Lactose

Studies in people

• Benefit

  Milk symptom relief²

  In people with lactose intolerance, lactose-free milk caused far fewer symptoms than regular milk did.

• Benefit

  Gut bacteria in allergic infants³

  In infants with cow's milk allergy, adding lactose to their formula raised helpful gut bacteria and lowered others.

Animal and lab studies only

• Concern

  Gut bacteria and inflammation¹⁰

  In animal studies, lactose fed the growth of gut bacteria that made an inflammatory disease worse.

Study type not stated

• Concern

  Digestive discomfort from milk sugar⁴

  People who cannot digest lactose get belly pain, gas and diarrhea, and may have higher risk of other diseases.

• Concern

  Milk sugar digestion⁵

  Lactose is the sugar in milk; some people lack the enzyme to digest it, causing gas, bloating and diarrhea.

• Concern

  Gut symptoms after dairy⁶

  Lactose can cause belly pain, bloating and diarrhoea in people who cannot digest it well.

• Concern

  Milk digestion⁷

  Many adults worldwide cannot digest lactose well, but some can still drink a glass of milk with a meal.

• Concern

  Milk reactions in babies⁸

  Lactose intolerance and cow's milk allergy have very similar gut signs, which may lead to misdiagnosis.

• Concern

  Gut symptoms from dairy⁹

  Lactose intolerance is when lactose in dairy foods causes stomach symptoms, but it is often confused with other gut problems.

The signal at the top counts the findings in people and in animal and lab studies. A concern in studies of people outranks animal and lab studies, and “No concerns” needs at least two findings in people. Findings whose study type is not stated are shown but not counted. This page is a reference, not medical advice. It describes what regulators and published research say. Talk to a doctor or dietitian about your own diet.