Non-alcoholic fatty liver disease, or NAFLD for short, is becoming increasingly common, estimated to affect nearly one-third of adults in Western countries like Australia. It is caused by the accumulation of excess fat in the liver, which can lead to inflammation and scarring, and eventually, liver damage.
There is no single treatment for a fatty liver, but lifestyle modifications, such as dietary changes and weight loss, have been shown to be effective in managing the condition.
A recent systematic review and meta-analysis examined the effectiveness and acceptability of two different dietary interventions for NAFLD: the Mediterranean diet and Calorie (energy) restriction. The researchers analysed data from 26 studies, 23 randomised controlled trials and 3 clinical controlled trials, involving 3037 participants. Of these, 9 studies looked at Calorie-restricted interventions, 13 studied the Mediterranean diet and 4 looked at components of the Mediterranean diet, including increasing intakes of whole grains, reducing red meat consumption and incorporating olive oil into the diet in place of other fats.
The findings of the study showed that both the Mediterranean diet and Calorie restriction were effective in improving liver function and reducing liver fat and liver stiffness in people with NAFLD. There was consistent evidence that Mediterranean dietary interventions improved one or more measures of liver health, and this occurred even with minimal weight loss. However, with Calorie restriction interventions, greater improvements in liver function were seen with higher amounts of weight loss.
The study authors suggest that the combination of Calorie restriction and a Mediterranean-style eating plan may be an achievable strategy to achieve weight loss and improvements in NAFLD.
However, they note that there was a lot of variability between the studies included in the review and many were short to medium term. They suggest that larger long-term studies using consistent outcome measures are needed.
They also highlight the importance of considering the acceptability and sustainability of dietary changes to ensure that an individual with NAFLD who benefits from making dietary changes can maintain these over the long-term. For example, most of the studies looking at the Mediterranean diet were conducted in Mediterranean regions with food environments and cultural dietary habits conducive to this way and eating. Whether these findings would also be seen in populations with different habitual dietary patterns (e.g., South-East Asia) is uncertain, although previous studies have shown that participants from non-Mediterranean populations can adopt and maintain a Mediterranean-style eating pattern for up to a year.
- Haigh and colleagues. The effectiveness and acceptability of Mediterranean diet and calorie restriction in non-alcoholic fatty liver disease (NAFLD): A systematic review and meta-analysis. Clin Nutr. 2022
Dr Kate Marsh is an is an Advanced Accredited Practising Dietitian, Credentialled Diabetes Educator and health and medical writer with a particular interest in plant-based eating and the dietary management of diabetes and polycystic ovary syndrome (PCOS).
Contact: Via her website www.drkatemarsh.com.au