The parts of fruits and vegetables most throw away could save your health—and the planet
· Medical Xpressedited by Sadie Harley, reviewed by Andrew Zinin
Sadie Harley
Scientific Editor
Meet our editorial team
Behind our editorial process
Andrew Zinin
Chief Editor
Meet our editorial team
Behind our editorial process Editors' notes
This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility:
fact-checked
peer-reviewed publication
trusted source
proofread
The GIST Add to Preferred Sources
Most of us routinely discard the peels, skins, stalks and seeds of fruits and vegetables at mealtime. But new research from King's College London suggests these scraps could be a valuable—and overlooked—source of dietary fiber, offering potential benefits for both public health and the environment.
The study, published in the International Journal of Food Sciences and Nutrition, analyzed 12 common types of fresh produce in the U.K.
It found that 'root-to-tip' components—the parts typically thrown away, such as peels, skins and stalks—contained significantly higher levels of dietary fiber than the portions we normally eat in 10 out of 12 cases.
Health and waste, a double crisis
Globally, dietary fiber intake falls short of recommendations in most developed nations, while food waste has reached crisis proportions. The United Nations has set Sustainable Development Goals to address both issues.
In the U.K. alone, only 4% of British adults meet the recommended minimum daily intake of 30g of dietary fiber, consuming an average of just 16.4g per day. At the same time, approximately 10 million metric tons of food is wasted annually, with fresh fruits and vegetables representing 36% of this.
Dietary fiber is particularly important. It plays a crucial role in digestive health, helps reduce the risk of type 2 diabetes and heart disease, and promotes feelings of fullness. It can reduce the risk of cardiovascular disease, certain cancers and premature mortality.
Up to five times more fiber in the waste
The study, which was carried out by a team of experts from across King's College London's Department of Nutritional Sciences and King's Food, examined produce commonly used in foodservice settings. This included butternut squash, bell peppers, broccoli, kiwifruit, pineapple and watermelon. In the laboratory analysis, the team measured the total dietary fiber content of both the 'root-to-tip' components (peels, skins, seeds, stalks) and the parts typically consumed.
The key findings showed that in 10 of the 12 produce types analyzed, 'root-to-tip' components contained more fiber than commonly consumed parts.
For example:
- The watermelon rind contained 2.10g of fiber per 100g—roughly equivalent to the fiber in a slice of whole-wheat bread.
- Butternut squash skin and seeds contained 9.25g per 100g—nearly as much fiber as a bowl of bran flakes. To put this in perspective, just 100g (3.5 ounces) of butternut squash skin and seeds (about the size of a small apple) could provide nearly one-third of your daily recommended fiber intake.
- Pineapple skin and core contained 453.7% (five times) more fiber than the flesh. Eating just the skin and core of a pineapple could provide as much fiber as eating five portions of the flesh alone.
- However, broccoli stalks contained 28.4% less fiber than the florets we typically eat—so in this case, most people are already eating the more fiber-rich part.
"The variation in fiber content between the parts of the food we consume and those most throw away was striking," says project lead Dr. Rachel Gibson, a reader in nutrition and dietetics from the Department of Nutritional Sciences at King's College London.
"The 'root-to-tip' components in our study represented between 25% and 48% of the total weight of the produce. That means people are discarding a significant portion of the produce we buy. And these are parts of the plant that could help address our dietary fiber deficit.
"This isn't just a nutritional loss; it's also a financial one; you're effectively throwing away a substantial portion of what you've paid for."
Dr. Balazs Bajka, senior lecturer in nutritional sciences, who led the laboratory fiber testing in the study, adds, "Importantly, this is not about encouraging people to eat '100g (3.5 ounces) of butternut squash skin and seeds' to increase fiber intake.
"Rather, by making better use of the often-overlooked parts of fruits and vegetables as part of everyday meals, we have an opportunity to increase dietary fiber intake in a simple and sustainable way. Emerging research also suggests that consuming a wider variety of fiber sources may help maximize the health benefits associated with dietary fiber."
The proof is in the (fibrous) pudding
To understand how people might begin incorporating these foods into their diet and gain a better understanding of people's attitudes toward them, the researchers introduced a 'root-to-tip' menu at King's College London.
Before it was launched, they tested the concept on a focus group of 40 university staff and students.
Feedback from participants revealed important barriers to root-to-tip eating:
- A "mental discomfort" about eating these items.
- Concerns about digestibility.
- A lack of nutritional information online, particularly on social media, where trends rapidly change and credibility is unclear.
"Interestingly, participants viewed nutritional benefits—particularly fiber content—as a stronger motivator than environmental sustainability when considering whether to adopt 'root-to-tip' eating," lead author Georgia Browne (research assistant, King's College London) adds.
Caterers and manufacturers could make an impact
While the researchers emphasize that 'root-to-tip' eating doesn't require dramatic dietary changes, just simple modifications to food preparation, they state that changes are required at the food manufacturing stage or at the places we go to eat out for tangible results on health at a population level.
"At home we can do things such as leaving skins on kiwifruit, using broccoli stalks in stir-fries, or incorporating bell pepper seeds into dishes. However, for real change to reduce food waste and improve fiber intake at scale, it would be great to see caterers and food manufacturers exploring what fruit and vegetable waste is generated and looking at ways to use it to enhance the healthiness of meals," adds Gibson, who specializes in workplace, diet and health, as well as dietary patterns and health.
The future of sustainable eating
While the research provides valuable insights, several limitations should be noted. For example, the study examined only 12 types of produce—each measured for fiber content when raw (so cooking methods could alter fiber content and digestibility).
The researchers hope that future studies will look to better understand how 'root-to-tip' eating can be practically and safely implemented across diverse populations and settings.
Concluding, Gibson says, "This isn't about perfection and this isn't about forcing people to eat unpalatable food—it's about recognizing the nutritional value in components we've been conditioned to discard, which is exactly why we trialed the root-to-tip menu at King's.
"Even small steps toward using more of the plant can have cumulative benefits for health and the environment."
Publication details
The dietary fibre content of fruit and vegetable kitchen preparation waste and UK consumers' dietary fibre-related attitudes regarding its consumption, International Journal of Food Sciences and Nutrition (2026). DOI: 10.1080/09637486.2026.2734852
Journal information: International Journal of Food Sciences and Nutrition
Key medical concepts
Clinical categories
Nutrition & Healthy eatingGastroenterologyHealthy livingFamily medicineCommon illnesses & Prevention Provided by Taylor & Francis Who's behind this story?
Sadie Harley
BSc Life Sciences & Ecology. Microbiology lab background with pharmaceutical news experience in oil, gas, and renewable industries. Full profile →
Andrew Zinin
Master's in physics with research experience. Long-time science news enthusiast. Plays key role in Science X's editorial success. Full profile →
Citation: The parts of fruits and vegetables most throw away could save your health—and the planet (2026, October 29) retrieved 29 October 2026 from https://medicalxpress.com/news/2026-10-fruits-vegetables-health-planet.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.