Most adults in the UK are missing out on a significant source of dietary fibre by discarding the outer layers and cores of fruits and vegetables, according to new research from King’s College London. Scientists are urging the public to adopt a “root-to-tip” approach to cooking, which involves consuming parts of produce that are typically thrown away, such as watermelon rind, pineapple cores, and butternut squash seeds.
Official statistics indicate that only 4% of adults meet the recommended daily intake of 30g of fibre. This nutrient is essential for proper digestion, helps maintain satiety, and is associated with a reduced risk of heart disease and bowel cancer. The study suggests that by ignoring these discarded sections, consumers are losing both nutritional value and money.
High Fibre Content in Discarded Parts
The research team analysed 12 raw or uncooked fresh foods, including beetroot, bell pepper, broccoli, butternut squash, cauliflower, celeriac, curly kale, fennel, kiwi fruit, leek, pineapple, and watermelon. The analysis revealed that many discarded components contain higher concentrations of fibre than the parts people typically eat.
For example, watermelon rind contains 2.10g of fibre per 100g, which is roughly equivalent to the fibre content in a slice of wholemeal bread. Butternut squash skin and seeds contain 9.25g per 100g, nearly matching the fibre levels found in a bowl of bran flakes. Pineapple skin and core contain five times more fibre than the flesh alone. While broccoli stalks contain slightly less fibre than the florets, they remain a valuable source.
Dr Rachel Gibson, the project lead, noted that the findings highlight a substantial loss of nutrients. “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,” she said. The study emphasizes that cooking methods such as steaming, microwaving, or quick sautéing tend to preserve these nutrients best, rather than destroying them.
Practical Application and Expert Advice
To demonstrate the viability of this approach, King’s College London has been experimenting with root-to-tip meals in its canteen. Over a nine-week period, these dishes accounted for a third of total daily hot menu sales. Staff and students were offered items such as banana skin curry. However, the study noted that diners choosing these new dishes were less likely to finish their meals compared to those eating from the conventional menu.
Health experts advise that while these food hacks are useful, they require careful preparation. Kirsten Jackson, a dietitian with the British Dietetic Association who specializes in irritable bowel syndrome (IBS), recommends washing produce thoroughly before consumption. She suggests blending pineapple cores into smoothies to make them more palatable but advises against eating tough skins. Jackson also recommends chopping broccoli stalks and freezing them for later use in soups or stir-fries.
She cautioned that individuals should increase their fibre intake gradually to avoid bloating, noting that those with IBS may find it harder to tolerate high fibre levels. The British Nutrition Foundation also issued warnings about certain parts of produce. Green potatoes and rhubarb leaves contain toxic compounds and should be avoided entirely. Additionally, tough stalks and seeds may not be suitable for young children.
Dr Gibson clarified that the goal is not to force people to eat unpalatable food but to recognize the value in components that have been conditioned to be discarded. Simple changes, such as leaving skins on kiwi fruit or adding bell pepper seeds to dishes, can contribute to a healthier diet without requiring a complete overhaul of cooking habits.
Source: BBC
