Two slices of ham a day can raise type 2 diabetes risk by 15%, research suggests

Eating processed or red meat increases the risk of type 2 diabetes, with just two slices of ham a day raising the danger by 15%, the largest study of its kind suggests.

Research led by the University of Cambridge and involving 2 million people worldwide provides the most comprehensive evidence yet of a link between meat and the disease that presents one of the most pressing dangers to global health.

More than 400 million people have been diagnosed with type 2 diabetes, which is a leading cause of blindness, kidney failure, heart attacks, strokes and lower limb amputation. As well as maintaining a healthy weight and moving more, evidence suggests one of the main ways to lower the risk of the disease is improving diet.

Experts who conducted a meta-analysis of data involving 1.97 million adults from 20 countries across Europe, the Americas, eastern Mediterranean, south-east Asia and the western Pacific say the results support recommendations to limit consumption of processed and red meat.

Their findings were published in the Lancet Diabetes & Endocrinology journal.

Prof Nita Forouhi, of the University of Cambridge, a senior author 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 the consumption of processed meat and unprocessed red meat to reduce type 2 diabetes cases in the population.”

Researchers analysed data from 31 study groups through InterConnect – a project funded by the EU to understand more about type 2 diabetes and obesity in different populations.

They found habitual daily consumption of 50g of processed meat – equivalent to two slices of ham – was associated with a 15% higher risk of type 2 diabetes in the next 10 years.

Consuming 100g of unprocessed red meat a day – the equivalent of a small steak – was associated with a 10% higher risk of the disease.

Habitual consumption of 100g of poultry a day was associated with an 8% higher risk. When further analyses were conducted 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 persisted, the researchers found.

“While our findings provide more comprehensive evidence on the association between poultry consumption and type 2 diabetes than was previously available, the link remains uncertain and needs to be investigated further,” Forouhi said.

In the UK, the NHS advises those eating more than 90g of red meat such as beef, lamb, mutton, pork, veal, venison and goat, or processed meat such as sausages, bacon, ham, salami and corned beef a day to cut down to 70g or less.

The InterConnect data allowed the research team to “more easily account for different factors, such as lifestyle or health behaviours, that may affect the association between meat consumption and diabetes”, the researchers said.

The lead author, Dr Chunxiao Li, also of Cambridge, said that while previous studies had pooled together existing results, the new analysis examined data from individual participants in each study.

That technique, said Prof Nick Wareham, director of the MRC epidemiology unit at Cambridge and a senior author on the paper, allowed researchers to “provide more concrete evidence of the link between consumption of different types of meat and type 2 diabetes than was previously possible”.

Experts not involved with the research said that while it proved only an association, and not causation, the results aligned with current healthy eating recommendations.

Prof Naveed Sattar, of 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 cutting red and processed meats from diets may not only protect people from heart disease and stroke but also from type 2 diabetes, a disease on the rise worldwide.”

Dr Duane Mellor, of Aston University, said the overall message to moderate meat intake was in line with advice to reduce the risk of type 2 diabetes, including a diet heavy 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.