Research reveals sobering reasons to give soft drink the flick

2 mins to read

If soft drink is your vice, you may change your mind after reading these startling research findings. Kathryn Terrill explains.

Everyday health

Researchers have found a link between several serious disease states and soft drink consumption. One such study conducted by Australian researchers has shown that drinking large amounts of soft drink is linked to an increased risk of asthma and chronic obstructive pulmonary disease (COPD) in adults.

Researchers surveyed nearly 17 000 South Australian residents aged 16 years and over. Of these, 11.4% said they consumed more than 500 mL of soft drink daily, including cola, lemonade, sports drinks and flavoured mineral water.

After adjusting for socio-demographic factors, intake of fruit and vegetables, weight and other life style factors, compared to those surveyed who didn’t drink soft drinks, those who consumed more than half a litre per day had higher rates of asthma (14.7 vs 11.9%) and COPD (6.0 vs 4.2%). This is concern considering soft drink consumption has dramatically increased in Australia from around 47.3 litres per person per year in 1969, to 113 litres per person (both children and adults) in 1999.

The authors also found something interesting in relation to the combination of smoking and soft drink consumption. Those who currently smoked and consumed more than 500 mL of soft drink daily had a 6.6-fold greater risk of COPD and a 1.5-fold greater risk of asthma than those who neither smoked nor consumed soft drinks.

Although it is not exactly clear why soft drink consumption is a risk factor for asthma and COPD, the authors have some compelling hypotheses. Asthma and COPD are both inflammatory diseases, and foods that promote inflammation may influence their progression. Soft drink contains sugar, which may increase the risk of allergic airway inflammation, and may stimulate an unhelpful immune response in the lungs. This may be only part of the picture, however, as the study didn’t differentiate whether people were consuming diet soft drinks or not. An additional factor may be that plastic bottles containing soft drinks have chemicals called phthalates, which some studies have shown may be linked to asthma.

If that is not enough to swear you off soft drinks for life, another recent Australian study by the same authors has shown a link between soft drink consumption and mental health issues. This time 4741 South Australian participants aged 16 and over were surveyed, and 12.5% of them consumed more than 500 mL of soft drink daily.

The study found that those consuming high levels of soft drink were 60% more likely to have issues with stress, depression, suicidal ideation and/or other forms of psychological distress compared to those who didn’t drink soft drink at all. These results were also adjusted for factors such as socio-economic status, fruit and vegetable consumption, and other lifestyle factors.

Again, the exact reasons for these results are unclear, but sugar is a main suspect. The authors claim that there may be a link between the inflammatory effects of sugar and depression. They also postulate that other chemicals in soft drinks may be involved, but further study is needed. Another factor is the possible link between soft drinks increasing the risk of chronic diseases such as diabetes and obesity, which could itself contribute to psychological distress.

References available upon request