AI Insight
Researchers at King's College London analyzed the fiber content of 12 common fruits and vegetables, comparing typically consumed parts with normally discarded components like skins, seeds, and stems. They found that 10 of the 12 produce types contained significantly more fiber in the waste parts than in the flesh, with butternut squash seeds and skin containing over four times more fiber than the flesh, and pineapple skin and core containing 450% more fiber than the edible portion. The team recommends adopting "root to tip" cooking practices to improve dietary fiber intake, as only 4% of British adults currently meet the recommended 30 grams of daily fiber.
Why it matters
This research provides quantitative evidence for utilizing whole fruits and vegetables to address widespread fiber deficiency in the population. Implementing these findings in commercial and home kitchens could simultaneously reduce food waste, lower food costs, improve public health through increased fiber consumption, and enhance food system resilience against climate-related disruptions.
Understand the Science
Some people are convinced that fruit and vegetable skin is 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 “root to tip” eating and start cooking with squash peel, watermelon rind and pepper stalks to improve the public’s intake of dietary fibre, the team says.
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“We’ve really got to shift our purchasing habits to buy whole fruits and vegetables, and then use all of the fruits and vegetables in dishes,” says Rachel Gibson at King’s 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’s College London’s canteen piloted a “root to tip” 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. “Everything we pull out of the ground that we can eat, we should be eating.”
Christian Reynolds at City St George’s University of London says the research is an “exciting investigation”. But he points out that the most carbon-intensive food waste is 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 says.
International Journal of Food Sciences and Nutrition
DOI: 10.1080/09637486.2026.2734852
Source: Scientists confirm fruit and vegetable skin really is good for you