FROM JOURNAL OF HEPATOLOGY
Higher dietary intake of red meat and processed meats such as salami may increase the risk of nonalcoholic fatty liver disease and insulin resistance, new research suggests.
In a cross-sectional study, published in the March 20 edition of the Journal of Hepatology , researchers used food-frequency questionnaires to examine red and processed meat consumption in 789 adults aged 40-70 years, including information on cooking methods.
They found that those who reported a total meat intake above the median had a significant 49% higher odds of nonalcoholic fatty liver disease (NAFLD) (95% confidence interval, 1.05-2.13; P = .028) and 63% greater odds of insulin resistance (95% CI, 1.12-2.37, P = .011), even after adjustment for potential confounders such as body mass index, physical activity, smoking, alcohol, and saturated fat and cholesterol intake.
Those whose intake of red and/or processed meat was above the median had a 47% greater odds of NAFLD (P = .031), and a 55% greater odds of insulin resistance (P = .020).
Even when the analysis was limited to nondiabetic participants, the study still showed a significant relationship between higher intake of red and processed meat, and insulin resistance (J Hepatol. 2018 Mar 20. doi: 10.1016/j.jhep.2018.01.015).
“It can be claimed that the harmful association with meat may, at least partially, be related to a generally less healthy diet or lifestyle characterizing people who eat more red or processed meat, rather than a causal effect of meat,” wrote Shira Zelber-Sagi, PhD, of the department of gastroenterology at Tel Aviv Medical Center, and coauthors. “However, in the current study we meticulously adjusted the association with meat for other nutritional and lifestyle parameters to minimize confounding as much as possible.”
There was also a significant association between unhealthy cooking methods such as frying, broiling, and grilling – which are known to increase the quantity of heterocyclic amines (HCA) in the meat – and insulin resistance.
Individuals who ate one or more portions of meat cooked by these methods showed a higher incidence of insulin resistance compared with those who ate fewer than one portion per week (36.00% vs. 22.20%, P = .004). Researchers also used the food-frequency questionnaires to calculate the quantity of participants’ HCA intake, and found a significantly higher odds of insulin resistance in individuals whose HCA intake was above the median.
Even among the 305 individuals with NAFLD, higher total meat intake, and higher red and processed meat intake, the prevalence of insulin resistance was higher.
In this group, high HCA intake and high consumption of meat cooked by the unhealthy methods were associated with a fourfold higher odds of insulin resistance.
“Potential mechanisms for NAFLD may be related to the formation of reactive species during HCA metabolism, which can cause oxidation of lipids, proteins, and nucleic acids, resulting in oxidative stress, cell damage, and loss of biological function,” the authors wrote. “HCAs were also demonstrated to be bioactive in adipocytes in vitro, leading to increased expression of genes related to inflammation, diabetes and cancer risk.”
The authors noted that their findings supported the recommendations in dietary guidelines for cardiometabolic health, which suggest no more than one to two 100-g servings per week of red meat, and no more than one 50-g serving per week of processed meats.
“Although the specific effect of different types of meat and their quantities in NAFLD requires further research, these recommendations may be helpful in the treatment of patients with NAFLD at least in terms of CVD and diabetes prevention, and maybe for NAFLD prevention by reducing insulin resistance.”
The Israeli Ministry of Health supported the study. No conflicts of interest were declared.
SOURCE: Zelber-Sagi S et al. J Hepatol. 2018 Mar 20. doi: 10.1016/j.jhep.2018.01.015 .