Lactose Intolerance: Bloating and Diarrhea After Dairy, Testing and Care

What it involves

MedlinePlus explains that lactose is the sugar in milk and other dairy products, and the body needs an enzyme called lactase to digest it. Lactose intolerance develops when the small intestine does not make enough lactase, and it is very common in adults and rarely dangerous.

Who this is for

• Patients with bloating, gas, cramps, or diarrhea after dairy
• Patients who suspect dairy but are unsure because symptoms vary
• Patients whose bowel symptoms resemble irritable bowel syndrome
• Patients cutting out dairy who want to keep getting enough calcium

What to expect

• Questions about which foods bring on symptoms and how soon afterward
• A discussion of other causes with similar symptoms, such as irritable bowel syndrome or celiac disease
• A plan for confirming it, which MedlinePlus says may involve a breath test or a short trial without lactose
• Advice on dairy swaps and calcium and vitamin D intake

How it shows up

MedlinePlus says symptoms often occur 30 minutes to 2 hours after having milk products and may be worse with large amounts. They include abdominal bloating, cramps, diarrhea, gas, and nausea. Only people who have digestive symptoms are said to be lactose intolerant, even if their intestines cannot digest all the lactose. The bloating and gas guide and diarrhea guide cover other causes.

Why it happens and who gets it

MedlinePlus says about 36 million American adults have lactose intolerance, and it is more common among adults with Asian, African, or Native American heritage and less common in people of northern or western European background, though it can still occur. Illness or injury of the small intestine, including surgery, infections, celiac disease, Crohn disease, and any illness that causes diarrhea, can lower lactase. If it follows a diarrheal illness, levels return to normal within a few weeks.

How it is tested

Other problems, such as irritable bowel syndrome, can cause the same symptoms, so confirming matters. The IBS guide explains the overlap. MedlinePlus lists the lactose hydrogen breath test as the most common test, along with a lactose tolerance test, stool pH, and small intestine biopsies. A one to two week trial of a completely lactose-free diet is also sometimes tried. A provider decides which route fits.

Eating with lactose intolerance

Cutting down on milk products that contain lactose most often eases symptoms, per MedlinePlus, and it advises checking labels for hidden lactose in non-dairy foods. Most people with low lactase can drink up to half a cup of milk at once without symptoms, and larger servings of more than 8 ounces may cause problems. Foods that may be easier to digest include buttermilk, cheeses, yogurt, goat's milk, aged hard cheeses, and lactose-free milk and milk products.

Enzymes and calcium

MedlinePlus says lactase enzyme supplements are widely used and effective, and can be added to milk or taken as capsules or chewable tablets. Cutting out dairy can leave you short of calcium, vitamin D, riboflavin, and protein, and it says adults need 1,000 to 1,500 mg of calcium a day depending on age and sex. Leafy greens, canned salmon, sardines, and calcium-fortified orange juice are sources. The vitamin D and B12 guide explains related blood tests.

When to be seen

MedlinePlus advises contacting a provider if an infant under 2 or 3 has symptoms, if a child is growing slowly or not gaining weight, if symptoms get worse or do not improve with treatment, or if new symptoms develop. Blood in the stool, weight loss, or fever are not typical of lactose intolerance and need a provider to look into them. See the food allergy guide for the difference between an intolerance and an allergy, since milk allergy is an immune reaction.

Sources

• MedlinePlus — Lactose intolerance
• MedlinePlus — Lactose Intolerance (health topic)