gut. Many individuals with lactose intolerance can consume small portions of yogurt without symptoms, especially if it contains active cultures. However, tolerance varies widely. Some may still experience discomfort, particularly if consumed in large quantities or on an empty stomach. It’s also important to distinguish between plain yogurt and flavoured or sweetened varieties, which may contain added milk solids and higher lactose levels.
Are those with autoimmune conditions like celiac disease more susceptible?
Yes, individuals with autoimmune conditions such as celiac disease are more susceptible to lactose intolerance, particularly the secondary type. Ingestion of gluten triggers an immune response that damages the villi – the finger like projections in the small intestine responsible for nutrient absorption and enzyme production, including lactase. Other autoimmune or inflammatory conditions affecting the gut, such as inflammatory bowel disease, can have a similar effect.
Disclaimer: The information in this article is for educational and informational purposes only and is not intended as medical advice. While the author has incorporated expert medical guidance while producing the story and ensured full authentic information is provided to the reader, you should always seek the advice of a qualified healthcare provider regarding a medical condition or treatment. Never disregard professional medical advice or delay in seeking it because of something you have read here.