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Vitamin C Improves Circulation in Postural Tachycardia Syndrome

  [ 8 votes ]   [ 2 Comments ]
By Julian M. Stewart et al. • www.ProHealth.com • February 27, 2013


Editor's Comment: Dr. Julian Stewart has been researching POTS (postural orthostatic tachycardia syndrome) among adolescents with ME/CFS for well over a decade. In previous studies, he found that these adolescents suffered from “low flow” POTS, a condition in which blood flow to the lower extremities is slow. Typical symptoms of low flow POTS are decreased CO2 (hypocapnia), resulting in faintness; increased vasoconstriction, resulting in restricted blood flow; skin pallor; and tachycardia (rapid heartbeat, especially upon standing). In this study, Dr. Stewart's group found that vitamin C, administered systemically (not orally), normalized blood flow to the legs in all patients. The researchers concluded that the normalizing effect of vitamin C was due to its powerful antioxidant properties.

Ascorbate improves circulation in postural tachycardia syndrome

~Source: Am J Physiol Heart Circ Physiol. September, 2011

By Julian M. Stewart et al.

Abstract

Low flow postural tachycardia syndrome (LFP) is associated with vasoconstriction, reduced cardiac output, increased plasma angiotensin II, reduced bioavailable nitric oxide (NO), and oxidative stress. We tested whether ascorbate would improve cutaneous NO and reduce vasoconstriction when delivered systemically. 

We used local cutaneous heating to 42°C and laser Doppler flowmetry to assess NO-dependent conductance (%CVCmax) to sodium ascorbate and the systemic hemodynamic response to ascorbic acid in 11 LFP patients and in 8 control subjects (aged 23 ± 2 yr). We perfused intradermal microdialysis catheters with sodium ascorbate (10 mM) or Ringer solution. Predrug heat response was reduced in LFP, particularly the NO-dependent plateau phase (56 ± 6 vs. 88 ± 7%CVCmax). Ascorbate increased baseline skin flow in LFP and control subjects and increased the LFP plateau response (82 ± 6 vs. 92 ± 6 control). Systemic infusion experiments used Finometer and ModelFlow to estimate relative cardiac index (CI) and forearm and calf venous occlusion plethysmography to estimate blood flows, peripheral arterial and venous resistances, and capacitance before and after infusing ascorbic acid. CI increased 40% after ascorbate as did peripheral flows. 

Peripheral resistances were increased (nearly double control) and decreased by nearly 50% after ascorbate. Calf capacitance and venous resistance were decreased compared with control but normalized with ascorbate. These data provide experimental support for the concept that oxidative stress and reduced NO possibly contribute to vasoconstriction and venoconstriction of LFP.

Source: Am J Physiol Heart Circ Physiol. 2011 September; 301(3): H1033–H1042. Published online 2011 May 27. doi:  10.1152/ajpheart.00018.2011. Julian M. Stewart, Anthony J. Ocon, and Marvin S. Medow Department of Physiology, New York Medical College, Valhalla, New York 





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Article Comments Post a Comment

This article
Posted by: zen242
Mar 21, 2013
Hi
This study found that IV ascorbic acid in very large quantities improved local blood flow only in this subset of POTS. It was not found to improve the global hemodynamics in this subset. It would be virtually impossible to orally injest that much ascorbic acid.
Reply Reply

This study does NOT support the use of oral Vitamin C in POTS!
Posted by: POTSgrrl
Mar 21, 2013
While I am a fan of Dr. Stewart and the excellent research he has done on POTS, CFS/ME and other disorders, this research study does not support the use of oral Vitamin C pills, or even IV ascorbate as a treatment for POTS.

First, this study was focused on "low flow" POTS patients - and that is a fairly small percentage of overall POTS patients. Low flow POTS patients tend to have too much vasoconstriction, which is why ascorbate, a vasodilator, improved blood flow in their legs. However, a much larger percentage of POTS patients are "high flow" - that is, they have too much vasodilation. Giving these patients ascorbate would likely make them much worse, and might even be dangerous.

Second, Dr. Stewart was not giving these patients IV ascorbate to treat their POTS. He was using it as an drug during an experiment to dilate their leg veins, to better understand the physiology of POTS. This was not meant to be translational research. For comparison, alcohol dilates leg veins too, but that doesn't mean it's a good treatment for POTS.

Third, the ascorbate given in this study was an EXCESSIVE amount and it was given by IV. The oral dose needed to see this much vasodilation would be even more excessive, and it's not clear that an oral dose would even be able to reach this concentration in the blood.

Fourth, the excessive IV ascorbate only improved the "low flow" POTS patents blood flow temporarily while they were supine (laying down) position, not in the upright position.

Finally, and most importantly, the IV ascorbate made most people in this study (both POTS patients and healthy control subjects) much worse when in the upright position on the tilt table.

Before you promote your products with someone else's legit research, without their permission I might add, you might want to read the full journal article and learn a little bit more about the condition.
Reply Reply
 
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