An Atkins-style diet that emphasizes animal protein may actually be linked to higher incidence of type 2 diabetes, according to a large observational study. Low-carbohydrate eating habits were associated with 12% elevated risk of new onset diabetes over more than 20 years of follow-up, found Lawrence de Koning, PhD, of Harvard School of Public Health, and colleagues.
Controlling for animal protein and fat eliminated the significance of the association whereas adjustment for vegetable fat and protein intake strengthened it.. Note that an Atkins-style diet that emphasizes animal protein and red/processed meat may actually be linked to higher incidence of type 2 diabetes, according to a large observational study.
The main drivers were red and processed meat and the heme iron found in red meat, de Koning's group reported here at the American Diabetes Association (ADA) meeting. Carbohydrates can drive up glucose levels, so low-carb diets have been seen as a way to prevent diabetes. Shifting toward protein for the bulk of calories might improve insulin sensitivity and metabolic rate through the "high thermic effect of protein," the researchers said in the poster presentation. But indiscriminately cutting carbs in favor of protein may have unintended consequences, suggested Sue Kirkman, MD, senior vice president of medical affairs and community information for the ADA.
"If you're not eating carbohydrates, you've got to eat something," she said. "It's a little too simplistic to say carbs increase glucose and cause diabetes.Indeed, it's too simplistic to say a high-protein diet is harmful, too " de Koning said.
"It's important to replace red and processed meat with chicken and fish and also vegetable sources of protein and fat, so nuts and legumes would be top choices," he said in an interview.
A wealth of literature supports the link between red and processed meats and diabetes, "particularly through heme iron," de Koning said.
The prevailing hypothesis for the link involving red meat -- and the heme iron it is a major dietary source of -- is that eating red and processed meats may encourage development of diabetes because of oxidative stress from accumulation of heme iron in tissue systemically and within the pancreas, de Koning explained.
"Beta-cells in particular are sensitive to oxidative stress, so we believe that the heme iron leads to beta cell dysfunction and perhaps dysregulation," he told MedPage Today.
For the red and processed meats, which included pork, the sodium nitrites added to processing to improve flavor and extend shelf life may play some role, he speculated.
Following findings in the Nurses Health Study suggesting no overall significant link between diabetes incidence and carbohydrate intake but an increased risk with red and processed meat, de Koning's group looked for similar relationships among men.
They analyzed food frequency results and diabetes incidence findings for 41,140 men in the Health Professionals Follow-Up study who had no baseline cardiovascular disease, cancer, or diabetes.
Participants completed food questionnaires every four years.
Over more than 20 years of follow-up, 2,761 men developed type 2 diabetes.
After adjustment for smoking, body mass index, physical activity, coffee and alcohol intake, family history of diabetes, and total energy intake, the hazard ratios for diabetes incidence showed the following trends:
-Progressive increase with higher low-carbohydrate score for overall proportion of a diet composed of protein and fat..
-A dose-dependent increase with greater score for low-carbohydrate, high animal protein and fat diet..
-A flat, nonsignificant association with greater low-carbohydrate, high vegetable protein and fat diet score..
Adjusting for BMI appeared to attenuate the associations but not eliminate them, the researchers noted.
Controlling the high vegetable protein and fat score for whole grains, nuts, or legumes as components for glycemic index didn't appear to have much effect.Kirkman cautioned that the observational findings could not be interpreted as causal. And although the researchers attempted to control for other potential factors, no model can entirely eliminate confounding, she noted.De Koning added that the study did not account for how foods were cooked, which might be a factor in the impact of red and processed meats.But the finding of a diabetes incidence link to red and processed meats in similar large cohorts of both women and now men supports generalizability. "It's not so much men are choosing more wrong proteins than women," de Koning said in an interview. "It's just that if you choose wrong proteins, being a man or a woman, you will increase your risk of diabetes."
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