Alcohol, processed meat and being overweight have been "strongly" linked to stomach cancer for the first time.
A study's set out who is at risk - highlighting those who have three or more alcoholic drinks a day and anyone who eats the equivalent of two rashers of bacon daily.
Experts at the World Cancer Research Fund say citrus fruits may decrease the risk.
However, eating citrus fruits may decrease the risk, experts said.
Most people are diagnosed with stomach cancer when their cancer has already started to spread across the body.
Men are twice as likely as women to develop stomach cancer.
Is more common in older adults.
WCRF scientists said there is "strong evidence" that drinking about three or more alcoholic drinks per day increased the risk of stomach cancer, as did being overweight or obese.
There is also "strong evidence", they said, that consuming processed meat, or foods preserved by salting, increased the risk. Examples include ham, bacon, pastrami and salami, as well as hot dogs and some sausages.
Processed meat is already linked to bowel cancer, while being overweight or obese is also linked to 10 different cancers.
"These findings will hopefully help people better understand what increases their risk of cancer so that they can make informed decisions about their lifestyles choices," said WCRF spokeswoman Dr Rachel Thompson.
