Intrinsic isotopic 13C labelling of polyphenols

After 34 days of plant growth under 13CO2, degree of labelling was found to be higher than 90 atom% 13C for most polyphenols, predominantly consisting of highly and fully labelled isotopomers; the total plant material contained more than 88 atom% 13C. Such highly labelled compounds can be used in future studies to dissect both metabolism and bioavailability of polyphenols in humans.