Scientists warn that consumption of diet high in animal protein may increase the risk of a disease which causes fat build-up in the liver, a condition that can lead to cardio vascular diseases or cancer.
The findings also showed that foods containing fructose, such as soda and sugar, may not be as harmful as thought. Non-alcoholic fatty liver disease (NAFLD), is a major health concern, as it can lead to permanent scarring (cirrhosis) and subsequently to cancer and malfunction of the liver.
This may result in life-threatening complications for which a liver transplant is needed. Additionally, NAFLD also contributes to an increased risk of cardiovascular diseases such as diabetes mellitus and atherosclerosis.
NAFLD is diagnosed when accumulation of fat in the organ exceeds 5 per cent of hepatocytes (the cells that make up the majority of the liver).
It is estimated that about one billion people worldwide may have NAFLD with a prevalence of 20-30 per cent in Western countries.
It parallels one of world's most rapidly growing health concerns, obesity, which is also one of the most important risk factors in NAFLD.
In its early stages NAFLD can be treated through diet and lifestyle changes, such as weight loss, but it can progress to more serious liver diseases.
However, there is still a lot of debate whether weight loss alone is enough to reverse NAFLD, while emerging evidence suggests that the composition of the diet, rather than the amount of calories consumed, might also be important in NAFLD.
"A healthy lifestyle is the cornerstone of treatment in patients with NAFLD, but specific dietary recommendations are lacking", said Louise Alferink, from the Erasmus Medical Centre in The Netherlands.
"The results from this study demonstrate that animal protein is associated with NAFLD in overweight elderly people", said Alferink.
"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", he said.
"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", he added.
"In fact, we even found a slight beneficial association, which was attenuated when adjusted for metabolic factors", said Alferink.
"These results should be interpreted with caution, but we hypothesise 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", he said.