Dietary Salt in Rheumatoid Arthritis

Inflammatory and Vascular Response to Dietary Salt in Rheumatoid Arthritis

In this study investigators propose to address the following hypotheses: 1) Reduction in dietary sodium will decrease inflammation in patients with rheumatoid arthritis (RA). 2) Reduction in dietary sodium will decrease blood pressure in patients with RA. 3) Reduction in dietary sodium will decrease tissue sodium in patients with RA.

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:

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

Exclusion Criteria:

1. Pregnancy
2. Receiving dialysis
3. Organ or bone marrow transplant
4. Taking diuretics, uncontrolled hypertension (>160/100 mmHg), or cardiac failure requiring treatment.
5. Severe edema (as judged by the investigator)
6. Diabetes mellitus treated with an insulin pump
7. Major surgery within the previous 3 months
8. Severe co-morbid conditions such as active cancer likely to compromise study participation
9. Unwillingness, or other inability, to cooperate
10. Contraindication to MRI
11. 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).