Throughout history patients with Rheumatic diseases (RMD) have used different diets trying to improve the symptoms and dietary manipulation is still widely used today. There are several potential mechanisms by which diet may be related to pathways involved in inflammation, such as decreasing the inflammatory process, increasing antioxidant levels, changing the lipid profile, influencing composition of the intestinal bacterial flora.
The common dietary programs used by people with RMD include vegetarian or vegan, Mediterranean, elimination diets or fasting periods. Moreover, many dietary supplements are available both as combination formulas and as single-ingredient supplements.
The most studies, investigating diet influence on RMD symptoms in human, were conducted among Rheumatoid Arthritis (RA) patients as an adjunctive therapy. Further, there is a wide variation in evidence robustness probably due to the complexity of studying the relationship between diet and disease activity.
Diets Several controlled studies among RA patients have been performed.
Mediterranean diet intervention studies have shown tendency to pain reduction and improvement of physical function after 3–6 months.
An intervention study, comparing 7–10 days fasting followed by 13 months vegetarian diet and the ordinary diet, showed significant pain reduction in the intervention group. Though, there was no significant difference in physical function or morning stiffness compared to RA patients adhered to an ordinary diet.
Vegan diet intervention studies did not report statistical significant difference in pain, physical activity or morning stiffness compared to an ordinary diet.
One study compared 6 weeks of elimination diet to an ordinary diet. Due to inadequate data reporting, no between-group analyses were possible, the authors of the study concluded: “When the dietary and placebo groups were compared the dietary group did better for all 13 variables for which differences between them were significant”.
Cholesterol lowering diet study among 17 Systemic Lupus Erythematosus (SLE) patients showed increased quality of life (measured by questionnaire) after 12 weeks study period compared to the control group.
Ramadan fasting study among 40 SLE patients did not reveal any influence of fasting on disease activity or patients’ quality of life during the fasting period or 3 months after fasting compared to non-fasting SLE patients.
Non-randomised controlled low-salt, uncooked vegan diet study among 53 fibromyalgia patients revealed improvements in pain, joint stiffness, quality of sleep, quality of life and general health after 3 months of study period.
Dietary supplements Several studies of fish oil supplementation have been performed among RA patients and have generally shown positive results on pain reduction, morning stiffness, and improvement in physical activity and decreased use of pain relief medications. The potential benefit of eating whole foods with high omega-3 content has not been evaluated.
Studies, investigating Vitamin D supplementation in RA patients did not find any disease modifying effect.
Interventional studies of antioxidant supplementation in patients with RMD have been inconclusive.
Current data regarding potential therapeutic effects of probiotics suggest plausible benefits, though evidence grade is still low.
There is some evidence that herbal therapy containing Gama Linolenic Acid oils (evening primrose, borage, or blackcurrant seed oil) reduce some RA symptoms.
Alcohol Studying effects of alcohol on RMD activity is complicated not least in relation to the treatment. Two observational studies among RA patients, showed tendency towards an inverse association between alcohol use and disease severity.
Conclusion The effects of dietary manipulation in RMD patients are still uncertain due to small study samples and potential risk of bias. Higher drop-out rates and weight loss in the groups with manipulated diets indicate that potential adverse events should not be ignored.
However, there is some evidence that fasting followed by a vegetarian diet and Mediterranean diet improve pain, but not stiffness and physical function among RA patients, when compared to an ordinary diet.
Several controlled studies showed that dietary supplements of moderate-to-high doses of omega-3 fatty acids have a beneficial effect on several parameters of RA activity.
Evidence regarding diet influence on RMD’s other than RA is very weak.
Disclosure of Interest None declared
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