Milder than onion, high in prebiotic fibre, and grit hides in the layers.
Leeks are alliums, related to onion and garlic. They are high in inulin, a prebiotic fibre that feeds gut bacteria — which is also why they cause gas in some people.
Alliums — onion, garlic, leek, shallot, chives — are among
the most consistently studied vegetables for blood pressure and cholesterol. The active
compounds are organosulphur compounds formed when the cells are cut or
crushed.
They are also high in prebiotic fibre, which feeds gut bacteria and is the
reason alliums are among the most common IBS triggers.
Per 100g raw. Values vary considerably across the allium family.
Based on the nutrients and fibre this food supplies. These are supporting foods, not treatments.
Cut and wait. The beneficial compounds form after the cells are
damaged. Ten minutes between chopping and heat lets the reaction
complete.
Wash leeks properly. Split lengthways and fan the layers
under running water — grit collects deep inside.
Add chives at the very
end. Heat destroys them.
Do not brown them hard if you want
sweetness — gentle heat draws out sugars, high heat makes them bitter.
Cutting an allium ruptures cells and lets an enzyme meet its substrate, producing the
sulphur compounds behind both the smell and the effects. Applying heat immediately deactivates
the enzyme before much has formed.
The inulin content is a genuine double edge. It is
excellent prebiotic fibre that feeds beneficial gut bacteria, and it is also fermented into
gas, which is why onion and garlic top the list of IBS triggers.
IBS: alliums are among the most common triggers, because of the
fructans. Garlic-infused oil carries the flavour without the fructans, which are not
oil-soluble.
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.