High meat intake increases diabetes risk, study shows

A Singaporean population study has confirmed that a high intake of red meat and poultry can increase a person's risk of diabetes. Fish and shellfish, however, do not pose any risk, researchers say.

Recently, many studies have shown that plant-based diets, rather than diets that favor a high meat intake, are more beneficial to health. For instance, last month, Medical News Today reported on a study that linked vegetarian diets with lower cholesterol levels.

At the same time, many existing studies link meat consumption with a higher risk of developing diabetes.

New research from the Duke-NUS Medical School in Singapore confirms previous findings and adds new considerations as to why eating too much meat can predispose individuals to diabetes.

Prof. Woon-Puay Koh, a professor of clinical sciences at the Duke-NUS Medical School, and her colleagues evaluated the link between red meat, poultry, fish, and shellfish and type 2 diabetes, taking into account the impact of heme iron - which is iron content absorbed from meat - intake.

The researchers' findings were published in the American Journal of Epidemiology.

Red meat and poultry increase risk

The researchers analyzed data from the Singapore Chinese Health Study, involving 63,257 adults aged between 45 and 74. These were recruited between 1993 and 1998, and they were followed-up by means of two interviews: one in 1999 to 2004, and the other in 2006 to 2010.

It was found that people who had a higher dietary intake of red meat and poultry were at an increased risk of diabetes. Both fish and shellfish consumption, however, were not found to pose any dangers.

Individuals who ate the most red meat, the researchers noted, had a 23 percent higher risk of diabetes than those who ate little red meat. Eating a lot of poultry was linked with a 15 percent increase in risk of diabetes.

Fortunately, the researchers also noted that where meat was replaced with fish and shellfish, the risk increase was reduced.

In this context, the researchers also looked at the impact of heme iron on the relationship between meat consumption and diabetes. They found that a higher intake of heme iron was associated with an increased risk of developing the condition.

Is heme iron the only culprit?

Next, the researchers tested whether or not adjusting for the content of heme iron intake in the individuals' diets would impact the risk in any way. What they learned was intriguing.

"After additional adjustment for heme iron intake, the association between red meat intake and [diabetes] risk [...] remained statistically significant, whereas the association with poultry intake disappeared."

This, the researchers argue, may suggest that there are substances present in red meat, other than iron, that could be responsible for the increased risk of diabetes, but the same does not hold true for poultry.

Still, in the case of poultry, the study suggests that some chicken parts may pose less of a risk than others. Breast meat, for instance, has a lower heme iron content than chicken thighs, so it may be more healthful in the long run.

Prof. Koh explains that this study should not scare people into giving up meat. Rather, she thinks, they should be more mindful of the quantities and types of meat that they integrate into their meals.

"We don't need to remove meat from the diet entirely. Singaporeans just need to reduce the daily intake, especially for red meat, and choose chicken breast and fish/shellfish, or plant-based protein food and dairy products, to reduce the risk of diabetes."

Prof. Woon-Puay Koh

While Prof. Koh's study specifically targets the dietary habits of Singaporeans, her findings are relevant on a global level; they confirm previous research on the health impact of high meat consumption.

They also add a couple of new considerations: that heme iron may not be the only culprit in red meat, and that replacing some types of meat with fish or shellfish can reduce the diabetes risk increase.