Profile of Polyphenols in a European Diet
- Dietary phenolic compounds are secondary metabolites, widely distributed in the plant kingdom and consumed in large amounts in the human diet. Studies have shown a positive correlation between an increased consumption of polyphenols and a reduced risk of cardiovascular disease, neurodegenerative diseases and certain types of cancer, suggesting that these compounds are beneficial for human health. Besides the strong antioxidant capacities, dietary polyphenols have been shown to posses other properties by which cell activities are regulated. An accurate assessment on the nature and distribution of these compounds in diet enables epidemiological analysis to realize the relation between the intake of these substances and the risk of development of several diseases. Such an assessment requires a polyphenol intake database to support clinical and epidemiological studies. The present research studies the main contributors to human polyphenol intake in a typical European diet by profiling the polyphenol content of a number of selected fruits and vegetables contributing most to an average European daily polyphenol intake. A total of 42 methanolic extractions from the fleshes and peels of 20 different fruits and vegetables were prepared and subjected to chemical characterisation using HPLC interfacing of an ESI-Ion Trap mass spectrometer or an ESI-TOF mass spectrometer. The peaks in tandem MS chromatograms were assigned based on the structural information of the most commonly occurring food polyphenols reported in the literature. The presence of more than 60 different compounds was confirmed using this method. For most fruits and vegetables the number of qualitatively observed polyphenols was considerably lower than reported in the literature. However, around 20 compounds not previously described in the literature could be identified. Storage of the samples was investigated and it was observed that after 12 months refrigeration, the majority of phenolic constituents had decomposed. A new approach, Van Krevelen analysis, was applied for identification of further unassigned peaks in the mass spectra. Findings on polyphenolic contents of the samples, compared and confirmed with the literature and the polyphenolic compounds which have not been reported in a specific fruit or vegetable so far, reported for each sample individually
