The peels and seeds of fruits and vegetables that are typically thrown away are full of fiber, according to a new study from King’s College London.
Researchers put 12 of the most common fruits and vegetables to the test: pineapple, watermelon, butternut squash, broccoli and peppers. What they found was “striking.” Peels, peels, seeds and stems contained more fiber than the actual fruit.
Their findings suggest that adding more of these commonly discarded items to meals could increase fiber intake while reducing waste.
In the UK alone, only 4% of British adults meet the minimum recommended daily intake of 30g of fiber, consuming an average of just 16.4g per day. At the same time, around 10 million tons of food are wasted every year, with fresh fruits and vegetables accounting for 36% of this.
5x more fiber in the skin
Pineapple peel and core had the densest fiber content, with 453.7% more fiber than pulp. To reach this number, about five servings of the fruit would be needed.
Butternut squash peel and seeds contained 9.25 grams of fiber per 100 grams, almost a third of the UK recommended daily intake of 30 grams.
Watermelon rind contained 2.10 grams of fiber per 100 grams, which is about the equivalent of a slice of whole wheat bread.
Researchers found that waste accounted for 25% and 48% of the total weight of the products, respectively.
Researchers examined whether a “root-to-tip” diet, which incorporates discarded edible plant ingredients into meals, could increase fiber intake and reduce food waste.
“Importantly, this is not about encouraging people to eat ‘100g of butternut squash peel and seeds’ to increase fiber intake,” Bajka said.
“In fact, by making better use of the often-overlooked components of fruits and vegetables as part of daily meals, we have the opportunity to increase fiber intake in a simple and sustainable way.”
Fiber plays an important role in digestive health and reduces the risk of cardiovascular disease, type 2 diabetes and certain cancers, the press release said.
Consumers value nutrition over sustainability
The researchers acknowledged several limitations: the small range of product types they tested, the methods used, and the need to consider the risks associated with consuming hides.
“Future research should also address any unintended consequences that may arise from increased consumption of root-to-tip components, including managing exposure to nutrient-unfriendly plant residues that can cause adverse health effects when consumed above safe limits,” the authors write.
They identified pesticide residues, heavy metals and naturally occurring toxic compounds as potential concerns that require further investigation. And they didn’t determine whether including peels, seeds and kernels would improve health outcomes.
“The researchers stated that they need to conduct further research to quantify any increase in fiber intake from eating from root to tip and to examine the associated health consequences,” the researchers concluded.
According to Gibson, this approach would not require a drastic change in diet, but rather a question of how to incorporate these peels, seeds and kernels into the food we normally eat.
“This isn’t about perfection,” Gibson said. “And this isn’t about forcing people to eat inedible foods – it’s about recognizing the nutritional value of the ingredients we’ve been conditioned to avoid, which is exactly why we tried the root-to-tip menu at King’s.”
Even small steps, the press release concludes, can have a positive impact on health and the environment.
