Dietary Salt in Rheumatoid Arthritis

Study Overview
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Brief Summary
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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.

Detailed Description
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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.

Official Title
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Inflammatory and Vascular Response to Dietary Salt in Rheumatoid Arthritis

Conditions
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Rheumatoid Arthritis

Intervention / Treatment
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* Other: salt


Participation Criteria
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Eligibility Criteria
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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).

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: This will be a random-order, 2 period crossover study with washout
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: low salt diet<br>low-sodium diet (50mmol/24hours x 8 weeks ) Subjects will choose a rotation of low-sodium meals from a predetermined list from a commercial vendor (Mom's Meals) that will be used to provide 2 meals (lunch and dinner)/day that the vendor will deliver at approximately 7 day intervals. Staff of the Vanderbilt Diet,Body Composition, and Human Metabolism Core determine breakfast and snacks appropriate for theHS andLS diets and provide instructions to subjects. | Other: salt<br>* Participants will randomly eat a high salt diet for 8 weeks and a low salt diet for 8 weeks<br>|
| Other: high salt diet<br>high-sodium diet (200mmol/24hours x 8weeks) Subjects will choose a rotation of low-sodium meals from a predetermined list from a commercial vendor (Mom's Meals) that will be used to provide 2 meals (lunch and dinner)/day that the vendor will deliver at approximately 7 day intervals. Staff of the Vanderbilt Diet,Body Composition, and Human Metabolism Core determine breakfast and snacks appropriate for theHS andLS diets and provide instructions to subjects. | Other: salt<br>* Participants will randomly eat a high salt diet for 8 weeks and a low salt diet for 8 weeks<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Tissue sodium | Investigators will measure change in tissue sodium using 3.0 T MRI equipped with a 23Na coil. | 2 scans, one at end of low salt diet at week 8, and one at end of high salt diet at week 20 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in DAS 28 | Investigators will measure change in DAS28, a measurement of disease activity that includes 28 joint count of tenderness and swelling, a disease activity scale (0-100), and sedimentation rate. | Will be measured at beginning and end of each diet period at weeks 0, 8, and 12, 20 | 
| Change in blood pressure | Investigators will measure change in blood pressure, blood pressure will be measured over a 24 hour period. | will be measured at beginning and end of each diet period at weeks 0,8 and 12, 20 |