Mol Nutr Food Res. 2012 Dec;56(12):1906-16. doi: 10.1002/mnfr.201200225. Epub 2012 Oct 27.
- 1
- Institute of Food Research, Norwich Research Park, Norwich, UK.
Abstract
SCOPE:
Sulforaphane
(a potent anticarcinogenic isothiocyanate derived from glucoraphanin)
is widely considered responsible for the protective effects of broccoli consumption. Broccoli
is typically purchased fresh or frozen and cooked before consumption.
We compared the bioavailability and metabolism of sulforaphane from
portions of lightly cooked fresh or frozen broccoli, and investigated the bioconversion of sulforaphane to erucin.
METHODS AND RESULTS:
Eighteen healthy volunteers consumed broccoli soups produced from fresh or frozen broccoli
florets that had been lightly cooked and sulforaphane thio-conjugates
quantified in plasma and urine. Sulforaphane bioavailability was about
tenfold higher for the soups made from fresh compared to frozen broccoli,
and the reduction was shown to be due to destruction of myrosinase
activity by the commercial blanching-freezing process. Sulforaphane
appeared in plasma and urine in its free form and as several
thio-conjugates forms. Erucin N-acetyl-cysteine conjugate was a
significant urinary metabolite, and it was shown that human gut
microflora can produce sulforaphane, erucin, and their nitriles from
glucoraphanin.
CONCLUSION:
The short period of blanching used to produce commercial frozen broccoli
destroys myrosinase and substantially reduces sulforaphane
bioavailability. Sulforaphane was converted to erucin and excreted in
urine, and it was shown that human colonic flora were capable of this
conversion.
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
