cruciferous vegetable
Meaning of cruciferous vegetable: The cabbage family, named for its cross-shaped flowers and marked out chemically by the sulfur compounds behind its bitterness.
Definition of cruciferous vegetable
Cruciferous vegetables are members of the cabbage family, whose four petals form the shape of a cross. Broccoli, cauliflower, kale, cabbage, Brussels sprouts, bok choy, watercress, turnips and radishes all belong to it. They share a group of sulfur-containing compounds called glucosinolates, which give them their sharp taste and their strong smell during cooking.
What makes them chemically distinctive?
These plants store glucosinolates, sulfur compounds that sit harmlessly inside the cell until the tissue is damaged. Chewing, chopping or crushing breaks the cell walls and releases an enzyme called myrosinase, which converts the stored compound into substances known as isothiocyanates. Those are responsible for the peppery bite of a radish and the sulfurous smell of overcooked cabbage. In the living plant the same reaction is a defense, so an insect biting into a leaf gets a mouthful of irritant.
Do they affect cancer risk?
Isothiocyanates, and sulforaphane from broccoli in particular, are among the most studied plant compounds in laboratory cancer research. They switch on the cell's own detoxifying enzymes, slow the growth of tumor cells in culture and push those cells toward self-destruction. In people the picture is much less clear. Population studies show weak and inconsistent associations, and trials of concentrated extracts have not shown that they prevent cancer. Part of the difficulty is that cooking changes everything: boiling destroys the enzyme and leaches the compounds into the water, while brief steaming preserves both.
How do they differ from one another?
| Vegetable | Notable feature |
|---|---|
| Broccoli and broccoli sprouts | Highest sulforaphane content |
| Cabbage and Brussels sprouts | Strong sulfur smell when overcooked |
| Kale and collard greens | Rich in vitamin K |
| Radish, watercress, mustard greens | Sharp peppery taste |
All of them count as a nonstarchy vegetable, low in calories and useful sources of fiber, vitamin C and folate.
Are there reasons to limit them?
Large quantities contain compounds that interfere with the thyroid gland's uptake of iodine, an effect that matters mainly where dietary iodine is already scarce, and cooking reduces it. The vitamin K content interacts with warfarin, a blood-thinning medicine whose dose is set against a steady vitamin K intake, so sudden large swings in consumption alter how the drug behaves. The fiber and sulfur compounds also produce gas, which is the usual complaint about them.
Also known as
Used in a sentence
The dietary assessment recorded a regular intake of cruciferous vegetables.
Good to know
The vitamin K in these vegetables affects warfarin control, so steadiness of intake matters more than the amount eaten.
Word origin
Where “cruciferous vegetable” comes from
From the Latin crux, meaning cross, and ferre, to bear, describing the four petals set in the shape of a cross.