Large long-term observational studies conducted throughout the world come to the conclusion that a high consumption of red meat, i.e. beef, lamb or pork, is associated with increased type 2 diabetes risk. The data of the Potsdam EPIC study also indicate this: The daily consumption of 150 grams of red meat increases the disease risk by about 80 %. The scientists observed a similar risk increase in connection with smoking more than 20 cigarettes a day, with an increase in waist circumference of 7.6 cm or in connection with a predisposition inherited from the father or mother. Until now, however, studies have not yet determined which metabolic processes underlie the risk association between the consumption of red meat and type 2 diabetes and whether certain substances contained in the meat such as ferritin play a role.
To learn more about the associations, the team made up of epidemiologists from the German Institute of Human Nutrition, metabolomics experts from Helmholtz Zentrum München and clinicians of the University of Tübingen analyzed the blood samples of 2,681 Potsdam EPIC study participants. Of these, 688 were diagnosed with type 2 diabetes during the study. The scientists gathered information about the study participants’ eating habits and meat consumption through questionnaires.
In total, the researchers analyzed 127 different biomarkers in the blood of the participants; 21 of these markers – both in women and in men – were associated with meat consumption. In six of these biomarkers, the observed changes in concentrations were additionally related to increased diabetes risk. The study participants with high ferritin levels and low levels of the protein building block glycine had an increased risk of diabetes. Moreover, in these participants, the concentrations of four lipids were altered which are released from the liver into the blood.
“High ferritin levels indicate that the iron depots are full and can point to a high iron absorption. As scientific research shows, excess ferritin causes the body’s cells to increasingly form highly reactive molecules that damage the cells. Scientists refer to this as oxidative stress,” said Clemens Wittenbecher, lead author of the study. “Since glycine is an integral component of the body’s systems to protect the cells against oxidative stress and at the same time to counteract inflammatory responses, high ferritin levels and low glycine values suggest that the body is exposed to increased oxidative stress and is less well protected against inflammation,” Wittenbecher went on to say. “This in turn could explain the relationship between the consumption of red meat and diabetes, since according to the latest state of knowledge oxidative stress and inflammatory responses contribute to the emergence of type 2 diabetes.” The altered lipid concentrations would also indicate a disturbed lipid metabolism of the liver, which could also contribute to pathogenesis of the disease.
“Our results suggest that it is not a single substance contained in red meat that is associated with diabetes risk. Rather, habitual high consumption of red meat affects the metabolism via various routes in a way that in the long term favors the emergence of type 2 diabetes,” said study leader Matthias Schulze.
"Observational studies like the EPIC study are not suitable to prove causal risk relationships unequivocally. However, they give a good indication of the metabolic mechanisms that could underlie such a relationship,” said Wittenbecher. "Our findings not only provide new approaches to examine the effects of meat consumption more specifically and in greater detail in metabolic studies,” Schulze added. “They also support the current dietary recommendation to reduce the consumption of red meat to prevent type 2 diabetes.”
Wittenbecher et al.; DOI: 10.3945/ajcn.114.099150
The DZD partners Clemens Wittenbecher, Matthias Schulze, Kristin Mühlenbruch, Janine Kröger, Simone Jacobs, Olga Kuxhaus, Anna Floegel, Hans-Georg Joost and Heiner Boeing of the German Institute for Human Nutrition (DIfE), Jerzy Adamski and Cornelia Prehn of Helmholtz Zentrum München and Andreas Fritsche of the Institute for Diabetes Research and Metabolic Diseases of Helmholtz Zentrum München at the University of Tübingen.