The findings of the study, published in the journal Nutrition, Metabolism & Cardiovascular Diseases supports the view that dietary antioxidants are associated with improved glycemic biomarkers in healthy adults, as well as in diabetic patients.
According to the World Health Organization (WHO), approximately 150 million people have diabetes mellitus worldwide, and this number may double by the year 2025 due to population growth, ageing, unhealthy diet, obesity and sedentary lifestyle.
The researchers, based at the University of Athens, said recent studies suggested that oxidative stress is related to diabetes, possibly originating through increased free-radical production, with the theory proposed that pancreatic cells are particularly susceptible to reactive oxygen species, due to their low free-radical quenching enzymes.
“Thus, by damaging mitochondria, oxidative stress could induce apoptosis of pancreatic beta cells, blunt insulin secretion and dysregulate glucose levels,” they continued.
The Greek scientists also report that total dietary antioxidant capacity has been found to be inversely related to markers of inflammation, suggesting that inflammation and oxidative stress are interrelated.
And they explained that the hypothesis that a diet high in antioxidants could be inversely related to the development of diabetes prompted their decision to evaluate the relationship between glycemic indices (glucose, insulin and insulin resistance) and dietary antioxidant intake, in apparently healthy adults as well as in adults with diabetes.
The authors said they based this study on a random sub-sample from the well documented ATTICA study, with participants consisting of 551 men and 467 women from all parts of the Attica region in Greece. Complete nutritional and biochemical information was included, they added.
Dietary habits were evaluated using a validated food-frequency questionnaire, with participants reporting their daily or weekly average intake of several food items including fruit, vegetables, legumes, non-alcohol beverages, chocolate, honey, jam, nuts, rice, pastas and grains.
The authors noted previous research suggesting that a diet rich in antioxidant containing fruit and vegetables was associated with a reduction of diabetes risk by 13 per cent.
Overall dietary habits were assessed using a composite index that evaluates adherence to the Med diet, and the dietary antioxidant capacity was measured by ferric-reducing antioxidant power (FRAP), total radical-trapping antioxidant parameter (TRAP) and Trolox equivalent antioxidant capacity (TEAC), they said.
The researchers said that participants were categorised as non-diabetic, impaired fasting glucose (IFG) and diabetic and were also defined for socio-demographic, lifestyle and health factors such as smoking, exercise and hypertension. People with type 1 diabetes were not included in the ATTICA study, they added.
The results indicated that higher total dietary antioxidant intake is correlated with lower levels of glycemic indices in healthy individuals, as well as in pre-diabetic and diabetic ones, and the findings are an important consideration for public health planners, claim the researchers.
And the scientists added that the observed, protective association of dietary antioxidant intake to diabetes biomarkers was independent of age, gender and physical activity status, but did not hold in obese individuals.
The authors admit limitations in relation to the cross-sectional nature of their study, and they stress that aetiologic, mechanistic conclusions cannot be addressed effectively as a result.
They said that further research is required, with perhaps the inclusion also of antioxidant supplement usage, in order to substantiate causality between high antioxidant consumption and improved glycemic biomarkers in the general population.
Source: Nutrition, Metablolism & Cardiovascular Diseases
Published online ahead of print
Title: Dietary antioxidant capacity is inversely associated wtih diabetes biomarkers
Authors: C Stefanadis et al