Dietary Salt in Rheumatoid Arthritis

The study is a random-order, 2 period crossover study with washout. Participants will be randomly assigned to be on the high-sodium diet (200mmol/24hours x 8weeks) or low-sodium diet (50mmol/24hours x 8 weeks ) with crossover separated by 4-week washout period. Investigators will allow a 7-day window on the diet (i.e., to facilitate scheduling the diet can be between 7-9 weeks), and investigators will allow a 1-week window for the washout (i.e., washout can be 3-5 weeks).

Investigators will measure changes in inflammation (as measured by DAS28 (using tender and swollen joint count, disease activity and sedimentation rate)), blood pressure measured over a 24 hour period, and tissue sodium (using Magnetic Resonance Imaging (MRI)).

If a relatively simple dietary modification has a clinically important effect on inflammation and blood pressure regulation in vivo in patients with RA, this will have far-reaching implications for the treatment of RA and prevention of Cardiovascular disease in this population.

Inclusion criteria

• Male and female patients older than 18 years who are willing to participate.
• Satisfy the ACR criteria for the diagnosis of RA.
• Have stable disease activity as evidenced by no clinically meaningful change in immunomodulating or corticosteroid therapy in the past 1 month.
• Have moderate disease activity as reflected by a minimum of 3 swollen and tender joints.

Exclusion criteria

• Pregnancy
• Receiving dialysis
• Organ or bone marrow transplant
• Taking diuretics, uncontrolled hypertension (>160/100 mmHg), or cardiac failure requiring treatment.
• Severe edema (as judged by the investigator)
• Diabetes mellitus treated with an insulin pump
• Major surgery within the previous 3 months
• Severe co-morbid conditions such as active cancer likely to compromise study participation
• Unwillingness, or other inability, to cooperate
• Contraindication to MRI
• Presence of a condition that could make 24-hour blood pressure monitoring difficult: atrial fibrillation, inability to operate machine, receiving anticoagulants, presence of a condition that in the opinion of the investigator may be exacerbated by blood pressure cuff inflation (e.g., lymphedema).