Sulforaphane absorption and excretion from fresh broccoli sprouts and a semi‐purified broccoli powder rich in glucoraphanin in healthy men

Abstract

Glucoraphanin (GRP) from broccoli exhibits properties of cancer prevention only after hydrolysis to the isothiocyanate (ITC) sulforaphane (SF). Our objective was to evaluate the absorption of SF from fresh broccoli sprouts rich in the hydrolyzing enzyme myrosinase and a GRP‐rich broccoli powder lacking myrosinase, individually and in combination. Four subjects each consumed four meals consisting of dry cereal, yogurt and either fresh broccoli sprouts, broccoli powder, both or neither. A seven day washout period separated meals. Blood was collected at 0, 0.5, 1.0, 1.5, 3.0 and 24 h after each meal. Urine was collected over 24 h. The 24 h urinary SF recovery, as the N‐acetyl cysteine conjugate, was 78, 65 and 31% of the GRP ingested from broccoli sprouts, combination and broccoli powder meals, respectively. Sulforaphane recovery was delayed from broccoli powder (1/5 during the first 6 h), compared to the sprouts and combination meals (3/5 during the first 6 h). Plasma ITC appearance was similarly delayed from the broccoli powder. These data are consistent with data from our previous study and indicate a delayed appearance in plasma and urine of SF from the broccoli powder relative to sprouts. Combining broccoli sprouts with the powder favored earlier and elevated levels of SF absorption from broccoli powder, suggesting that sprouts’ myrosinase supports exogenous GRP hydrolysis, offering the potential for development of foods that modify the health impact of broccoli products. (Supported by Univ. of IL)