Drinking just two soft drinks a day could dramatically increase the risk of developing a deadly lung disease, concerning research suggests.
Chronic obstructive pulmonary disease (COPD) is an umbrella term for a group of lung conditions, including emphysema and chronic bronchitis, that cause breathing difficulties.
It affects more than 1.7million Britons, and about 30,000 die from COPD every year as it can trigger organ failure and raise the risk of serious lung infections. Studies suggest most patients survive around ten years after diagnosis, although this can vary widely.
It has long been associated with smoking. However, as smoking rates have fallen and research has improved, a more complex picture has emerged.
Today, around one in four COPD cases occur in those who have never smoked. Experts say these are often linked to long-term exposure to air pollution, second-hand smoke – particularly in childhood – and workplace dust or chemical fumes, as well as factors such as poor housing, repeated respiratory infections earlier in life and certain genetic conditions.
Now US researchers say diet may also play an important role. It has long been known that sugar can trigger inflammation, increasing the risk of obesity, heart disease, diabetes and bowel disease. But scientists now believe high-sugar diets may also contribute to airway inflammation and bacterial growth in the lungs.
Researchers from West Virginia University analysed data from more than 11,000 adults enrolled in the National Health and Nutrition Examination Survey between 2015 and 2020.
Participants reported their daily food and drink intake, including how many calories they consumed from sugar-sweetened beverages.
Even when smoking, body weight and exposure to harmful substances were taken into account, those who consumed 10 per cent or more of their daily calories from sugary drinks were 39 per cent more likely to be diagnosed with COPD. For someone eating around 2,000 calories a day – the recommended daily intake for women – this equates to roughly 50g of sugar, or just over one can of Coca-Cola.
Official UK guidelines recommend adults consume no more than 30g a day of free sugars (that’s sugar added to foods or found in fruit juices and syrups) and that these sugars make up no more than 5 per cent of daily calories.
Although the study does not prove sugary drinks directly cause COPD, the consistent association suggests reducing intake could play a role in prevention.
The researchers say healthcare professionals, specifically dental hygienists, have a responsibility to educate patients about the risks of sugary drinks.
The researchers pointed to what is known as the ‘fructose hypothesis’ to explain the potential link. The sugar used in most soft drinks is called sucrose. It is made up of two smaller sugars joined together – glucose and fructose – which means roughly half the sugar in a drink such as cola is fructose. A standard can of Coca-Cola contains about 39g of sugar – meaning roughly half is fructose.
Fructose is primarily processed in the liver, which can increase the production of uric acid, a natural waste product.
This can trigger inflammation and oxidative stress – in which harmful molecules damage cells – both of which are key features of COPD. The researchers also suggest fructose may activate inflammatory pathways linked to cellular ageing, contributing to tissue damage and reduced lung function.
However, they noted sugary drinks could also influence COPD risk indirectly through chronic inflammation linked to obesity, leading to impaired lung function.
Dr Nick Hopkinson, respiratory consultant and medical director at Asthma + Lung UK, says: ‘It’s not certain what mechanism might increase the risk of COPD in people who consume sugary drinks, but we know that higher levels of glucose in the airways may increase the risk of infections, and a high-sugar diet can also increase levels of inflammation which might contribute to lung damage.’
While occasional sugary drinks are unlikely to pose a major risk, he adds: ‘If you’re over 40 – when COPD risk starts to increase – and live in an area with high levels of air pollution, your risk will be exacerbated by a high-sugar diet.’
Common symptoms of COPD include a persistent cough, excessive mucus and shortness of breath. However, lifestyle changes can slow the patient’s decline.
This is the case for Anita Brough, 60, from Sheffield, who was diagnosed with the condition at 47, despite being a fit yoga teacher.
‘I was told that I had the lungs of someone 30 years older than me,’ she says. ‘It was really scary. But after making a really conscious effort with my diet – avoiding ultra-processed food and drink and staying away from empty calories – I have managed to reduce that to eight years.’
NHS figures show that serious breathing problems, including COPD, have led to more emergency hospital admissions than any other medical condition.
