What lactose intolerance is – and how to manage it
Bloating, cramps or diarrhea after a glass of milk, a latte or a bowl of muesli? Then lactose may be the culprit. Lactose intolerance is very common – worldwide, around two thirds of adults digest lactose poorly. It is not dangerous, but it can be very unpleasant. The good news: most people can manage it well without giving up good food.
What is lactose and where is it found?
Lactose (milk sugar) is a sugar found in the milk of mammals. It consists of two building blocks, glucose and galactose. To absorb it, the body needs the enzyme lactase, which is produced on the surface of the small intestine. If there is too little lactase, undigested lactose passes into the large intestine, where bacteria ferment it. The result: gas, bloating, rumbling, cramps and sometimes diarrhea, usually 30 minutes to two hours after eating.
Lactose is found mainly in milk and dairy products such as milk, cream, yogurt, quark and fresh cheese. It can also be found in:
- sweet baked goods and desserts
- ready-made sauces and soups
- some processed meats
- some tablets and supplements
- protein powders based on whey
In the EU, milk and milk products must be highlighted in the ingredient list as allergens.
Why can some people digest it and others can’t?
All healthy babies produce lactase so that they can digest breast milk. In most people around the world, lactase production gradually decreases after weaning – this is the biological norm. In some populations, especially in Northern Europe and among some pastoral peoples in Africa and the Middle East, a genetic change means that lactase continues to be produced into adulthood.
There are different forms of lactose intolerance:
- Primary (genetic): lactase declines after childhood – the most common form
- Secondary: the small intestine is damaged, for example by celiac disease, Crohn’s disease or a gut infection
- Temporary: for example after a stomach bug, when the gut lining needs time to recover
Congenital lactase deficiency, in which babies cannot digest lactose from birth, is very rare.
What happens in the gut?
Lactase is produced on the tips of the intestinal villi, tiny finger-like projections in the small intestine. If they are damaged – for example by celiac disease, inflammatory bowel disease or an infection – lactase production decreases. Once the cause is treated and the villi recover, lactose tolerance often improves again.
The gut bacteria also play a role: in some people, the gut flora adapts to regular, small amounts of lactose, which can reduce symptoms.
Possible symptoms:
- bloating, gas, a feeling of fullness and cramps
- diarrhea or loose stools
- nausea
- in some people, also tiredness or headaches
The severity depends on how much lactose you eat and how much lactase you still produce.
Can lactose intolerance be reversed?
Primary lactose intolerance is genetic and cannot be cured – but it can be managed very well. Secondary lactose intolerance often improves when the underlying condition is treated.
What helps:
- Get a diagnosis: the hydrogen breath test is the standard test; a genetic test can show the primary form. Celiac disease should be ruled out if symptoms are severe.
- Find your limit: most people with lactose intolerance tolerate up to about 12 g of lactose at once – roughly a glass of milk – especially when eaten with other foods.
- Choose wisely: lactose-free dairy products, aged cheese and yogurt are often well tolerated.
- Use lactase enzyme tablets when needed, for example when eating out.
- Probiotics: some studies suggest that certain strains may relieve symptoms, but the evidence is limited.
What could it be confused with?
Similar symptoms can be caused by:
- irritable bowel syndrome (IBS)
- small intestinal bacterial overgrowth (SIBO)
- celiac disease
- fructose malabsorption or other FODMAP sensitivities
- a milk protein allergy, which is something different from lactose intolerance
Keeping a food and symptom diary can help, but persistent symptoms should be examined by a doctor.
Lactose in medications
Lactose is a common filler in tablets, for example in painkillers, hormone preparations or vitamin tablets. The amounts are usually very small and cause symptoms in only very few people. If you are very sensitive, ask your pharmacist about lactose-free alternatives.
What to use instead
Milk alternatives:
- lactose-free cow’s milk – the same nutrients, just with the lactose already broken down
- oat milk
- almond milk
- coconut milk
- tiger nut milk (horchata)
- soy milk – closest to cow’s milk in protein content
Choose plant drinks that are fortified with calcium, as dairy products are an important source of calcium for many people.
Fermented alternatives:
- lactose-free yogurt
- coconut yogurt with live cultures
- oat milk kefir
- tofu-based spreads
Cheese alternatives:
- aged hard cheeses (naturally almost lactose-free)
- cashew spreads
- almond cheese with nutritional yeast
Why do aged cheeses contain less lactose?
During cheese making, most of the lactose ends up in the whey. During ripening, bacteria convert the remaining lactose into lactic acid. The longer a cheese matures, the less lactose remains – in parmesan, gruyère, emmental or mature cheddar, it is often no longer detectable. These cheeses are usually well tolerated even by people with lactose intolerance.
Yogurt is also often better tolerated than milk, because its bacteria help to break down lactose.
Lactose sources at a glance
| Product or Group | Contains Lactose? | Risk for Lactose Intolerant Individuals | Lactose-Free Alternative |
|---|---|---|---|
| Milk (cow, goat) | Yes | High risk | Lactose-free milk, plant-based milks (almond, oat) |
| Yogurts and kefirs | Yes | Medium (often better tolerated) | Lactose-free yogurt, coconut yogurt, plant-based kefirs |
| Fresh cheeses (cottage) | Yes | High | Lactose-free versions, tofu, cashew spreads |
| Aged cheeses (cheddar, parmesan) | Trace amounts | Usually well tolerated | Not needed in most cases |
| Sweet baked goods | Often | Depends on recipe | Homemade dairy-free baking |
| Cold cuts (sausages, salami) | Possible | Check the label | Products labeled “lactose-free” |
| Medications (tablets, pills) | Often, in small amounts | Usually low | Ask your pharmacist |
| Supplements and probiotics | Sometimes | Usually low | Products labeled “lactose-free” |
3 simple lactose-free recipes
1. Homemade coconut yogurt
Ingredients:
- 400 ml full-fat coconut milk
- 2 probiotic capsules
Preparation: Warm the coconut milk slightly (not hot), open the capsules and stir in the contents. Pour into a clean jar, cover with a breathable cloth and leave to ferment in a warm place for 12–24 hours. Store in the fridge for up to 5 days. Discard it if it smells unpleasant or shows mold.
2. Creamy millet pudding
Ingredients:
- 1/2 cup millet
- 1.5 cups almond milk
- 1 tbsp vanilla paste
- 1 tsp honey (optional)
Preparation: Rinse the millet and cook it in the almond milk until soft. Blend with the remaining ingredients until smooth. Serve with fruit and nuts.
3. Cashew “cheese” spread
Ingredients:
- 1 cup cashews (soaked overnight)
- 2 tbsp nutritional yeast
- juice of 1/2 lemon
- pinch of garlic, salt and pepper
Preparation: Blend everything into a smooth paste. Keeps in the fridge for up to 4 days.
Did you know…
- Aged cheeses like parmesan or gruyère contain only traces of lactose.
- Lactose can be hidden in spice mixes and soup powders.
- The ability to digest lactose in adulthood spread in Europe only in the last few thousand years, along with dairy farming.
In summary
Lactose intolerance is common, harmless and easy to manage once you know your limits. You don’t usually need to avoid dairy completely: lactose-free products, aged cheeses, yogurt and lactase tablets make it easy to keep enjoying your food – and to get enough calcium.
