[Eddy]

Vitamin C and Hyperglycemia in the EPIC-Norfolk Study

[REDLAN]

read through the study - seems to be quite a well done study.

Essentially what they found was that plasma vitamin C was lower in those with diabetes. They also found that vitamin C was lower in those with undiagnosed diabetes but an HbA1C of greater than 7% - which eliminates treatment of diabetes as a cause of the lower vitamin C.

They then went on and did a linear regression analysis of the data, and showed that Vitamin C levels were related to HbA1C levels - rising HbA1C meant lower vitamin C levels. It shows that there is a relationship between HbA1c and vitamin C.

The study was done because it has been noted that people with diabetes have lower vitamin C levels, and they wanted to confirm that this was indeed the case. Previous studies were either too small, or were done on a highly selective population (i.e. sick people in hospital) and therefore subject to selection biases.

They discuss 2 possible mechanisms - low vitamin C levels are linked to a cause for type 2 diabetes, or vitamin C is used up combating the effects of diabetes (preventing harm caused by high levels of circulating glucose)

The study would have been better if they did not have to correct for age - age is a huge confounding factor, and older people have lower vitamin C levels than younger people. In the study group higher Hba1C's were also associated with older subjects too.

What the study does not show.

1) whether the difference in vitamin C is clinically significant.

and importantly...

2) whether vitamin C supplementation will make any difference to the progression of diabetes.

(studies like this that get picked up by the media often go on to draw such conclusions in the press releases even though the data from the study does NOT support such conclusions)

[Eddy]

Originally Posted by REDLAN

They discuss 2 possible mechanisms - low vitamin C levels are linked to a cause for type 2 diabetes, or vitamin C is used up combating the effects of diabetes (preventing harm caused by high levels of circulating glucose)

Originally Posted by REDLAN

What the study does not show.

1) whether the difference in vitamin C is clinically significant.

and importantly...

2) whether vitamin C supplementation will make any difference to the progression of diabetes.

A very curious, albeit limited, data point:

Prior to my DX, I'd been having wicked intestinal problems for nearly three months. Putrid flatulence every few minutes, the ability to mold a toilet bowl within days after use, and plenty of all-around nasty stuff. I started taking about 15g/day of vitamin C.

I slowly increased my vitamin C dose. In the few weeks prior to DX, I was taking 55-80 g/day (65 average) of vitamin C... and never hitting bowel tolerance. I'd typically have 20g with each meal.

The day before I had my DKA encounter (plenty of ketones, intestines shutting down, vomiting bile, et cetera), I only consumed 45g of vitamin C.

I can't get my mind off that. Although nowhere near statistically significant/valid, I tend to think that #2 is likely correct, and that vitamin C has some beneficial effects. I need to start increasing my tolerance and experiment. I've only been taking a gram or three post-DX.

[Eddy]

In addition to

hypos from: niacin, vitamin C, ... what else?

I've been experimenting with vitamin C again... and having "coincidental" hypos again.

Today, my preprandial BG was 67. I consumed 5.5 U of raisins, 2 U of fructose, and 5 g of vitamin C. (The fructose was in the Emergen-C brand vitamin C packets.)

Rather than bolus the "proper" 7.5 U of Novolog, I used only 3 U. An hour later -- when raisins and fructose should be done and the Novolog nearing its 1h:15m completion point -- my BG was 80.

I had 4 U of homemade raisin bread, 1 U of fruit juice, 3 U of human R, and took a nap. My 3 hr postprandial BG was 87.

I did my afternoon basal. Because I was running late -- I overslept! -- I did 0.5 U Novolog mixed with 1.5 U human N; my standard is 3 U human N.

Another 4 U of bread, another 1 U of fruit juice, a shower... and I was down to 69. I had another 1 U of juice, then a bit more than 4 U of human R to cover the bread. We shall see where I end up.

There's definitely something to be said about vitamin C. Although my data sampling is too small to be statistically valid, the effect is consistent: Once I reach a certain threshold, something about vitamin C helps lower my BG.

[BlueSky]

I find the study conclusion intriguing :

An inverse association was found between plasma vitamin C and HbA1c. Dietary measures to increase plasma vitamin C may be an important public health strategy for reducing the prevalence of diabetes.

They are suggesting, based on a statistical association, that low plasma Vitamin C actually causes diabetes. .

[slipperyelm]

I wonder how many people might be dashing out to stock up on vitamin C after reading this thread.

BTW, I believe the info sheet that came with my glucometer mentions that its measures of glucose are affected by high Vit C levels. Don't remember if they say it will read higher or lower than in reality --reality as tested by another means, I suppose.

[Eddy]

Originally Posted by slipperyelm

I wonder how many people might be dashing out to stock up on vitamin C after reading this thread.

I'd love to know what others observe. Be careful, of course. (I also have no idea what the mechanism is, nor how it affects insulin-resistant folks versus insulin-deficient.)

Originally Posted by slipperyelm

BTW, I believe the info sheet that came with my glucometer mentions that its measures of glucose are affected by high Vit C levels. Don't remember if they say it will read higher or lower than in reality --reality as tested by another means, I suppose.

IIRC, vitamin C causes some meters to read higher-than-actual. Mine had no such warning... and vitamin C without reducing my bolus has definitely triggered some hypos. (I hit 41 over the weekend because I didn't reduce my bolus enough.)

[Eddy]

Originally Posted by BlueSky

I find the study conclusion intriguing :

They are suggesting, based on a statistical association, that low plasma Vitamin C actually causes diabetes. .

I have no idea...

Another thing that keeps rattling around in my head:

Illness causes increased insulin requirements. Ill people also can tolerate -- and therefore need, if one subscribes to the "one needs as much C as one can tolerate" theory -- higher doses of vitamin C.

Echinacea also caught my attention during personal use. It's supposed to help the immune system... and I've had some hypos that I finally blamed on echinacea. (I've experimented even less with echinacea than with vitamin C, however. I think I've taken echinacea about five times post-DX.)

Finally, the concept of breakfast-time citrus consumption amuses me. I have to wonder if that started because someone felt better, perhaps due to reduced insulin resistance. Pure speculation, mind you.

[BlueSky]

Originally Posted by Eddy

... vitamin C causes some meters to read higher-than-actual. ...

Large amounts of vitamin c will also distort HBA1c test results.

[Eddy]

Originally Posted by BlueSky

Large amounts of vitamin c will also distort HBA1c test results.

...for the better, as I understand. And, despite the large doses I'd been taking prior to DX, I still turned a 12.9% A1c at DX. The day before DKA kicked my rear, I'd taken "only" 45 g of the stuff... as opposed to my usual 65-ish grams. (My record was 80 g in one day.) Although highly circumstantial, the timing still piques my interest.

[Eddy]

Vitamin C Foundation News

May 2002

Megadose Vitamin C consumption does not cause kidney stones.
Intake of vitamins B6 and C and the risk of kidney stones in women
Curhan, G. C., Willett, W. C., Speizer, F. E., Stampfer, M. J.
J Am Soc Nephrol 10:4:840-845, Apr 1999

Abstract

Urinary oxalate is an important determinant of calcium oxalate kidney stone formation. High doses of vitamin B6 may decrease oxalate production, whereas vitamin C can be metabolized to oxalate. This study was conducted to examine the association between the intakes of vitamins B6 and C and risk of kidney stone formation in women. The relation between the intake of vitamins B6 and C and the risk of symptomatic kidney stones were prospectively studied in a cohort of 85,557 women with no history of kidney stones. Semiquantitative food-frequency questionnaires were used to assess vitamin consumption from both foods and supplements. A total of 1078 incident cases of kidney stones was documented during the 14-yr follow-up period. A high intake of vitamin B6 was inversely associated with risk of stone formation. After adjusting for other dietary factors, the relative risk of incident stone formation for women in the highest category of B6 intake (> or =40 mg/d) compared with the lowest category (<3 mg/d) was 0.66 (95% confidence interval, 0.44 to 0.98). In contrast, vitamin C intake was not associated with risk. The multivariate relative risk for women in the highest category of vitamin C intake (> or =1500 mg/d) compared with the lowest category (<250 mg/d) was 1.06 (95% confidence interval, 0.69 to 1.64). Large doses of vitamin B6 may reduce the risk of kidney stone formation in women. Routine restriction of vitamin C to prevent stone formation appears unwarranted.

[Eddy]

Originally Posted by BrianSCohen

You migth start a separate thread on this.

Separate from the existing vitamin C thread?

Originally Posted by BrianSCohen

I was taking megadoses of vitamin C for some time, but feared that it might be having a negative effect. Linus Pauling was a big fan of it, and there is a bunch of studies that say it helps type 2 diabetics maintain diabetic control.

Interesting...

Originally Posted by BrianSCohen

There are however indications that for some it may have a bad impact as in High Doses of Vitamin C Supplement Increase Blood Glucose Levels - Diabetes Health.

Ascorbic acid and glucose are very similar molecules. Some meters are "confused" by vitamin C. Seeing how old the article is, and that it fails to mention the meter, I wish that I had more information. Were the readings artifacts? Does vitamin C indeed have the opposite effect in some to what it does in me? I wish that I knew...

Originally Posted by BrianSCohen

In my case, I have been concerned that various factors may be causing problems with my HbA1c test, which has been about 1% higher than might be expected given my average blood glucose levels.

What assay method was used for your A1c? Have you tried both with and without your vitamin C regimen?

Originally Posted by BrianSCohen

There seems to be a bunch of research that indicates that megadoses of vitamin C may adversely impact (ie. ruin) the HbA1c test as in Protein Glycation: Ascorbate Antagonism.

The final two paragraphs are badly written. They talk about how a "misleadingly low" A1c would be bad... yet, by their own prior admission:

"This suggests that the AA-associated lowering of GHb reflected a genuine in vivo decrease in glycation."

The objective is to prevent side effects from lots of sugar molecules being in the blood, and from lots of sugar molecules being stuck to proteins.

My observations are that vitamin C -- for me -- decreases the number of sugar molecules floating around. Other studies indicate that vitamin C decreases the number of sugar molecules stuck to the proteins.

Perhaps it's because I'm half-awake and running on three hours of sleep, but I'm arriving at a different conclusion than yours.