Linaceae
Linum usitatissimum
Flax · Linseed
- Part used
- seed
- Native range
- A cultigen of the Fertile Crescent; among the oldest domesticated plants
- Morphology
- A slender annual to a metre with narrow alternate leaves and pale blue five-petalled flowers, each lasting a single morning, followed by round capsules of glossy brown seeds.
What is in it
Evidence
Good evidence as a bulk-forming laxative and reasonable evidence for modest reductions in blood pressure and cholesterol. Lignan effects on hormone-sensitive conditions are studied and unresolved.
Safety
Must be taken with adequate fluid; bulk laxatives without water can cause obstruction. Raw or immature seed contains cyanogenic glycosides in quantities that matter at high intake. Oestrogenic lignan activity means caution in hormone-sensitive cancers.
Interactions: May slow absorption of other oral drugs taken at the same time; Additive with anticoagulants at high intake
Regulatory: Permitted as a food and as a listed medicine ingredient.
How the traditions classify it
Three systems, rating the same plant. Where they disagree, none of them is correcting the others — they are separate frameworks that arrived at their categories independently.
Historical use
Cultivated for fibre and oil for at least eight thousand years, and used medicinally as a demulcent poultice and a laxative. Its species name means most useful.
Recorded as history and attributed where possible. Long use establishes that a plant was widely used, not that it worked, and not that it was safe.
Worth knowing
Flax is a reminder that a plant can be enormously important without being interesting pharmacologically. It clothed Europe for eight thousand years, it produced linseed oil for paint and putty, and its medicinal action is essentially mechanical: mucilage swells in water and moves the bowel.
That mechanical action is also why its evidence is among the better in this collection. A bulk laxative does not need to be absorbed, does not need a receptor, and does not depend on the preparation surviving the liver. It just needs to be swallowed with enough water.
Nomenclature verified against GBIF backbone taxonomy.