A recent systemic review published in PLOS One evaluated evidence linking dietary intake and diabetic retinopathy.
Diabetic retinopathy, a complication of diabetes, is a leading cause of vision loss and blindness worldwide. It is becoming a major public health concern especially given the rapid increase of diabetes incidence. Diabetic retinopathy causes damage to the blood vessels inside the retina at the back of the eye. Since this condition affects almost all patients with type 1 diabetes and over 60% of patients with type 2 diabetes will develop a form of it within 20 years of diagnosis, the prevention and management of diabetic retinopathy are pivotal.
While dietary intake plays an important part of diabetes care and management, with many guidelines being developed, there is limited information and guidelines available for the prevention and management of diabetic retinopathy. Specific dietary guidelines are inconclusive as to whether particular foods are associated with an increase or decrease in the risk of developing diabetic retinopathy. Previous studies have focused either on specific food groups or nutrients but not the entire food spectrum and potential links and impact on diabetic retinopathy as a clinical outcome.
In a bid to address this clinical gap, researchers evaluated 31 observational and interventional studies which investigated macro and micronutrient intakes, dietary patterns, and food and drink intake in relation to diabetic retinopathy. Their results were recently published in PLOS One.
The Mediterranean Diet is the Most Beneficial
They found that diets that included fruit and vegetables (which are high in dietary fibre, with a low glycaemic index, and rich in antioxidants), oily fish, and adherence to a Mediterranean diet had a protective effect, including reduced glucose-induced retina damage, on patients at risk of developing diabetic retinopathy. It was not surprising that the Mediterranean diet, which includes food components such as olive oil, red wine, and fibre, as having protective effects given it is considered one of the healthiest diets worldwide. The Mediterranean diet is believed to help alleviate diabetic complications such as insulin resistance, oxidative stress, and inflammation, all factors which can have a negative impact on the retina.
More Calories, More Risk
In comparison, diets that were high in calories increased the risk of developing diabetic retinopathy. Higher caloric diets increase the metabolic burden in an individual, along with increased oxidative stress, which can subsequently increase the risk of developing diabetic retinopathy. Interestingly though, no specific association was observed between diabetic retinopathy and carbohydrates, which are a key contributor to high-calorie diets. Therefore, perhaps the quality of the carbohydrate plays an important role; and monitoring both the quality of carbohydrates and reducing overall calorie intake may have a more beneficial effect on diabetes patients at risk of developing the disease. No association was observed between sodium intake or vitamin Dand diabetic retinopathy. However, the impact or link between antioxidants, fatty acids, alcohol, and proteins with diabetic retinopathy remains unclear.
Hence the review indicates there is indeed a correlation between specific dietary components and diabetic retinopathy, therefore diet plays an important part in the prevention and management of the disease. A reduction in calories, an increase in dietary fibre and oily fish, and adherence to a Mediterranean diet could help reduce the risk of developing diabetic retinopathy and slow the disease progression. However, the researchers note that further studies are required to confirm these observations and therefore potentially help create more informed dietary guidelines for preventing and managing diabetic retinopathy.
Written by Lacey Hizartzidis, PhD
Reference: Wong MYZ, Man REK, Fenwick EK, Gupta P, Li LJ, van Dam RM, Chong MF, LamoureuxEL. Dietary intake and diabetic retinopathy: A systematic review. PLoS One. 2018 Jan 1;13(1):e0186582. doi: 10.1371/journal.pone.0186582. eCollection 2018.