Lactose Intolerance
Lactose Intolerance - created via CMS
TL;DR
Lactose intolerance is reduced lactase enzyme activity, not an allergy. Most people can still tolerate small amounts, especially with meals. Lactase supplements and hard cheeses and yoghurt make dairy manageable for the majority.
Overview
Lactose intolerance is difficulty digesting lactose, the sugar in milk, due to low levels of the enzyme lactase, causing bloating, cramps, gas and diarrhoea within a few hours of dairy. It is very common — most adults worldwide have some degree of lactase decline — and it is harmless, though uncomfortable. Management is dietary adjustment rather than total dairy avoidance: hard cheeses and live yoghurt are usually well tolerated, lactose-free milk is widely available, and lactase enzyme tablets taken with dairy help many people. Completely avoiding dairy requires attention to calcium and vitamin D intake.
Common Symptoms
- •Bloating and abdominal distension 30 minutes to 2 hours after dairy
- •Excess wind
- •Cramping abdominal pain
- •Loose stools or diarrhoea
- •Audible gut rumbling
- •Nausea in some people
Common Causes
- •Primary lactase non-persistence — the normal genetic default in most of the world
- •Secondary loss after gastroenteritis, coeliac disease or Crohn's
- •Congenital lactase deficiency, which is very rare
- •Small intestinal bacterial overgrowth amplifying symptoms
Root Causes
Lactase is produced by the brush border of the small intestine and normally declines after weaning. Without it, lactose passes undigested into the colon where bacteria ferment it, producing hydrogen, methane and short-chain fatty acids. The gas causes distension and the osmotic load draws water in, producing the loose stools.
How It's Diagnosed
Diagnostic Markers
- Hydrogen breath test after a lactose load — a rise of 20 ppm or more is positive
- Symptom resolution on a two-week lactose elimination then recurrence on rechallenge
- Genetic testing for LCT-13910 C/T polymorphism
- Coeliac serology to exclude a secondary cause
- Faecal calprotectin if inflammatory bowel disease is suspected
When to See a Doctor
See a doctor before self-diagnosing if symptoms are new in adulthood with weight loss, blood in stool, fever, or symptoms that persist despite removing lactose, since coeliac disease, inflammatory bowel disease and other conditions can mimic it. Children with suspected lactose intolerance should always be assessed rather than placed on restrictive diets.
Supplements Studied For This
Diet & Lifestyle
Suggested Pattern
Full dairy avoidance is usually unnecessary and risks calcium and iodine shortfall. Most people with lactase non-persistence tolerate about 12 g of lactose — roughly one cup of milk — in a single sitting when taken with other food. Hard aged cheeses contain almost no lactose, and live yoghurt is well tolerated because bacterial lactase digests it in the gut. Spread dairy across the day rather than eliminating it.
Eat more
- Hard aged cheeses — cheddar, parmesan, gouda
- Live yoghurt and kefir
- Lactose-free milk, which is nutritionally equivalent
- Fortified plant milks with added calcium and iodine
- Butter, which contains negligible lactose
- Calcium-rich non-dairy foods such as tinned sardines and leafy greens
Avoid
- Large glasses of milk on an empty stomach
- Soft fresh cheeses such as ricotta and cottage cheese in large portions
- Milk-based desserts and ice cream in quantity
- Whey protein concentrate, which retains lactose — isolate is lower
- Hidden lactose in some medications, bread and processed meats
Supporting Research
Effect of lactase on symptoms and hydrogen breath levels in lactose intolerance: A crossover placebo-controlled study
Galacto-Oligosaccharide RP-G28 Improves Multiple Clinical Outcomes in Lactose-Intolerant Patients
The use of probiotics and prebiotics can enable the ingestion of dairy products by lactose intolerant individuals
The effect of oral supplementation with Lactobacillus reuteri or tilactase in lactose intolerant patients: randomized trial
Bifidobacterium animalis subsp. lactis Bi-07 supports lactose digestion in vitro and in randomized, placebo- and lactase-controlled clinical trials
Frequently Asked Questions
Who It Affects
Around 65 to 70 per cent of the global adult population has reduced lactase activity, ranging from under 5 per cent in Northern Europe to over 90 per cent in parts of East Asia.
Highest prevalence in East Asian, West African, Indigenous American and Southern European populations. Lactase persistence is the genetic minority worldwide, concentrated in Northern European and some pastoralist African groups.
Quick Facts
- •Around 65-70% of the global adult population has reduced lactase activity
- •Hard cheeses like cheddar contain less than 0.1 g lactose per serving
- •Live-culture yoghurt is often tolerated because bacteria pre-digest the lactose
- •Lactase enzyme tablets (typically 3000-9000 FCC units) taken with dairy reduce symptoms
- •Long-term dairy avoidance without substitutes risks inadequate calcium intake
Lifestyle Tips
- •Take dairy with a meal rather than alone — transit slows and symptoms drop
- •Try lactase tablets immediately before eating, not afterwards
- •Reintroduce gradually; regular small exposure improves colonic adaptation
- •Check calcium intake reaches 700 to 1000 mg daily from any source
- •Read labels for whey, milk solids and curd if you are very sensitive
- •Keep a symptom diary to find your own personal threshold
My Notes
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This information is for educational purposes only. Always consult a healthcare professional before starting any supplement regimen.