Intravenous Vitamin C in Cancer Care: Evidence Review and Practical Guidance for Integrative Oncology Practitioners

Abstract

Intravenous vitamin C (IVC) is a common therapy used by naturopathic doctors and other licensed integrative practitioners. With several proposed mechanisms of action related to cancer care, it is often used in integrative oncology settings. Despite its common use, there are no published evidence-based resources on the efficacy, safety, and procedural considerations for the use of IVC in practice. The objectives of this review are to summarize the evidence on high-dose IVC in supportive cancer care and to provide a resource of practical clinical guidance for IVC application. In cancer care, IVC is most commonly used at doses high enough to achieve a potential cancer cell cytotoxicity. This review focuses on IVC at doses of ≥15 g which we have defined as high-dose. To date, there are 23 published clinical trials evaluating the use of high-dose IVC in cancer support. Based on data from these clinical studies, IVC used concurrently with oxidative therapies, such as chemotherapy and radiotherapy, seems to produce the greatest likelihood for improvements in quality of life and additive anti-tumour effects compared with IVC as monotherapy or with non-oxidative therapies. IVC has shown promise in improving quality of life in patients with breast cancer and advanced pancreatic and ovarian cancers. Limited evidence suggests survival and/or tumour response may be improved with the inclusion of IVC in patients with advanced pancreatic cancer, non-small cell lung cancer, and RAS-mutated colorectal cancer. IVC does not offer curative potential, and further research is needed to explore its effectiveness relevant to mortality outcomes. Practical guidance including assessment, monitoring, dosing, safety, and communication with other healthcare providers is discussed.