The goal of this study is to compare pain levels in individuals with Sickle Cell Disease while following the Mediterranean Diet to pain levels while following their usual diet.

This is an exploratory, randomized, crossover-controlled feeding study of a 4-week Mediterranean Diet or usual diet control among 24 adults with sickle cell disease and chronic pain (30 will be recruited, with an estimated 24 participants completing the study).

Inclusion Criteria:

• Sickle Cell Disease Diagnosis
• Chronic non-vaso-occlusive pain experienced on average ≥ 3 days per week for > 6 months (based on a response of "Most days," "Every day," or "Some days" and not "Never" to the question "In the past 6 months, how often have you had pain?")
• Ability to speak, read, write, and understand English
• A Mediterranean Eating Pattern for Americans (MEPA-III) score <13, indicating that they do not follow a Mediterranean diet.

Exclusion Criteria:

• Having taken systemic antimicrobials (to treat an infection in the previous 4 weeks)
• History of colon cancer or inflammatory bowel disease (given potential untoward effects on the gut microbiome)
• History of Clostridium difficile infection in the preceding 12 weeks; (4) unable to agree to maintain physical activity at the current level for the duration of the study
• Currently following a Mediterranean diet, vegan diet, or dietary restrictions (e.g., religious, food intolerance/allergy) that preclude adoption of a Mediterranean diet
• Lack of access to a space to safely store and reheat food items
• Living in a facility that provides meals.
• Pregnancy or breastfeeding
• More than 7 in-patient hospital stays in the last year
• Currently receiving dialysis treatment