Two of Britain's best-known nutrition experts say millions have been left confused by treating all sugar as equally harmful. Professor Tim Spector and Professor Sarah Berry insist the sugar naturally found in fruit should not be lumped together with the refined sugar added to cakes, biscuits, sweets and fizzy drinks.
The pair set out to bust some of the biggest myths surrounding sugar in the latest episode of the ZOE Science & Nutrition podcast. ZOE is a nutrition science company that combines cutting-edge nutrition research with personalised dietary advice through its app and home testing kits. Prof Spector is its scientific co-founder and one of the world's 100 most-cited scientists, while Professor Berry is ZOE's Chief Scientist and Professor of Nutrition at King's College London, where she led the world's largest study into how blood sugar responds to food.
Wartime rationing study
Prof Spector's words come as researchers today claimed cutting babies' sugar intake could slash their risk of dementia decades later. The new study found those exposed to wartime sugar rationing before birth and during their first two years of life were around 20% less likely to develop dementia than others.
Fruit sugar vs added sugar
Prof Berry said many people wrongly assume fruit is unhealthy simply because it contains sugar. "I absolutely disagree with the narrative that fruit, just because it's high in sugar, is bad for us," she said. "We cannot think of sugar and fruit in the same way." She explained that the sugar in whole fruit is "intrinsic" – naturally enclosed within the fruit's structure alongside fibre, vitamins and hundreds of beneficial plant compounds. That means an orange is processed by the body very differently from a glass of orange juice.
Professor Berry pointed to randomised controlled trials comparing whole fruit, fruit puree, fruit juice and equivalent amounts of refined sugar. The evidence consistently shows whole fruit delivers the greatest health benefits. Fruit puree comes next because it still contains the fruit's nutrients. Fruit juice performs less well after much of the fibre has been removed. Refined sugar has the poorest health outcomes.
Smoothies and orange juice
She also challenged the idea that smoothies are unhealthy, saying they remain a good source of fibre and beneficial plant compounds – provided the pulp is left in rather than strained out. Professor Spector admitted his own views had changed over the years. "I was brought up on orange juice. I gave it to my kids. It was part of our family," he said. "But orange juice is essentially full of sugar. It's got some vitamins, got potassium, but essentially a lot of it is this sugar that is going from the fruit. Not eating it as the whole orange, it's being released much quicker than you would get eating an orange, and you're not getting that fibre to also dampen down that absorption. So it's a really unnatural sugar rush you're getting from orange juice. Delicious though it might be, it should be a rare treat, not a daily option."
Myths tackled
The podcast also tackles several of the biggest questions surrounding sugar, including whether it really causes diabetes, whether athletes need sugar for energy, why some of the healthiest foods naturally contain sugar and whether cutting it out altogether is the right approach. Instead, the experts argue people should focus on cutting back on added or "free" sugars while continuing to eat whole fruit, where the sugar is packaged together with fibre and nutrients that fundamentally change how the body processes it.
