Harnessing The Power Of Cruciferous Vegetables: Developing A Biomarker For Brassica Vegetable Consumption Using Urinary 3,3´-Diindolylmethane

Abstract

Glucobrassicin gives rise to indole-3-carbinol (I3C), a compound with potent anti-cancer effects in preclinical models. We previously showed that urinary 3,3´-diindolylmethane (DIM, the predominate metabolite of I3C), can discriminate between consumption of high and low doses of glucobrassicin-containing vegetables. However, the quantitative relationship between glucobrassicin exposure and urinary DIM level is unclear. We hypothesized that a range of glucobrassicin exposure from Brassica vegetables is reflected in urinary DIM and that this effect plateaus. Forty-five subjects consumed vegetables at 1 of 7 discrete dose levels (25 to 500 umol) of glucobrassicin for 2 days. Urine was collected for 24 hours afterward, and DIM was measured by LC/ESI-MS/MS-SRM. Urinary DIM excretion increased predictably with increasing glucobrassicin dose, plateauing between 200 and 300 umol of glucobrassicin. Glucobrassicin dose and urinary DIM correlated (R=0.82). The positive and strong correlation between glucobrassicin dose and urinary DIM supports its use as a biomarker of glucobrassicin exposure and I3C uptake.