Abstract/Summary

Broccoli contains the glucosinolate glucoraphanin which, in the presence of myrosinase, can hydrolyse to the isothiocyanate sulforaphane, reported to have anti-carcinogenic activity. However, the myrosinase enzyme is denatured on cooking. Addition of an active source of myrosinase, such as from powdered mustard seed, to cooked brassica vegetables can increase the release of health beneficial isothiocyanates, however this has not previously been proven in-vivo. The concentration of sulforaphane metabolite (sulforaphane N-acetyl-L-cysteine (SF-NAC) in 12 healthy adults after the consumption of 200g cooked broccoli, with and without 1 g powdered brown mustard, was studied in a randomized crossover design. During the 24 hour period following consumption of the study sample all urine was collected. SF-NAC content was assayed by HPLC. When study subjects ingested cooked broccoli alone, mean urinary SF-NAC excreted was 9.8 ± 5.1 µmol per g creatinine, whilst when cooked broccoli was consumed with mustard powder this increased significantly to 44.7 ± 33.9 µmol SF-NAC per g creatinine. These results conclude that when powdered brown mustard is added to cooked broccoli the bioavailability of sulforaphane is over four times greater than that from cooked broccoli ingested alone.