ABSTRACT
Polyphenols are considered to be key active constituents of fruits and vegetables and
responsible for many of the health protective effects of diets rich in these foods. While their
structure varies considerably, following ingestion, most (w95%) persist to the colon where they encounter the human gut microbiota. Here they may undergo considerable structural
alteration to compounds that may have enhanced biological properties or possibly degraded
into inert metabolites and excreted. As such, the human gut microbiota may have a
significant influence on the final outcomes of polyphenol ingestion. Moreover, inter-
individual variation in the composition of the microbiota means that certain compounds are
metabolized in different ways, and this is reflected in the considerable variability seen in
excreted polyphenol metabolites. Consequently, polyphenols as active ingredients in
functional foods may turn out to be beneficial for only a certain proportion of the
population. Clearly, this may further have an impact on disease risk and health protection.
This chapter considers the potential role of the human gut microbiota in polyphenol
metabolism and highlights the level of current understanding of this process.
