Peels and stems hold more fibre in 10 of 12 foods: study

Researchers at King's College London have found that the parts of fruits and vegetables most people throw away, such as peels, stems, cores and seeds, contain more fibre than the parts usually eaten in 10 out of 12 common types of produce. The study, published in the International Journal of Food Sciences and Nutrition and reported on Thursday, October 29, 2026, tested produce commonly used in British catering kitchens, including butternut squash, bell peppers, broccoli, kiwi fruit, pineapple and watermelon. The researchers call this way of eating the whole plant "root-to-tip".

Fibre is the part of plant food that the body cannot fully digest. The researchers' own framing is that root-to-tip eating could help people get more of it, and the study suggests that some of it is sitting in kitchen bins: a quarter to nearly half of the weight of some common fruits and vegetables is being thrown away, and in most of the items tested that portion was the richer source of fibre.

The finding will sound familiar in many Indian homes. Using the whole vegetable, including peels and stalks, in chutneys, stir-fries and dals is part of several regional cooking traditions, often for reasons of thrift and taste. This study gives a measured, laboratory basis for one benefit of such habits, though it tested produce used in British kitchens and did not study Indian recipes.

There is also a waste angle. Food thrown away in catering kitchens is a cost to businesses and adds to landfill. If the discarded parts can be cooked into appealing dishes, kitchens can serve more fibre while buying the same amount of produce. That is why the researchers are now testing root-to-tip dishes on real diners in the university's food venues, where they will look at sales, how acceptable diners find the food and how much is left on plates.

The study has limits. It measured fibre in the produce, not what happens in the body when people eat these parts, and the authors set out further limitations in the paper. It does not say all peels are safe or pleasant to eat. Some produce may carry pesticide residue or soil on its skin, so washing remains important, and readers with digestive conditions should follow their doctor's advice on fibre.

Short-term: The results give chefs, caterers and home cooks a reason to look again at what they peel and discard. The university's own food outlets are already trying root-to-tip dishes as part of a follow-up project.

Long-term: If diners accept such dishes, the approach could raise fibre in everyday meals and cut kitchen waste at the same time, and it may encourage similar testing of produce and recipes in other countries, including India.

Who is affected: People trying to eat more fibre, caterers and canteen managers looking to reduce waste, nutrition researchers, and households that already cook with peels and stalks.

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