Scientists have linked the Northern diet with a reduced risk of death

A healthy northern diet may be associated with a reduced risk of death, but its ability to prevent severe liver disease remains unconfirmed. This conclusion was reached by researchers who studied the data of more than 64 thousand Swedish residents over 24 years. Using a statistical model, they assessed how the risks might change with prolonged adherence to different diet options. What is included in the northern diet, how to understand the figures obtained and why the overall benefit of nutrition does not guarantee protection from a particular disease — in the Izvestia article.

The Northern diet without exotics

The Northern, or Nordic, diet relies on foods that are traditional to the Nordic countries. In its healthy version, vegetables, berries, whole grains, fish and dairy products with low fat content occupy an important place.

Unlike short-term diets for weight loss, we are talking about the composition of a habitual diet for a long time. Scientists do not evaluate the effect of a single product, but a combination of different food groups and their place in the daily diet.

Similar principles are reflected in the Northern Nutrition Guidelines of 2023. They provide a predominantly plant-based diet: vegetables, fruits, berries, legumes, potatoes, and whole grains. Fish and nuts, moderate amounts of low-fat dairy products, restriction of red meat, and minimal consumption of processed meat and foods with high amounts of salt and sugar are also recommended.

Such principles can be represented through quite familiar dishes: whole grain porridge, vegetable side dish, fish, legumes and berries. What matters is the general structure of the diet, not the origin of products from a particular country.

Scientists have linked a plant-based diet to a reduction in liver fat

How scientists tracked nutrition over 24 years

The work led by Michael Frieden, a researcher at Aarhus University, was published in The American Journal of Clinical Nutrition. The analysis included 64,406 middle-aged and older men and women from two Swedish population-based studies. Nutritional information was collected repeatedly: in 1997, in 2008-2009, and in 2019. The participants filled out questionnaires about their eating habits. This allowed for dietary changes, although it did not provide a continuous record of everything a person had eaten over the decades.

The responses were compared with medical registers: data on hospitalizations, outpatient care, oncological diseases and deaths. The researchers were interested in severe adverse liver outcomes, including cirrhosis and cancer, as well as death from any cause.

The authors compared the scenarios of compliance with a healthy northern diet adapted to the study population, a diet based on the recommendations of NNR2023 and the absence of a simulated intervention in nutrition.

What did the calculations show for life expectancy?

For a healthy Northern diet, the model showed a 2.67 percentage point reduction in the 24-year risk of death from any cause compared to the scenario without dietary intervention. This is the absolute risk difference over the entire period. In terms of a conditional thousand people, it would mean about 27 fewer deaths in 24 years — under the conditions and assumptions of the model.

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The confidence interval for this difference corresponded to a decrease of 1.85–3.51 percentage points. Thus, the calculation indicated a reduction in risk, although the exact magnitude of the possible effect remains uncertain.

Why convincing protection of the liver failed

For severe liver diseases, the results were less certain. The estimated risk over 24 years was 0.53% with a healthy Northern diet, 0.70% with a diet based on NNR2023 recommendations, and 0.64% without intervention.

According to point estimates, a healthy northern diet looked preferable to a regular diet. However, the difference was only 0.11 percentage points, and the confidence interval included zero effect. This means that the authors did not establish a statistically convincing reduction in risk.

The same problem occurred with other comparisons. Therefore, the values of 0.53%, 0.70% and 0.64% cannot be used as a proven rating of diets for the ability to protect the liver.

This conclusion does not prove a complete lack of benefits for the liver. It shows that it was not possible to reliably confirm a reduction in the risk of severe outcomes in this analysis.

How to understand the result in everyday life

The Northern diet is interesting primarily as a sustainable way to build a diet around a variety of plant foods, whole grains, and fish. This approach is based on eating habits that persist for a long time.

The NNR2023 recommendations, for example, provide a guideline of 500-800 g of vegetables, fruits and berries per day, as well as 300-450 g of fish per week, including at least 200 g of oily fish. These values relate to general regional recommendations; in the study, the scientists modeled adapted diet options.

The findings support interest in a healthy Northern diet, but do not turn it into a proven way to prevent severe liver diseases. Studies in other populations and additional data are needed to verify this effect.