Fiber, once synonymous with 1970s diets and bran cereal, is staging a comeback. Yesterday, the online supermarket Ocado reported that sales of prunes have increased by 60 percent in the past year and spelt by 59 percent.

The increase is being driven by younger consumers, with the online supermarket finding 62 percent of Gen Z shoppers were trying to up their fiber intake, compared with 36 percent of over-65s. On TikTok videos about #fibermaxxing—meeting or exceeding fiber consumption guidelines—have gone viral, with high-fiber recipes notching up millions of views.