Diet-Genetic Interactions – Absorption and metabolism of phytonutrients from different Brassica vegetables

National Cancer Institute, Frederick MD

Investigators

Abstract

The purpose of this agreement is to investigate the absorption and metabolism of phytonutrients from different Brassica vegetables, including broccoli, kale, and bok choy. Flavonoid absorption from Brassica vegetables has not been well evaluated, and absorption & metabolism of isothiocyanates from kale and bok choy have not been well evaluated in humans. This Inter-Agency Agreement will capitalize on joint expertise of the NCI DCP NSRG and the USDA Beltsville Human Nutrition Research Center to conduct a human feeding study to better evaluate absorption of phytonutrients from Brassica vegetables. Volunteers will consume a Brassica-free diet to wash out isothiocyanates and flavonoids. After the washout period, volunteers will report to the USDA Nutrition Center for a pharmacokinetic challenge. A nurse will fit the volunteer with a venous catheter and a baseline blood sample will be collected, as well as a baseline urine sample. Volunteers will then consume a Brassica challenge dose. The dose will be 200 grams of a single Brassica vegetable with 16 ounces of water. Following the dose, blood samples will be collected hourly and urine will be collected every 2 hours for 6 hours. Flavonoids and isothiocyanates in plasma and urine will be evaluated by HPLC and LC-MS. Gene expression after consumption will be compared amongst the different Brassica vegetables and compared to a placebo meal, with focus on cancer pathways.