Total (poly)phenol analysis by the Folin-Ciocalteu assay as an anti-inflammatory biomarker in biological samples

The Folin-Ciocalteu method is a well-established and widely used assay for measuring total (poly)phenol content in food/plant products. In recent years, there has been growing interest in applying this method to human samples due to its simplicity and efficacy. However, biological matrices such as blood and urine contain several interference substances that must be eliminated beforehand. This mini-review summarizes the current state of knowledge regarding the use of the Folin-Ciocalteu assay to measure total phenolic content in human urine and blood samples, as well as the preceding cleaning methods to remove interferences. Higher total (poly)phenol levels measured by the Folin-Ciocalteu method have been associated with a decrease in mortality and several risk variables. We focus on the application of this sustainable assay as a biomarker of poly(phenol) intake and its potential use as an anti-inflammatory biomarker in clinical laboratories. The Folin-Ciocalteu method, with a clean-up extraction step, is a reliable tool for determining total (poly)phenol consumption. Here, we also recommend using the Folin-Ciocalteu assay as means to measure anti-inflammatory activity.