There's a strong association between daily servings of red meat, especially processed meat, and a nearly 20% increased risk of type 2 diabetes, researchers found.
Replacing red meat with healthier proteins, such as low-fat dairy, nuts, or whole grains, can significantly lower the risk, according to a study was published online at the American Journal of Clinical Nutrition.
Researchers reviewed questionnaire responses from 37,083 men followed for 20 years in the Health Professionals Follow-Up Study, from 79,570 women followed for 28 years in the Nurses’ Health Study I, and from 87,504 women followed for 14 years in the Nurses’ Health Study II. Diet was assessed by validated food-frequency questionnaires, and data were updated every four years. Diabetes was confirmed by a validated supplementary questionnaire.
During more than 4 million person-years of follow-up, 13,759 diabetes cases occurred. After adjustment for age, body-mass index and other lifestyle factors, eating both unprocessed and processed red meat was associated with diabetes risk in each cohort (all P-trend, 0.001). Pooled HRs (with 95% CIs) for a one serving per day increase of unprocessed, processed, and total red meat consumption were 1.12 (1.08 to 1.16), 1.32 (1.25 to 1.40), and 1.14 (1.10 to 1.18), respectively.
Researchers also updated a meta-analysis, combining data from their new study with data from existing studies that included a total of 442,101 participants, 28,228 of whom developed type 2 diabetes during the study. After adjusting for age, body-mass index, and other lifestyle and dietary risk factors, the researchers found that a daily 100-gram serving of unprocessed red meat (about the size of a deck of cards) was associated with a 19% relative risk (95% CI, 1.04 to 1.37) of type 2 diabetes. They also found that one daily serving of 50 g of processed meat, for example, one hot dog or sausage or two slices of bacon, was associated with a 51% increased risk (95% CI, 1.25 to 1.83)
The solution is substitution. Simply swapping in one serving of nuts per day was associated with a 21% lower risk of type 2 diabetes; low-fat dairy, a 17% lower risk; and whole grains, a 23% lower risk.
This study finds that both unprocessed and processed meats pose a type 2 diabetes risk, thus helping to clarify the issue. Several mechanisms may explain the association. It may be mediated through the effects of heme-iron derived from red meats. Iron is a strong prooxidant that catalyses several cellular reactions that result in reactive oxygen species, and increases the level of oxidative stress that can damage to tissues such as pancreatic beta cells. Also, high body iron stores have been shown to be associated with an elevated risk of diabetes, the authors wrote.
Also, although unprocessed and processed meats contain similar amounts of saturated fat, sodium and nitrites in processed meats might partially explain the higher relative risk. Finally, adjustment for BMIs suggests that weight gain and obesity partially explain the diabetes.