Our paper was intended to provide a critical view of our present knowledge on proanthocyanidins, one of the major classes of polyphenols present in food. The focus was placed on their chemistry, physico-chemistry, and health effects. Two main reasons may explain why this paper has been highly cited. Firstly, we have seen a rapid development of the research on polyphenols and their effects on human health. Secondly, research on proanthocyanidins is facing specific obstacles due their polymeric nature, lack of commercialized standards, and difficulties in their analysis. We were among the first to stress their quantitative importance in food and to summarize their biological effects in a critical way.

“We were among the first to stress their quantitative importance in food and to summarize their biological effects in a critical way.”

This paper does not describe a new discovery. It is a review that came out of a position paper of the European NEODIET (Nutrient Enhancement Of Dietary Ingredients In European Trade) concerted action, one of whose objectives was to identify research challenges regarding potentially beneficial factors in plant-food, with the aim to encourage scientists to carefully target their research on priority needs. Thus—literature from different fields—chemistry, biology, food science, nutrition, or epidemiology was examined and discussed in a synthetic way. Data about dietary proanthocyanidins, which initially appeared to be somewhat contradictory—for example, they have been considered pro- or anti-carcinogenic depending on the authors—were systematized in what we expected to be clear and concise statements.

This is the second of our publications which has been selected as a Fast Moving Front in Agriculture Sciences—the previous selection was one entitled "Dietary intake and bioavailability of polyphenols" as published in the J. Nutr.130, 2073S, 2000. Both are review papers. Many reviews are more like lists of references and do not receive much attention. My coauthor Augustin Scalbert—when a Ph.D. student—remembers his tutor urging him to write a review paper because it was something good to add as a line in a CV. He chose to wait a little longer to produce an original review thought to be useful for other researchers. With this in mind, his article entitled: "Antimicrobial properties of tannins" was published in 1991 in Phytochemistry, 30: 3875 and has been cited over 200 times.

Celestino Santos-Buelga: I am a food chemist and began working on phenolics over 15 years ago. My research was first focused on anthocyanins and flavanols—i.e., catechins and proanthocyanidins—in grapes and wines and their relation with definition and stability of color in red wine. The knowledge I gained in proanthocyanidin chemistry and analysis led me to begin, in the mid-1990s, an alternative line of research about dietary proanthocyanidins (occurrence, intake) and their biological effects. The bulk of my research in this field has been developed at the University of Salamanca (Spain) with periodic stays as a visiting researcher in other European laboratories, along with regular external collaborations through concerted and bilateral partnerships in European Union projects.

Augustin Scalbert began his research at the Institut National de la Recherche Agronomique on the chemistry of the main polyphenols present in wood and bark (lignins and tannins). Later, after having realized that major progress had been made earlier when the first mass and NMR spectrometers were introduced in research laboratories, he decided to be involved in biology research and more particularly on the role of the diet in the prevention of diseases.

Our collaboration was easy to start with a focus on proanthocyanidins as I had been working on the chemistry and properties of proanthocyanidins for a few years already.

Anybody can easily recognize the presence of proanthocyanidins in food and beverages. As phenolic polymers, they interact with mucosal and saliva proteins in the mouth and are responsible for their puckering effect when, for example biting a grape seed or grape skin or when tasting cider or a young and tannic red wine. This astringency contributes to deter herbivores from feeding on proanthocyanidin-containing fruits before seed maturity. Later, this astringency is lost by further polymerization with aldehydes, as has been well demonstrated in the persimmon fruit. This paper summarizes such data and also stresses the possible role of proanthocyanidins in human health and in the mechanisms of action which cannot be directly perceived by the consumer.