Vitamin C Competes With Sugar

[fabiomln]

there is some evidence that vitamin C competes with sugar.
So someone says that: Glucose and ascorbic acid are constantly competing for insulin transport so diets high in sugar and carbohydrates will decrease the amount of ascorbic acid that enters cells and thus create undesirable effects on the immune response.

But I have another question: if glucose and ascorbic acid are constantly competing for insulin transport, is it possible that high levels of vitamin C will DECREASE the amount of SUGAR that enters cells???

 

[Spokey]

Not likely, cells uptake glucose preferentially to vitamin C apparently.

 

[Mittir]

This does not directly answer the question, but shows benefit of using large dose
vitamin C among diabetic patients. Here is an interesting study using 500 mg and
1000 mg of vitamin C in diabetic patients. In 1000 mg group fasting glucose, HbA1c ,
total cholesterol decreased significantly and insulin decreased by almost 50 percent.
There is insignificant change in 500 mg group. It seems like the dose of vitamin
C is the deciding factor.

Effect of vitamin C on blood glucose, serum lipids & serum insulin in type 2 diabetes patients.
Afkhami-Ardekani M1, Shojaoddiny-Ardekani A.
Author information
Abstract
BACKGROUND & OBJECTIVE:
Diabetes mellitus is one of the most common metabolic disorders that causes micro- and macro-vascular complications. Because of additive effects of hyperglycaemia and hyperlipidaemia for cardiovascular diseases, lipid abnormalities should be evaluated in diabetes. As vitamin C is known for its beneficial effects on serum lipids and glycated haemoglobin (HbA1c), we evaluated the effect of different doses of vitamin C on blood glucose, serum lipids and serum insulin in individuals with type 2 diabetes mellitus.
METHODS:
A total of 84 patients with type 2 diabetes referred to Yazd Diabetes Research Center, Iran, were included in the study. They received randomly either 500 mg or 1000 mg daily of vitamin C for six weeks. Fasting blood sugar (FBS), triglyceride (TG), total cholesterol (TC), low and high density lipoprotein (LDL, HDL), glycated haemoglobin HbA(Ic) and serum insulin were measured before and after vitamin C consumption and the results were analyzed.
RESULTS:
A significant decrease in FBS, TG, LDL, HbA1c and serum insulin was seen in the group supplemented with 1000 mg vitamin C. The dose of 500 mg vitamin C, however, did not produce any significant change in any of the parameters studied.
INTERPRETATION & CONCLUSION:
Our results indicate that daily consumption of 1000 mg supplementary vitamin C may be beneficial in decreasing blood glucose and lipids in patients with type 2 diabetes and thus reducing the risk of complications.

Fulltext: http://medind.nic.in/iby/t07/i11/ibyt07i11p471.pdf

 

[Mittir]

This case report claims high dose intravenous vitamin C supplementation can
give false high blood sugar reading. They did not say anything about vitamin C
blocking insulin's transport. They recommends patients to wait about 8 hours
after taking vitamin C injection to measure blood sugar. They mentioned that
regular oral dose of vitamin C does not affect blood sugar reading.The serum
concentration from regular oral dose is way lower than mega dose injections.
http://care.diabetesjournals.org/conten ... l.pdf+html

There is another similar report from 1999 where they found after
discontinuing 4500 mg of vitamin C the fasting blood glucose
dropped from 121 to 99 and blood sugar was stable when he started
1500 mg of vitamin C. They did not say anything about false reading.
High blood sugar with 4500 mg was probably false reading.
http://diabeteshealth.com/read/1999/09/ ... se-levels/

 

[Spokey]

I read about a study recently where pre-loading with vitamin C moved the graph of the insulin response further alone the time axis. I wondered if this is because insulin get's used pretty quickly while a high serum level of vitamin C exists; for transport before the blood glucose has gone up significantly. That idea suggests to me that in order to get the most vitamin C in to cells one could consume it's sources prior to consuming glucose/starch. And that taking vitamin C after a high starch meal would result in a lot of it getting excreted.

:2cents

 

[yerrag]

I accompanied a friend who's consulting with a biochemist for his lung cancer, which has metastasized to his bones. I was told that because glucose and vitamin C share a similar 6-carbon structure, sugar would push out vitamin C from cells when taken together with his megadose vitamin C therapy. But he told me that fructose only has a 5-carbon structure. I didn't ask the biochemist then, but I assume that taking fructose would not push out vitamin C from cells.

If that's the case, is it even practical to feed pure fructose? Given that fructose is only available in combination with glucose, in sugar, honey, and in fruits. Is there such a thing as pure fructose?

Given his thinking that taking glucose would push out vitamin C from cells, the biochemist encourages beta oxidation of fats for energy. What is the impact of not using glucose for energy when respiratory oxidation is suppressed? Or would vitamin C be converted to glucose to provide the fuel for respiratory oxidation?

 

[Logan-]

the oxidised form (DHA) is transported into the cells faster than the reduced form by facilitated diffusion through several isoforms of the glucose transporter (GLUT) [18–20], a process that can be inhibited by glucose in some but not all cell types [21].

Duarte, T. L., & Lunec, J. (2005). Review Part of the Series: From Dietary Antioxidants to Regulators in Cellular Signalling and Gene Expression Review: When is an antioxidant not an antioxidant? A review of novel actions and reactions of vitamin C. Free Radical Research, 39(7), 671–686. doi:10.1080/10715760500104025