Eating processed or red meat increases the risk of type 2 diabetes. Just two slices of ham a day increases the risk by 15%, according to the largest study of its kind.
Research led by the University of Cambridge, involving 2 million people worldwide, provides the most comprehensive evidence yet of a link between meat and the disease that poses one of the most urgent threats to global health.
More than 400 million people have been diagnosed with type 2 diabetes, a leading cause of blindness, kidney failure, heart attacks, strokes and lower-limb amputations. In addition to maintaining a healthy weight and exercising more, evidence suggests that one of the most important ways to reduce your risk of the disease is to improve your diet.
Experts who conducted a meta-analysis of data from 1.97 million adults from 20 countries in Europe, North and South America, the Eastern Mediterranean, Southeast Asia and the Western Pacific say the results support recommendations to limit consumption of processed and red meat.
Their findings were published in the journal Lancet Diabetes & Endocrinology.
Prof Nita Forouhi from the University of Cambridge, one of the lead authors of the study, said: “Our research provides the most comprehensive evidence to date of an association between eating processed meat and unprocessed red meat and a higher future risk of type 2 diabetes. It supports recommendations to limit consumption of processed meat and unprocessed red meat to reduce the incidence of type 2 diabetes in the population.”
Researchers analysed data from 31 study groups through InterConnect, an EU-funded project to understand more about type 2 diabetes and obesity in different population groups.
They found that consuming 50 grams of processed meat daily – equivalent to two slices of ham – was associated with a 15% increased risk of type 2 diabetes over the next 10 years.
Eating 100 grams of unprocessed red meat per day – the equivalent of a small steak – was associated with a 10% higher risk of the disease.
Usual consumption of 100 grams of poultry per day was associated with an 8% higher risk. When further analyses were performed to test the findings under different scenarios, the association for poultry consumption became weaker, but the associations with type 2 diabetes for processed meat and unprocessed red meat remained, the researchers found.
“Although our findings provide more comprehensive evidence on the association between poultry consumption and type 2 diabetes than previously available, the association remains uncertain and needs further investigation,” Forouhi said.
In the UK, the NHS advises people who eat more than 90g of red meat a day, such as beef, lamb, mutton, pork, veal, venison and goat, or processed meats such as sausages, bacon, ham, salami and corned beef, to reduce this to 70g or less.
The InterConnect data allowed the research team to “more easily account for different factors, such as lifestyle or health behaviors, that may influence the association between meat consumption and diabetes,” the researchers said.
Lead author Dr Chunxiao Li, also from Cambridge, said previous studies had pooled existing results, but the new analysis examined data from individual participants in each study.
The technique, said Prof Nick Wareham, director of the MRC’s epidemiology unit in Cambridge and one of the paper’s lead authors, allowed researchers to “provide more concrete evidence for the link between consumption of different types of meat and type 2 diabetes than has previously been possible”.
Experts not involved in the study said that while it only showed an association, not causation, the results were in line with current recommendations for healthy eating.
Prof Naveed Sattar from the University of Glasgow said: “This is an important study which, despite the inevitable observational nature of the evidence, is very well done. The data suggest that cutting red and processed meat from the diet may protect people not only against heart disease and stroke, but also against type 2 diabetes, a disease that is increasing worldwide.”
According to Dr Duane Mellor of Aston University, the general message to moderate meat consumption is in line with advice to reduce the risk of type 2 diabetes, which includes a diet rich in vegetables, fruit, nuts, seeds, beans, peas and lentils.
“This should be accompanied by regular physical activity to minimise the risk of developing type 2 diabetes,” Mellor said.