Drinking more than three alcoholic drinks a day and eating processed meat and food preserved by salting could increase the risk of stomach cancer, according to the World Cancer Research Fund International (WCRF).
It is the first time the WCRF, which represents a network of charities has linked alcohol consumption and carrying excess weight with stomach cancer.
It advised people to abstain from alcohol, or follow national guidelines and maintain a healthy weight.
The new report also upgrades the link with processed meat from its research in 2007, suggesting there is strong evidence that it can increase the risk of stomach cancer.
A research team from Imperial College in London looked at 89 studies of 17.5 million patients, including 77,000 cases of stomach cancer.
The research is part of its Continuous Update Project which looks at global cancer prevention and survival linked to diet, nutrition, exercise and weight.
According to Cancer Research UK there were 7,067 new cases of stomach cancer in the UK in 2013.
Men are twice as likely to be diagnosed as women and it is more common in later life. The prognosis is often poor as it is frequently diagnosed at a late stage, said WCRF.
Its report with the American Institute for Cancer Research, Continuous Update Project Report: Diet, Nutrition, Physical Activity and Stomach Cancer, found there was “strong evidence” that tucking into processed meat, which is preserved by smoking, curing or salting or by adding preservatives, could increase the risk of stomach cancer.
The list of foods include ham, bacon, pastrami and salami, hot dogs and some sausages. The study said “there is concern that nitrite and nitrate from processed meat may be involved in carcinogenesis, due to reactions during the curing process in the body.”
The Meat Advisory Panel said the average consumption of processed meat in the UK was 17g, “well below” the report’s cut off of 50g.
It also pointed out that most British sausages made from fresh meat, are not preserved in the same way as salami and should not be classed as processed meat.
Researchers also said there was “strong evidence” that eating foods which have been preserved in salt, such as pickled vegetables and salted or dried fish increases the risk of stomach cancer.
The WCRF advised people to eat little, if any, processed meat and eat no more than 500g (cooked weight) of red meat a week.
They should stick to less than 6g of salt a day and eat less food that has been processed with salt.
There was also some evidence suggesting that meals of grilled or barbecued meat or fish could increase the risk of stomach cancer.
Researchers also found some evidence that a low consumption of fruit increases the risk and that including citrus fruit in the diet could decrease the risk of developing stomach cancer.
Other causes of stomach cancer are smoking, infection with the helicobacter pylori bacterium and industrial chemical exposure.