Can meat consumption increase glucose intolerance and insulin resistance?
Obesity is a growing epidemic in the United States and is one of the major contributing factors for diseases such as diabetes. Managing obesity can be challenging and obtaining the benefits from dietary approaches can be difficult. Various factors affect these dietary approaches, including the content of each macronutrient. Macronutrients play an important role in normal metabolic functions of the body. Some diets focus on carbohydrate content, others on the amounts of fats or proteins. Each diet is different and each food group provides different nutritional value. Due to recent advances in food production, meat and sugars have become part of our everyday diets. The impact of sugars in diabetes patients is well-established; however, other food groups lack this evidence to highlight the impact they have in diabetes. Various studies have pointed to the fact that meat can greatly contribute to obesity and ultimately diabetes.
For example, the SUN project followed 18,527 people for a mean of 8.84 years through questionnaires. In this study, Amelia Mari-Sanchis and colleagues sought to understand the effects of processed meats in healthy individuals and their risk of developing type 2 diabetes. After the follow-up period, a cox regression analysis adjusted for confounders highlighted the association between meat consumption and the incidence of type 2 diabetes. It was found that 146 patients who consumed more than three servings of meat per day significantly increased the risk of diabetes (HR 1.85; 95% CI 1.03-3.31; P<0.031). This research ultimately found that processed meats can predispose patients to develop diabetes secondary to obesity (noted as an increase in body mass index).
Similarly, a recent study looked into the effects of meat intake on fasting glucose and insulin concentrations. This meta-analysis study was comprised of 50,345 participants in total from 14 different trials. The analyses showed that unprocessed meat intake was associated with higher fasting glucose levels, but not insulin. Those patients consuming processed red meat were associated with greater concentrations of both insulin and blood glucose. However, these findings were attenuated when researchers adjusted for body mass index (BMI). This can possibly be explained by the independent effect of BMI on meat intake and the levels of insulin and blood glucose. The pathways by which these metabolic effects are seen are quite complex and not well-understood. Hence, other studies looked at these metabolic effects and saw that nitrosamines present in processed meats have toxic effects on pancreatic beta cells. An increase in the markers of inflammation was also seen, which can ultimately lead to injury in the vascular endothelium, thus impairing blood glucose homeostasis. Additionally, the high content of fat may promote obesity in some patients, which can increase the risk of glucose intolerance and insulin resistance. Lastly, another hypothesized mechanism looks into the content of iron in meats and its oxidative effects. Swaminathan and colleagues found that this pro-oxidant effect is due to hydroxyl radical production that leads to pancreatic beta cell secretory dysfunction, further highlighting the impact it has on diabetes.
In conclusion, various studies highlight the impact meat consumption has on diabetes. Processed meats in particular are of greater concern due to the presence of preservatives, additives, nitrates, and nitrites, which can result in toxicity to pancreatic beta cells due to nitrogen deposition. Additionally, the fat content in certain types of meats plays a major role in the development of type 2 diabetes. High content of saturated fats and cholesterol have been noted to have a similar effect, predisposing to obesity and other metabolic imbalances. The mechanism by which meats cause these metabolic effects is not fully understood. Nonetheless, special consideration should be taken when managing a patient’s diet as more evidence is needed in this area. Limiting meat content can help improve health outcomes and decrease overall incidences of obesity and diabetes. However, close monitoring should be implemented when choosing to implement such practices; benefits and risks need to be taken into consideration.
- Greater than 3 servings per day of processed meats can potentially increase the risk of glucose intolerance and insulin resistance.
- Nitrosamines found in certain meat preservatives can have toxic results to pancreatic beta cells, therefore impairing insulin homeostasis.
- Each dietary pattern should be modified based on each patient’s lifestyle and outcomes of their therapy in order to obtain achievable goals.
Researched and prepared by Pablo A. Marrero-Núñez – USF College of Pharmacy Student Delegate – Doctor of Pharmacy Candidate 2017, reviewed by Dave Joffe, BSPharm, CDE
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