Can drinking lots of soft drinks lead to lung problems?

By Sophie Ramsey

Adults who consume large amounts of soft drinks are more likely to have asthma and chronic obstructive pulmonary disease (COPD) than those who drink none, say researchers. But it's unclear whether the sugary drinks are to blame.

What do we know already?

Asthma and COPD are illnesses that make the airways in your lungs narrowed and inflamed, so you have difficulty breathing. In asthma, this can happen because the airways are extra-sensitive to things that are normally harmless, such as pollen and dust mites. In COPD, the airways have been damaged, usually because of smoking.

Both asthma and COPD have become more common in recent decades, but it's not clear why. Many reasons have been suggested, including changes to people’s diets that could be behind the rise in obesity, which is a risk factor for both conditions. In particular, some research suggests that the rise in soft drink consumption might play a role, as the high sugar content of these beverages might promote inflammation in the lungs.

To investigate this, researchers looked at nearly 17,000 people aged 16 years and older who had taken part in a large health study in South Australia. Participants were asked how many litres of soft drinks they usually drank each day and whether they'd been diagnosed with asthma or COPD.

What does the new study say?

Asthma and COPD were more common among people who consumed more than half a litre of soft drinks a day. About 15 in 100 had asthma and 6 in 100 had COPD, compared with 12 in 100 and 4 in 100, respectively, in people who didn't drink these beverages at all.

The researchers estimated that people who drank more than half a litre a day were 26 percent more likely to have asthma and 79 percent more likely to have COPD after factoring in other things that might have affected their risk, such as whether they smoked or were overweight.

The researchers also looked separately at people who smoked versus those who never smoked. Among current smokers, those who drank more than half a litre a day were 1.5 times more likely to have asthma than those who avoided these beverages and more than six times more likely to have COPD. But for non-smokers, there was only a slight increase in risk of asthma and COPD among those who drank a lot of soft drinks, with the difference being too small to rule out being down to chance.

How reliable is the research?

This type of study can't show that one thing caused another. So, although it found a link between soft drinks, asthma, and COPD, it can't prove that drinking lots of these beverages was what raised people's risk. It could be that people who drank a lot of soft drinks were less healthy in other ways, such as eating fast-food frequently, and this is what increased their risk. It's also possible that people started drinking high amounts of these beverages after they developed these conditions, rather than before.

The study had other shortcomings as well, including not distinguishing between regular and sugar-free soft drinks, and relying on participants to describe their drinking habits, lifestyle, and health, which leaves room for error.

What does this mean for me?

This study suggests that drinking high amounts of soft drinks may raise your risk of asthma and COPD, particularly if you smoke, but we need more research to explore this. However, we do know that consuming a lot of sugary drinks isn't good for your health in other ways, adding calories to your diet and increasing your risk of weight gain, obesity, and related illnesses, such as diabetes and heart disease. The sugar in these drinks can also cause tooth decay.

So, you might want to rethink your beverage choices if soft drinks have become a dietary staple, rather than just an occasional treat.

Source:

Shi Z, Dal Grande E, Taylor AW, et al. Association between soft drink consumption and asthma and chronic obstructive pulmonary disease among adults in Australia. Respirology. 2012; 17: 363-369.