Biggest fibre boost could be scraps in your bin, experts say

Eating a kiwi with the skin on, external provides 50% more fibre than having a peeled one, for example.

For their study, the scientists at King's College London analysed 12 raw or uncooked fresh foods - beetroot, bell pepper, broccoli, butternut squash, cauliflower, celeriac, curly kale, fennel, kiwi fruit, leek, pineapple and watermelon.

• watermelon rind contained 2.10g of fibre per 100g – roughly equivalent to the fibre in a slice of wholemeal bread

• pineapple skin and core contained five times more fibre than the flesh

Project lead Dr Rachel Gibson said the findings suggested people are throwing away a significant amount of fibre.

King's College London has been experimenting in its canteen, external, offering staff and students root-to-tip meals, such as banana skin curry.

At home, people might want to try leaving skins on kiwi fruit, using broccoli stalks in stir-fries or adding bell pepper seeds to dishes, the researchers suggest.

Gibson said: "This isn't about perfection and this isn't about forcing people to eat unpalatable food – it's about recognising the nutritional value in components we've been conditioned to discard."

Over the nine-week period, "root-to-tip" dishes made up a third of total daily hot menu sales at the university.

Kirsten Jackson, a dietitian with the British Dietetic Association who specialises in irritable bowel syndrome (IBS), says the food hacks are useful as long as produce is washed thoroughly.

Some stalks may need to be cooked or finely chopped to make them more palatable, she adds.

"Just because a broccoli stalk doesn't fit into tonight's meal doesn't mean it needs to go in the bin. Chop it up, freeze it and add it to a soup or stir-fry another day," she said.

Green potatoes and rhubarb leaves contain toxic compounds, while tough stalks and seeds may not be suitable for young children.