The Complex Link Between Meat and Diabetes

A new study associates the consumption of processed meat and unprocessed red meat with a higher risk of developing type 2 diabetes. However, there is some nuance.

Over 38.4 million Americans have diabetes, primarily type 2 diabetes, and its rates are expected to double by 2050. The exact cause of the condition is unknown, but some risk factors include genetics, obesity, and lack of physical activity.

A new study led by researchers at Harvard University and published in The Lancet Diabetes and Endocrinology suggests that higher intakes of processed and unprocessed red meat may contribute to the development of type 2 diabetes.

In the study, researchers used the global InterConnect project to analyze data from 31 study cohorts in 20 countries, which is nearly two million participants.

Processed meats refer to meats that have been preserved by smoking, salting, curing, or adding chemical preservatives. They include deli meats, bacon, and hot dogs.

Meanwhile, consuming 100 grams of unprocessed red meat daily — equivalent to a small steak — was linked to a 10% higher risk of type 2 diabetes.

“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,” Professor Nita Forouhi of the Medical Research Council (MRC) Epidemiology Unit at the University of Cambridge, and a senior author on the paper, said in a statement.

The study suggests that replacing 50 g of processed meat with 100 g of unprocessed red meat may reduce the risk of type 2 diabetes by 7%. A similar effect may be achieved when 50 g of processed meat is replaced with 100 g of poultry.

However, replacing unprocessed red meat with poultry did not appear to reduce diabetes risk.

How can meat consumption increase diabetes risk?

Several mechanisms potentially explain how meat consumption may increase diabetes risk. For example, eating a lot of meat could worsen insulin sensitivity or the function of pancreatic beta cells, which play a critical role in maintaining glucose homeostasis.

Moreover, meat is rich in protein, and some research has indicated a potential link between a high intake of animal proteins and a higher risk of type 2 diabetes.

Nitrate or nitrite additives and the formation of N-nitroso compounds during meat processing are associated with an elevated risk for the condition.

What do experts say?

Dr. Duane Mellor, a dietitian, and spokesperson for the British Dietetic Association, says that the study authors were not able to evaluate the effect of family history, insulin resistance, or waist circumference, all of which are strongly associated with the risk of developing diabetes and could potentially explain the findings.

The overall message to moderate meat intake is in line with national healthy eating guidelines and advice to reduce risk of developing type 2 diabetes, which include eating a diet which is based on vegetables, fruit, nuts, seeds, beans, peas, and lentils along with some wholegrain and moderate amounts of meat and dairy with limited amounts of added fat, salt, and sugar.

Mellor

Future studies should explore the differences between study populations from different regions, for example, in cooking methods used which can change some of the properties of meat, according to Dr. Hilda Mulrooney, reader in nutrition and health at London Metropolitan University.

She adds that while a body mass index cut-off of 25 used in the study is appropriate to a Caucasian population, it may be less so for other groups.

The risks of red and processed meats

While it is yet to be determined if processed meat actually raises the risk of type 2 diabetes, its consumption is a known risk factor for cancer.

In 2015, the World Health Organization’s International Agency for Research on Cancer classified the consumption of processed meat as “carcinogenic to humans.” The evidence concluded that eating 50 grams of processed meat every day raises the risk of colorectal cancer by 18%.

Such a daily portion was also linked to an increased likelihood of breast, prostate, and pancreatic cancers, as well as overall cancer mortality.

The same agency classified the consumption of red meat as probably carcinogenic to humans, citing limited evidence of its carcinogenic effect.

What is a healthy diet for diabetes?

More studies are needed to prove the role of processed and red meats in type 2 diabetes development. Meanwhile, the American Diabetes Association defines a healthy diet as combining the following components:

• Non-starchy vegetables — broccoli, carrots, cauliflower — as a foundation for the plate.
• Lean proteins, such as fish, poultry, and eggs, and plant-based protein sources.
• Quality carbohydrates like starchy vegetables, fruits, whole grains, and low-fat milk.
• Less added sugars, commonly found in cakes, cookies, ketchup, and fizzy drinks.
• Healthy fats, such as olive oil, nuts, avocados, and some types of fish.
• Less processed foods like pre-packaged meat, bread, and cereals.
• Water or zero-calorie beverages.

Limiting the consumption of red and processed meats may not necessarily reduce the risk of type 2 diabetes, but it can have many other health benefits, including a lower risk of cancer.