Some people are convinced that fruit and vegetable skin are particularly nutritious, and now scientists have confirmed the idea. They have discovered that these parts of fruits and vegetables often contain far more fibre than the flesh we normally consume.
The finding suggests cooks are unwittingly discarding fibre-rich food by chucking out the seeds, skins and stems of fruits and vegetables when preparing a meal.
Home cooks and caterers should adopt 鈥渞oot to tip鈥� eating and start cooking with squash peel, watermelon rind and pepper stalks to improve the public鈥檚 intake of dietary fibre, the team says.
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鈥淲e鈥檝e really got to shift our purchasing habits to buy whole fruits and vegetables, and then use all of the fruits and vegetables in dishes,鈥� says at King鈥檚 College London.
Gibson and her colleagues tested the fibre content of 12 fruits and vegetables, including butternut squash, kiwi fruit, watermelon, broccoli and bell pepper. The team measured the fibre content both in the parts typically consumed and the parts that usually go to waste.
They found that, in 10 of the 12 produce types, the normally wasted components contain more fibre than the commonly consumed parts. Butternut squash seeds and skin, for example, contained 9.25 grams of fibre per 100 grams, compared with 2 g of fibre per 100 g of squash flesh. Meanwhile, the skin and core of a pineapple core contains 450 per cent more fibre than the flesh. These skin and core components are often tough to chew, but the researchers say they can be blended, grated or roasted to make them more palatable.
Just 4 per cent of British adults meet the recommended minimum daily intake of 30 g of dietary fibre, with the average adult consuming around half that per day.
Gibson suggests caterers could use the findings to design fibre-rich meals using more produce that would otherwise go to waste. This could reduce food waste and cut costs for commercial kitchens, as well as increasing dietary fibre intake, she says.
King鈥檚 College London鈥檚 canteen piloted a 鈥渞oot to tip鈥� menu in May 2025. Meals included a West African peanut stew made with all of a butternut squash, kale stalks and leek tops, and a watermelon salad featuring pickled watermelon rind.
Eating a larger proportion of harvested fruit and vegetables will also improve the resilience of the food system in the face of climate shocks, says Gibson. 鈥淓verything we pull out of the ground that we can eat, we should be eating.鈥�
at City St George鈥檚 University of London says the research is an 鈥渆xciting investigation鈥�. But he points out that the most carbon-intensive food waste is meat and dairy products. Reducing fruit and vegetable waste is therefore 鈥減art of the solution, but it鈥檚 not the only thing we need to do鈥�, he says.
International Journal of Food Sciences and Nutrition
