A team of Scottish scientists has uncovered further evidence that cod liver oil can benefit people suffering from rheumatoid arthritis.

A study published today in the journal Rheumatology shows that people taking a cod liver oil supplement could cut their reliance on anti-inflammatory drugs by more than 30%.

Many patients with the condition take non-steroidal anti-inflammatory drugs (NSAIDs), which include ibuprofen, but at higher doses than normally used for pain relief. They have been linked to side-effects including increased risk of heart attacks, strokes and gastro-intestinal bleeding at these levels.

The new study, by experts at the Ninewells Hospital and Medical School in Dundee and Dundee University, found that 39% of a test group taking cod liver oil tablets were able to reduce their intake of anti-inflammatory drugs by 30%.

One of the research team, Professor Jill Belch, said: "This study offers hope to many rheumatoid arthritis patients for whom cod liver oil supplements can offer a natural pain management treatment without the harmful side-effects associated with the use of anti-inflammatory drugs.

"It reinforces previous research that has shown cod liver oil, and its high content of omega-3 essential fatty acids, to have significant anti-inflammatory properties in patients with rheumatoid arthritis."

The condition affects around 350,000 people in the UK, with women more likely to be affected than men. It is an auto-immune disease which causes pain, swelling and inflammation in the joints and can leave people feeling generally unwell and tired.

Rheumatoid arthritis also puts sufferers at higher risk from strokes and heart attacks.

The researchers in Dundee analysed 97 patients with rheumatoid arthritis who took NSAIDs. They were given either 10g of cod liver oil containing 2.2g of n-3 (omega-3) essential fatty acids, or "dummy" pills.

Details of NSAID dose and clinical indicators linked to rheumatoid arthritis disease activity were recorded at the start of the study and after four, 12, 24 and 36 weeks.

At 12 weeks, patients were instructed to gradually reduce and, if possible, stop their NSAID intake. A total of 58 patients (60%) completed the study. Out of 49 patients in the cod liver oil group, 19 (39%) were able to have cut their daily NSAID requirement by more than 30% at the nine- month point.

Out of 48 patients in the placebo group, just five (10%) were able to reduce their daily NSAID requirement by more than 30%. No difference was observed in the clinical parameters of how the disease behaved during this time.

The authors said: "The main objective of the study was to assess whether rheumatoid arthritis patients were able to reduce their NSAID intake without any worsening of their disease activity. This was achieved in all of the clinical parameters studied."

They concluded: "This study suggests that cod liver oil supplements containing n-3 fatty acids can be used as NSAID-sparing agents." They added the findings were important at a time "when there are increasing concerns about adverse events associated with NSAID use".