Vitamin C

GillianH said:

Hi I currently take 2000mg slow release metformin which is due to be reviewed in 3 weeks but obviously because of the current covid situation this may be postponed. I have been doing some research on vitamin c reducing blood sugars in type 2 diabetics. I have recently started taking 500mg once a day slow release vitamin c tablets. However my research says that 500mg twice a day is best for helping blood sugars. I was unsure if the slow release vitamin c were any different to regular vitamin c or if there was any reason why I shouldn’t increase these to twice a day? Any advice gratefully received.

Click to expand...

I just started a thread about vitamins but quick answer is I - as a layperson not medically trained - am doing similar myself right now by drinking powdered vit c laced water throughout the day. 2000-4000mg a day as I have mild symptoms. I return to 1000x2000 once well. Some useful links in the below thread that might help you decide.

https://www.diabetes.co.uk/forum/threads/vitamins-and-diabetes.173214/

I take a 1000mg tablet per day as that's what I have they say 2 x 500 per day is optimal I may change to that at some point maybe.

RCT trial described here

https://dom-pubs.onlinelibrary.wiley.com/doi/abs/10.1111/dom.13571
Note: trial sample sizewas very small (31 participants) The HbA1c average was only just diabetic so not representative of most T2D . Age range was quite high too (61-70 yrs)

The medications were noted and listed. Surprisingly that the average LDL and HDL in the TC were all low, and the HDL was lower than the LDL. Also there was evidence of high(ish) trigs indicating oxidative stress is present in most of them.

The results were based entirely on the use of CGM continuous monitors, and there was no independant check on their accuracy. Not sure from the methodology description that each participant used the same CGM for all readings, so that the results will be delta changes on the same instrument, or of they relied on the calibration accuracy between instruments. As one who parallel tests daily with two different machines I know from n=1 experience that they neither track nor maintain their accuracy, so the 1.1 mmol/l changes noted in the conclusion falls into the accuracy variations one would get naturally anyway and may not be actual proof that AA supplementation decrease occurred as claimed.

The other comfounder they did not consider is that Vitamin C is essential is producing haemoglobin in the red blood cells, ao increasing tha AA may be improving the RBC value and the haematocrit value, which could affect the meters performance.

Very good evaluation, Oldvatr! I do worry about the effects on kidneys of high doses of Vit C. No-one wants kidney stones.

Dr Snoddy said:

Very good evaluation, Oldvatr! I do worry about the effects on kidneys of high doses of Vit C. No-one wants kidney stones.

Click to expand...

Anything you can link to that suggests this is a risk?

HSSS said:

Anything you can link to that suggests this is a risk?

Click to expand...

https://www.healthline.com/nutrition/side-effects-of-too-much-vitamin-c
This is [usually] a reputable source that I use.

Anyone on a plant based diet should read this.
https://www.healthline.com/nutrition/side-effects-of-too-much-vitamin-c#iron

Oldvatr said:

https://www.healthline.com/nutrition/side-effects-of-too-much-vitamin-c
This is [usually] a reputable source that I use.

Anyone on a plant based diet should read this.
https://www.healthline.com/nutrition/side-effects-of-too-much-vitamin-c#iron

Click to expand...

Having read the article and many of the sources (or their abstracts) it seems to me that for those already at risk of kidney stones or iron overload should exercise some caution. It seems, like in many things, there some considerable debate but for those people the risk might be there of making their conditions worse. Generally it doesn’t appear to be a worry though. I’m reassured after checking I have more to gain by taking it than not.

HSSS said:

Having read the article and many of the sources (or their abstracts) it seems to me that for those already at risk of kidney stones or iron overload should exercise some caution. It seems, like in many things, there some considerable debate but for those people the risk might be there of making their conditions worse. Generally it doesn’t appear to be a worry though. I’m reassured after checking I have more to gain by taking it than not.

Click to expand...

chacun a son gout.

Vitamin C is an essential vitamin that we all need. The problem comes into play only when larger doses than a diet could naturally provide are used. A classic example is Vitamin E which can be dangerous in high doses, Vitamin C is less of a problem, but again a sustained intake may not be advisable since it is known that one form of kidney stones is a crystallation of oxallate, which ascorbic acid boils down to in the excretion pathway.

As mentioned in another thread, iron is essential, but excess iron is not excreted except through blood loss, so can build up unnoticed to lethal levels, The savvy medics in the last centuries understood this which is why blood letting and leeches were so popular. The warning I gave is about a silent killer.and should not be shrugged off. Even though diabetics tend to get whole blood panel testing once a year which should highlight any such problem, it is not a guarantee and in fact the ferritin levels are only checked in women who are still of child bearing ability.

Oldvatr said:

chacun a son gout.

Vitamin C is an essential vitamin that we all need. The problem comes into play only when larger doses than a diet could naturally provide are used. A classic example is Vitamin E which can be dangerous in high doses, Vitamin C is less of a problem, but again a sustained intake may not be advisable since it is known that one form of kidney stones is a crystallation of oxallate, which ascorbic acid boils down to in the excretion pathway.

As mentioned in another thread, iron is essential, but excess iron is not excreted except through blood loss, so can build up unnoticed to lethal levels, The savvy medics in the last centuries understood this which is why blood letting and leeches were so popular. The warning I gave is about a silent killer.and should not be shrugged off. Even though diabetics tend to get whole blood panel testing once a year which should highlight any such problem, it is not a guarantee and in fact the ferritin levels are only checked in women who are still of child bearing ability.

Click to expand...

All fair points.

Blood panels don’t tend to check vitamins unless there’s a specific reason in my experience

Vit c has been shown to be lower than it should be in type 2 diabetes so we “should” have some leeway before it becomes an issue

I know personally my ferretin has for years been chronically low, I ask for the test knowing this. Iron supplements do little. I appreciate I am an exception not the norm.

HSSS said:

All fair points.

Blood panels don’t tend to check vitamins unless there’s a specific reason in my experience

Vit c has been shown to be lower than it should be in type 2 diabetes so we “should” have some leeway before it becomes an issue

I know personally my ferretin has for years been chronically low, I ask for the test knowing this. Iron supplements do little. I appreciate I am an exception not the norm.

Click to expand...

Would be interesting if your ferritin levels improve as a result of AA supplementation. Also your Red Cell count and size statistics since if these go up then you will be producing more haemoglobin, and may affect the HbA1c. Not conclusive proof again since any infection would negate these gains so keep an eye on the leukocyte values too.

Oldvatr said:

Would be interesting if your ferritin levels improve as a result of AA supplementation. Also your Red Cell count and size statistics since if these go up then you will be producing more haemoglobin, and may affect the HbA1c. Not conclusive proof again since any infection would negate these gains so keep an eye on the leukocyte values too.

Click to expand...

Yep once things calm down again I’ll try and get them all rechecked. I’ll be overdue hb1ac by then too.

I take 1000mg Vit C daily, not because of my T2, but it seems to ease my hayfever! I also crave citrus if I"m run down or sickening for something so I increase to 2000mg, my understanding is as a water soluble vitamin, is that you don't need/use is just excreted in your urine

lessci said:

I take 1000mg Vit C daily, not because of my T2, but it seems to ease my hayfever! I also crave citrus if I"m run down or sickening for something so I increase to 2000mg, my understanding is as a water soluble vitamin, is that you don't need/use is just excreted in your urine

Click to expand...

This is what the GP journal says about this
https://www.practiceupdate.com/content/high-dose-vitamin-c-and-risk-of-kidney-stone-formation/3076

Basically if you are ingesting an excess of Vit C than the body needs, then you are increasing the risk of developing painful kidney stones. Not life threatening, but exceedingly uncomfortable. The risk starts to get significant at 1000 mg per day and above. Especially at risk are those with low GFR ratios i.e. typically older age people and diabetics but also those with kidney damage.