A diet built around whole grains, fruits, vegetables and unsaturated fats may offer meaningful benefits for people with type 2 diabetes and non-alcoholic fatty liver disease, according to a new clinical trial from Uppsala University.
In the randomized study, published in Nature Communications, researchers followed 150 adults with type 2 diabetes or prediabetes for one year and compared the effects of three different eating patterns on liver fat, blood sugar control and other metabolic markers. Participants were assigned to follow either a healthy Nordic diet, a low-carbohydrate anti-lipogenic diet high in polyunsaturated fats or standard dietary advice based on current Nordic Nutrition Recommendations.
After one year, the healthy Nordic diet produced the strongest overall results. Participants following this pattern reduced liver fat by just over 20% on average, and more than half experienced remission of fatty liver disease. Blood glucose control also improved more in the Nordic diet group than in either the low-carbohydrate group or the usual-care group.
“This makes these results equally important for people with non-alcoholic fatty liver disease as those with type 2 diabetes,” said Ulf Risérus, professor of clinical nutrition and metabolism at Uppsala University and the study’s senior author.
The healthy Nordic diet emphasized foods commonly eaten in Northern Europe, including whole grains such as oats and rye, fruits and vegetables, berries, legumes, fish, rapeseed oil and low-fat fermented dairy products. Saturated fat intake was kept relatively low, while dietary fiber intake was high. Participants were allowed to eat freely from recommended foods rather than follow a calorie-restricted plan.
The low-carbohydrate anti-lipogenic diet also reduced liver fat and LDL cholesterol, but it did not lead to the same degree of long-term improvement in blood glucose levels. That finding surprised the researchers, who initially expected the low-carbohydrate approach to perform best.
“The study shows that both the anti-lipogenic diet and the Nordic diet were relatively similar in reducing liver fat as well as ‘bad’ LDL cholesterol,” Risérus said. “But the healthy Nordic diet was more effective in reducing blood glucose over the long term and also had more beneficial effects on body weight, inflammation and lipid profile, as well as reducing signs of liver damage.”
Across all three groups, participants were advised to limit red and processed meats, sugar-sweetened beverages, sweets and snack foods with added sugars. Even so, the Nordic diet group showed broader metabolic improvements despite no formal calorie limits.
Although weight loss played a role, it did not fully explain the results. The researchers found that weight loss accounted for just over half of the reduction in liver fat, suggesting that the composition of the diet itself contributed independently to improved liver and metabolic health.
“This is very interesting, as it suggests that the diet itself has contributed to reducing fat deposits in the liver, but probably also to improved blood glucose levels and lipid values as well as reducing inflammation,” Risérus said.
Lead author Michael Fridén noted that adherence was high across all groups, an important consideration for long-term diabetes care. Unlike many dietary studies that rely on calorie restriction, participants in this trial were able to eat to satiety within the recommended food framework.
“There has been a great need to find new, evidence-based diets for long-term diabetes care,” Risérus said. “Our results are important for future dietary recommendations and are particularly relevant for people with type 2 diabetes or prediabetes who also struggle with fatty liver disease.”
The researchers caution that diet should be viewed as a complement to medical care, not a replacement. Still, the findings suggest that a fiber-rich, lower–saturated fat eating pattern rooted in familiar foods may offer a sustainable option for improving metabolic health.
The NAFLDiet study was supported by the Heart-Lung Foundation, the Swedish Research Council FORMAS, the Swedish Diabetes Foundation and Excellence of Diabetes Research in Sweden. Some study foods were donated by the Lantmännen Research Foundation. Open access funding was provided by Uppsala University.