Fruit and vegetable skins, seeds and cores are often more fibre-rich than the flesh people normally eat, according to a team of scientists who tested the fibre content of common produce. The findings, published in the International Journal of Food Sciences and Nutrition, suggest that home cooks and commercial kitchens routinely throw away valuable fibre when they peel and trim their ingredients.
Rachel Gibson and her colleagues at King's College London measured the fibre content of 12 fruits and vegetables, including butternut squash, kiwi fruit, watermelon, broccoli and bell pepper. The researchers compared the parts typically consumed with those that usually go to waste. In 10 of the 12 produce types, the discarded components contained more fibre than the portions people commonly eat.
The gap was often large. Butternut squash seeds and skin contained 9.25 grams of fibre per 100 grams, compared with 2 grams per 100 grams for the squash flesh. The skin and core of a pineapple contained 450 per cent more fibre than its flesh. Many of these parts are tough to chew, but the researchers note that they can be blended, grated or roasted to make them more palatable.
The research comes at a time when most people are not getting enough fibre. Only 4 per cent of British adults meet the recommended minimum daily intake of 30 grams, and the average adult consumes around half that amount each day. Gibson argues that using more of each harvested crop could help close that gap while also reducing food waste and cutting costs for commercial kitchens.
King's College London's canteen tested this approach in May 2025 with a "root to tip" menu. Dishes included a West African peanut stew made with an entire butternut squash, kale stalks and leek tops, and a watermelon salad featuring pickled watermelon rind. Gibson said that eating a larger share of harvested produce could also make the food system more resilient to climate shocks. "Everything we pull out of the ground that we can eat, we should be eating," she said.
Christian Reynolds at City St George's, University of London, described the research as an "exciting investigation" but cautioned that it addresses only part of the problem. He noted that the most carbon-intensive food waste comes from meat and dairy products. Reducing fruit and vegetable waste is therefore "part of the solution, but it's not the only thing we need to do," he said.