Rigorous evidence review finds fishy, “green” diets can reduce pain in inflammatory arthritis; omega-3s may ameliorate rheumatoid arthritis but work better when omega-6 intakes are lower than average
by Craig Weatherby

A recent health-blog post in The New York Times summarized the results of one of the largest analyses of the effects of various diets on various types of arthritis.

It reminded us that fish, fish oil, and “green” diets have long shown promise as adjuncts to conventional therapies... as I found 10 years ago while researching a book co-authored with Leonid Gordin, M.D., concerning conventional and alternative therapies (The Arthritis Bible, Healing Arts Press 1999).

Key Points
  • Among all non-Western diets, evidence review finds greatest pain benefit from Mediterranean-type diets high in produce, olive oil, and fish.
  • Other studies reported benefit from fish oil, especially when intake of pro-inflammatory omega- fats is low.
(“Green” diets are ones high in fish and whole fruits and vegetables and low in starch, omega-6 fats, and red meat.)

Since then, we have even more evidence that omega-3s and “green” diets low in meat may help alleviate symptoms in people with osteoarthritis and rheumatoid arthritis alike… with more effect in the latter, thanks to its inflammatory nature.

Like other auto-immune disorders, rheumatoid arthritis is characterized by major inflammation in patients' connective tissues.

Omega-3s moderate inflammation, which is the source of much the pain in rheumatoid arthritis, which affects 1.3 million Americans annually... mostly women.

New evidence review supports fishy, green, Mediterranean-type diets
A Norwegian review team used stringent criteria of the Cochrane Database system to scrutinize the results from 15 clinical trials testing the anti-arthritis effects of vegetarian, Mediterranean, and allergen-elimination diets (Hagen KB et al. 2009).

Because all of the trials they reviewed were small, with certain weaknesses or risks of bias, the Norwegians were unable to draw firm conclusions.

But as health blogger Anahad O'Connor of the Times wrote Tuesday, “…the one that had the greatest effect was a Mediterranean-type diet emphasizing foods like fruits, vegetables, grains, fish and olive oil, while limiting red meat” (O'Connor A 2009).

They noted that in one Swedish study, people on a Mediterranean-type diet reported about 14 percent less pain, but no gains in dexterity, mobility, or morning stiffness within 12 weeks (Sköldstam L et al. 2003).

And three studies from Greece indicate that long term consumption of an Mediterranean-type diet is beneficial (Linos A et al. 1991; Drosos AA et al. 1997; Linos A et al. 1999).

The authors of these three Greek studies attributed most of the observed symptomatic benefits to the anti-inflammatory effects of the antioxidants in plant foods.

But as the authors of the Swedish study noted, the lean white fish consumed in these studies contain many fewer omega-3s than fatty cold-water fish like tuna and salmon (Sköldstam L et al. 2003).

Encouraging evidence for omega-3 fish oil in inflammatory disorders
In 2003, a German team published the results of a double-blind crossover clinical study involving 68 RA patients divided into two groups of 34 subjects each.

One group ate a normal western diet (WD) for 8 months and the other ate an anti-inflammatory diet (AID) low in the pro-inflammatory omega-6 fat called arachidonic acid (less than 90 mg/day).

Patients in both groups were randomly assigned to receive placebo or fish oil capsules (30 mg/kg body weight) for 3 months.

The AID group taking fish oil showed significant reductions in the numbers of tender and swollen joints. 

As the authors wrote, “A diet low in [omega-6] arachidonic acid ameliorates clinical signs of inflammation in patients with RA and augments the beneficial effect of fish oil supplementation” (Adam O et al. 2003).

In 1995, doctors at Albany Medical College reported the encouraging results of a double-blind, placebo-controlled, clinical trial in which 66 RA patients took fish oil or corn oil along with the aspirin-like non-steroidal anti-inflammatory drug (NSAID) pain reliever called diclofenac (Kremer JM et al. 1995).

They found that patients taking fish oil exhibited clinical improvements, including a reduction in the number of tender joints, and that these improvements were associated with significant decreases in levels of inflammatory immune system proteins.

Importantly, as they said, “Some patients who take fish oil are able to discontinue NSAIDs without experiencing a disease flare” (Kremer JM et al. 1995).

Fish oil is no cure for any kind of arthritis, and its benefits in rheumatoid arthritis, while seemingly significant for many, are limited.

But, combined with a diet low in red meats and omega-6 rich oils like corn and soy, it seems to help and is well worth trying.

  • Adam O, Beringer C, Kless T, Lemmen C, Adam A, Wiseman M, Adam P, Klimmek R, Forth W. Anti-inflammatory effects of a low arachidonic acid diet and fish oil in patients with rheumatoid arthritis. Rheumatol Int. 2003 Jan;23(1):27-36. Epub 2002 Sep 6.
  • de Lorgeril M, Renaud S, Mamelle N, Salen P, Martin J-L, Monjaud I, et al. Mediterranean alpha-linolenic acid rich diet in secondary prevention of coronary heart disease. Lancet 1994;343:1454–9.
  • Drosos AA, Alamanos I, Voulgari PV, Psychos DN, Katsaraki A, Papadopoulos I, et al. Epidemiology of adult rheumatoid arthritis in northwest Greece 1987–1995. J Rheumatol 1997;24:2129–33.
  • Linos A, Kaklamani VG, Kaklamani E, Koumantaki Y, Giziaki E, Papazoglou S, et al. Dietary factors in relation to rheumatoid arthritis: a role for olive oil and cooked vegetables? Am J Clin Nutr 1999;70:1077–82.
  • Linos A, Kaklamanis E, Kontomerkos A, Koumantaki Y, Gazi S, Vaiopoulos G, et al. The effect of olive oil and fish consumption on rheumatoid arthritis: a case control study. Scand J Rheumatol 1991;20:419–26.
  • O'Connor A. The Claim: Some Foods Can Ease Arthritis Pain. The New York Times, August 25, 2009. Accessed at http://www.nytimes.com/2009/08/25/health/25real.html
  • Sköldstam L, Hagfors L, Johansson G. An experimental study of a Mediterranean diet intervention for patients with rheumatoid arthritis. Ann Rheum Dis. 2003 Mar;62(3):208-14.