Lactose intolerance, milk drinking and symptoms in people
What it found
Many people who lack the enzyme to break down lactose can still drink a glass of milk with a meal without major symptoms.
Milk drinking is lowest in countries where this trait is most common.
What they found
Studies in people
Milk drinking trends
Milk consumption is falling in the USA. It is lowest in countries where most people genetically lack the enzyme to digest lactose.
Symptoms with meals
People with lactose intolerance who do not also have irritable bowel syndrome can often drink a glass of milk with a meal. They experience no symptoms or only minor ones.
Genetic roots of digestion
A genetic change near the lactase gene lets some groups keep digesting milk into adulthood. This trait is common in people from Northern Europe and some nomadic African tribes because it helped them survive.
Other findings
Ways to get nutrients
To help people get calcium and vitamin D, experts suggest drinking small amounts of milk with food. They also point to lower-lactose options like hard cheeses, yogurt and treated milk products.
What the authors conclude
- They note that many people who cannot fully digest lactose can still handle a glass of milk if they drink it with a meal.
- They highlight that eating hard cheeses, yogurt and treated milk products helps people get enough calcium and vitamin D.
How it was done
Between 65% and 70% of adults worldwide genetically lose the ability to digest lactose after childhood. The authors wanted to look at what this means for nutrition and health.
The authors gathered and evaluated recent research on people who genetically stop making enough lactase. They looked at how this affects milk drinking habits and symptom management around the world.
What it can’t tell you
- We summarised it from the abstract only.
- This work gathers existing research rather than testing a new treatment in a controlled trial.
- It cannot prove exactly how much milk any one person can drink without symptoms.
Who paid
- Authors work at
- Johns Hopkins University School of Medicine, USA; Johns Hopkins University, USA
The paper
- Title
- Lactase Non-persistence and Lactose Intolerance
- Type
- ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
- Evidence
- Studies in people
- Summarised from
- Abstract only
- Cite
- Bayless TM, Brown E, Paige DM (2017). Lactase Non-persistence and Lactose Intolerance. Current gastroenterology reports. doi:10.1007/s11894-017-0558-9PubMed 28421381DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error