Lack of vitamin C increases the risk of eye disease in pregnant diabetics

It is commonly known that pregnant diabetics have an increased risk of developing an eye disease called diabetic retinopathy. The diet plays a major role and it appears that a vitamin C deficiency increases the risk, according to a Danish study of pregnant type 1 diabetics that is published in the journal Antioxidants. The authors also mention that vitamin C is a vital antioxidant that protects cells and tissues against oxidative stress caused by free radicals.

Diabetic retinopathy is one of the most widespread eye disorders in the Western world. The disease is caused by a narrowing of the blood vessels in the eye that can reduce the blood supply and lead to retinal bleeding. The risk goes up according to how long a person has had diabetes, where typical symptoms are elevated levels of HbA1c (long-term glucose), hypertension, impaired kidney function, and lipid disturbances. The pregnancy itself also appears to increase the risk of diabetic retinopathy, and pregnant diabetics are therefore twice as likely to develop this disease.
The new study was carried out by researchers at Aarhus University Hospital. They looked at the link between blood levels of vitamin C in pregnant type 1 diabetics and their risk of developing retinopathy. A total of 29 women participated. Blood levels of vitamin C were measured in the first, second, and third trimester, as well as after giving birth. At least twice during pregnancy and up to four months following delivery, vision tests were conducted. Also, the scientists conducted a fundus examination that is able to detect macular oedema and other signs of diabetic retinopathy.
Using an international scale from 0 (no retinopathy) to 4, the degree of retinopathy was assessed. At study start in the first trimester, 12 women did not have retinopathy, while 17 women had retinopathy in the stages 1-3. The progression of retinopathy increased in nine women, remained unchanged in 17 women, and improved in three women. None of the participants had reached stage 4 of the disease.
It turned out that blood levels of vitamin C during the first trimester were especially good predictors of the risk of developing retinopathy. The lower the vitamin C levels, the higher the risk. Blood levels of vitamin C during the second trimester and the average vitamin level throughout the entire pregnancy, however, did not affect the risk.
This small study of pregnant type 1 diabetics is the first to suggest that low levels of vitamin C may be linked to an increased risk of developing retinopathy or experiencing a worsening of the condition. Although more studies are needed, this study may turn out to be of vital importance to pregnant type 1 diabetics.

How does vitamin C protect against diabetic retinopathy?

Although there is still a lot of uncertainty when it comes to the different pathological processes involved in the development of diabetic retinopathy, recent research suggests a link between the disease and the body’s vitamin C metabolism.
Firstly, vitamin C is involved in the body’s collagen synthesis that is important for blood vessel structure, skin, and bones. Secondly, vitamin D is an effective antioxidant that protects the cells in the eye and brain against free radical damage. We humans generate free radicals as a natural byproduct of various metabolic processes. The free radical burden is increased by things like diabetes, overweight, smoking, and a lot of other factors. Oxidative stress is an imbalance between free radicals and antioxidants and is believed to set the stage for the development of diabetic retinopathy.
The vitamin C concentration in the vitreous body of the eye is 10 times lower in patients with advanced diabetic retinopathy compared with healthy, non-diabetic controls, suggesting that vitamin C plays a role in the development of diabetic retinopathy.

• Vitamin C during pregnancy is vital for the mother and the unborn child
• Vitamin C is important for collagen formation, blood vessel structure, bones, cartilage, iron uptake, immune defense, and as an important antioxidant
• Vegetables, fruit, berries, and herbs are all good sources of vitamin C
• Storage and cooking can deplete levels of vitamin C in food
• A large intake of sugar reduces the effectiveness of vitamin C
• There are specific pregnancy supplements on the market that contain vitamin C

References:

Bente Juhl et al. Low Levels of Vitamin C during Pregnancy; a Risk Marker of Progression of Diabetic Retinopathy in type 1 Diabetic Women? Antioxidants. 2023

Muhammad Abdullah et al. Vitamin C (Ascorbic Acid) StatPearls 2022