Preventing Gestational Diabetes With Vitamin C

How to Get More Vitamin C During Pregnancy

Author: Dr. Stephen Chaney

Does the belief that some mothers are preventing gestational diabetes with vitamin C have any merit?

Each year about 280,000 women in the United States will develop gestational diabetes in the second or third trimester of pregnancy. Gestational diabetes has increased by 56% between 2000 and 2010 and now represents 7% of all pregnancies in the US.

These are alarming statistics because gestational diabetes can have devastating consequences for both the mom and the unborn baby. For example, gestational diabetes:

Can cause excessive birth weight that causes the baby to become stuck in the birth canal, which requires a C-section and/or may cause brain damage to the baby.
Can cause early (preterm) birth and/or respiratory distress symptom in the newborn infant.
Can lead to preeclampsia (high blood pressure), which causes several other problems.
Is associated with an increased risk of obesity and type 2 diabetes later in life for both the mom and her baby.

Because of these risks it is of paramount importance that you get your blood sugar levels under control if you develop gestational diabetes. The first line of defense against gestational diabetes is diet, exercise, and weight management (more about that later). If that fails to get your blood sugar under control, your physician may recommend oral diabetes medications. However, the American Diabetes Association does not recommend their use during pregnancy because their safety has not been established in pregnant women. Instead, they recommend insulin because that does not cross the placenta.

So, what can you do? Gestational diabetes is like type 2 diabetes in that it is caused by insulin resistance. In last week’s issue of “Health Tips From the Professor,” I discussed two recent publications that suggest vitamin C improves blood sugar control in type 2 diabetics. Could vitamin C do the same thing for gestational diabetes? One recent study, (C. Liu et al, Clinical Nutrition), says the answer may be yes.

How Was The Study Done?

This study recruited 3,009 pregnant women from the ongoing Tongji Maternal and Child Heart Cohort study in the Wuhan region in China. Their average age was 28 and their average BMI was 20, which is in the healthy range. [Note: This is significantly different than in the United States, where a significant percentage of women enter pregnancy in the overweight or obese category.]

Gestational Diabetes was assessed by an oral glucose tolerance test (the most accurate method) during weeks 24-28 of pregnancy (third trimester). Of the participants, 344 (11.4%) developed gestational diabetes.

Diet and supplement use were assessed during their first prenatal care visit and at the beginning of each trimester. The assessment was conducted by a trained interviewer. The adequacy of vitamin C intake was based on Chinese standards and was divided into inadequate (<115 mg/day (range = 10-110), adequate (115-200 mg/day), and above adequate (greater than 200 mg/day (range = 200-567)).

In terms of supplementation:

44% of the population used supplements containing vitamin C.
6% of the population got their supplemental vitamin C from a multivitamin.
Not surprisingly, multivitamin use was much higher in the group with above adequate vitamin C intake.

The major findings of this study were:

Dietary intake of vitamin C was inversely proportional to gestational diabetes.
Women with above average dietary vitamin C intake had a 26% lower risk of developing gestational diabetes.
The primary dietary sources of vitamin C in the Chinese population were, in descending order, green leafy vegetables, cabbage, citrus fruits, chili peppers, and berries. These 5 foods accounted for 80% of the vitamin C in their diet.
A multivitamin supplement had no effect on gestational diabetes.

The authors concluded: “Sufficient dietary vitamin C intake (more than 200 mg/day) may protect pregnant women from developing gestational diabetes. Therefore, sufficient vitamin C from fruits and vegetables should be recommended.” This means preventing gestational diabetes with vitamin C may be possible.

The authors pointed out that their data on multivitamin use was consistent with a recent US study (Y. Song et al, Diabetes Care, 34: 108-114, 201) showing that multivitamin use did not affect the risk of developing type 2 diabetes, but vitamin C supplementation did decrease risk. The authors said: “Whether pure vitamin C supplements have an effect on gestational diabetes risk needs further research.”

What Does This Study Mean For You?

A recent study conducted in China reported that >200 mg/day of dietary vitamin C reduced the risk of developing gestational diabetes during pregnancy by 26%.
The study found that multivitamin use did not affect the risk of developing gestational diabetes but did not assess the effect of vitamin C supplementation on the risk of developing gestational diabetes.
The Chinese consume a primarily plant-based diet. Fruit and vegetable consumption is much less in the US. Consequently, dietary vitamin C intake in the US is much less. For example:
The average dietary vitamin C intake in the Chinese study was 163 mg/day. In contrast, the average intake for women of childbearing age in the US is 91 mg/day.
In the US 12% of women of childbearing age are deficient in vitamin C and an additional 20% are getting less than the RDA of vitamin C from their diet.

This is a small study and needs to be confirmed by larger studies. However, the idea that vitamin C may help reduce the risk of developing gestational diabetes is consistent with recent studies suggesting vitamin C helps with blood sugar control in type 2 diabetes (see my recent issue of “Health Tips From The Professor:” Vitamin C and Diabetes).

So, what should you do to reduce the risk of gestational diabetes if you are pregnant or treat it if it develops when you are pregnant?

#1: Diet: Here is what the American Diabetes Association recommends:

Eliminate sodas, sweets, and highly processed foods from your diet. Also avoid alcohol and cigarette smoking.
Consume a variety of whole foods from all 5 food groups. This includes fruits, vegetables, whole grains, beans, low-fat dairy, and low-fat meats.
Practice portion control. You are not really eating for two. Frequent small meals are better than 2 or 3 large meals.
You may want to consider a moderately low carb diet, but this is not the time to be cutting out nutrient-rich food groups. If you wish to go this route, I would suggest the low-carb version of the Mediterranean diet (minus the red wine, of course).

#2: Exercise: Exercise is a key component for controlling blood sugar levels. Consult with your physician about the best exercise program for you.

#3: Weight Management: The current recommendation for weight gain during pregnancy is between 25 to 35 pounds if you are at normal weight and 15-25 pounds if you are overweight. If you are gaining more than that, ask your physician for referral to a dietitian who can help you limit your weight gain. This is not the time to go on any extreme weight-loss diet.

For example, contrary to what you hear from keto advocates, this is not the time to go on the keto diet. Recent studies suggest that ketosis adversely affects brain development in the fetus. Until we know more, there is no reason to risk harm to your unborn baby.

#4: Diabetes Medications: The American Diabetes Association does not recommend diabetes medications if you develop gestational diabetes during pregnancy. They recommend insulin instead. However, some physicians still prescribe diabetes medications for women with gestational diabetes.

#5: Vitamin C: If you wish to avoid insulin or diabetes medications, you may want to try increasing your vitamin C intake first. Based on the current study and other recent studies, here are my recommendations:

Start with adding more vitamin C-rich fruits and vegetables to your diet. If your diet is like that of most US women of childbearing age, you will want to more than double your dietary vitamin C intake.
Consider adding a vitamin C supplement. In my previous “Health Tips From The Professor” I discussed a study showing that 1,000 mg/day improved blood sugar control in people with type 2 diabetes.
Don’t think of vitamin C as a “magic bullet.” It will not control gestational diabetes by itself. It should be thought of as part of a holistic program that includes diet, exercise, and weight management.
The only caution I am aware of for vitamin C supplementation during pregnancy is that the newborn baby may metabolize vitamin C more rapidly. You will want to continue vitamin C supplementation while you are breastfeeding as a precaution.

The Bottom Line

A recent study conducted in China reported that >200 mg/day of dietary vitamin C reduced the risk of developing gestational diabetes during pregnancy by 26%.
The study found that multivitamin use did not affect the risk of developing gestational diabetes but did not assess the effect of vitamin C supplementation on the risk of developing gestational diabetes.
The idea that vitamin C may help reduce the risk of developing gestational diabetes is consistent with recent studies suggesting vitamin C helps with blood sugar control in type 2 diabetes.
The Chinese consume a primarily plant-based diet. Fruit and vegetable consumption is much less in the US. Consequently, dietary vitamin C intake in the US is much less.

So, what should you do to reduce the risk of gestational diabetes if you are pregnant or treat it if it develops when you are pregnant?

#1: Diet: Here is what the American Diabetes Association recommends:

Eliminate sodas, sweets, and highly processed foods from your diet. Also avoid alcohol and cigarette smoking.
Consume a variety of whole foods from all 5 food groups. This includes fruits, vegetables, whole grains, beans, low-fat dairy, and low-fat meats.
You may want to consider a moderate low carb diet, but this is not the time to be cutting out nutrient-rich food groups. If you wish to go this route, I would suggest the low-carb version of the Mediterranean diet (minus the red wine, of course).

#2: Exercise: Exercise is a key component for controlling blood sugar levels. Consult with your physician about the best exercise program for you.

For example, contrary to what you hear from keto advocates, this is not the time to go on the keto diet. Recent studies suggest that ketosis adversely affects brain development in the fetus. Until we know more, there is no reason to risk harm to your unborn baby.

Start with adding more vitamin C-rich fruits and vegetables to your diet. If your diet is like that of most US women of childbearing age, you will want to more than double your dietary vitamin C intake.
Consider adding a vitamin C supplement. Don’t think of vitamin C as a “magic bullet.” It will not control gestational diabetes by itself. Instead, it should be thought of as part of a holistic program that includes diet, exercise, and weight management.

For more details read the article above.

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.