Eating meat is linked with diabetes risk, new studies suggest

For sausage, salami and steak lovers, the news has not been good. Scientists have been consistently finding links between red and processed meat consumption and heart disease, some types of cancer and earlier death.

Now, two recent studies have added to the growing body of evidence that a meat heavy diet may increase the risk of Type 2 diabetes.

In one of the studies, published on Aug 20 in The Lancet Diabetes And Endocrinology, researchers analysed data from nearly two million adults participating in 31 studies across 20 countries, including the US and parts of Europe and Asia.

Researchers reviewed survey data on participants’ diets and then looked at their health an average of 10 years later.

After adjusting for other risk factors such as smoking, a higher body mass index, physical inactivity and a family history of diabetes, they found that for every 51g of processed meat the participants ate each day, their risk for Type 2 diabetes increased by 15 per cent. (This is equivalent to a medium-sized sausage or two to three slices of bacon.)

For every 99g of unprocessed red meat they consumed daily, their risk increased by 10 per cent. (This is about the size of a small steak.)

The data also suggested that one serving of poultry per day was associated with an 8 per cent increase in Type 2 diabetes risk, but this finding was less consistent and only significant in the European studies, so more research is needed, said Dr Nita Forouhi, a professor of population health and nutrition at the University of Cambridge, who led the study.

The takeaway, she said, is that the less red and processed meat you eat, the better.

These findings jibe with previous research, including a large US study published in October.

There are several potential explanations for why regular meat consumption might increase Type 2 diabetes risk, Dr Forouhi said.

Red and processed meats tend to be higher in saturated fats than in unsaturated fats, a composition associated with greater insulin resistance, which can lead to Type 2 diabetes.

People who eat more meat may also eat fewer healthful foods, such as fruits and vegetables, Dr Forouhi added.

Cooking meat at high temperatures, such as through pan frying or grilling over an open flame, can also form certain compounds that may cause cell damage, inflammation and insulin resistance – all of which can contribute to Type 2 diabetes.

A study published last week in the journal Nature Metabolism added evidence for another longstanding hypothesis: that heme iron – a type of iron found in high levels in red meat (and to a lesser extent in fish and poultry) – may contribute to Type 2 diabetes.

Researchers followed nearly 205,000 predominantly white US adults for up to 36 years, during which time about 21,000 of them developed Type 2 diabetes.

Those with the highest heme iron consumption – mainly coming from eight to 10 servings of unprocessed red meat per week – were 26 per cent more likely to develop Type 2 diabetes than those with the lowest consumption. They also had higher lipid levels, markers of insulin resistance and inflammation, and other compounds linked with Type 2 diabetes in their blood, the study revealed.

This added to existing evidence suggesting that heme iron is likely an important player in the link between red meat and Type 2 diabetes, said Dr Frank Hu, a professor of nutrition and epidemiology at the Harvard T.H. Chan School of Public Health, who led the study.

On the other hand, heme iron did not explain the link between processed red meat and Type 2 diabetes, Dr Hu said. Other components, such as their preservative and sodium levels, are probably more important to the risk of processed meats, he added.

Iron is an essential nutrient, but too much may cause inflammation and damage the pancreas, increasing diabetes risk, said Dr Dariush Mozaffarian, a cardiologist and professor of medicine at Tufts University, who was not involved with the study.

While regular consumption of both red and processed meats have been associated with poorer health, processed meats have the strongest and most consistent link with Type 2 diabetes and other conditions, Dr Mozaffarian said. This is clearly a “class to avoid”, he said.

Processed meats include not only stereotypically unhealthy products such as hot dogs and bacon, but also potentially healthy seeming ones like turkey sausages and deli meats.

This does not mean you should never eat these foods, Dr Mozaffarian said. Instead, think of them as occasional treats, he added.

As for red meat, there is not enough data to say exactly how much is too much, Dr Hu said, but based on the current evidence, a serving or two per week – like a small pork chop or a couple of meatballs over spaghetti – is probably acceptable.

Dr Hu recommended shifting from a “meat-centric” diet to one that incorporates plenty of plant-based foods such as whole grains, fruits, vegetables and legumes – all of which have been linked with a lower risk of Type 2 diabetes. NYTIMES