New biomarkers to measure actual fish intake

The challenge

Accurately understanding what people really eat is essential to assess the impact of diet on health. Although many individuals report following a healthy diet or complying with nutritional guidelines, traditional methods to measure intake—such as surveys or food diaries—have clear limitations. Foods may be forgotten, portion sizes underestimated, or responses influenced by subjective perception, compromising data reliability.

On the other hand, more precise methods, such as conventional blood analyses, require travel, specialised personnel and equipment, making them difficult to apply in large-scale population studies or broad nutritional programmes.

The solution

A promising alternative is the Dried Blood Spot (DBS) system, a technique that allows blood samples to be collected, stored and transported on a special paper card. Instead of using tubes with liquid blood, a few drops of blood (obtained via a finger prick) are placed on the paper. This minimally invasive method, easy to perform even at home, greatly simplifies sample collection and facilitates access to objective nutritional information.

The results

• A study carried out at AZTI has shown that the DBS system can detect changes in blood omega-3 fatty acid levels depending on fish intake. For example, the omega-3 fatty acid EPA increased rapidly after fish consumption, while other omega-3s such as DHA required more time to show changes. These findings confirm that the DBS technique can reflect both short-term dietary changes and longer-term consumption patterns.
• This advance in applied lipidomics opens up new possibilities for developing reliable, accessible and scalable nutritional biomarkers, enabling objective assessment of the intake of key foods such as fish and improving the quality of nutritional studies and public health strategies.