A new study published in the medical journal Osteoporosis International has cast doubt on the benefits of fish oil supplementation for preventing bone loss among people with knee osteoarthritis.

The research led by the University of Sydney and the University of Adelaide, investigate whether supplementation with high dose omega-3 fish oil could have an impact on bone mineral density among 202 people aged 40 and older who were affected by the disease.

Patients were split into groups and randomised to receive either a high or low dose of omega-3 fish oil supplementation for two years, with bone mineral density assessed at the start of the study (baseline) and two years on.

The study found that after two years there were no differences in the two-year bone density measures between the high and low-dose groups, even when additional adjustments for factors such as age, gender, study centre and uses of bone-related drugs during the study period was taken into account, as well as when using intention-to-treat analysis or limiting the assessment to older participants.

Mild adverse events such as headache and gastrointestinal intolerance were common, but did not occur more frequently in either group, while there were no serious adverse events related to the intervention.

The team concluded: “A two-year supplementation with high-dose omega-3 fish oil did not alter bone loss among men and women with knee osteoarthritis.”

Dr Katherine Free, research liaison and communications manager, said: “Omega-3 essential fatty acids can help control the immune system and fight joint inflammation, and there is evidence that fish oil supplements can improve the symptoms of rheumatoid arthritis.

“But what works for one form of arthritis may not work for others, and this study adds to previous evidence that fish oil supplements are not effective at improving the symptoms of osteoarthritis.

“Despite this, it is important that people with arthritis eat a healthy balanced diet, which includes eating two portions of fish a week.”

Medical research can be confusing, and it’s vital to keep an open mind. One of the reasons there is so much research is that many studies contradict each other. This sounds surprising but there is always the chance of variables in the design of the research, unequal selection of subjects, lack of tight control during the trial, and many others. Eventually the total of many investigations when analysed together can hopefully reveal the true conclusion.

In addition the objectives defined at the start and the measurements taken during must be reflected in a useful outcome at the end. So, in this study, a varying dose of Omega-3 fatty acid was found to have no effect on the long term bone density of the subjects, all people with osteoarthritis of the knee. The obvious implication is therefore not to take it. But is this the whole story? Other work has shown to most people’s satisfaction that Omega-3 is anti-inflammatory, and has a marked effect on the immune system and therefore on inflammatory arthritis like Rheumatoid.

Osteoarthritis has its origins in Biomechanics but as we all know inflammation of the joint is a very noticeable part of the process, and one that unchecked can contribute to the damage to cartilage. So perhaps we should not be surprised that it has no effect on bone density and osteoporosis, but that does not diminish its value. It is beneficial in many conditions, a part of a generally healthy diet, and is safe to take. And the anti-inflammatory action can be valuable in osteoarthritis too.