Peppery when raw, sweet when roasted — and the greens beat the root.
Turnips are sharp raw and become distinctly sweet when roasted. As with radish, the leaves carry more nutrition than the root.
Brassicas share glucosinolates — sulphur compounds that break
down into isothiocyanates when chopped or chewed. These are behind most of the research
interest in the cabbage family, and behind the bitter or peppery edge.
They are also
consistently high in vitamin C and vitamin K for very few calories.
Per 100g raw.
Based on the nutrients and fibre this food supplies. These are supporting foods, not treatments.
Small turnips are sweeter. Large ones turn woody and bitter.
Roast rather than boil — the sugars caramelise and the flavour changes completely.
Do not boil brassicas to death. Prolonged boiling
releases the sulphur smell and leaches the water-soluble vitamins into water you then pour
away.
Steam, roast or stir-fry instead.
Glucosinolates convert to isothiocyanates via an enzyme called myrosinase, released
when plant cells are damaged. Heavy cooking destroys myrosinase, which is why very well-cooked
brassicas produce fewer of these compounds than lightly cooked or raw ones.
Chopping
and then waiting a few minutes before cooking lets the reaction happen first — the same
principle as resting crushed garlic.
On blood thinners: high in vitamin K, which interacts with warfarin.
You do not have to avoid it — keep intake steady rather than swinging week to week, and
tell your doctor.
Kidney disease: potassium may need limiting. Ask your doctor for your
numbers.
IBS: several vegetables are high-FODMAP and commonly trigger
symptoms — tolerance is personal.
This is information, not a prescription. If you are managing a diagnosed condition or taking medication, talk to your doctor before making a large change to your diet.
Nutrition figures on this page come from standard food composition data. These links let you check the numbers and read the underlying research yourself rather than taking our word for it.