Researchers in the UK have identified that discarding fruit and vegetable scraps represents a missed opportunity for vital nutritional intake. According to experts, parts commonly thrown away, such as peels, seeds, and stalks, are an overlooked source of dietary fibre. The study encourages a shift toward "root-to-tip" eating habits, specifically highlighting items like watermelon rind, pineapple cores, and butternut squash seeds.
Current official figures indicate that only 4% of adults consume the recommended 30g of fibre per day, despite its established benefits for gut health, digestion, and reduced risks of heart disease and bowel cancer. As a general rule, the skins of fruits and vegetables contain more fibre than their interiors. For instance, consuming a kiwi with its skin provides 50% more fibre than eating it peeled.
Scientists at King's College London analyzed 12 raw or uncooked fresh foods, including beetroot, bell pepper, broccoli, butternut squash, cauliflower, celeriac, curly kale, fennel, kiwi fruit, leek, pineapple, and watermelon. Their findings revealed that many discarded sections contain higher fibre concentrations than the parts people typically eat. Watermelon rind was found to contain 2.10g of fibre per 100g, roughly equivalent to a slice of wholemeal bread. Butternut squash skin and seeds contained 9.25g per 100g, nearly matching the fibre content of a bowl of bran flakes. Additionally, pineapple skin and core held five times more fibre than the flesh, while broccoli stalks also provided significant amounts, though slightly less than the florets.
Project lead Dr Rachel Gibson noted that these findings suggest people are discarding a substantial amount of fibre, representing both a nutritional and financial loss. To demonstrate this concept, King's College London has experimented with root-to-tip meals in its canteen, such as banana skin curry. Over a nine-week trial, these dishes accounted for a third of total daily hot menu sales, though diners choosing them were less likely to finish their meals compared to those eating from the conventional menu.
For home cooks, researchers suggest leaving skins on kiwi fruit, using broccoli stalks in stir-fries, or adding bell pepper seeds to dishes. While cooking can alter fibre content, methods like steaming, microwaving, or quick sautéing tend to preserve nutrients best. Dr Gibson emphasized that the goal is not perfection or forcing people to eat unpalatable food, but rather recognizing the value in components society has been conditioned to discard.
Kirsten Jackson, a dietitian with the British Dietetic Association specializing in irritable bowel syndrome (IBS), supports these hacks provided produce is washed thoroughly. She suggests blending pineapple cores into smoothies but advises against eating tough skins. Some stalks may require cooking or fine chopping to improve palatability. Jackson recommends chopping and freezing unused broccoli stalks for future soups or stir-fries rather than binning them. She also advises increasing fibre intake gradually to avoid bloating, noting that individuals with IBS may find it harder to tolerate.
The British Nutrition Foundation warns that some items should be avoided entirely. Green potatoes and rhubarb leaves contain toxic compounds, while tough stalks and seeds may not be suitable for young children.
Sources: BBC News UK.