This Cancer Bites diet blog Vitamin C Infusion for Cancer, is written by guest writer Christine Tsilas. This blog was originally posted to the Oncology Network of Dietitians of Canada on August 2019 and has been republished with permission from the author and the network. Some edits were made to make the post suitable for a general audience, but did not change the opinion of its original author.
Christine graduated from the Master of Science in Foods and Nutrition (MScFN) Internship program at Western University in June 2019, and she recently obtained her title as a Registered Dietitian. In her Dietetic Internship, Christine had the opportunity to work with Rebecca Chessman, RD, as her preceptor at St. Joseph’s Health Centre in the Oncology Clinic. During this time, she created a resource for health professionals summarizing the evidence for intravenous vitamin C in cancer treatment.
You can use this Table of Contents to help you navigate the information in this post
What is Vitamin C Infusion?
An infusion refers to an IV infusion. IV is short for intravenous meaning that the contents drip into the vein (intra-venous). Chances are you have had an IV infusion at some point in your life.
Most times the liquid dripping into you was either saline (salt water, also called “normal saline”) or 5% dextrose (also called D5W) and these can also be mixed with medication. This post will cover the evidence for a high dose vitamin C IV which is used by many complimentary or alternative health practitioners as a treatment for cancer outside of the conventional medical system.
History of IV Vitamin C for Cancer
The use of vitamin C infusion as a cancer therapy is controversial. IV vitamin C was first developed as a therapeutic agent for cancer in the 1970s (1). Initial studies suggested improved survival times for those treated with supplemental vitamin C which then sparked wider interest in its use (2, 3).
IV vitamin C has long been used in the field of Complementary and Alternative Medicine (CAM) as part of cancer treatment. Surveys of practitioners attending CAM conferences in the United States in 2006 and 2008 found that 172 (86% of respondents) had administered IV vitamin C to patients, including 2,888 cancer patients, during that time (4).
Based on Canadian Cancer Society discussion forums, it appears there is public interest in IV vitamin C treatments (8). As IV vitamin C may be currently used or may be a treatment of interest to cancer patients, it is important for dietitians [and the public] to understand the current evidence surrounding its use and effectiveness.
How does Vitamin C Infusion Work?
When vitamin C is taken orally (from food or supplements), blood levels of the vitamin are tightly controlled (<0.30 mmol/L), whereas high blood levels are achievable with IV vitamin C administration (up to 20 mmol/L) (9, 10).
In vitro (experimental studies in petri dishes), high dose vitamin C has been shown to kill cancer cells but not normal cells (11, 12). In animal studies, high-dose vitamin C infusion was found to prevent the growth of transplanted aggressive cancers (12, 13, 14, 15, 16).
A few processes have been proposed for the potential anti-cancer effects of vitamin C infusion. The most widely accepted process is based on high dose vitamin C acting as a pro-oxidant, and leading to the formation of hydrogen peroxide which causes damage to cancer cells (11, 12, 17, 18).
Does Vitamin C Infusion have Anti-tumor Effects in Humans?
Two systematic reviews have explored the potential anti-tumor effects of IV vitamin C in cancer patients as a stand alone therapy or with other treatment, such as chemotherapy or radiation therapy (19, 20).
Review by Fritz and Colleagues (2014)
- 1 randomized controlled trial
- 7 uncontrolled trials
- 6 observational studies
- 14 case reports
In all of these, a high-dose of IV vitamin C of 5 grams or more was administered (19).
The randomized controlled trial showed that IV vitamin C in combination with standard chemotherapy trended toward longer time to relapse and improved survival compared to standard chemotherapy alone (21).
Based on preliminary findings, the authors report IV vitamin C in addition to chemotherapy may have potential to improve tumor response (22) and patient survival time (23).
Review by Jacobs and Colleagues (2015)
- 1 randomized controlled trial
- 8 non-randomized phase I or II trials
- 1 cohort study
- 6 case reports (20)
They found no consistent evidence for anti-tumor effects or improved survival outcomes with IV vitamin C administration in a controlled setting (20).
The authors report that the trials were generally small, included a variety of cancer types, most were non-randomized (participants got to choose whether to receive IV vitamin C or not), lacked a control group, and often used IV vitamin C in combination with another agent (20).
Does IV Vitamin C Improve the Quality of Life in Cancer Patients?
In the systematic reviews by Jacobs and others (2015) and Fritz and others (2014), these groups explored the effects of IV vitamin C on quality of life (19, 20). All together they found, there is weak evidence that IV vitamin C may improve cancer-related quality of life and symptom severity, or reduce the toxicity of chemotherapy.
Non-randomized studies assessing oral and vitamin C infusion on cancer and chemotherapy-related quality of life using validated questionnaires found patients reported decreases in common symptoms such as fatigue, pain, nausea/vomiting, insomnia, and appetite loss, following administration of IV vitamin C (24, 25).
They also found improvements in reported overall health, and enhanced physical, emotional, cognitive, and social functioning. In contrast, another clinical trial found no significant benefit of IV vitamin C to quality of life (10).
One retrospective cohort study found that breast cancer patients treated with IV vitamin C in addition to standard therapy had a statistically and clinically significant reduction in chemotherapy-related side effects compared to patients treated with standard therapy alone (26).
As well, a randomized trial of ovarian cancer patients found reductions in chemotherapy-related toxicities (21).
Due to a lack of double blind, placebo-controlled trials, it is unclear how much of quality of life scores are related to the effects of the cancer, the chemotherapy, the IV vitamin C, or other types of supportive care (20).
The way quality of life was reported, the IV vitamin C dose and frequency, and the length of IV vitamin C administration varied in these studies. As well, a possible placebo effect cannot be ruled out (20). This is why the evidence for IV vitamin C improving cancer-related quality of life is weak.
Is a Vitamin C Infusion Safe?
Evidence from systematic reviews has found IV vitamin C therapy to be mostly well-tolerated and safe (19, 20). Recent reviews report that vitamin C infusion has demonstrated a good safety profile, however screening for glucose-6-phosphate dehydrogenase deficiency, iron and copper storage diseases, impaired renal function, history of kidney stones or oxaluria, and pregnancy/lactation is recommended (27, 28).
Some negative effects reported in clinical trials that may be related to vitamin C infusion include; nausea (23, 29), diarrhea, and thirst/dry mouth (23). As well, health care providers must be careful to prevent any potential interaction between excess circulating vitamin C and the patient’s chemotherapy (27).
Summary of Vitamin C Infusion for Cancer
Although the existing research suggests that IV vitamin C may be a safe added therapy in the treatment of cancer and chemotherapy-related quality of life, these findings must be interpreted with caution as there is limited high-quality clinical evidence on its safety and effectiveness (19, 20).
There is a lack of randomized controlled trials, and the methods used in the studies published so far are different from each other which makes it difficult to make a recommendation. Until high-quality, placebo-controlled trials are completed, the use of IV vitamin C as a cancer therapy cannot be recommended, and you need to be aware of the lack of data supporting its use (20).
1. PDQ® Integrative, Alternative, and Complementary Therapies Editorial Board. PDQ High-Dose Vitamin C.
Bethesda, MD: National Cancer Institute. Updated <12/13/2017>. Accessed <04/03/2019>. [PMID: 26389504].
2. Memorial Sloan Kettering Cancer Center. c2019. Vitamin C. Updated <08/03/2018>
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References for Vitamin C Infusion for Cancer
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