THE PART OF RHUBARB EXPERTS SAY YOU MUST NEVER EAT – AND THE HIDDEN DAMAGE IT CAN QUIETLY DO TO YOUR GUT AND KIDNEYS

Rhubarb is a spring staple in British crumbles, yet its oversized leaves hide potent natural toxins. Here is how to enjoy the stalks while keeping families, pets and soil safe.

Every spring, clumps of rhubarb burst back into life on British plots, promising tangy crumbles, pies and jams. Yet tucked behind those glamorous red stalks are oversized leaves loaded with natural chemicals that behave very differently in the body.

Rhubarb is unusual because one part of the plant supports digestion with fibre, vitamins and mild laxative compounds, while another part can upset the stomach and burden the kidneys if it ends up on your plate. Understanding that divide is what keeps the plant safe.

Rhubarb leaves, stalks and what is really inside

Botanically, rhubarb is a perennial that thrives in the UK, but only the leaf stalks are meant to be eaten. Herbal guides are clear that the broad green blades contain high levels of oxalic acid and must be discarded.

Those edible stalks are rich in gentle dietary fibre and derivatives of anthraquinone, substances that stimulate the bowel and have made rhubarb a traditional remedy for occasional constipation when used in modest doses.

Analyses also point to stilbene-type compounds and minerals such as phosphorus, potassium, calcium, magnesium and iron, together with vitamin C, which offers antioxidant support, boosts immunity and helps the body absorb iron.

The overall acidity of the stalks comes mainly from malic acid, with relatively little oxalate, and they also provide vitamin K. Even so, herbalists advise using rhubarb’s laxative side only in short courses of around two to three weeks.

Why rhubarb leaves are poisonous even though the plant is edible

The concern centres on oxalic acid, which is concentrated in the leaves together with natural anthraquinone glycosides that can irritate tissues and strain the kidneys. "It is not harmful in small quantities but ingesting very large amounts over a prolonged period (much more than you could comfortably consume) can affect the absorption of calcium and some other nutrients and can lead to kidney stones", explained Geoff Stebbings, speaking to Express.

When someone eats a substantial serving of rhubarb leaf, the oxalate can bind calcium in the gut, trigger sharp nausea, vomiting, diarrhoea and cramping stomach pain, and in more serious cases contribute to breathing difficulties and signs of kidney damage.

Toxicology reports suggest that a potentially fatal dose of pure oxalic acid sits somewhere between 15 and 30 grams, and with rhubarb leaves containing around 0.5 to 1 percent oxalate, that would mean several kilos of leaves for a deadly dose.

Real-world problems tend to come instead from smaller but still significant amounts, such as using the leaves like spinach in a recipe, while the low-oxalate stalks remain safe to enjoy baked, stewed or poached in the usual way.

Handling rhubarb leaves safely in gardens and kitchens

For home gardeners, the simplest protection is to break or cut each stalk at the base, then trim off the leaf outdoors so it never travels into the kitchen or onto a chopping board by mistake.

Rhubarb leaves are only poisonous if eaten, not touched, so you can move them without gloves and compost them. "You can put the leaves on the compost heap or just cut them off and leave them around the plant to decompose. They will not harm other plants or 'poison' the compost or soil", says Geoff Stebbings.

During composting, oxalate levels fall as the tissue breaks down, and the intensely sour taste of the raw leaf means most cats and dogs will ignore it, apart from the odd inquisitive puppy or kitten.

In the kitchen, rhubarb stalks still deserve respect, since their fibre and anthraquinone content can loosen the bowels if you eat a lot, so many guides suggest using that effect only for short spells. If anyone ever swallows leaf tissue and then feels unwell, prompt medical or veterinary advice is the safest next step.

2026-03-12T13:50:38Z