Study: Red Meat and Heme Iron Linked to Type 2 Diabetes

A new study confirms the link between eating meat and the risk of developing type 2 diabetes (T2D) by demonstrating that the link isn’t exclusive to western diets.

Researchers from Singapore and China wanted to find out if the association between meat and T2D could be replicated in an eastern population.

Woon-Puay Koh (pictured), PhD, a professor in the Office of Clinical Sciences at Duke University-National University of Singapore Medical School, in Singapore, said there are a number of important differences between eastern and western diets. Those differences prompted researchers to take an eastern-specific look at the issue of meat and diabetes risk, something they had never seen done before.

One key difference between western and eastern diets is that people in Singapore and China tend to eat more fish and less red meat, and the red meat they eat tends to be pork, rather than beef, due to religious dietary restrictions.

Koh said food preparation methods are also different — meat tends to be cooked using lower-temperature methods like steaming and stewing. The diabetes risk profile is also different — in Singapore, T2D is associated with a lower BMI than in the west.

Despite the dietary differences, the association between meat and T2D persisted.

“Our findings are very similar to the studies from western population,” Koh told MD Magazine. “In addition, we demonstrated that the risk could be reduced if red meat or poultry was substituted by fish or shellfish.”

The basis of the new research was the Singapore Chinese Health Study, a massive public health study that tracked 63,000 Chinese patients between 1993 and 1998. The participants ranged in age from 45-74. Two follow-up interviews were conducted with each patient between 1999 and 2010. After those follow-ups, a total of 5,207 cases of T2D were reported.

Patients in the highest quartile of red meat intake had a 1.23 adjusted hazard ratio for T2D versus the lowest quartile of red-meat eaters. High poultry intake was associated with a 1.15 adjusted hazard ratio, and high consumption of fish and shellfish resulted in an adjusted hazard ratio of 1.07.

Next, Koh said, researchers sought to look at one chemical in particular.

“In trying to understand the underlying mechanism for the role of red meat and poultry in the development of diabetes, we also investigated the association between dietary heme-iron content from all meats and the risk of diabetes, and found a dose-dependent positive association,” Koh said.

When the results were adjusted for the heme-iron content, the link between high red meat consumption and T2D remained, suggesting that other chemicals aside from heme iron were contributing to the elevated T2D risk of red meat.

“Conversely, the association between poultry intake and diabetes risk became null, suggesting that this risk was attributable to the heme-iron content in poultry,” Koh said.

Koh was not surprised that red meat in particular would be problematic in diabetes, noting that saturated fatty acids, branched chain amino acids, advanced glycation end products and trimethylamine N-oxide “also have been shown in experimental studies to have strong mechanistic links with insulin resistance.”

All told, Koh said the data suggests staying away from red meat, and poultry can lower T2D risk — no matter which hemisphere a person lives in.

The study, “Meat, Dietary Heme Iron, and Risk of Type 2 Diabetes Mellitus: The Singapore Chinese Health Study,” was published online in American Journal of Epidemiology last month.