Eating just two slices of ham a day raises the risk of type 2 diabetes by 15 per cent, according to a major study.
Research led by the University of Cambridge involving two million people found eating processed or red meat raised the risk of developing the disease.
The findings, published in the Lancet Diabetes & Endocrinology journal, found consuming 100g of unprocessed red meat a day – equivalent to a small steak – was linked to a 10 per cent higher risk of type 2 diabetes.
Habitual daily consumption of 50g of processed meat – equivalent to two slices of ham – raised the risk by 15 per cent, while consuming 100g of poultry a day was associated with a 10 per cent higher risk.
Researchers said the link between poultry and diabetes was less conclusive and needed further investigation.
Dr Vikram Murthy, a GP and co-founder of the Murthy Health clinic, told i it has been well documented that high amounts of red or processed meat can increase the risk of diabetes.
The NHS recommends limiting the consumption of either to a maximum of 70g a day.
Red meat includes beef, lamb, mutton, pork, veal, venison and goat, while examples of processed meat are sausages, bacon, ham, salami and corned beef.
Dr Murthy said these types of meat lead to a spike in glucose levels which can lead to diabetes.
“Whenever you eat something your body produces insulin, which regulates your glucose levels within your body,” he said.
“If you are exposed to higher levels of insulin, you develop insulin resistance or insulin sensitisation. That can be caused by having higher amounts of certain types of food – in this case, red meat or things like ham.
“That can cause you to have a higher risk of developing diabetes because your body is having to produce more and more of the insulin for longer periods of time, and so your body essentially becomes less reactive to it, and as a result, you need to produce more and more to get the same effects.”
He said red meat can help people who are low in iron but there is not really a safe amount of ham or processed meat that should be consumed.
“There isn’t really a way to be safe unless you completely omit it,” he said.
“If you have it in moderation, then it’s reducing the risk.”
Dr Murthy said having high amounts of protein tends to increase glucose levels, which can contribute to insulin resistance.
In the UK, adults are advised to eat 0.75g of protein for each kilogram they weigh. This tends to be about 55g for men and 45g for women. Many people eat more protein than they need.
“For people who have diabetes, what we always try and advocate is for them to have what are known as complex carbohydrates,” he said. “That would be like brown rice or wholemeal bread, these kind of things, because they slowly help release glucose.”
The study also pointed to high levels of saturated fat that could also help explain the link between some meat and a higher risk of developing type 2 diabetes, as well as harmful additives and compounds formed during cooking.
The Government recommends that men and women eat a maximum of 30g and 20g of saturated fat per day respectively.
Lucy Diamond, a diabetes specialist dietitian and clinical director at Oviva, said, said the research indicated that the NHS guidance on consuming up to 70g of red or processed meat “should be even lower”.
She told i there were limitations to the research in that it relied on people self-reporting what they ate.
“Is a ham sandwich once a week going to give you diabetes?” she said. “Unlikely. But this gives us strong evidence to stick to the NHS guidance.”
Other factors leading to a higher diabetes risk
Dr Murthy said genetics are a “significant strong factor” in determining whether someone is more likely to develop diabetes.
He said the disease is known to affect South Asian communities which tend to have something called the “thrifty gene”, which was likely developed to help people get through food shortages.
“It’s very easy for those communities to have excess stores of fats which, unfortunately, can be quite detrimental in causing patients to develop diabetes,” he said.
A high Body Mass Index (BMI) – a measure of body fatness – and a high waist-to-hip ratio are other risk factors, he added.
Men have traditionally been more likely to develop diabetes than women, although that is believed to be linked to lifestyle choices rather than biological factors.
Ms Diamond said the study took into account BMI but did say there was a stronger link to diabetes in those with a higher body fat percentage.
She said it has previously estimated that dietary and lifestyle factors were 90 per cent responsible for causing type 2 diabetes.
“Preventative measures focusing on healthy eating, regular physical activity, maintaining a healthy weight, and avoiding smoking and excessive alcohol consumption can drastically reduce the incidence of type 2 diabetes,” she said.
