Healthy Nordic diet good for both type 2 diabetes and non-alcoholic fatty liver disease

Evaluated the effect of three different diets

The study was a randomised controlled trial in which 150 people with type 2 diabetes, or prediabetes, were randomly assigned to follow one of three diets for one year:

1) An anti-lipogenic diet, meaning a low-carbohydrate diet also low in animal-derived foods and high in polyunsaturated fats derived from plants. Emphasis was placed on high-fat foods such as sunflower oil, walnuts, pumpkin and sunflower seeds, low-carbohydrate vegetables and protein-rich beans, lentils and some lean dairy products.

2) A healthy Nordic diet, which can be seen as a Nordic variant of the Mediterranean diet. It was low in saturated fat, but high in dietary fibre from whole grains, fruits and vegetables, with an emphasis on foods such as oat and rye flakes, oat bran, rye bread, crispbread, rapeseed oil, almonds, apples, pears, blueberries, raspberries, cabbage and peas, along with mackerel and salmon, low-fat natural yoghurt and cultured milk products, and plant-based cooking fat.

3) Control group, meaning usual care based on dietary advice according to the current Nordic Nutrition Recommendations, which is a diet rich in different types of fruits, vegetables, legumes, olive oil, and lean dairy products.

In all three groups, participants were to limit their consumption of red and processed meats, sweetened drinks, sweets and candy, and snacks with added sugar.

The benefits of the Nordic diet surprised the researchers

All three diets were expected to have beneficial effects, but the researchers wanted to investigate which was the most effective in reducing both liver fat and blood glucose levels. That the Nordic diet turned out to be so good surprised the researchers, who had assumed that the anti-lipogenic diet would yield the best results.

“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. 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,” Ulf Risérus explains.

The study also shows that the diets were surprisingly easy to follow.

“Even though the participants were allowed to eat as much as they wanted from the foods recommended, they still lost weight. In many previous studies of different diets, calorie intake has been restricted, which is effective in the short term, but increases hunger and can be difficult to follow in the longer term,” says Michael Fridén, the lead author of the study.

Can be used to treat diabetes

Although some of the beneficial effects of the healthy Nordic diet could be explained by the participants’ weight loss, the researchers found that weight loss only explained just over half (56 per cent) of the effect on liver fat.

“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. There has been a great need to find new, evidence-based diets for long-term diabetes care. Our results are important for future dietary recommendations and are particularly important for overweight people with Type 2 diabetes or prediabetes,” says Ulf Risérus.

The study was funded by Hjärt-lungfonden, the Swedish Government research council Formas, the Swedish Diabetes Foundation, and Excellence of Diabetes Research in Sweden (EXODIAB).

Sandra Gunnarsson