Clinical researchers at the University of Glasgow published in the September issue of the Annals of the Rheumatic Diseases an unassuming, almost self-effacing study on the effect of diet on rheumatoid arthritis. Here is the stated objective of the study:
“To overcome obstacles to healthy eating by a community-based intervention promoting a Mediterranean-type diet in patients with rheumatoid arthritis or RA living in socially deprived areas of Glasgow.”
What was this modest paper doing amongst all the high-powered papers on the molecular mechanisms of rheumatic diseases and the latest potent therapies based on insights into those mechanisms?
Methods: A hundred and thirty (130) female patients with RA aged 30–70 years (median 55) and disease duration of 8 years were recruited from three hospital sites. The intervention group (75 patients) was taught how to switch to the Mediterranean diet, which is rich in fruits, vegetables, fish, and olive oil. They attended weekly 2-hour sessions for 6 weeks in the local community, including hands-on cooking classes backed up with written information. The control group (55 patients) were given dietary written information only. Both groups completed food frequency questionnaires (FFQs), and clinical and laboratory measures were assessed at baseline, 3 and 6 months.
Results: By way of introduction, statistical significance requires that a “p value” will be <0.05. That means that the result has less than 5% probability of being due to chance rather than due to the treatment. If the p value is < 0.01, the result has less than 1% probability of being due to chance, and is considered “highly significant”.
Significant benefit was shown in the intervention group compared with controls. For patient global assessment at 6 months, p = 0.002; pain score at 3 and 6 months, p = 0.011 and 0.049; early morning stiffness at 6 months, p = 0.041; and Health Assessment Questionnaire score at 3 months, p = 0.03. Analysis of the FFQs showed significant increases in weekly total fruit, vegetable, and legume consumption and improvement in the ratio of monounsaturated:saturated fat intake and systolic BP in the intervention group only. The cooking classes were positively received by patients and tutors; cost/patient for the 6-week course was £84 ( EUR124 or $168).
So what’s the big deal?
I think that the study is important for three main reasons:
- Once again, simple measures, in this instance a good diet, proved to be the most effective means of warding off disease. Diet rich in fruits and vegetables, fish, and olive oil has been shown to improve cardiac health (note the reduced systolic blood pressure in the intervention group), weight control and diabetes, and certain cancers (notably colon cancer).
- The Mediterranean diet can also be dubbed “the anti-inflammatory diet”. Among many factors that mediate inflammation, there is a class of small molecules called prostaglandins. Not all prostaglandins are born equal; some are pro-inflammatory (they cause inflammation) and others are anti-inflammatory. RA is caused, in part, by the pro-inflammatory prostaglandins. Steroids, by the way, inhibit the synthesis of prostaglandins, hence their anti-inflammatory action. There are other drugs that inhibit the synthesis of prostaglandins that are not steroids. These are called non-steroidal anti-inflammatory drugs or NSAID, like aspirin and ibuprofen (Advil). Indeed, these drugs are the first line of defense in newly diagnosed RA. But the drugs are not risk-free. Steroids taken on a chronic basis have many serious adverse effects: suppression of the immune response, bone loss, fluid retention, mood disturbances. NSAID cause stomach irritation, ulcer, and bleeding. On the other hand, olive oil and fish (part of the Mediterranean diet) are rich in monounsaturated fatty acids. Rather than the sledgehammer effect of the drugs, these fatty acids very subtly divert the synthesis of prostaglandins from the pro-inflammatory to the anti-inflammatory ones. No immunosuppression, no bone loss, no ulcer. Once again, nature provided a clean and simple solution that has eluded the best minds in drug development.
- The inflammatory response is gradually assuming a central role in many diseases that have not been on the usual suspects list: diabetes, atherosclerosis, coronary heart disease, all the autoimmune diseases (such as rheumatoid arthritis, lupus, systemic sclerosis or scleroderma), and even certain cancers. The effect on our health and our national health budget of an anti-inflammatory diet, such as the Mediterranean diet, could, therefore, be enormous. I can foresee a time when insurance companies would reduce the premiums of people who stick to a regimen of regular exercise and an anti-inflammatory diet, just as they do now for non-smokers.
So, hooray to the modest clinicians who published this unassuming work. Their conclusion:
“Results demonstrate that a 6-week intervention can improve consumption of healthier foods. If implemented more widely, it may prove a popular, inexpensive, and useful adjunct to other RA treatment.”
To this, I would add, “This study provided a scientific basis for a wider adoption of a diet that could revolutionize our eating habits, our health, and our healthcare.” I guess those Scots are not given to such overt enthusiasm; is it the climate?