Taking Vitamin C rich foods/sources as part of the daily diet/nutrition may reduce the risk of specific cancers such as lung cancer and glioma. Vitamin C supplements are also available with calcium to alleviate the digestive difficulties. Vitamin C, in turn, improves the absorption of calcium by our body. In regards to cancer treatment, the lack of optimal absorption of Vitamin C from its oral supplements and foods/sources has been a limitation. However, different studies demonstrate the benefits of intravenous Vitamin C in cancer including improving the efficacy of treatments, reducing the toxicities and improving the quality of life of cancer patients.
Vitamin C, also known as ascorbic acid, is a strong antioxidant and one of the most commonly used natural immunity boosters. Being an essential vitamin, it is not produced by the human body and is obtained through a healthy diet. It is also one of the most common water soluble vitamins present in many fruits and vegetables. Lack of intake of Vitamin C via foods/diet for more than 3 months may result in Vitamin-C deficiency called scurvy.
Taking Vitamin C rich foods has many health benefits due to its antioxidant, anti-inflammatory, anti-cancer and immune-boosting properties. It helps in maintaining a healthy and robust immune system, connective tissue, lowering blood pressure and improving the cardiovascular health. Vitamin C helps the body to make collagen which aids in wound healing. The antioxidant properties of Vitamin C helps to protect our cells from damage caused by free radicals. Free radicals are reactive compounds produced when our body metabolizes food. These are also produced due to environmental exposures such as cigarette smoking, air pollution or ultraviolet rays in sunlight.
Foods/Sources of Vitamin C
We can easily meet our daily requirements of Vitamin C by including a variety of Vitamin C rich fruits and vegetables in our diet. The top foods/sources of Vitamin C include :
- Citrus fruits such as oranges, lemons, grapefruits, pomelos, and limes.
- Green peppers
- Red peppers
- Kiwi fruit
- Tomato juice
- Red cabbage
Vitamin C and Calcium Absorption
Vitamin C when taken along with calcium, can improve the calcium absorption. A study by Morcos SR et al. also demonstrated that Vitamin C/ascorbic acid, orange and pepper juices can enhance the absorption of intestinal calcium. When taken together, Vitamin C and calcium can maximize the bone strength.
Vitamin C/ascorbic acid is acidic in nature. As a result, high intake of Vitamin C foods/sources or pure Vitamin C supplements may lead to digestive difficulties. Hence, in the market, Vitamin C supplements are also available along with Calcium, and are sold as calcium ascorbate supplements. Calcium ascorbate supplements contain calcium carbonate which can neutralize the acidic effect of Ascorbic Acid/Vitamin C.
The Recommended Dietary Allowance of Vitamin C is 75 mg for adult women and 90 mg for adult men. When 30-180 mg of Vitamin C is taken orally per day through foods and supplements, 70-90% is absorbed. However, for intakes greater than 1g/day, the absorption rate falls to less than 50% (Robert A. Jacob & Gity Sotoudeh, Nutrition in Clinical Care, 2002).
Benefits of Taking Vitamin C Rich Foods in Cancer
Due to their impressive health benefits, many clinical trials investigated Vitamin C rich foods/sources to study their possible benefits in cancer. Several studies were carried out to study the association of Vitamin C intake with cancer risk or to study its impact on cancer treatments.
Vitamin C & Cancer Risk
1. Association with Lung Cancer Risk
In a study published in 2014, the researchers carried out a meta-analysis of different studies that evaluated the association of intake of Vitamin C rich foods or supplements and lung cancer risk. To identify the studies, the researchers carried out literature search in databases, especially Pubmed, Wan Fang Med Online and Web of Knowledge (Luo J et al, Sci Rep., 2014). The meta-analysis included 18 different articles that reported 21 studies involving 8938 lung cancer cases. Out of these, 15 studies were conducted in the United States, 2 in the Netherlands, 2 in China, 1 in Canada and 1 in Uruguay. 6 of the 18 articles used for the meta-analysis were based on case-control/clinical studies and 12 were based on population/cohort studies.
The results of the analysis showed that high vitamin C intake was significantly associated with a decrease in the risk of lung cancer, especially in the United States and in cohort studies. The results didn’t show a major impact of Vitamin C in the studies from the 6 case-control/clinical articles.
Meanwhile, the researchers also carried out a dose-response analysis using data from 14 studies including 6607 cases. The findings of the study showed that for every 100 mg/day increase in the intake of Vitamin C, there was a 7% decrease in the risk of developing lung cancer.(Luo J et al, Sci Rep., 2014).
These findings indicate that a high intake of Vitamin C rich foods may have the potential to reduce lung cancer risk.
2. Association with Brain Cancer (Glioma) Risk
In a study published in 2015, the researchers carried out a meta-analysis of different studies that evaluated the association of Vitamin C intake and glioma/brain cancer risk. For the pertinent studies, the researchers carried out literature search in databases, especially Pubmed and Web of Knowledge until June 2014 (Zhou S et al, Neuroepidemiology.,2015). The analysis included 13 articles that reported 15 studies involving 3409 glioma cases from the United States, Australia, China, & Germany. The researchers found significant protective associations in the American population and case-control studies.
Key Take-aways :
The findings of the study indicate that vitamin C intake may reduce the risk of glioma, especially among the Americans. However, more clinical studies are needed to establish the same.
Impact on Cancer Treatments and Quality of Life
Well-designed clinical trials on the use of oral Vitamin C supplements/food sources found no benefits for people with cancer. High dose Vitamin C from oral supplements/foods is not absorbed optimally to achieve high concentrations as obtained through intravenous Vitamin C infusion and hence did not show benefits. Vitamin C given intravenously was found to show beneficial impact unlike the dose in the oral form. Vitamin C intravenous infusions were found to be safe and may improve efficacy and lower toxicity when used along with radiation and chemotherapy treatments. There have been many clinical studies investigating the beneficial effects of using high dose Vitamin C in different cancers.
1. Benefits in Glioblastoma (Brain Cancer) Patients treated with Radiation or TMZ chemo drug
A clinical study published in 2019 evaluated the safety and impact of administering pharmacological ascorbate (Vitamin C) infusion along with Radiation or the chemotherapy TMZ in glioblastoma (brain cancer) patients. Radiation and TMZ are the two common standard of care treatments for glioblastoma (brain cancer). The study evaluated data from 11 brain cancer patients (Allen BG et al, Clin Cancer Res., 2019).
The researchers found that high dose intravenous Vitamin C/ascorbate infusions improved the overall survival of glioblastoma patients from 12.7 months to 23 months, especially in subjects that had a known marker of poor prognosis. High dose intravenous Vitamin C/ascorbate infusions reduced the severe side-effects of fatigue, nausea and hematological adverse events associated with TMZ and radiation therapy. The only negative effects associated with ascorbate/Vitamin C infusion that the patients experienced were dry mouth and chills.
Key Take-aways :
The findings indicate that administering high dose intravenous Vitamin C/ascorbate infusions along with Radiation therapy or TMZ in Glioblastoma patients may be safe and tolerable. High dose intravenous Vitamin C may also enhance the efficacy of the treatment as indicated by the improvement in overall survival of the patients.
2. Benefits in Elderly Acute Myeloid Leukemia Patients treated with a hypomethylating agent (HMA)
Hypomethylating agents (HMA) are used for the treatment of Acute Myeloid Leukemia and Myelodysplastic Syndromes (MDS). However, the response rate of certain hypomethylating drugs are generally low, only about 35-45% . (Welch JS et al, New Engl. J Med., 2016)
In a recent study conducted in China, the researchers evaluated the impact of administering low dose intravenous Vitamin C along with a specific HMA in elderly acute myeloid leukemia (AML) patients. The researchers analyzed the clinical outcomes of 73 elderly AML patients who received either a combination of low dose intravenous Vitamin C and the HMA or HMA alone. (Zhao H et al, Leuk Res., 2018)
The researchers found that patients who took this HMA in combination with Vitamin C had a higher complete remission rate of 79.92% versus 44.11% in those who took the HMA alone. They also found that the median overall survival (OS) was 15.3 months in the group which received both Vitamin C and the HMA compared with 9.3 months in the group which received HMA alone. They determined the scientific rationale behind the positive impact of Vitamin C on this specific HMA response. Hence, this was not just a random effect.
Key Take-aways :
Taking low dose intravenous Vitamin C along with the specific HMA drug may be safe and effective in elderly AML patients. In addition, it may also improve the overall survival and clinical response of AML patients treated with the HMA. These findings show a synergistic effect of intravenous Vitamin C and a hypomethylating agent in AML patients.
3. Impact on Inflammation in Cancer Patients
A study published in 2012 investigated the impact of high dose intravenous Vitamin C on inflammation in cancer patients. The study included data from 45 patients who were treated at the Riordan Clinic, Wichita, KS, United States. These patients were diagnosed with either prostate cancer, breast cancer, bladder cancer, pancreatic cancer, lung cancer, thyroid cancer, skin cancer or B-cell lymphoma. They were administered with high doses of Vitamin C post their standard conventional treatments.(Mikirova N et al, J Transl Med. 2012)
Inflammation and elevated C-reactive protein (CRP) are associated with poor prognosis and decreased survival in many types of cancer.(Mikirova N et al, J Transl Med. 2012) The results of the study showed that intravenous Vitamin C can significantly reduce the levels of markers which increase inflammation such as IL-1α, IL-2, IL-8, TNF-α, chemokine eotaxin and CRP. The researchers also found that the decrease in CRP levels during Vitamin C treatment correlated with decrease in few tumor markers.
These findings indicate that high dose intravenous Vitamin C treatment may reduce inflammation in cancer patients.
4. Impact on Quality of Life of Cancer Patients
In a multi-center observational study, the researchers examined the effects of high dose intravenous Vitamin C on the quality of life of cancer patients. For the study, the researchers examined data from patients with newly diagnosed cancer who received high dose intravenous Vitamin C as an adjuvant therapy. Data from 60 patients were obtained from the participating institutions in Japan between June and December 2010. The analysis on quality of life was carried out using questionnaire-based data obtained before, and at 2 and 4 weeks of high dose intravenous Vitamin C therapy.
The studies showed that high dose intravenous Vitamin C administration significantly improved the global health and quality of life of the patients. They also found improvement in physical, emotional, cognitive, and social functioning at 4 weeks of Vitamin C administration. The results showed significant relief in symptoms such as fatigue, pain, insomnia and constipation. (Hidenori Takahashi et al, Personalized Medicine Universe, 2012).
Key Take-aways :
These findings indicate that high dose intravenous Vitamin C administration can improve the quality of life of cancer patients.
In summary, Vitamin C foods are great antioxidants with several health benefits and should be part of our daily diet. Vitamin C also improves absorption of calcium by our body and maximizes bone strength. It has also shown potential in reducing the risk of specific cancers such as lung cancer and glioma. When it comes to cancer treatment, oral Vitamin C is insufficient due to sub-optimal absorption. However, intravenous Vitamin C infusions have shown to improve therapeutic efficacy and tolerability of specific chemotherapy drugs. These have also shown the potential for increasing patients’ quality of life and decreasing toxicity of radiation and chemotherapy treatment regimens. High dose vitamin C (ascorbate) infusions have also shown potential in reducing toxicity of specific chemotherapies in pancreatic and ovarian cancers. (Welsh JL et al, Cancer Chemother Pharmacol., 2013; Ma Y et al, Sci. Transl. Med., 2014).
Cancer patients often have to deal with different chemotherapy side effects which affect their quality of life and look out for alternative therapies for cancer.Taking the right nutrition and supplements based on scientific considerations (avoiding guesswork and random selection) is the best natural remedy for cancer and treatment related side-effects.