Gout causes severe pain, often in the big toe, and results from high levels of uric acid, which can form crystals that lodge in joints.
Photo / Thinkstock
Gout causes severe pain, often in the big toe, and results from high levels of uric acid, which can form crystals that lodge in joints.
Photo / Thinkstock
Obesity might be a risk factor for gout, but new research has suggested that being overweight doesn't make it any worse for those who suffer from the painful disease.
The finding, published this month in the journal Rheumatology, has surprised the New Zealand researchers which investigated the links between gout and obesity.
Gout causes severe pain, often in the big toe, and results from high levels of uric acid, which can form crystals that lodge in joints.
The disease, estimated to affect between five and ten per cent of New Zealanders, is linked to high intakes of sugary drinks and alcohol - and obesity.
Obesity's effects on the immune system are thought to underlie some of its connections to chronic diseases - the link seeming to be the fat tissue itself.
Fat cells have been shown to secrete many factors that local immune cells respond to, and this promotes a state of overstimulation of the immune system, or chronic inflammation, which impairs normal immune function.
Dr Jacquie Harper of the Malaghan Institute has long been investigating the immune responses that drive gout, and was surprised to find the connection between gout and obesity was not what was previously believed.
When foods such as liver, kidneys and sardines were broken down by the body, uric acid was released.
This acid had many important health benefits, and the body was equipped to deal with it - but only up to a certain point.
A gout attack is triggered by uric acid crystallising in the joints, with the immune system perceiving the crystals as a threat and launching an immune response against them.
New research by Malaghan Institute arthritis and inflammation group leader Dr Jacquie Harper has suggested that being obese does not make gout any worse for sufferers of the disease.
It is the resulting inflammation which causes swelling, reddening of the skin and debilitating pain.
Uric acid levels are higher in obese individuals, increasing their likelihood that they will develop gout.
But what had been unclear up until now, however, was whether their gout attacks were worse than those in non-obese individuals, because of their existing low level of inflammation.
Dr Harper's research, carried out in collaboration with Auckland Rheumatologist Associate Professor Nicola Dalbeth and colleagues, would suggest not.
Using an animal model of gout, the team investigated the effect of diet driven obesity on immune cell activity.
"Our study is novel in that we focused specifically on immune cells not associated with fat tissue, to determine the wider implications of obesity on immune function," she said.
"We found that obesity elevates the background inflammatory activity of these immune cells, just as it does with fat-associated immune cells.
"Interestingly however, rather than making things worse, the presence of the crystals actually decreased background inflammation.
"It was definitely a surprise - it certainly wasn't what we expected."
While this was good news for obese people prone to gout because it suggested their gout was no worse than that which occurred in some lean individuals, the down side was that the study further supported the growing evidence that obesity impaired immune function.
Dr Harper said the findings could have wider implications for other conditions, and warranted further studies.
"It provides a new starting point for looking at the human condition," she said.
"It also indicates that a lot of diseases associated with obesity are more complex than just your weight."
