Eating fish at least twice a week may help reduce inflammation and joint pain in people with rheumatoid arthritis (RA), according to a new analysis published recently in Arthritis Care & Research.
Fish oil supplements have long been known to improve pain as well as increase remission rates in RA patients taking triple therapy. This is among the first studies to show that fish itself – with lower concentrations than supplements of the active ingredients, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) – may be just as good.
But, the study authors say more studies are needed, noting, “…we cannot draw firm conclusions about the impact of frequent fish consumption on RA activity.”
For the analysis, researchers led by Sara Tedeschi, MD, at Brigham and Women’s Hospital, in Boston, used data from 176 people with moderate RA who were part of a larger, heart disease study. Participants filled out a food questionnaire at the start of the study indicating how often they’d eaten fish during the previous year: less than once a month, once a month, once or twice a week or more than twice a week. They were also asked to indicate the type of fish and how it was prepared. Fish included cooked or raw tuna, salmon or sardines (including sushi and sashimi) as well as “other broiled, steamed, baked or raw fish (trout, sole, halibut, poke, grouper, etc.).” Shellfish, such as shrimp, scallops and crab; fried fish; and fish in mixed dishes, such as stir-fried shrimp or fish with vegetables, were excluded.
Disease severity was measured using a disease-activity score called DAS28-CRP, which measures the number of tender and swollen joints in 28 locations, as well as C-reactive protein, which is a marker of body wide inflammation. It is measured on a scale of 2 to 10; a score less than 2.6 is considered remission and a score above 5.1 is considered high disease activity.
After taking into account race, gender, body mass index (BMI), smoking status, and the use of fish oil supplements, arthritis drugs and other factors, the researchers found that the more fish participants ate, the more their pain and inflammation improved. Eating fish at least twice a week led to a reduction of nearly half a point in the DAS28-CPR score compared to eating it less than once a month or not at all. To put it in perspective, that’s about one-third the reduction seen in people taking the arthritis drug methotrexate.
Experts think fish and fish oil supplements improve arthritis symptoms because they contain the omega-3 fatty acids DHA and EPA, which are potent anti-inflammatories. Omega-3s made up of DHA and EPA (also called long-chain omega-3s) are found mainly in certain fish, including salmon, sardines and tuna. (Plant-based omega-3s – found, for example, in flaxseed, walnuts and leafy greens – contain alpha-linolenic acid (ALA) but no DHA or EPA, and they do not have the same health benefits.) Fish oil supplements have proven effective in treating not just arthritis but also heart disease and depression. For people with RA, who are at higher risk of both, getting omega-3 fatty acids through fish and fish oil supplements may help with these conditions as well as pain due to arthritis-related inflammation.
Association, Not Causation
Daniela di Giuseppe, PhD, at the Karolinksa Institute in Stockholm, has also studied RA and fish consumption, but was not involved in this study. She points out that the current study doesn’t actually prove that eating fish affects RA. It’s possible, for example, that people who eat more fish have a healthier lifestyle or better overall diet, which might explain their improved symptoms.
Having people try to recall what they ate a year ago and how it was cooked can be unreliable, too.
Although these factors create limitations in the reliability of food studies, David Felson, MD, a rheumatologist and professor at Boston University Medical Center, says there’s lots of evidence for the benefits of good fats. Dr. Felson has researched the effect of dietary fat, including fish oil, on knee osteoarthritis (OA).
“Eating more [omega-3] fats is a good dietary choice for many reasons. That fish may help relieve arthritis symptoms is just another reason,” he says.
Author: Linda Rath for the Arthritis Foundation
- Best Fish for Arthritis
- Fish Oil Supplements for Arthritis
- The Benefits of Omega-3 Fatty Acids for Arthritis
- Nutrition Guidelines for People with Rheumatoid Arthritis