Nutrients Intake, Antioxidant Micronutrient Status and Vision Disorders among Diabetics Attending Cape Coast Teaching Hospital in the Central Region of Ghana

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Globally, complications related to diabetes, including diabetic retinopathy (DR), cataract, macular oedema and dry eye syndrome represent the chief causes of blindness in adults but good antioxidant status may delay or prevent these. Using a cross-sectional design, the study assessed the relationship between intake and serum status of antioxidant micronutrients and vision disorders among 100 outpatient diabetic patients in Cape Coast, Ghana. Body Mass Index, glycated haemoglobin (HbA1c), fasting plasma glucose (FBG), serum concentrations of vitamin A, vitamin C and total antioxidants were determined. Visual acuity (VA), intra-ocular pressure (IOP), cup-to-disc- ratio (CDR) and funduscopy were conducted on the participants. Twenty four (24) hour dietary recall and food frequency questionnaires were used to assess dietary intakes of antioxidant nutrients. Data was analyzed using IBMS-SSPS (version 23). Nineteen percent of the participants were males and 81% were females, while 90% of the participants had of type 2 diabetes. Average age of participants was 59.7 years with no gender difference. Mean BMI (30.8 kg/m2) put the participants as obese, although males had low mean BMI (p=0.002). Systolic blood pressure was higher in the males than females (148.7 versus 132.7 mmHg, p=0.004). Majority of participants (86%) had high HbA1c, 64% had high FBG, 33% were overweight and 48% were obese. One in 2 participants had cataract (50%), 27% had dry eye syndrome, 20% had uncorrectable refractive error (UNRE), 15% had DR and 2% had Diabetes Macular Oedema (DME). Vision problems were not significantly associated with duration of diabetes. Majority of participants reported daily or 1-3 times per week consumption of antioxidant-rich foods such as leafy vegetables, fruits, oily fish and nuts. Intakes of vitamin A, vitamin E, and Zinc were inadequate by 16.8%, 41.7% and 65% respectively based on Recommended Daily Allowances (RDA) while vitamin C and selenium intakes were in excess by 5.7% and 100.9% respectively. Biochemically, serum vitamin A (0.023±0.01)μmol/L and vitamin C (0.26±0.1) μmol/L were low while twenty four percent (24%) of the subjects had low total antioxidant status (TAS) (mean=24.4±5.3 μmol/L). Participants with inadequate vitamin C intake were more likely to have cataracts (31 versus 13%, p=0.046) than those with high intake, those with inadequate selenium status were more likely to have DME (2% for low, versus 0 for normal and high intake, p=0.002) and those with inadequate Zinc status were more likely to have cataracts (44% for low, 1% for normal and 5% for high intake, p=0.0013) and DR (10% for low, 5% for normal and 0% for high intakes, p=0.028). On the other hand, high selenium intakes was associated with higher level of UNRE (2% for low, 5% for normal and 13% for high intakes, p=0.043) and cataracts (11% for low, 3% for normal and 36% for high intakes, p=0.041). Adequate dietary fibre intake showed to reduce the risk of diabetic vision by 2-fold. In conclusion, hyperglycemia, overweight/obesity and vision impairment were common among the diabetics studied. Significant proportions of the participants had inadequate intakes and serum status of antioxidant micronutrients and in addition to fibre were associated with vision impairment.
A thesis submitted to the Department of Biochemistry and Biotechnology in partial fulfilment of the requirements for the award of Master of Philosophy Degree in Human Nutrition and Dietetics