Quantitative analysis of absorption, metabolism, and excretion of benzoxazinoids in humans after the consumption of high- and low-benzoxazinoid diets with similar contents of cereal dietary fibres: a crossover study

Benzoxazinoids (BXs) are a group of wholegrain phytochemicals with potential pharmacological properties; however, limited information exists on their absorption, metabolism, and excretion in humans. The aim of this study was to investigate the dose-dependent uptake and excretion of dietary BXs in a healthy population. Blood and urine were collected from 19 healthy participants from a crossover study after a washout, a LOW BX diet or HIGH BX diet, and analysed for 12 BXs and 4 phenoxazinone derivatives. We found that the plasma BX level peaked approximately 3 h after food intake, whereas BXs in urine were present even at 36 h after consuming a meal. No phenoxazinone derivatives could be detected in either plasma or urine. The dominant BX metabolite in both plasma and urine was 2-beta-d-glucopyranosyloxy-1,4-benzoxazin-3-one (HBOA-Glc), even though 2-beta-d-glucopyranosyloxy-4-hydroxy-1,4-benzoxazin-3-one (DIBOA-Glc) was the major component in the diet. The dietary BX treatment correlated well with the plasma and urine levels, illustrating strong dose-dependent BX absorption, which also had a rapid washout, especially from the plasma compartment.