It’s common in integrative medicine circles to think of intravenous (IV) vitamin C administration in the context of immune system support for colds, the flu, and even cancer, but is this the limit of its effects? Research demonstrates that IV vitamin C is also extremely beneficial in supporting cardiovascular health in general, including supporting optimal blood pressure levels in pre-hypertensive individuals and in those diagnosed with hypertension. These effects make IV vitamin C an excellent treatment option for individuals who need to bolster their immune systems but who could also use some additional cardiovascular support.
Can Intravenous Vitamin C Therapy Really Help Reduce Blood Pressure?
Fairly recent research suggests that oral intake of higher doses of vitamin C may have a protective blood pressure-lowering effect in individuals with mild hypertension. In fact, compared to those who were given placebo in a randomized controlled trial, individuals who were given vitamin C had a smaller spike in blood pressure in response to a stress test. Their blood pressures also returned to pre-stress levels 40 minutes post-test. On the other hand, blood pressure levels remained slightly elevated at the 40-minute mark in the placebo group.  This slower recovery time noted in the placebo group has been associated with increased cardiovascular risk.
Despite this promising research, studies on oral intake of vitamin C in hypertension have been mixed. In some cases, patients who were given lower doses did not quite experience the decrease in blood pressure that was seen in study participants who were given higher doses. This may be because vitamin C’s effect on blood pressure is dose-dependent.
Additionally, there is a limit to the amount of vitamin C that is absorbed intestinally when orally administered. Intestinal vitamin C absorption takes place via a dose-dependent active transport process that maintains plasma levels at 50–100 μmol/l. As a result, less than half of orally administered doses exceeding one gram per day is absorbed.
On the other hand, when we administer higher doses (1-200 grams) of vitamin C intravenously, we’re able to see plasma concentrations of up to 20 mmol/L, which is 100-fold greater than what we see with oral administration.
Should We Be Worried About Hypotensive Episodes When Administering IV Vitamin C In Normotensive Patients?
As we’ve discussed, IV vitamin C is commonly administered for the purposes of immune system support, particularly in cases of various forms of cancer. In addition to promoting anti-neoplastic activity, research also suggests that high dose IV vitamin C promotes anti-viral and anti-bacterial activity, supports recovery after injury or surgery, alleviates disease-related fatigue, and improves overall quality of life.[4-8] Given the fact that IV vitamin C also supports healthy blood pressure levels, some have raised concerns about its administration inducing a hypotensive state in normotensive patients.
In theory, this is a highly appropriate concern; however, the current research demonstrates that while administering vitamin C intravenously at higher doses can lead to a decrease in blood pressure in pre-hypertensive and mildly hypertensive patients, blood pressure tends to remain steady with its administration in normotensive patients. In other words, if your patients’ blood pressures are already within the normal range, administering IV vitamin C is unlikely to result in hypotension.
Does Administering IV Vitamin C Along With Other Nutrients (B Vitamins, Glutathione, Zinc, and Magnesium) Alter Its Effect on Blood Pressure?
Interestingly, research demonstrates that administering IV vitamin C in conjunction with vitamin B12 results in an increase in blood pressure compared to when IV vitamin C is administered alone. In contrast, when vitamin C was administered along with glutathione, magnesium, zinc, and B vitamins other than vitamin B12, no increase in blood pressure was noted. Again, this is compared to when vitamin C was administered alone.
Are There Any Precautions That We Should Take Before Administering IV Vitamin C?
IV vitamin C is generally viewed as safe, but there are a few precautions that we should take before administering it. For example, we should definitely ensure that our patients’ kidneys are functioning optimally. If kidney function is suboptimal, it would be best for us to avoid IV vitamin C administration altogether or to otherwise adjust our treatment protocol based on each patient’s kidney function.
As another highly relevant precaution, we should always check our patients for glucose-6-phosphate-dehydrogenase (G6PD) deficiency before administering supraphysiologic doses of IV vitamin C. This is because administering high doses of IV vitamin C can result in hemolysis and other unwanted complications in these patients.
Renal impairment and G6PD deficiency are the two most relevant precautions that we need to take into consideration when considering administering IV vitamin C. To learn more about safely addressing hypertension and other concerns using IV nutrients, enroll in the IV Therapy Academy course. You can learn more here.
Brody S, Preut R, Schommer K, Schürmeyer TH. A randomized controlled trial of high dose ascorbic acid for reduction of blood pressure, cortisol, and subjective responses to psychological stress. Psychopharmacology (Berl) 2002;159:319–324.5
Schuler JL, O’Brien WH. Cardiovascular recovery from stress and hypertension risk factors: a meta-analytic review. Psychophysiology 1997;34:649–659.
Ried K, Travica N, Sali A. The acute effect of high-dose intravenous vitamin C and other nutrients on blood pressure: a cohort study. Blood Press Monit. 2016;21(3):160–167.
Fritz H, Flower G, Weeks L, Cooley K, Callachan M, McGowan J, et al. Intravenous vitamin C and cancer: a systematic review. Integr Cancer Ther 2014;13:280–300.12
Lee WJ. The prospects of vitamin C in cancer therapy. Immune Netw 2009;9:147–152.13
Oudemans-van Straaten HM, Spoelstra-de Man AM, de Waard MC. Vitamin C revisited. Crit Care 2014;18:460.14
Mikirova N, Hunninghake R. Effect of high dose vitamin C on Epstein–Barrviral infection. Med Sci Monit 2014;20:725–732.15
Carr AC, Vissers MC, Cook JS. The effect of intravenous vitamin C on cancer- and chemotherapy-related fatigue and quality of life. Front Oncol 2014;4:283.