Effects of Dietary Nitrate in Women With Secondary Amenorrhea

Excessive exercise, disordered attitudes toward eating, physical and psychological stress, and/or hormonal imbalances may result in cessation of menstruation (secondary amenorrhea). The accompanying lack of estrogen may impair muscle power and oxygen recovery after exercise by reducing nitric oxide levels. The purpose of this study is to determine whether ingestion of beetroot juice containing nitrate, an alternative source of nitric oxide, can help reverse these changes.

Inclusion Criteria: * Women age 18-44 years old * Missed \>3 consecutive periods in the last 12 months if previously regularly menstruating (average cycle 21-35 d) OR * Missed \>6 consecutive periods in the last 12 month if previously irregularly menstruating (spontaneous menstruation, average cycle \ 35 d) Exclusion Criteria: * Unable to provide informed consent * Currently diagnosed with primary amenorrhea (no history of menstruation by age 15) or oligomenorrhea (menstrual cycle \>35 d or \140/\>90) * Currently taking proton pump inhibitors, antacids, xanthine oxidase inhibitors, or on hormone replacement therapy * An answer of yes to any of the seven questions on the first page of the Physical Activity Readiness Questionnaire (PAR-Q) indicating that the participant is not physically ready for exercise without a medical exam. These exclusions include the following: * If participant's doctor has ever said that he/she has a heart condition and that he/she should only do physical activity recommended by a doctor * Pain in chest when doing physical activity * In past month, chest pain when not doing physical activity * If participant has ever lost balance because of dizziness or has ever lost consciousness * Muscle, bone, or joint problem that could be made worse by physical activity * Currently on prescribed drugs for blood pressure or heart condition. * If the participant knows of any other reason he/she should not do physical activity.