Eating just 50 grams of processed meat per day — about the equivalent of two slices of ham — appears to correlate to a 15 per cent higher risk of developing Type 2 diabetes within the next decade, according to a new study.
The study, published Tuesday in The Lancet Diabetes & Endocrinology, suggests that eating 100 grams of unprocessed meat a day, which is equivalent to a small streak, was associated with a 10 per cent higher risk of developing Type 2 diabetes.
Though the link was a correlation, not a clear causation, it adds to a growing body of research raising concerns about the health effects of processed meats.
“The findings for processed meat and many health conditions including Type 2 diabetes, heart disease and cancer have been consistent and strong,” said senior author Nita Forouhi, a professor of epidemiology at the University of Cambridge in the United Kingdom.
“Our research adds meaningfully to the existing evidence by including a very large population of nearly two million participants from 31 studies in 20 countries as well as including as many as 18 studies that had not previously reported their findings,” she told Global News in an email on Wednesday.
Type 2 diabetes is a condition where the body becomes resistant to insulin or doesn’t produce enough of it, leading to high blood sugar levels, according to Diabetes Canada. It usually develops later in life and is often linked to lifestyle factors like diet and exercise.
In contrast, Type 1 diabetes is an autoimmune disorder where the body attacks insulin-producing cells in the pancreas, resulting in little to no insulin production. Type 1 typically occurs in childhood and requires lifelong insulin therapy, while Type 2 can often be managed with lifestyle changes and medication.
Type 2 diabetes affects more than 500 million people worldwide and is estimated to affect one billion people by 2050, the study said.
In Canada, Type 2 diabetes is one of the fastest-growing diseases, with more than 60,000 new cases yearly, Health Canada reports. It is also a lifelong condition, and high blood glucose levels over a long period can cause blindness, heart disease, nerve damage and stroke.
Red meat consumption has previously been linked to an increased risk of Type 2 diabetes. However, the authors of the study wanted to further examine the impact of red meat, processed meat and poultry consumption (such as chicken, turkey, or duck) on the development of Type 2 diabetes.
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To determine the association between the consumption of processed meat, unprocessed red meat and poultry and Type 2 diabetes, the team led by researchers at the University of Cambridge used the global InterConnect project to analyze data from 31 study cohorts in 20 countries.
The researchers analyzed data from 1.97 million participants and took into account factors such as age, gender, health-related behaviours, energy intake and body mass index.
Not only did the study find a link between processed and unprocessed meats and Type 2 diabetes, but it also identified a smaller risk associated with poultry consumption.
Daily consumption of 100 grams of poultry was associated with an eight per cent higher risk of Type 2 diabetes. However, the researchers said further analyses showed this association weakened under different scenarios, while the links between Type 2 diabetes and both processed and unprocessed meats remained strong.
“We found that regular, habitual poultry consumption may be related with potentially raised risk of future Type 2 diabetes but these findings need further research because when we looked at alternative ways of analyzing the data, the findings were attenuated and no longer significant,” Forouhi said.
“For now, therefore it would be premature to offer guidance on poultry consumption based on these results. Our findings for processed meat and for unprocessed red meat are strong and they stood up to all different types of analysis.”
What could be behind the link?
The underlying mechanisms that appear to link meat intake with the development of Type 2 diabetes are not fully established, the researchers note. However, there are a few potential explanations for this association, they added.
Forouhi said that meat is not eaten in isolation. People who consume more red and processed meats often have dietary patterns that include fewer fruits and vegetables and less fibre — foods known to benefit health.
Also, there is a clustering of lifestyle patterns that can affect the risk of Type 2 diabetes, she said.
For example, people who consume more meat typically are also more likely to drink alcohol, smoke and be less physically active.
Meat consumption might increase the risk of Type 2 diabetes through several mechanisms that can impair insulin sensitivity or pancreatic function, she said.
For example, red meat is high in saturated fats and low in healthier polyunsaturated fats. A 2016 study published in Plos Medicine found that replacing saturated fats with polyunsaturated fats is linked to improved insulin resistance.
“Meat is the main source of haem iron, which has been linked with the risk of Type 2 diabetes. Some cooking methods for meat, such as high-temperature frying or grilling may generate chemicals called advanced glycation end-products that may be harmful,” Forouhi explained.
Another potential mechanism could involve trimethylamine N-oxide (TMAO), a substance produced by gut bacteria during the digestion of choline and L-carnitine, which are found in high amounts in red meat, the study said. While the exact link is still not fully understood, TMAO might play a role in increasing diabetes risk.
Nitrate and nitrite additives, along with the formation of N-nitroso compounds during meat processing, are also linked to a higher risk of Type 2 diabetes.
Nitrates are used as food additives, mainly in processed meats, to increase shelf life and to avoid bacterial growth. However, a 2023 study published in Plos Medicine found that higher exposure to these additives was associated with higher Type 2 diabetes.
The Canadian Food Guide recommends reducing the intake of processed meats like hot dogs, sausages and ham, which have been linked to an increased risk of colorectal cancer. Instead, it suggests focusing on plant-based foods such as vegetables, fruits, whole grains and plant-based proteins.
Regular consumption of these foods can benefit health by providing higher levels of dietary fibre, which is associated with a lower risk of cardiovascular disease, colon cancer and Type 2 diabetes, it states.
The World Health Organization (WHO) also recommends a diet with little or no red and processed meat.
“In relation to human health, red meat can be an important element of a healthy diet, particularly at key life stages. It is rich in highly bioavailable vitamins and minerals – particularly iron and vitamin B12 – and other essential compounds for growth, development and good health,” the WHO said. “Excess consumption of red meat and processed meat, however, is associated with increased risk of NCDs, including cancer, cardiovascular disease (CVD) and Type 2 diabetes.”
If you’re looking to adjust your diet and reduce your meat consumption, Forouhi recommends having smaller meat servings, eating meat less often or swapping meat for alternative protein-rich foods.
“Reducing meat-eating occasions each week or month can include meat-free days. Other non-meat protein sources include fish, poultry and eggs, legumes like beans and lentils, nuts and even whole grains can be good sources, and healthy dairy in moderation, without added sugar,” she said.
Diabetes Canada advises that because Type 2 diabetes can often be prevented or delayed, reducing your risk involves making lifestyle changes like eating healthier, being more active and losing weight if you are living with obesity.
“A good first step is to include more vegetables, more plant-based protein such as beans and lentils, whole grains, dairy, lean meat, oily fish, nuts and healthy oils such as olive oil. You can also reduce consumption of highly processed foods, refined grains such as white bread, sugary food and sugary drinks,” the organization said.
