Sulforaphane absorption and excretion following ingestion of a semi-purified broccoli powder rich in glucoraphanin and broccoli sprouts in healthy men

Abstract

Sulforaphane (SF) is a chemopreventive isothiocyanate (ITC) derived from the myrosinase-catalyzed hydrolysis of glucoraphanin, a thioglucoside present in broccoli. Broccoli supplements often contain glucoraphanin but lack myrosinase, putting in question their ability to provide dietary SF. This study compared the relative absorption of SF from air-dried broccoli sprouts rich in myrosinase and a glucoraphanin-rich broccoli powder lacking myrosinase, individually and in combination. Subjects (n=4) each consumed 4 meals consisting of dry cereal and yogurt with 2 g sprouts, 2 g powder, both, or neither. Blood and urine were analyzed for SF metabolites. The 24 h urinary SF recovery was 74%, 49%, and 19% of the dose ingested from broccoli sprouts, combination, and broccoli powder meals, respectively. Urinary and plasma ITC appearance was delayed from the broccoli powder compared to the sprouts and combination. A liver function panel indicated no toxicity from any treatment at 24 h. These data indicate a delayed appearance in plasma and urine of SF from the broccoli powder relative to SF from myrosinase-rich sprouts. Combining broccoli sprouts with the broccoli powder enhanced SF absorption from broccoli powder, offering the potential for development of foods that modify the health impact of broccoli products.