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The bit you throw away has more fibre than the bit you eat, in 10 of 12 foods

Qurexa Editorial Team1 November 20266 min read 0 0
The bit you throw away has more fibre than the bit you eat, in 10 of 12 foods

What happened

Researchers at King's College London tested the parts of fruit and vegetables most of us bin. They found that in 10 out of 12 foods, the discarded part held more fibre than the part we normally eat. The study was published in the International Journal of Food Sciences and Nutrition, and coverage appeared at the end of October 2026. The team looked at 12 raw foods. Among them were beetroot, broccoli, butternut squash, kiwi, pineapple and watermelon. For each one they compared the usual edible part with the skin, stalk, leaves, seeds or rind. Some of the numbers are striking. Watermelon rind came in at 2.10 grams of fibre per 100 grams. That is roughly what you would get from a slice of wholemeal bread. Butternut squash skin and seeds together reached 9.25 grams per 100 grams. Broccoli was one of the exceptions. Broccoli stalks had about 28.4% less fibre than the florets people usually eat. So the rule is not universal. The researchers call the idea 'root-to-tip' eating: using the whole plant rather than trimming it down.

Why this matters

Britain has a fibre problem, and it is not a small one. The recommended minimum is 30 grams of fibre a day for adults. According to the figures quoted alongside this study, only about 4% of UK adults manage it. That means roughly 96 of every 100 of us fall short. Fibre is not just about keeping you regular, although it does that. It feeds the bacteria in your large intestine, helps steady blood sugar, and is linked in large population studies to lower rates of heart disease and bowel cancer. There is a second reason this particular study is interesting. Most advice about eating more fibre asks you to buy something extra: more pulses, more wholegrains, a supplement. This advice asks you to throw away less of what you have already paid for. That is unusual, and it is worth noticing. At a time when food bills are tight, 'use the bit you were binning' is a rare piece of health advice that costs nothing and reduces waste at the same time.

What the evidence actually says

This is a laboratory study of food composition. That is important for understanding what it does and does not show. What it shows well: the fibre content of peels, stalks, seeds and rinds, measured directly. Those numbers are measurements, not estimates. What it does not show: that eating peel makes you healthier. Nobody was fed anything and followed over time. The study did not test health outcomes at all. The link between more fibre and better health comes from other, separate research. The researchers themselves were careful about this, and it is worth repeating their caution rather than talking over it. Dr Balazs Bajka, who led the laboratory testing, said the study is not about encouraging people to eat 100 grams of butternut squash skin and seeds to increase fibre intake. In other words, the figures are per 100 grams, which is a lot of squash skin. Nobody is suggesting you sit down to a bowl of it. Dr Rachel Gibson, the project lead, is reported to advise increasing fibre gradually to avoid bloating, and notes that people with IBS may find extra fibre harder to tolerate. That last point deserves weight. For some people with gut conditions, a sudden jump in fibre makes things worse, not better. 'More fibre is good' is true across a population and not automatically true for every individual on a given week.

Qurexa perspective

We deliver groceries as well as prescriptions, so this is one we can be useful about without overclaiming. The honest observation is that root-to-tip eating works best when produce arrives in good condition and unpeeled. If you are planning to eat the skin of a squash or the stalks of a cauliflower, you want it fresh and you want to give it a proper wash. We would also gently point out the thing nobody in a food story says: this only saves you money if you actually use it. Buying more vegetables with the intention of eating the peel, and then binning the whole thing in a week, is worse than what you were doing before. Start with one item you already buy every week. That is it.

Practical advice

If you want to try this, here is how to do it without a kitchen disaster. Go slowly. Add one new fibre source at a time and give your gut a week or two. Increasing fibre sharply causes wind and bloating in most people. This settles, but only if you let it. Drink more water as you add fibre. Fibre works by holding water. Without the water it can make constipation worse rather than better. Wash well. Skins and rinds are the parts that touch soil, handling and transport. Give them a good scrub under the tap. Pick the easy wins first. Potato and carrot skins need nothing more than a wash. Squash skin softens if you roast it. Broccoli and cauliflower stalks are fine grated or sliced thin, though remember broccoli stalk is actually lower in fibre than the florets. Harder ones: watermelon rind needs pickling or cooking to be pleasant. Squash seeds are best roasted. Skip it if it hurts. If you have IBS, Crohn's disease, ulcerative colitis, a narrowing anywhere in the bowel, or you have had bowel surgery, talk to your GP, pharmacist or dietitian before loading up on fibre. For some people the right advice is the opposite of this article. Do not eat the parts that are actually not food. Rhubarb leaves, potato sprouts and green potato skin are not in this category. 'Root-to-tip' does not mean everything is edible.

What to know

King's College London researchers measured fibre in 12 raw fruits and vegetables and found that in 10 of them, the part usually thrown away contained more fibre than the part eaten. Watermelon rind held 2.10g per 100g, about the same as a slice of wholemeal bread. Butternut squash skin and seeds reached 9.25g per 100g. Broccoli was an exception, with stalks about 28.4% lower in fibre than the florets. Only around 4% of UK adults hit the recommended 30g of fibre a day, so there is plenty of room to improve. But this was a food composition study, not a health trial, and the researchers warned against treating the per-100g figures as a serving suggestion. Build up slowly, drink water, and get individual advice first if you have a gut condition such as IBS. Sources: King's College London, 'Eating root-to-tip could help your health and the planet', October 2026, https://www.kcl.ac.uk/news/eating-root-to-tip-could-help-your-health-and-the-planet; Medical Xpress, 'The parts of fruits and vegetables most throw away could save your health and the planet', 30 October 2026, https://medicalxpress.com/news/2026-10-fruits-vegetables-health-planet.html; Discover Magazine, 'Peels, Seeds, and Other Scraps Contain More Fiber Than the Parts We Eat in 10 of 12 Fruits and Vegetables', October 2026, https://www.discovermagazine.com/peels-seeds-and-other-scraps-contain-more-fiber-than-the-parts-we-eat-in-10-of-12-fruits-and-vegetables-49871 This article is for general information and does not replace advice from a doctor, pharmacist or other qualified healthcare professional.

#fibre#nutrition#gut health#King's College London#food waste#healthy eating

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