Animal Protein Linked to NAFLD Risk

Results from a study presented at The International Liver Congress suggest that consuming high amounts of animal protein may increase the risk of developing non-alcoholic fatty liver disease (NAFLD). The authors also found that fructose consumption may not be as harmful as previously thought.

NAFLD is characterized by build-up of fat in the liver that can lead to cirrhosis, liver cancer, and other complications that may require a liver transplant. NAFLD can also increase the risk of diabetes and atherosclerosis. NAFLD is diagnosed when fat accumulation composes more than 5% of liver cells.

Approximately 1 billion individuals worldwide have NAFLD, with 20% to 30% of incidences occurring in Western countries. Incidence of NAFLD has been growing along with obesity. While early stage NAFLD can be treated with diet and lifestyle changes, it cannot be reversed once the disease progresses.

Currently, there is much debate about whether weight loss can reverse NAFLD. New evidence suggests that diet can also influence NAFLD. The authors of the current study argue the consuming large amounts of animal protein can influence NAFLD development.

"A healthy lifestyle is the cornerstone of treatment in patients with NAFLD, but specific dietary recommendations are lacking," said lead author Louise Alferink, MD. "The results from this study demonstrate that animal protein is associated with NAFLD in overweight elderly people.”

Many individuals living in Western countries consume a high portion of animal protein, including red and processed meats, which has been suggested to cause numerous health events.

“This is in line with a recently proposed hypothesis that a Western-style diet, rich in animal proteins and refined food items, may cause low-grade disturbances to the body homeostasis, glucose metabolism and acid based balance,” Dr Alferink said.

Included in the study were 3440 patients, of whom 30% were lean and 70% were overweight. Approximately 35% of patients had NAFLD, as diagnosed by ultrasound. Each patient’s macronutrient intake was recorded through food frequency questionnaires, which were assessed by the authors using the nutrition density method, according to the study.

The authors discovered strong associations between macronutrients and NAFLD in overweight patients. Total protein intake was linked to a higher risk of NAFLD, which was mainly driven by the intake of animal protein.

After accounting for metabolic factors, animal protein remained strongly linked to NAFLD, while total protein did not, according to the study.

Additionally, a diet rich in monosaccharides and disaccharides was linked to a lower risk of developing NAFLD.

“Another interesting finding is that, although current guidelines advise against foods containing fructose, such as soda and sugar, our results do not indicate a harmful association of mono- and disaccharides with NAFLD per se,” Dr Alferink said. “In fact, we even found a slight beneficial association, which was attenuated when adjusted for metabolic factors. These results should be interpreted with caution, but we hypothesise [sic] that increased consumption of healthy food items within the mono- and disaccharide-group, such as fruits and vegetables rich in antioxidants, could partly explain these results.”

However, this finding did not remain true after metabolic factors were accounted for, according to the study.

The authors also conducted substitution analyses to determine if replacing 1 macronutrient with an isocaloric macronutrient was linked to NAFLD. The authors did not discover consistent substitution effects, which underscores the need for a diverse diet, according to the study.

"This large population-based study indicates that increased dietary protein, in particular of animal origin, increases the likelihood of developing NAFLD and should be taken into account when counselling patients at risk of developing NAFLD," said Philip Newsome, PhD, Centre for Liver Research & Professor of Experimental Hepatology, University of Birmingham, UK, and European Association for the Study of the Liver Governing Board Member.