Effect of High-Dose Guarana And Cancer-Related Fatigue

Inclusion Criteria: * Have a confirmed diagnosis of a malignant solid tumor between 4 and 36 months post-treatment (pathology report or MD documentation). * Completed all forms of standard treatment (surgery, chemotherapy, radiation therapy, and/or immunotherapy) between 4 and 36 months prior to enrollment in the study. * Be 18 years of age or older. * Have cancer-related fatigue, as indicated by a response of a 4 or greater when asked to rate their level of fatigue at its worst in the past week on an 11-point scale anchored by "0": = 'no fatigue' and "10" = 'as bad as you can imagine' as taken from a single item question on the Symptom Inventory Questionnaire. * Be able to read English (since the assessment materials are in printed format). Exclusion Criteria: * Participants must not: Have used guaraná supplements within the previous two months. * Self-report that they are very sensitive to caffeine. * Uncontrolled hypertension * Have an allergy to walnuts, seaweed, soybeans and/or chocolate. * Use medications for which caffeine intake is contraindicated including: β-adrenergic agonists, and/or medications that contain pseudoephedrine.