The Truth About Lactose Intolerance: Symptoms, Causes, Tests, and Diet Tips in India

• Understand what lactose intolerance is and how it differs from milk allergy.
• Recognise common symptoms like bloating, gas, and diarrhoea after consuming dairy.
• Learn why lactose intolerance is common in Indians and how age, genetics, and gut health play a role.
• Explore diagnostic options and when to get medical tests done.
• Get practical, Indian-context diet tips to enjoy dairy wisely or choose safe alternatives.
• Find answers to frequently asked questions and references to credible medical sources.

What Is Lactose Intolerance?

Lactose intolerance is a digestive problem in which your body cannot properly digest lactose, the natural sugar found in milk and dairy products such as curd, paneer, cheese, and ice cream.

This happens when your small intestine does not make enough of an enzyme called lactase. Lactase breaks down lactose into simpler sugars (glucose and galactose) that can be absorbed into the blood. When lactase is low, undigested lactose passes into the large intestine, where it is fermented by bacteria, producing gas and other by-products that cause uncomfortable symptoms.

Lactose Intolerance vs. Milk Allergy

Many people confuse lactose intolerance with a milk (dairy) allergy, but they are very different:

• Lactose intolerance is a digestive issue due to enzyme deficiency.
• Milk allergy is an immune reaction to milk proteins (like casein, whey).

Key differences:

• Symptoms of lactose intolerance: Bloating, gas, stomach cramps, diarrhoea after dairy.
• Symptoms of milk allergy: Rash, hives, swelling, breathing difficulty, vomiting, and in severe cases, anaphylaxis – which is a medical emergency.

Lactose intolerance is usually uncomfortable but not dangerous. Milk allergy can be serious and needs strict avoidance and medical care.

How Common Is Lactose Intolerance in India?

Lactose intolerance is quite common among Indians, especially in adults. In many Asian, African, and South American populations, the body naturally produces less lactase as people grow older, leading to lactase non-persistence. Studies have shown that a significant portion of Indian adults may have some degree of lactose malabsorption, even if they are not formally diagnosed.

However, not everyone with low lactase has severe symptoms. Some people can tolerate small amounts of dairy, especially traditional Indian fermented products like curd (dahi) and buttermilk (chaas).

Common Symptoms of Lactose Intolerance

Symptoms typically appear 30 minutes to 2 hours after consuming milk or dairy products and can vary from mild to severe depending on how much lactose you consume and how much lactase your body produces.

Typical Symptoms

• Bloating and a feeling of fullness or heaviness in the stomach
• Excessive gas (flatulence)
• Abdominal cramps or pain
• Loose stools or diarrhoea
• Stomach rumbling or gurgling sounds
• Nausea; sometimes vomiting (less common)

Less Obvious or Indirect Symptoms

• Frequent episodes of diarrhoea after meals containing dairy
• Discomfort or urgency after drinking milk-based tea/coffee
• Symptoms that improve when dairy is avoided and return when reintroduced

If these symptoms are persistent or severe, or if you notice blood in stools, significant weight loss, or fever, consult a doctor immediately as it may indicate another condition (such as inflammatory bowel disease, infections, or celiac disease).

What Causes Lactose Intolerance?

Lactose intolerance is mainly due to reduced lactase production in the small intestine. This can occur for several reasons:

1. Primary Lactase Deficiency (Most Common)

This is the most common type globally and in India. Here, a person is born with normal lactase levels, but production naturally declines after childhood. Many adults, therefore, become less tolerant to milk as they age.

2. Secondary Lactase Deficiency

In this type, another condition damages the small intestine and temporarily or permanently reduces lactase production. Causes include:

• Gastrointestinal infections (like viral or bacterial diarrhoea)
• Celiac disease
• Crohn’s disease or other inflammatory bowel diseases
• Intestinal surgery or injury

Once the underlying condition is treated and the gut heals, lactase levels may improve.

3. Congenital Lactase Deficiency (Rare)

This is a rare genetic disorder in which babies are born with little or no lactase. They develop severe diarrhoea as soon as milk feeding starts and require strict medical management and special formulas.

How Is Lactose Intolerance Diagnosed?

If you suspect lactose intolerance, do not self-diagnose based only on symptoms. Many digestive problems can mimic lactose intolerance. A doctor may suggest one or more of the following approaches:

1. Symptom and Diet Review

Your doctor will ask about:

• Frequency and pattern of your symptoms
• Foods you eat, especially dairy sources
• Any weight loss, fever, or blood in stool

Sometimes you may be advised to temporarily avoid lactose for 1–2 weeks and then slowly reintroduce it to see if symptoms return. This is often a first, simple step.

2. Hydrogen Breath Test

This is a non-invasive test often used to confirm lactose malabsorption.

• You drink a lactose-containing liquid.
• Your breath is analysed at intervals to measure hydrogen gas.
• High levels of hydrogen indicate that lactose is not properly digested and is being fermented by bacteria in the large intestine.

3. Lactose Tolerance Blood Test

In this test, after drinking a lactose solution, your blood sugar levels are measured. If your blood sugar does not rise as expected, it means your body is not breaking down and absorbing lactose efficiently.

4. Stool Acidity Test (Common in Infants)

In infants and very young children, undigested lactose can lead to acidic stools. Stool samples are tested for acidity and certain by-products.

5. Tests to Detect Underlying Conditions

Sometimes your doctor may recommend additional tests to rule out other digestive disorders. These may include:

• Blood tests for celiac disease or infections
• Endoscopy or colonoscopy in selected cases
• Imaging or other specialised tests depending on your symptoms

Managing Lactose Intolerance: Practical Tips for Indians

Lactose intolerance does not always mean you must completely give up dairy. Many people can handle small portions or certain dairy products better than others. Management is highly individual and often involves trial and error.

1. Know Which Foods Contain Lactose

Common Indian and everyday foods rich in lactose:

• Milk (cow, buffalo, toned, full cream)
• Milk-based beverages (tea/coffee with a lot of milk, milkshakes, lassi)
• Paneer, khoya, condensed milk, rabri, kheer, kulfi, ice cream
• Milk powder used in sweets and bakery items

Hidden sources of lactose (always check ingredient labels):

• Breads, biscuits, cakes, pastries
• Instant soups and noodles with creamy bases
• Some chocolates and flavoured drinks
• Processed foods containing milk solids, whey, casein, or milk powder

2. Choose Dairy Wisely

Many Indians with mild to moderate lactose intolerance can tolerate:

• Curd (dahi) and yoghurt – Fermentation breaks down part of the lactose and beneficial bacteria help digestion.
• Buttermilk (chaas) – Usually lighter and easier to digest.
• Ghee – Contains negligible lactose, usually safe for most people.
• Hard cheeses (like aged cheddar) – Lactose content is lower than in milk (if consumed, do so in moderation).

What often causes more trouble:

• Plain milk in larger amounts
• Cream-based dishes (shahi paneer, malai kofta, creamy gravies)
• Ice creams and milk-based desserts

3. Try Smaller Portions and Spread Intake

Some strategies that may help:

• Have small servings of milk or dairy rather than a large glass at once.
• Consume dairy with a meal rather than on an empty stomach.
• Distribute dairy intake throughout the day (for example, a little dahi with lunch and small amount of milk in tea).

4. Use Lactose-Free or Low-Lactose Alternatives

If symptoms are frequent or severe, you may need to reduce or avoid lactose and choose alternatives:

• Lactose-free milk – Milk treated with lactase enzyme; tastes slightly sweeter but easier to digest.
• Plant-based milks – Such as soy milk, almond milk, coconut milk, oat milk (choose fortified versions with calcium and vitamin D).
• Non-dairy curd/yoghurt – Made from soy, almond, or coconut (check labels for added sugars).

5. Ensure Adequate Calcium and Vitamin D

If you reduce dairy, you must get calcium and vitamin D from other sources to maintain bone health.

Calcium-Rich Indian Foods

• Ragi (finger millet)
• Green leafy vegetables: spinach (palak), fenugreek leaves (methi), amaranth (chaulai)
• Til (sesame seeds) and til chikki
• Chana, rajma, soybeans, and other pulses
• Almonds and other nuts
• Fortified plant-based milks (check labels)

Vitamin D Sources

• Regular, safe sun exposure (10–20 minutes, depending on skin type and climate)
• Fortified foods (some milk alternatives, breakfast cereals)
• Egg yolks and fatty fish (for non-vegetarians)

Your doctor may recommend supplements if dietary intake is inadequate.

6. Protein-Rich Indian Foods Without Dairy

If you limit or avoid dairy, you still have many high-protein options in India:

• Dal (toor, moong, masoor, urad)
• Chana, rajma, chole (chickpeas, kidney beans, Bengal gram)
• Soy chunks, tofu, and soybeans
• Groundnuts (peanuts) and peanut chikki
• Eggs, chicken, fish, and lean meats (for non-vegetarians)

7. Consider Lactase Supplements (If Advised)

In some countries, lactase enzyme tablets or drops are used just before consuming dairy to help digest lactose. Availability and suitability vary, so always discuss with your doctor or dietitian before use.

When Should You See a Doctor?

Consult a healthcare professional if:

• You frequently have bloating, gas, or diarrhoea after dairy.
• Symptoms interfere with daily activities or sleep.
• You notice weight loss, fatigue, blood or mucus in stools, or fever.
• Children experience poor growth, chronic diarrhoea, or abdominal pain.

Timely evaluation helps rule out other underlying conditions and ensures proper nutrition, especially in children, pregnant women, and older adults.

Links to Relevant Tests and Packages at Seralis Lab

Specialised laboratory tests can help confirm lactose intolerance or identify other digestive issues that mimic it. Relevant offerings at Seralis Lab (where available) typically include:

• Hydrogen breath tests related to lactose or carbohydrate malabsorption
• Comprehensive gut health or digestive disorder panels
• Food intolerance or allergy profiles for individuals with broader food-related symptoms

Before choosing any test, consult your doctor to decide which investigation is most appropriate for your symptoms, medical history, and age.

FAQs

Question: Can lactose intolerance develop suddenly in adults?

Yes. Many people tolerate milk well in childhood but notice discomfort in their 20s, 30s, or later. This is because lactase production naturally declines with age in many populations, including Indians. Sudden onset along with other symptoms, however, may indicate an underlying gut problem and should be evaluated by a doctor.

Question: Is it safe to completely avoid dairy if I’m lactose intolerant?

You can avoid dairy if it consistently causes symptoms, but you must replace the nutrients it provides, especially calcium and vitamin D, through other foods or supplements. Work with a doctor or dietitian to ensure your diet remains balanced, particularly for children, pregnant women, and older adults.

Question: Can I eat curd if I am lactose intolerant?

Many people with lactose intolerance can tolerate moderate amounts of curd (dahi) and yoghurt because fermentation reduces the lactose content and the live cultures help digestion. Start with small portions and monitor your body’s response.

Question: Does boiling or heating milk remove lactose?

No. Heating or boiling milk does not remove lactose. The sugar remains present unless it is broken down by the lactase enzyme or removed during processing (as in lactose-free milk).

Question: Are children more likely to have lactose intolerance?

Primary lactose intolerance is less common in very young children and usually appears later in childhood, adolescence, or adulthood. However, secondary lactose intolerance due to infections or gut diseases can occur in children and infants. Persistent diarrhoea, poor weight gain, or irritability after feeding requires medical attention.

Question: Can I self-diagnose lactose intolerance by just avoiding milk?

While a short trial of avoiding lactose may give you a clue, self-diagnosis is not enough. Other conditions, including allergies, celiac disease, inflammatory bowel disease, and infections, can produce similar symptoms. Always consult a doctor for proper evaluation and testing.

Question: Is lactose intolerance permanent?

Primary lactose intolerance is usually long term. However, many people learn how much lactose they can tolerate and adjust their diets accordingly. Secondary lactose intolerance due to infections or gut injury may improve or resolve once the underlying condition is treated and the intestine heals.

References

• “Lactose Intolerance” by National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) (2020). Source
• “Lactose Intolerance” by Mayo Clinic Staff (2023). Source
• “Prevalence of lactose intolerance in different populations” by Savaiano DA and Boushey CJ, in “Handbook of Milk of Non-Bovine Mammals” (2006). Source
• “Lactose intolerance and health” by Suchy FJ et al., American Academy of Pediatrics Committee on Nutrition (Pediatrics, 2010). Source
• “Lactose Intolerance – Symptoms & Causes” by National Health Service (NHS), UK (2021). Source

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