Editor's note: This is the fourth in a series of summaries of nursing care–related systematic reviews from the Cochrane Library.
Are dietary interventions effective and safe in alleviating pain and joint stiffness in rheumatoid arthritis?
TYPE OF REVIEW
This is a Cochrane review without meta-analysis.
RELEVANCE FOR NURSING
Rheumatoid arthritis (RA) is an autoimmune inflammatory disease that affects the synovial tissues within joints, typically the small joints of the hands and feet. RA affects between 0.3% and 1% of the general population and is more common in middle age. Its course is variable and unpredictable, but in many patients RA results in persistent pain and stiffness, progressive joint destruction, functional decline, and premature death. Dietary changes are considered promising and may be worth trying before more expensive and invasive interventions such as joint replacement surgery.
CHARACTERISTICS OF THE EVIDENCE
Fifteen trials in the United States and Europe (14 randomized controlled trials and one controlled clinical trial) involving 837 patients were included in the review. Studies were chosen if at least one treatment group of RA patients received a dietary intervention; comparisons consisted of dietary interventions, placebo interventions, or usual diet. Participants' mean age ranged from 49.5 to 58.5 years; in 11 studies, 70% to 100% of participants were women. Interventions ranged from four weeks to 13 months.
Primary outcomes were pain, functional status, joint stiffness, fatigue, and adverse effects. Ten trials reported on weight loss. Because of the heterogeneity of interventions and outcome measures, as well as some inadequate data reporting, comparisons were made separately according to type of intervention and control group.
Two studies—fasting followed by 13 months of a vegetarian diet and 12 weeks of a Mediterranean-type diet—significantly reduced pain but had no effect on functional status or joint stiffness. Two studies found no significant differences in pain, function, or stiffness between an elemental diet (hypoallergenic, easy-to-digest liquids) and an ordinary diet. Two studies of vegan diets and one study of an elimination diet (foods are systematically removed to see if symptoms improve) were inconclusive.
Results show that dietary changes are hard to maintain long term and the elimination of one or more food groups (such as in a strict vegan diet) may lead to deficiencies in vitamins and minerals. Participants on a special diet were also significantly more likely to drop out of the study and to unintentionally lose weight than were those on their usual diet. The potential harmful effects of weight loss and subsequent low body mass index on RA patients, which was reported in seven of the studies, should be considered in light of evidence indicating that such factors are associated with severity of RA symptoms and may not be reversible.
BEST PRACTICE RECOMMENDATIONS
There's some evidence that fasting followed by a vegetarian or Mediterranean diet may be beneficial in RA patients, but the high drop-out rate needs to be considered when recommending this regimen. Moreover, the level of benefit needs to be weighed against the degree of change a patient is willing or able to make. When recommending such dietary interventions, clinicians must consider the value of exposing RA patients, who may be vulnerable to the adverse effects of diet restrictions, to potential nutritional risks.
Given the size and nature of the current studies, larger and longitudinal studies are needed. New trials should use specific comparable outcome measures and explore adverse effects in more detail.