Nonalcoholic fatty liver disease is a serious condition and a growing concern in Western societies. A recent, large-scale study finds an increase in risk with the consumption of animal protein.
Nonalcoholic fatty liver disease (NAFLD), as the name suggests, is a buildup of fat in the cells of the liver that is not related to alcohol consumption.
Although the liver contains quantities of fat in healthy individuals, if this quantity exceeds 5 to 10 percent of the total weight of the liver, it is considered as NAFLD.
NAFLD is a serious condition. It can lead to permanent scarring of the liver (known as cirrhosis) and potentially contribute to liver dysfunction and cancer. It is also a risk factor for type 2 diabetes, atherosclerosis, and other cardiovascular diseases.
Because one of the risk factors for developing NAFLD is obesity, the condition is increasing in line with the obesity epidemic. Currently, an estimated 20 to 30 percent of Western adults are thought to have NAFLD. Globally, as many as 1 billion people may have NAFLD.
In the early stages, weight loss and other lifestyle changes can be enough to prevent the disease from progressing to liver damage. Recent research also infers that the types of foods we eat might also play a role in the disease. To date, however, it has not been possible to draw exact dietary guidelines.
As lead study author Dr. Louise Alferink, from the Erasmus Medical Centre in Rotterdam, in the Netherlands, explains: “A healthy lifestyle is the cornerstone of treatment in patients with NAFLD, but specific dietary recommendations are lacking.”
A group of researchers recently set out to look at the influence of dietary components on NAFLD in elderly adults. They used participants from the Rotterdam Study, and their findings were presented this week at the International Liver Congress in Amsterdam, in the Netherlands.
The Rotterdam Study is an ongoing population-based research project. For the current study, data from 3,440 people were collated. Thirty percent of the participants were considered lean and the remaining 70 percent were overweight. The average age was 71, and their diet was assessed using a 389-item food frequency questionnaire.
NAFLD was found, using an ultrasound scan, in 35 percent of the participants.
Once the analysis was complete, the researchers found some significant associations between diet and NAFLD risk, with these associations being most pronounced in overweight individuals.
Total protein intake was linked to an increased risk of NAFLD, which was primarily driven by animal protein. Once metabolic factors were adjusted for, animal protein – but not total protein – remained a significant risk factor.
“The results from this study demonstrate that animal protein is associated with NAFLD in overweight elderly people. 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. Louise Alferink
Interestingly, the study appears to overturn another dietary theory associated with NAFLD. As Dr. Alferink explains:
“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. In fact, we even found a slight beneficial association, which was attenuated when adjusted for metabolic factors.”
The authors believe that this nonsignificant positive interaction might be because of healthy food items in the mono- and disaccharide food groups, such as fruits and vegetables, which are both rich in antioxidants.
These findings regarding fructose and meat consumption, if replicated, may help to inform doctors and patients of ways in which diet can be modified to either improve or prevent NAFLD from developing.