Clinically, multiple trials have demonstrated the safety of ascorbic acid when combined with chemotherapy in the treatment of several cancers including multiple myeloma, ovarian and pancreatic cancer [21,50,51,52]. Low dose IV ascorbate + arsenic trioxide trials—Phase I and II trials.

June 27, 2025 - To date, multiple in vitro preclinical studies have demonstrated that pharmacological concentrations of vitamin C exhibit cytotoxicity against various tumor cell lines while having no significant impact on normal cells.19, 20, 21 Moreover, in vivo preclinical studies have shown that extracorporeal administration of 4 g/kg vitamin C can achieve pharmacological concentrations in mouse plasma and significantly inhibit the occurrence and development of ovarian, pancreatic, and colorectal cancers.22, 23, 24 In the clinical setting, pharmacological concentrations of intravenous vitamin C have been proven to be safe and well-tolerated,25 prompting the initiation of subsequent clinical trials.

In general, this was achieved when administering 75 g infusions at least 3 times weekly, and was not significantly further increased at 100 g or more [14, 16, 110]. For those studies administering per kg of body weight, amounts ≥1.0 g VitC/kg [151] were needed to achieve plasma levels of at least 20 mM. We focus in detail only on those studies administering ≥1.0 g/kg or ≥ 75 g (high dose) and ≥ 10 g whole body dose (medium dose). The most studied combination treatment using high-dose IVC is together with chemo- and/or radiotherapy (RT) regimens. Eight such studies were identified, of which half were in conducted in the pancreatic cancer setting (Table 2).

July 25, 2025 - Giving vitamin C through an IV produces very high levels in the blood, which cannot be achieved with oral delivery. These high concentrations result in unique chemical reactions within cancer cells that render the cell more vulnerable to chemo- and radiation therapies.

February 13, 2025 - Work done in the early 2000s by NIH researchers found a marked difference between oral administration of vitamin C and IV administration. Very simply, IV administration results in higher plasma concentrations of vitamin C in the bloodstream.

Indeed, given the huge promise of immunotherapy in anti-cancer treatment, these results are very encouraging, and they indicate a possible combination approach for transforming the tumor microenvironment and increasing the therapeutic breadth of immunotherapy. However, no clinical trials have been conducted on the use of Vit-C in conjunction with ICB treatments, and additional investigations are required to give more emphasis on this important interaction; paving the way towards effective clinical trials.

March 1, 2009 - Peak plasma vitamin C concentrations ... cells. Plasma vitamin C concentrations that cause toxicity to cancer cells in vitro can be achieved clinically by intravenous, but not oral, administration of ascorbate....

By searching the database, we identified only one non-blinded randomized controlled trial meeting the above criteria (n = 25 ovarian stage III and IV cancer patients) [31], two nonrandomized phase I studies conducted among patients with disseminated pancreatic cancer (n = 25) [30,32], and three phase I or II trials conducted among patients with drug-resistant multiple myeloma (n = 68) [109,110,111,112]. Based on the observations that the combination of parenteral ascorbate with the conventional chemotherapeutic agents, carboplatin and paclitaxel, synergistically inhibited ovarian cancer in preclinical ovarian cancer models, Ma et al.

IV vitamin C has been generally well tolerated in clinical trials. IV administration of vitamin C of doses over 500 mg produces much higher blood concentrations of ascorbate than oral administration of the same dose. The use of IV vitamin C alone as ascorbate versus ascorbate formulations plus ...

However, when ascorbate is administered intravenously or intraperitoneally the tight controls are bypassed, and pharmacologic millimolar plasma concentrations of vitamin C can easily be achieved. For example, a phase I clinical study revealed that ascorbate concentrations could safely reach 25-30 mM with intravenous infusion of 100 g of vitamin C. In this study, plasma concentrations around 10 mM were sustained for at least 4 hours which, based on preclinical studies, is sufficient to kill cancer cells. Given the fact that cancer patients were only treated with vitamin C orally in the Mayo Clinic studies, the studies do not disprove high dose vitamin C’s efficacy as a cancer treatment.

Clinical trials in the 1970s involving ... was given orally instead95,96. As it turns out, the differences between oral and intravenous administration routes can affect the maximum achievable plasma concentration in patients....

These studies have also found that plasma concentrations of vitamin C are higher with IV administration than with oral administration and are maintained for more than 4 hours.[10,11] Early Phase Ascorbate Trials Combined With Standard Cancer Therapies · A phase I study published in 2012 examined ...

4 weeks ago - ... Medical supervision is essential. Despite promising results, several limitations remain: ... Importantly, older failed vitamin C trials used oral dosing, which is now understood to be pharmacologically irrelevant.

March 28, 2006 - Recent evidence shows that oral administration of the maximum tolerated dose of vitamin C (18 g/d) produces peak plasma concentrations of only 220 μmol/L, whereas intravenous administration of the same dose produces plasma concentrations about ...

5 days ago - High-dose IV vitamin C with chemotherapy may double survival in late-stage metastatic pancreatic cancer from 8 to 16 months. The study involved 34 patients, showing improved progression-free survival and no increase in adverse events.

There are no data suggesting that high-dose IV Vitamin C can be used effectively as a stand-alone anticancer agent. Existing data coming from heterogeneous trial methodologies and populations precludes meta-analysis at this point.

Due to significant differences in pharmacokinetic properties, extensive research into the use of vitamin C in intravenous infusions (at ‘pharmacological concentrations’) as an alternative to oral administration (at ‘physiological concentrations’) has been performed (Table 2) [3,5,19,36,37,38,39,40]. For example, the intravenous infusion of ascorbate at a dosage of 25 g daily, increased gradually to 75 g daily, started soon after completion of the standard therapy, might help to prevent the recurrence of stage IV ovarian cancer, without the negative chemotherapy-related side effects [41]. The intravenous route of vitamin C administration appears to be of particular interest, especially in the light of the results of the studies by Long et al.

Studies by Levine's group later suggested that the vitamin must be given intravenously to reach doses high enough to kill cancer cells. A few small trials in the past 5 years—for pancreatic and ovarian cancer—hinted that IV vitamin C treatment combined with chemotherapy can extend cancer survival.