A blood test developed as part of a research study was used to objectively detect whether an individual is adhering to a Mediterranean diet and to explore the link between adherence to the diet and a lower risk of type 2 diabetes.
The Mediterranean diet is a plant-based dietary plan that includes daily intake of whole grains, fruits, vegetables, beans, and lentils, as well as healthy fats like olive oil and nuts. It includes moderate consumption of seafood, cheese, yogurt, and eggs, and far less meat, sweets, and processed foods than a typical Western diet.
Research has shown that people who self-report that they follow a Mediterranean diet have a modestly lower risk of type 2 diabetes. However, self-reports can be subjective. The link between a Mediterranean diet and type 2 diabetes risk had not previously been evaluated using objective biological indicators, or biomarkers, of adherence to the diet.
The findings from the recent study were published Thursday in PLOS Medicine.
The researchers’ novel biomarker-based indicator of a Mediterranean diet measures levels of certain molecules in the blood. First, the researchers identified that blood levels of 24 fatty acids and five carotenoids could predict whether participants from a clinical trial of 128 people had been assigned to follow a Mediterranean diet. Levels of these molecules in a person’s blood were used to calculate a biomarker score, which the researchers used as a measure of the extent to which they were following a Mediterranean diet.
Next, the researchers applied the biomarker score in a study of 340,234 people living in eight European countries, of whom 9,453 developed type 2 diabetes during follow-up and had relevant biomarkers measured. Comparing them with 12,749 participants who remained free of type 2 diabetes, the researchers found that people whose biomarker score indicated greater adherence to a Mediterranean diet were less likely to develop type 2 diabetes.
For comparison, the researchers also asked participants to self-report their diet. They found that using the biomarker score identified a stronger link between the Mediterranean diet and reduced type 2 diabetes risk than when self-report was used. This finding suggests that previous self-report-based studies may have underestimated this association.
Based on these findings, the researchers contend that even a modest improvement in people’s adherence to a Mediterranean diet could meaningfully reduce the incidence of type 2 diabetes. However, since it is currently unknown to what extent the biomarker score is specific to the Mediterranean diet, they note that additional research is needed to confirm their findings.
“Our research, combining information from a dietary clinical trial and a large cohort study to identify and apply blood biomarkers for a dietary pattern, is exciting,” Nita Gandhi Forouhi, senior author and population health and nutrition professor at the University of Cambridge, said in a statement. “It should stimulate development of improved methods to study diet-disease associations which are typically limited by reliance on subjective recall of eating.”