Broccoli sprouts: an exceptionally rich source of inducers of enzymes that protect against chemical carcinogens.
Level 5 - mechanism / opinion, no new human data
Preclinical animal model and laboratory biochemical assays without human participants.
PubMed 9294217 · doi:10.1073/pnas.94.19.10367
What was done
Researchers quantified phase 2 detoxication enzyme-inducing glucosinolates (glucoraphanin) in 3-day-old cruciferous sprouts (broccoli and cauliflower) versus mature plants using a low-temperature multi-solvent extraction protocol. They also tested the ability of 3-day-old broccoli sprout extracts to inhibit dimethylbenz(a)anthracene (DMBA)-induced mammary tumorigenesis in a rat model.
What was found
Three-day-old sprouts of certain broccoli and cauliflower cultivars contained 10- to 100-fold higher levels of glucoraphanin than mature plants. Extracts of these sprouts reduced the incidence, multiplicity, and rate of development of mammary tumors in DMBA-treated rats (numerical values were not reported in the abstract). Sprouts also contained negligible amounts of indole glucosinolates compared to mature vegetables.
Why it matters
This paper demonstrated that 3-day-old broccoli sprouts are an exceptionally rich source of phase 2 enzyme inducers (specifically sulforaphane precursors), suggesting that small dietary quantities of young sprouts could offer anticarcinogenic effects comparable to much larger amounts of mature vegetables.
Limits
The study is entirely preclinical (in vitro biochemical assays and a rat carcinogenesis model) with no human clinical data. The abstract does not provide sample sizes, quantitative tumor rates, effect sizes, variance estimates, or safety data.
Cited by
- context Broccoli sprouts contain 100 times more sulforaphane than mature broccoli.