Meat consumption and its association with C-reactive protein and incident type 2 diabetes: the Rotterdam Study

OBJECTIVE

To investigate whether intake of different types of meat is associated with circulating C-reactive protein (CRP) and risk of type 2 diabetes in a prospective cohort study.

RESEARCH DESIGN AND METHODS

Our analysis included 4,366 Dutch participants who did not have diabetes at baseline. During a median follow-up period of 12.4 years, 456 diabetes cases were confirmed. Intake of red meat, processed meat, and poultry was derived from a food frequency questionnaire, and their association with serum high-sensitivity CRP was examined cross-sectionally using linear regression models. Their association with risk of type 2 diabetes was examined using multivariate Cox proportional hazards model, including age, sex, family history of diabetes, and lifestyle and dietary factors.

RESULTS

An increment of 50 g of processed meat was associated with increased CRP concentration (β_{processed meat} = 0.12; P = 0.01), whereas intake of red meat and poultry was not. When comparing the highest to the lowest category of meat intake with respect to diabetes incidence, the adjusted relative risks were as follows: for red meat (1.42 [95% CI 1.06–1.91]), for processed meat (1.87 [1.26–2.78]), and for poultry (0.95 [0.74–1.22]). Additional analysis showed that the associations were not affected appreciably after inclusion of CRP into the model. After adjustment for BMI, however, the association for red meat attenuated to 1.18 (0.88–1.59).

CONCLUSIONS

Intake of processed meat is associated with higher risk of type 2 diabetes. It appears unlikely that CRP mediates this association.Since the prevalence of type 2 diabetes has increased rapidly over the last decades, investigations into the effect of dietary and other lifestyle factors on type 2 diabetes have become important (1). One of the dietary factors of interest is meat. Three meta-analyses of prospective cohort studies showed that intake of processed meat is associated with a higher risk of type 2 diabetes (2–4). For red meat, two of these meta-analyses observed an adverse association (2,4), whereas one did not (3). For poultry, no data from meta-analyses were available. Results from six prospective studies on poultry, however, showed that it is not likely that poultry is associated with a higher risk of type 2 diabetes; three studies observed an inverse association (5–7), whereas three did not observe an association (8–10).Intake of red meat and processed meat may increase risk of type 2 diabetes by mechanisms that increase circulating proinflammatory markers. Positive associations have been observed between red meat or processed meat and the proinflammatory blood marker C-reactive protein (CRP), which in turn has been associated with higher risk of type 2 diabetes (11,12,13). The positive association between intake of meat and CRP might be explained by several biological pathways. The binding capacity of iron in the body could be exceeded by the intake of meat, which contains high amounts of heme iron. Free iron can increase oxidative stress, thereby acting as proinflammatory agent (14). Advanced glycation end products (AGEs), which occur naturally in meat and are formed through heat processing (15), may also have proinflammatory actions (16). Thus, the observed positive associations between intake of red meat and processed meat and CRP, and CRP and risk of type 2 diabetes may indicate that CRP mediates the association between intake of meat, especially red and processed meat, and risk of type 2 diabetes. Therefore, we investigated whether intake of red meat, processed meat, and poultry was associated with CRP and risk of type 2 diabetes in a Dutch population.