Can vitamin C help with blood sugar levels?

We recently reviewed several new studies on Vitamin C. Specifically, its effect on blood sugar control. The existing research suggests that it could theoretically improve it, but the evidence is still pretty mixed.

One reader sent us some studies to check out. They mentioned a reduction in blood glucose levels in patients who took vitamin C and had type 2 diabetes.
After reviewing the literature, we found that there were considerably more studies. Here is a summary of what they say.

What is vitamin C all about?

Vitamin C has long been one of the most studied supplements.

A few decades back there was a lot of hype around it because it is an antioxidant and oxidative damage to cells contributes to many diseases.

Unfortunately, high doses of vitamin C did not prove to be the salvation everyone was hoping for. In fact, such doses even had quite a few downsides.

This is not to say that supplements may not be useful in a particular context. Patients with type 2 diabetes usually have reduced vitamin C levels because the disease brings on a tremendous amount of oxidative stress. Such observations may suggest that vitamin C could have an effect on blood sugar control in these patients. However, the tests need to be looked at more closely.

Review of studies on vitamin C

This is what you need to know about new studies on vitamin C. Be warned, it's going to be a bit nerdy.

We've added 19 of them. 10 on insulin and 8 on HbA1c that also looked at glucose levels. Most of them were done on type 2 diabetics, but they weren't necessarily measuring glucose. Occasionally they were more interested in lipids, but mostly metabolic syndrome. Most didn't declare primary results, which shook our confidence a bit.

Two tests assessed only acute, intravenous vitamin C delivery. One study evaluated ultramarathoners who took vitamin C 7 days before and on race day. The largest trial was a randomized trial with 70 participants in vitamin C and placebo groups that had mixed results but did not show a dramatic reduction in HbA1c, glucose, or insulin. The next section will discuss the differences between the studies.

Overview of vitamin C meta-analyses

Meta-analyses can be useful for qualitative summaries of a group of studies. One, from 2017, examines all studies of which we are aware so far. Unfortunately, it found no reduction in glucose, HbA1c or insulin. Moreover, it has a number of problems.

First, it combined the fasting and post-meal states, which doesn't give us a good estimate. The meal studies were minimal, but they still muddy our water a bit.

It also doesn't make sense to combine data from healthy people and type 2 diabetics, because a small effect in normal people can be a large effect in diabetics. And remember the studies with intravenous vitamin C administration? Well, those won't be applicable to the vast majority of people.

So, in healthy people, the results don't happen.

In diabetics, there was a small but statistically significant reduction in fasting glucose (-0.44 mmol/L). No results were confirmed for insulin and HbA1c.

Studies longer than 30 days yielded better results. However, the addition of acute dose studies in people without diabetes limits their effects. It is also unclear how study length affects diabetics, especially if the study is longer than 2 months.

Future studies will hopefully be more rigorous and examine type 2 diabetics over a longer period of time. The longest studies were two small, four-month studies. The only thing that can be said from this is. The effect of vitamin C on type 2 diabetes has not been adequately investigated.

What could the future look like for vitamin C and blood sugar?

One study by the reader mentioned above may help us with this question. It was randomized, blinded, placebo-controlled, and conducted on type 2 diabetics.

The 30 participants took either a placebo or 500 mg of vitamin C twice a day for a total of four months. Then, for the next 4 months, the supplementation was switched. The researchers used a glucose monitor to record information on post-meal glucose levels, which transmitted the information to a computer throughout the day. )

The placebo group's post-meal glucose levels rose, while the vitamin C group's fell. The difference was significant.
On an empty stomach, the differences were minimal, so it is not clear whether vitamin C had a real effect. But more studies like this could overturn the results of previous research.

None of the studies comment on the ultimate consequences of diabetes: mortality and complications. And that's what we're all about. Such studies require a lot of people, time and money. And it doesn't make sense to invest this when we're still speculating over unclear results.

In the general public, vitamin C supplementation does not seem to reduce mortality, but in type 2 diabetics it may be different. Only time will tell.

Sources:
Sargeant LA, et al. Vitamin C and hyperglycemia in the European Prospective Investigation into Cancer--Norfolk (EPIC-Norfolk) study: a population-based study . Diabetes Care. (2000)
Kositsawat J, Freeman VL. Vitamin C and A1c relationship in the National Health and Nutrition Examination Survey (NHANES) 2003-2006 . J Am Coll Nutr. (2011)
Will JC, Byers T. Does diabetes mellitus increase the requirement for vitamin C? . Nutr Rev. (1996)
Wilson R, et al. Inadequate Vitamin C Status in Prediabetes and Type 2 Diabetes Mellitus: Associations with Glycaemic Control, Obesity, and Smoking . Nutrients. (2017)
Rehman K, Akash MSH. Mechanism of Generation of Oxidative Stress and Pathophysiology of Type 2 Diabetes Mellitus: How Are They Interlinked? . J Cell Biochem. (2017)
Ashor AW, et al. Effects of vitamin C supplementation on glycaemic control: a systematic review and meta-analysis of randomised controlled trials . Eur J Clin Nutr. (2017)
Mason SA, et al. Ascorbic acid supplementation improves postprandial glycaemic control and blood pressure in individuals with type 2 diabetes: findings of a randomized cross-over trial . Diabetes Obes Metab. (2019)
Jenkins DJA, et al. Supplemental Vitamins and Minerals for CVD Prevention and Treatment . J Am Coll Cardiol. (2018)

Source: www.examine.com - Does vitamin C improve blood sugar control?
By Wyatt Brown
Translated by.