The purpose of this study is to determine whether dietary supplementation with Vitamin D or Fish Oil can help to reduce physical and emotional symptoms in adolescent girls with endometriosis.

This is a randomized controlled trial designed to evaluate the effect of dietary supplementation on endometriosis symptom remediation. Adolescent and young adults females aged 12 to 25 years with a surgically-confirmed diagnosis of endometriosis will be eligible for study participation. Subjects will be excluded if they have concurrent chronic illnesses that affect gastrointestinal absorption of nutrients (e.g., celiac disease, IBD, cystic fibrosis), a history of renal stones, are pregnant, or non-English speaking. Once consented, subjects will be randomized to one of 3 treatment assignments: 1) vitamin D3 2000 IU daily (n=30), 2) fish oil 1000 mg daily (n=30), 3) placebo (n=30) and will take these daily for 6 months. Baseline nutrient intake from food and supplements will be assessed using the Food Frequency Questionnaire (FFQ). The 142 item survey assesses usual dietary intake during the past year. Validated rating scales including the visual analog scale (VAS), SF-36, and the World Endometriosis EPHect questionnaires will be used to measure pain and overall quality of life. The SF-36 measures 8 health concepts relevant across disease groups, including limitations to physical or social activities because of health problems, vitality, and general health perception. Patients will complete a full review of medication usage, past medical history, family history, and other lifestyle factors. Anthropometrics will be measured, and vital signs obtained. Measures will be repeated at 3-month intervals for a total of 6 months. Blood will be drawn at baseline, and at 6 months to measure levels of fatty acids, vitamin D, parathyroid hormone (PTH), and calcium.

Inclusion Criteria:

• Female
• Age 12 years -25 years
• Previously surgically diagnosed at Boston Children's Hospital with endometriosis
• At least 6 weeks following laparoscopy
• Minimum pain score within the 4 weeks preceding study baseline
• Must be able to swallow an empty 00 gelatin capsule at baseline
• Must be willing to stop all vitamins and nutritional supplements during trial

Exclusion Criteria:

• Concurrent chronic illnesses that affect gastrointestinal absorption of nutrients (e.g., celiac disease, IBD, cystic fibrosis)
• Vitamin D level of greater than or equal to 100 ng/ml at study baseline
• History of renal stones
• No access to text messages or email
• Pregnancy
• Non-English speaking