Data
Sulforaphane content by food
Published figures for every common source, each one carrying the method that produced it.
Quick answer
Sulforaphane and glucoraphanin content varies by more than an order of magnitude between studies of the same vegetable. Cultivar, growing conditions, storage, preparation and assay method all move the number. Any single figure quoted without its method is not usable, which is why every row in this table carries one.
Ask how much sulforaphane is in broccoli and you will get answers that differ by a factor of twenty. They are not all wrong. They are measuring different things.
Why this table exists
Sulforaphane figures circulate widely without the information needed to use them. The number depends on:
- Cultivar. Glucoraphanin content varies several-fold between broccoli varieties.
- Plant age. Young sprouts concentrate glucoraphanin far more densely than the mature vegetable. The 1997 study that established this reported three-day sprouts carrying on the order of twenty to fifty times the concentration found in mature broccoli by weight, with wide variation between seed lots.
- Growing conditions and storage. Both sulfur availability in the soil and time since harvest move the result.
- What was measured. Glucoraphanin content and sulforaphane yield are different quantities. Converting between them requires assumptions about hydrolysis that frequently go unstated.
- The assay. HPLC after controlled enzymatic hydrolysis, cyclocondensation assay for total isothiocyanates, and estimation from total glucosinolates give different answers and are not interchangeable.
A figure without its method attached cannot be compared to anything. Every row here carries one.
The table
Table in preparation. Rows are added as each source is verified.
How to read a figure from this table
A value in milligrams per 100 grams fresh weight tells you what was in the sample the researchers measured. It does not tell you what you will absorb.
Between the two sit preparation and conversion. Boiling destroys myrosinase and much of the yield goes with it. Steaming briefly preserves more. Chopping and resting before cooking allows conversion to happen before heat arrives. Chewing does work that swallowing does not.
The table gives you the starting quantity. The page on how much sulforaphane per day covers how much of a dose people absorb.