In a PhD study at the National Food Institute, Sofie Theresa Thomsen has developed a method to calculate the total health impact of replacing one food with another in the diet.
The method was then used to assess the health impact of replacing red and processed meat with fish, so the average intake reaches the recommended weekly intake of 350 grams of fish.
7,000 healthy years gained annually
The risk-benefit assessment weighed up both positive and negative implications for eating more fish in the place of red meat.
Thomsen noted that fish is an important source of healthy fatty acids and vitamin D but may also contain potentially harmful substances such as methylmercury. On the other hand, red and processed meat contributes to the intake of saturated fat in the Danish diet and is associated with the development of different types of cancer. But it is also an important source of nutrients such as dietary iron, the study reported.
Thomsen’s calculations show the Danish population could gain up to 7,000 healthy years of life each year. “They show that the Danish population as a whole can gain up to 7,000 healthy years of life annually, if all adult Danes eat fish in the recommended quantities while at the same time reducing their meat intake.
“This estimate covers among others the prevention of approximately 170 deaths from coronary heart disease per year,” she explained.
However, the health benefit calculation is impacted by a number of variables, including the type of fish people are substituting, as well as the age and sex of the persons whose diet is being altered.
‘Go easy on the tuna’
The study concluded the greatest health benefit comes from eating fatty fish, such as herring and mackerel, or a mixture of fatty and lean fish, such as plaice and pollock. A smaller health gain is achieved by eating only lean fish because fatty fish contain larger amounts of beneficial fatty acids, the research noted.
On the other hand, the calculations show a “significant” health loss if tuna is the only type of fish in the diet, because tuna is both low in beneficial fatty acids and can have high concentrations of methylmercury.
Furthermore, the study shows that it is possible to reduce the proportion of Danes who have an insufficient intake of vitamin D significantly by replacing some of the red and processed meat with a mixture of fatty and lean fish. The study also points out that the proportion of Danes with an insufficient intake of dietary iron will not increase despite the lowered meat intake.
Greatest gains: Men over 50 and pregnant women
The study shows large variations in the overall health impact when the red and processed meat is replaced with fish in the diet.
Everyone over the age of 50—but men in particular—as well as pregnant will reap the greatest health benefits from eating 350 grams of fish weekly, of which 200 grams are fatty fish, the study revealed.
For men, this is because the group as a whole is at higher risk than other population groups of developing cardiovascular disease. The risk is reduced by replacing part of the red meat with fish that contain fatty acids, which can prevent cardiovascular disease.
"In women of childbearing age, the health benefit is particularly large because the intake of fish containing healthy fish oils will not only benefit the women themselves. The health-promoting properties of fish will also have a beneficial effect in the development of their unborn children, which is taken into account in the overall calculations,” Thomsen explained.
