In this study we found a positive association between inflammatory and oxidative damage markers and visceral fat in overweight and obese subjects. Our results also suggest an inverse association between some antioxidants and visceral fat and that increased fruits and vegetables consumption may also have a weak but positive association with visceral fat loss independent of its calorie reducing effect.
In a small trial before, we have also demonstrated that supplementation with antioxidant vitamins improved antioxidant status and reduced tissue inflammation in obese diabetic patients . A recent meta-analysis has shown that increasing daily intake of green leafy vegetables may reduce the risk of type 2 diabetes . Taken together these studies results suggest a beneficial role of higher fruits and vegetables intake in subjects with visceral obesity mediated by decreased inflammatory response and mitigation of oxidative damage. Our study results show no significant differences in antioxidants, oxidative damage, inflammatory and endothelial dysfunction markers between obese subjects who lost visceral fat and those gained visceral fat at follow up. However, recent evidence revealed beneficial effects of high fruits and vegetables Mediterranean diets on CVD risk in overweight and obese subjects independent of weight change . Furthermore recent recommendations suggest the focus should mainly be on increasing fruit and vegetables rather than counting calories to combat obesity epidemics .
Our study results also suggest a weak but positive association between increased fruits and vegetables intake and decrease in visceral fat. Although replication of this finding is needed higher consumption of red/purple fruit and vegetables such as tomato, red onion, date, red cabbage, watermelon, cherries, red grapes, berries, strawberry and red plum has been associated with lower abdominal fat gain . Another study reported a beneficial effect of higher intake of both fruit and vegetable and cereal fiber on abdominal obesity prevention . Effects of fruits and vegetables on visceral obesity could be mediated by decreased inflammatory response, mitigation of oxidative damage associated with inflammatory cytokines that favor lipolysis and lipid oxidation instead of fat storage [14-16]. This is clearly an area for further research.
The average visceral fat and weight loss achieved by our study population in response to dietary education is around 3%. Although traditionally recommended weight loss target is around 5%, recent evidence suggests that small falls in weight can improve health provided they are long term [17, 18].
In conclusion we have demonstrated in this study that increased visceral fat is associated with increased oxidative stress. Our results also support a beneficial role of higher fruits and vegetables intake in subjects with visceral obesity however further replication of this finding is needed. These findings if proven, with availability of healthy food choices could have enormous public health implications for reduction of visceral obesity and its consequences in our community and worldwide. The benefits of antioxidant-rich diets in obese subjects may therefore need to be explored in larger intervention studies.
The main limitations of our study are the lack of a control group and the open design. Nevertheless we have adjusted for important prognostic differences such as age, marital status, physical activity and the number of education sessions in the analysis. Body composition measurements for example, were performed digitally and printed on a sheet with little room for observer error. Biochemical analyses were also carried by a laboratory technician not involved in the recruitment, dietary education or data collection. Another potential limitation was the reduced number of follow up blood samples.