Scientists in New Zealand have for the first time discovered a genetic link between sugary drinks and the occurrence of the debilitating arthritic disease, gout, in men.
A study, which was published in the international journal Annals of the Rheumatic Diseases, saw researchers at the University of Otago discover a human gene variant that can “turn bad” when affected by sugary drinks, raising the risk of developing gout.
The study found that that when the variant of the gene SLC2A9 behaves correctly, it helps transport uric acid out of the bloodstream and helps its excretion through the kidney. Gout is caused by high levels of uric acid in the blood.
“But when people with this gene variant consume sugary drinks, it takes on Jekyll and Hyde characteristics,” said Tony Merriman, study leader and associate professor from the Department of Biochemistry at the University of Otago.
“This study shows that sugary drinks reverse the benefits of a gene variant which would usually protect against gout,” said Merriman, adding that uric acid is instead transported back into the blood-stream and the risk of gout is increased.
“So, not only does sugar raise uric acid in the blood due to processing in the liver, but it also appears to directly interfere with excretion of uric acid from the kidney. This was a quite unpredictable interaction,” Merriman said.
“Evidence is now even stronger against sugary drinks,” he said.
Gout occurs when uric acid crystallises in the joints and the painful inflammatory response is gout. It is the most common form of arthritis in New Zealand, with particularly high rates in men—3.7% in European men, 11.7% in Maori men and 13.5% in Pacific men.
Researchers in the study examined blood samples to specifically focus on the SLC2A9 gene in 1634 people of European, Maori and Pacific ancestry between 2007 and 2012. Within the sample, 5% of European, 14.4% of Maori and 16.6% of Pacific people were drinking more than 1 litre of sugar-sweetened soft and/or fruit juice drink per day.
Here, researchers also found that consuming sugar-sweetened soft drinks increases the risk of gout in New Zealanders, including for Maori and Pacific people, independent of their weight. “Each daily 300ml serving of sugar-sweetened drink increases the chance of gout by 13%,” Merriman said.