Currently there is no biomarker to link consumption of whole grain cereals and their observed health benefits. A candidate for a biomarker of whole grain wheat and rye intake is a class of phenolic lipids, the alkylresorcinols (AR). Studies to determine the uptake of AR in humans were carried out with a low fiber diet based on white wheat bread (AR free) and a high fiber diet based on rye bran-enriched bread (AR rich). For each diet, two meal frequencies were used: nibbling (7 small meals/d) and ordinary (3 large meals/d). Ten human ileostomy-operated subjects started with the AR-free diet for 2 wk, wk 1 on either nibbling or ordinary and wk 2 on the other meal frequency in a crossover design, followed by a 1-wk washout period, before the AR-rich diet performed as the AR-free diet. Food and ileostomy samples were analyzed for AR. Approximately 40% of AR were recovered in effluent from the small intestine, indicating that 60% of AR are taken up from or converted in the small intestine (ileal digestibility) with no difference between nibbling and ordinary meal frequencies. AR absorbed by humans may be of importance as bioactive compounds, or as a biomarker of whole grain wheat and rye intake.