The importance of bioactive secondary compounds become more and more obvious since physiologists and nutritionists proved their antioxidative and radical scavenging properties as well as their anticancerogenic activity. Among these non-nutritive substances phenolic compounds are currently recognized to contribute to the value of vegetables, fruits and beverages. However, there are only some groups of phenolic compounds which have been investigated on a large scale, such as the hydroxycinnamic acids, flavonols, anthocyanidins. In contrast, the flavan-3-ols (catechins and proanthocyanidins) are so far underestimated since the commonly used analytical procedures are not convenient for their quantification. A new sensitive methode including chemical reaction detection (CRD) combined with HPLC has to be applied for the specific determination of flavan-3ols in plant food stuffs and beverages both fresh and after technological treatment. The qualitative and quantitative distribution of flavanols will be estimated in order to assess the dietary intake and their implication for the consumer's health and wellbeing.