New results from the Nordic SYSDIET study, recently published in the Journal of Nutrition, show that it is possible to assess dietary compliance from a blood sample. This is especially useful in controlled dietary intervention studies investigating the health benefits of specific diets, and it has the potential to supplement notoriously unreliable self-reporting on dietary compliance.
A Scandinavian research team was able to identify the study participants with the greatest apparent compliance to a healthy Nordic diet by testing for a set of diet-related biomarkers in the blood. The beneficial effects of the diet on cardiometabolic risk factors, such as elevated blood pressure and blood lipids, were also greatest in this group. There were 154 participants in the study.
Dietary biomarkers are compounds related to a certain food or nutrient that are measurable in bodily tissues and fluids such as blood. In the SYSDIET study, the intervention group was advised to follow a healthy Nordic diet rich in berries, vegetables, fatty fish, canola oil, and whole grains. Several blood biomarkers were assessed to reflect the consumption of different key components of the diet, such as serum alpha linoleic acid as a biomarker of canola oil consumption, EPA and DHA reflecting fatty fish consumption, plasma beta carotene as a biomarker for vegetable intake, and plasma alkylresorcinols reflecting whole grain consumption. High-fat dairy intake, which should be low in the healthy Nordic diet, was reflected by serum pentadecanoic acid.
The researchers conclude that when investigating the health effects of whole diets, it's useful to measure multiple biomarkers reflecting the intake of different components of the diet. This way of assessing compliance also helps to better detect changes in risk factors. Read the study abstract.
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