Bioavailability of Vitamin C

[OxC]

...our crude measurements have shown that these very high blood concentrations are only visible from minutes 5 to 25 after oral ingestion, and only with ascorbic acid (not sodium ascorbate).
...One benefit of our crude measurements was showing the difference between AA (ultrafine powder) and Sodium Ascorbate. Sodium ascorbate was either delayed or not absorbed (as we didn't measure longer than one hour)
...But the AA was noticed by our meter at minute five and if memory serves, peaked around minutes 20 to 25. So any test that is not measuring this soon and this often is going to MISS a lot of vitamin C (as ascorbic acid) entering the blood stream

These findings (and conclusions) are wildly different than a whole body of scientific studies have previously demonstrated. I believe you should very seriously consider the possibility that your "crude measurements" are invalid and misleading before trying to find physiological explanations for those measurements. I'll say it again: You cannot get reliable plasma ascorbate measurements using a glucose meter.

[OxC]

For AA to reach the blood this quickly (5 minutes!) something like this MUST be happening, and as I mentioned, we did not observe the same thing measuring sodium ascorbate.

Absolutely. Whenever I get sneezes from my hay-fever and take a glass of water with 2 tea-spoons of vitamin C, within 3 minutes it eases it already.

Two teaspoons of AA is about 10 grams, and a glass of water is typically about 12 ounces. The concentration of the solution you are swallowing is about 2.8%, or, in the same units as we have been talking about in blood, 158,000 uM. So, you see, swallowing this solution exposes the back of the throat and the back of the sinus cavity to a solution containing vitamin C somewhere in the neighborhood of 2000 times more concentrated than is found normally in blood.

I do not doubt that you experience relief in just minutes from hay fever sneezing after drinking this. I experience the same rapid relief of nasal congestion when I gargle a far less concentrated DHAA solution.

But the question here is how that vitamin C is getting to the cells that line your sinuses. One possible way is that exposure of the opening of the sinus cavity where it enters the throat to a solution containing an extremely high (158,000 uM) concentration of vitamin C allows small amounts to migrate into the sinuses, in much the same way as, say, eating a hot pepper or horseradish sauce allows sufficient of their constituents to enter the sinuses and cause the effects we've all experienced (i.e. runny nose).

Another possible way is that within only 3 minutes, sufficient vitamin C is absorbed into your bloodstream from the stomach to increase the blood concentration enough to deliver significantly larger quantities throughout the body, including to the sinuses.

Many, many studies on the absorption of AA do not support the second possibility. In fact, Owen's experience, derived from his blood glucose meter, is the only suggestion of such rapid blood absorption of AA that I have ever seen.

[Johnwen]

[ofonorow]

Lot to digest.
The point of our crude measurements are that if any study waits more than 30 minutes to do the measurement - it is probably invalid. They missed all the action!

And our "crude" experiments are entirely repeatable.

Of course there are always alternate explanations of what may be going on, and I am all ears.

#1: Why the vastly different readings after taking the same amount of ascorbic acid (ultra fine) powder and sodium ascorbate?

#2: The sinus membrane hypothesis. Oxc this seems reasonable, except for the fact that when I first noticed this, it was with my father during his last days at the hospital. He took a 500 mg pill. A tablet, so little opportunity to for any ascorbate to escape the pill as he swallowed. (He was having difficulty breathing, and the sinuses cleared within minutes of swallowing.. Leading me too)

Hickey/Roberts Ridiculous Dietary Allowance (Bioavailability. Pg 65)

Bioavailability measures absorption from the gut. The RDA committee suggest that this absorption occurs in the intestines by means of active transport. This may not be the only route, or even the dominant one. Vitamin C is a weak, organic acid, and such acids are normally absorbed rapidly through the stomach

Looking for the reference in pubmed - and will edit.

[OxC]

[b]The point of our crude measurements are that if any study waits more than 30 minutes to do the measurement - it is probably invalid. They missed all the action!
[/i].

Here is a study in which plasma was collected at 15 minutes and 30 minutes after oral doses of ascorbic acid. Refer to Figure 3. You will see that there is no "action" to miss at these times, that it is usually about one hour before significant increases in plasma ascorbate concentrations can be seen, and that peak values occur at around 2 hours. http://www.pnas.org/content/93/8/3704.full.pdf In this study, plasma ascorbate was measured using a reliable HPLC method. In study after study, whenever reliable analytical methods are used, the absorption profile of ascorbic acid is always like this. There is never a peak in 5 or 10 minutes followed by a drop to baseline in 30 minutes as the blood glucose levels you have previously reported show. I think the most reasonable explanation of your results is that the blood glucose meter measured exactly what it was designed to measure...your blood glucose levels.

[Johnwen]

[ofonorow]

Here is a study in which plasma was collected at 15 minutes and 30 minutes after oral doses of ascorbic acid. Refer to Figure 3. You will see that there is no "action" to miss at these times, that it is usually about one hour before significant increases in plasma ascorbate concentrations can be seen, and that peak values occur at around 2 hours. http://www.pnas.org/content/93/8/3704.full.pdf In this study, plasma ascorbate was measured using a reliable HPLC method. In study after study, whenever reliable analytical methods are used, the absorption profile of ascorbic acid is always like this. There is never a peak in 5 or 10 minutes followed by a drop to baseline in 30 minutes as the blood glucose levels you have previously reported show. I think the most reasonable explanation of your results is that the blood glucose meter measured exactly what it was designed to measure...your blood glucose levels.

First, to review our procedure - we also tested the FreeStyle lite device against vitamin C in water, and it was able to measure vitamin C in water at the same concentration as in the blood. (Furthermore, people from the Riordan clinic, who routinely measure vitamin C after IV/C - and if blood levels are zero, continue the IV, put out a paper showing how certain glucose meters provide a cheap and reliable substitute.)

When I look at the graphs of this paper you cite OxC - they look just like our sodium ascorbate measurements. So I looked to confirm that they really gave ascorbic acid (can you help with this? The type of vitamin C given makes all the difference in the world).

There is a section where they describe what looks to be the Vitamin C used for IV - but if given orally too, it was at least partially sodium ascorbate.

Vitamin C powder USP-FCC was a gift from Takeda USA Inc. Vitamin C was batch-prepared for clinical use by the NIH Clinical Center Pharmacy as a sterile solution of 50 mg/ml in water adjusted to pH 6.5 with NaOH.

I'll get to johnwens post after reviewing the links. The Hickey/Roberts reference is to a primer on Drugs (a book) but they expand on the fact that the lower the pH, the stronger the stomach acid, the stronger the effect moving "organic" acids through the stomach wall..

[ofonorow]

Here is a study in which plasma was collected at 15 minutes and 30 minutes after oral doses of ascorbic acid. Refer to Figure 3. You will see that there is no "action" to miss at these times, that it is usually about one hour before significant increases in plasma ascorbate concentrations can be seen, and that peak values occur at around 2 hours. http://www.pnas.org/content/93/8/3704.full.pdf In this study, plasma ascorbate was measured using a reliable HPLC method. In study after study, whenever reliable analytical methods are used, the absorption profile of ascorbic acid is always like this. There is never a peak in 5 or 10 minutes followed by a drop to baseline in 30 minutes as the blood glucose levels you have previously reported show. I think the most reasonable explanation of your results is that the blood glucose meter measured exactly what it was designed to measure...your blood glucose levels.

First, to review our procedure - we also tested the FreeStyle lite device against vitamin C in water, and it was able to measure vitamin C in water at the same concentration as in the blood. (Furthermore, people from the Riordan clinic, who routinely measure vitamin C after IV/C - and if blood levels are zero, continue the IV, put out a paper showing how certain glucose meters provide a cheap and reliable substitute.)

When I look at the graphs of this paper you cite OxC - they look just like our sodium ascorbate measurements. So I looked to confirm that they really gave ascorbic acid (can you help with this? The type of vitamin C given makes all the difference in the world).

There is a section where they describe what looks to be the Vitamin C used for IV - but if given orally too, it was at least partially sodium ascorbate.

Vitamin C powder USP-FCC was a gift from Takeda USA Inc. Vitamin C was batch-prepared for clinical use by the NIH Clinical Center Pharmacy as a sterile solution of 50 mg/ml in water adjusted to pH 6.5 with NaOH.

I'll get to johnwens post after reviewing the links. The Hickey/Roberts reference is to a primer on Drugs (a book) but they expand on the fact that the lower the pH, the stronger the stomach acid, the stronger the effect moving "organic" acids through the stomach wall..

[ofonorow]

[Johnwen]

[ofonorow]

Right, and no doubt some/most of the job of transporting vitamin C to the blood stream happens in the intestines.

The question is how taking a vitamin C pill can clear the sinus in 5 minutes?

Or how and why our readings from minutes 10 to 35 (w/glucose meter) after the ingestion of 4 to 5 grams of ascorbic acid rise markedly (and don't with the same amount of sodium ascorbate)

And while liposomal takes 2 to 3 hours to get the vitamin C in the blood (peak), it too can eliminate sinus drip in minutes after taking by mouth (this affect I assumed was because the liposomes enter the mucous membranes in the mouth)

Vitamin C (as ascorbic acid) can apparently reach the blood stream quicker than seems possible -- passing through the stomach and into the intestines (even with the small aperture/opportunity.) Still looking for the detailed Hickey/Roberts treatment of the "weak organic acid" effect they mention.. And there were reports that Nexium interferes with vitamin C absorption..

[Johnwen]

[Johnwen]

[ofonorow]

johnwen, I hope you are planning on writing a book! (If so, I look forward to it.)

GLUT proteins do not transport ASC (ascorbate ion) or AA (ascorbic acid)

NOT CORRECT!

Your argument then is with the authors of that book! (That GLUT does not transfer reduced ascorbate makes perfect sense to me.)

And yes, we have discussed many of the liposomal issues before. Even the notion that some vitamin C remains outside the liposomes (as an emulsion argument) but this does not appear to explain a) why taking a True-liposomal by mouth clears sinuses as rapidly as a 500 mg ascorbic acid tablet, but the professional measurements show that vitamin C levels in the blood don't peak for 2 to 3 hours. (Or the claim that Eme Blair's True-Liposomes are 98% encapsulated . The simplest explanation is that some of this nano sized spheres can make it through mucous tissue in the mouth to the sinuses.)

I still would like an answer to the question how a 500 mg ascorbic acid tablet, which must take some time to dissolve in the stomach can clear mucous from the sinuses in as little as five minutes. I don't think its possible that it reaches the small intestines in that short interval.

Now back to read your links..

Added - so your last link (vitamin C update in the mitochondria) says the following.

We found that the oxidized form of vitamin C, dehydroascorbic acid (DHA), enters mitochondria via facilitative glucose transporter 1 (Glut1) and accumulates mitochondrially as ascorbic acid (mtAA).

So which link again, claims that reduced vitamin C is taken up by GLUT???

[Johnwen]

Actually all of them do! However if you want to get down to the nitty gritty this one goes into a lot of detail!

http://www.researchgate.net/publication ... _and_GLUT8

Did you miss the via in your quote???

enters mitochondria via facilitative glucose transporter 1 (Glut1)

VIA; Preposition! By way of!!!!