The effect of different meals on the absorption of stable isotope-labelled phylloquinone

Abstract

Few studies have investigated the absorption of phylloquinone (vitamin K1). We recruited twelve healthy, non-obese adults. On each study day, fasted subjects took a capsule containing 20μg of 13C-labelled phylloquinone with one of three meals, defined as convenience, cosmopolitan and animal-oriented, in a three-way crossover design. The meals were formulated from the characteristics of clusters identified in dietary pattern analysis of data from the National Diet and Nutrition Survey conducted in 2000-1. Plasma phylloquinone concentration and isotopic enrichment were measured over 8h. Significantly more phylloquinone tracer was absorbed when consumed with the cosmopolitan and animal-oriented meals than with the convenience meal (P=0.001 and 0.035, respectively). Estimates of the relative availability of phylloquinone from the meals were: convenience meal=1.00; cosmopolitan meal=0.31; animal-oriented meal=0.23. Combining the tracer data with availability estimates for phylloquinone from the meals provides overall relative bioavailability values of convenience=100, cosmopolitan=046 and animal-oriented=0.29. Stable isotopes provide a useful tool to investigate further the bioavailability of low doses of phylloquinone. Different meals can affect the absorption of free phylloquinone. The meal-based study design used in the present work provides an approach that reflects more closely the way foods are eaten in a free-living population.