Nutrition for Controlling Diabetic Retinopathy: A Review of the Diabetes Visual Function Supplement Study

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Mild nonpriliferative diabetic retinopathy with  diabetic macular edema
With the numbers of people affected by both Type 1 and Type 2 Diabetes soaring in the US (an estimated 1 in 10 adults have diabetes currently in America, but that's expected to rise to 1 in 3 by 2050!), health care providers are actively looking for ways to not only treat this condition medically, but find ways to prevent the damage it causes to our body's most critical functions. The eyes are just one body part severely affected by uncontrolled blood sugar -- with diabetic retinopathy cited as the leading cause of blindness in American adults. Routine eye examinations are the best way to find early retinopathy during the stages before it has time to wreck vision; that's why your doctor takes retinal photographs and/or dilates the eyes every time you go in, even if you are seeing well that day. We know that better blood sugar control, exercise, and avoiding smoking can help reduce risks for diabetic related eye disease, but are there nutritional supplements that can be added to your diet to help protect your sight?  The Diabetes Visual Function Supplement Study investigated which nutritional additives could help protect your sight.  The study period was only 6 months in length with a small sample size (46 enrolled adults with both Type 1 and Type 2 diabetes were randomized between supplement and placebo groups).  But even over such a short reporting period, the results speak clearly about what else we can discuss with out patients for preventive care.

Science Behind the Nutrition

Lutein and Zeaxanthin: These carotenoids have proven essential to macular health, and are the most commonly recommended supplements for patients with sight threatening conditions like macular degeneration.  They are responsible for filtering out high energy blue wavelength light that can damage macular photoreceptors, and act as retinal tissue anti-oxidants.  Macular pigment optical density (MPOD) is the measurement of how much of these two carotenoids you have in your macula, and since your body cannot synthesize lutein or zeaxanthin by itself, diet is our sole method of intake. Studies show increased MPOD is linked to better visual acuity and contrast sensitivity in patients with nonproliferative diabetic retinopathy, and those with higher serum levels of lutein and zeaxanthin have a 66% lower risk of developing diabetic retinopathy.

Vitamin D: Vitamin D insufficiency has been linked to both the presence and the severity of diabetic retinopathy in both Type 1 and Type 2 patients.  And in fact, patients with lower vitamin D levels in general are much more likely to be diagnosed with diabetes, regardless of their body weight.  What role does vitamin D play in diabetes?  We don't fully understand exactly what the metabolic relationship is, but we do know that vitamin D appears to be vital to glucose metabolism and specifically in the eye can help regulate against neovascularization. Vitamin D can be absorbed through daily sunlight exposure, and also through dietary supplementation (milk is a great source!)

Curcumin (extracted from Tumeric): In animal models this supplement has proven to be protective against diabetic retinopathy, reducing inflammatory cytokine levels and neovascularization inducing VEGF.  A 4 week supplementation study in humans was associated with improved retinal blood flow, reduced retinal edema, and improved visual acuity in subjects.

Pycnogenol (pine bark extract): In a 3 month study, patients taking pycnogenol had statistically significant improvement in retinal edema, and blood flow through the central retinal artery compared to placebo.  Additionally 18 out of 24 patients in the treatment group experienced an improvement in visual acuity; none of the placebo group patients had visual improvement over the time of the study.

Benfotiamine (Vitamin B1 analog): This enzyme helps the body safely process harmful biproducts (sorbitol, protein kinase C, and others) of normal cellular glucose digestion.  In the retina, animal studies show it can prevent diabetic retinopathy, and it also helps prevent cellular death of the all important pericyte cells of retinal arteries (pericyte death causes the blood vessels to leak!).  It's also been shown to improve the symptoms of painful peripheral neuropathy in patients with reduced blood flow to their arms and legs.

Alpha Lipoic Acid: This is a potent antioxidant that targets mitochondrial cells (your body's cellular power house) -- a critical target because diabetic damage is linked to mitochondrial oxidative stress.  An 11 month dosage study in rat models showed that alpha lipoic acid was preventative against retinal vascular damage and the presence of diabetic retinopathy.

ZeaVision's EyePromise DVS formula via

Results of the Diabetes Visual Function Supplement Study

Compared to the placebo group, the supplement group had improved contrast sensitivity, less color vision perception errors, and lower C-reactive protein levels on blood work (a marker for systemic inflammation).  The supplemental group also had a 39% reduction in their Diabetic Neuropathy Symptom Score, a questionnaire that asks such questions as "does the patient experience numbness or tingling sensations in their feet or hands?"  There was also a minimal positive effect on hemoglobin A1C numbers for the supplemental treatment group -- with their mean A1C improving by 4% over the course of the study.  The placebo group's mean A1C worsened by 2.5% by comparison.

The supplement group showed statistically significant improvement in C-reactive protein levels after treatment (left) and increased macular pigment density and improved central visual field sensitivity (right) compared to the placebo group.  OCT measured macular thickness was unchanged in either group.  via

via
While many will point out that this study was funded by ZeaVision, the company now marketing the EyePromise DVS supplement formulation investigated, the results when combined with the plethora of other studies on these individual nutrients are promising.  Discussing dietary changes or supplements in the exam room is definitely a worthwhile endeavor, but with any nutritional supplement it is always best to have the patient discuss any new medications (even vitamins) with their PCP to make sure there are no cross-interactions.  In an era where we are limited in treatment for patients in the early stages of retinal damage from diabetes, these studies suggest that dietary supplementation can not only help resolution of early nonproliferative diabetic retinopathy, but they can even improve visual ability and be preventative for further retinal damage!

You can order EyePromise DVS nutriotional supplements direct from ZeaVision here.

I am in no way affiliated with ZeaVision and this is a not a sponsored post!  Just a discussion of some really intriguing research.

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