Heart Surgeon Clarifies the Difference Between Fruit Sugar and Added Sugar
Dr Jeremy London, a board-certified heart surgeon, has addressed a common nutritional debate: whether the sugar in fruit is the same as added sugar found in cakes, chocolate, and fizzy drinks. His conclusion: chemically identical but metabolically distinct.
Dr London stated: "Chemically, the sugar is identical. An apple has sugar, a glazed doughnut has sugar, but the way we metabolise those two things is completely different." He emphasised that whole fruit contains fibre, water, polyphenols, and antioxidants, which slow digestion and alter how the body processes sugar.
Fruit Juice and Dried Fruit Lose Key Benefits
Dr London stressed the importance of consuming whole fruits rather than fruit juices or dried fruits, which lose beneficial components during processing. "Whole fruit is more satiating, calorie for calorie, than sugary drinks or processed sugar. In the end, sugar is sugar but what it comes with makes a tremendous difference," he said.
The distinction between natural and added sugars is increasingly important for health, according to Harvard Medical School. Natural sugars occur in fruits, vegetables, and dairy, while added sugars are incorporated during manufacturing, processing, or preparation.
Sources of Added Sugar in the Diet
The primary sources of added sugar include fizzy drinks, confectionery, and breakfast cereals, many of which are ultra-processed and offer little nutritional value. In contrast, fruit provides a wealth of nutrients that reduce the risk of heart disease and cancer.
Harvard Medical School notes: "Natural and added sugars are metabolised the same way in our bodies. But for most people, consuming natural sugars in foods such as fruit is not linked to negative health effects, since the amount of sugar tends to be modest and is 'packaged' with fibre and other healthful nutrients. On the other hand, our bodies do not need, or benefit from, eating added sugar."
Health Risks of Added Sugar
Consumption of added sugar is linked to weight gain, type 2 diabetes, cancer, cardiovascular disease, and tooth decay. However, moderate consumption is acceptable. The NHS advises that added sugars should not exceed 5% of daily energy intake, equating to no more than 30g (about seven sugar cubes) for adults.
The NHS excludes naturally occurring sugars in milk, fruit, and vegetables from its definition of "free" sugars. Added sugars include white and brown sugar, honey, syrups, fruit juices, and smoothies. Experts warn that juicing reduces nutritional benefits and causes rapid blood sugar spikes.
Does Sugar Cause Cancer?
Nutritionist Nichole Andrews debunked the myth that sugar directly causes cancer. "As a cancer dietician, let me clarify: sugar all on its own will not cause cancer or have your cancer grow quicker. If you have a diet high in sugar, you're probably going to have excess calories... and then you're going to gain weight, gain fat tissue and it's the fat tissue that increases cancer risk."
