By Pat Anson, Editor

Saturated fatty acids are prime suspects in the onset of osteoarthritis, according a new study by Australian researchers who say fat changes the composition of cartilage, particularly in the hip and knee.

It’s one of the first studies to look at the association between osteoarthritis and saturated fatty acids found in foods such as butter, coconut oil, palm oil and animal fat.

When combined with simple carbohydrates in a high-fat, high carbohydrate diet – often called "junk food" – researchers found that fatty acids weaken cartilage and produce osteoarthritis-like changes in the knee.

"We also found changes in the bone under the cartilage on a diet rich in saturated fat," said Professor Yin Xiao of Queensland University of Technology’s Institute of Health and Biomedical Innovation. "Our findings suggest that it's not wear and tear but diet that has a lot to do with the onset of osteoarthritis

"Saturated fatty acid deposits in the cartilage change its metabolism and weaken the cartilage, making it more prone to damage. This would, in turn, lead to osteoarthritic pain from the loss of the cushioning effect of cartilage.”

Osteoarthritis is a joint disorder that leads to progressive joint damage. It can affect any joint in the body, but is most commonly felt in weight bearing joints such as the knees and hips. Nearly 40 percent of Americans over the age of 45 have some degree of knee osteoarthritis.

Xiao and his colleagues tested a variety of saturated fats and found that long term use of animal fat, butter and palm oil was the most damaging to cartilage. There was less damage caused by  lauric acid, a saturated fatty acid found in coconut oil.

"Interestingly, when we replaced the meat fat in the diet with lauric acid we found decreased signs of cartilage deterioration and metabolic syndrome so it seems to have a protective effect," said Sunder Sekar, a PhD student.

"Replacement of traditional diets containing coconut-derived lauric acid with palm oil-derived palmitic acid or animal fat-derived stearic acid has the potential to worsen the development of both metabolic syndrome and osteoarthritis."

Professor Xiao's previous research has found that antioxidants and anti-cholesterol drugs could slow the progression of joint damage caused by fatty acids.

The study was funded by the Prince Charles Hospital Research Foundation.