The Grapevine

Western Diet, With Its High-Fat Content, Linked To Arthritis

People who are obese often experience pain and stiffness in their joints. Known as osteoarthritis (or "wear and tear" arthritis), this joint inflammation involves the erosion of the cartilage, which is the connective tissue found between joints, and puts knees at particular risk. Experts consider obesity to be the number one preventable risk factor for osteoarthritis.

It was assumed the stress on the joints was what led to the development of this condition. However, recent findings from a new mouse study suggested bacteria found in the gut — largely governed by the diet — could be the driving force behind osteoarthritis. The study will be published in the journal JCI Insight on April 19.

A team of researchers, from the University of Rochester Medical Center in New York, fed mice a high-fat diet similar to that of a western “cheeseburger and milkshake” regimen. After three months, the mice became obese and diabetic. Their fat percentage was double as much as those rodents who were fed a healthy, low-fat diet.

High levels of pro-inflammatory bacteria were observed in the colons of the obese mice, while beneficial, probiotic bacteria was almost not present at all. This coincided with signs of inflammation across the body. The researchers induced a tear in a certain tissue of the knee to induce osteoarthritis. Compared to the healthy mice, the condition progressed much faster in the obese rodents, and within three months after the tear, all their cartilage disappeared.

Dr. Michael Zuscik, study author and associate professor of Orthopaedics at the university, emphasized the importance of the cartilage and the dangers of damaging it.

“When you lose that, it's bone on bone, rock on rock. It's the end of the line and you have to replace the whole joint. Preventing that from happening is what we, as osteoarthritis researchers, strive to do — to keep that cartilage,” he said.

The researchers were also able to identify an unexpected solution to prevent these effects — a prebiotic called oligofructose. Prebiotics are food ingredients that can induce the growth or activity of beneficial microorganisms.

When observing the obese mice who consumed the oligofructose supplement, two differences were noted. First, it was found their knee cartilage was as healthy as that of the non-obese mice. Second, they had also become less diabetic.

However, no change in body weight was observed in the obese mice who consumed the high-fat diet. Therefore, the researchers found evidence to suggest it may not be the stress of body weight on joints which is driving osteoarthritis. Rather, the key factor could be the inflammation caused by an unhealthy, western diet. 

“There are no treatments that can slow progression of osteoarthritis - and definitely nothing reverses it,” explained study author Dr. Eric Schott, a postdoctoral fellow at the university and soon-to-be clinical research scientist at Solarea Bio, Inc. “But this study sets the stage to develop therapies that target the microbiome and actually treat the disease.”