Our results suggest an inverse association between visceral fat and total adiponectin levels. We also found visceral fat loss was associated with a significant decrease in inflammatory markers and a non-significant increase in total adiponectin levels at follow up. These results add to our previously reported findings of increased inflammation and decreased antioxidant status in UAE subjects with visceral obesity [4, 5].
Given that abdominal obesity is more common in the UAE population and that the UAE has one of the highest prevalence of obesity related diabetes mellitus in the World these new preliminary findings may have important public health implications [1, 3]. This is because a number of factors secreted by visceral fat are implicated in the pathologies associated with obesity [2, 5,6,7]. For example, adiponectin a hormone one of many adipokines secreted by adipose tissue with a number of endocrine and paracrine effects on the cardiovascular system [9]. Adiponectin has insulin sensitizing properties and is thought to improve insulin sensitivity, cellular glucose uptake and reduce hepatic gluconeogenesis [8]. In addition adiponectin has been reported to have anti-inflammatory effects and reducing cardiovascular oxidative stress [9]. The role of adiponectin in insulin resistance and cardiovascular homeostasis is still not fully understood. Furthermore, the beneficial cardiovascular effects of high circulating adiponectin do not appear to translate into better clinical outcomes in patients with CVD and further research is therefore warranted [8]. Nevertheless the anti-inflammatory and anti-diabetic protective effects make adiponectin a promising therapeutic target [8, 9].
The relationship between adiponectin and insulin sensitivity is influenced by ethnic differences and was found to vary between different populations [10, 14]. In a south Asian population for example, which share some similarities with our study population, adiponectin was found to be associated with adiposity and insulin resistance [15]. Regional and ethnic differences in adiponectin values and other related adipokines may have an important role to play in the susceptibility of certain populations to obesity and associated CVD morbidities [11]. Because available research data in this area is limited more research involving different populations is needed.
We found both gestational (GDM) and type 2 diabetes in our study population were associated with lower adiponectin levels compared with healthy controls [16, 17]. A recent meta-analysis of prospective studies assessed the association of levels of adiponectin and other inflammatory markers with risk of type 2 diabetes, reported strong association between elevated inflammatory markers, low levels of adiponectin and risk of type 2 diabetes. However, the authors reported considerable heterogeneity between studies and suggested that more research is required to clarify the relationship between adipokines, including adiponectin and the risk of type 2 diabetes as well as its therapeutic potentials [17].
The positive association between adiponectin levels and HDL is consistent with previous studies [18, 19]. Given the known association between low levels of HDL and increased risk of CVD and reduced protective effects of HDL in patients with type 2 diabetes this finding may be of clinical interest [14]. The lack of association between adiponectin and other lipid profile markers may partly be explained by the use of statins known to reduce LDL-cholesterol and less likely to affect HDL levels.
The small increase in total adiponectin levels coupled with decreased WC (visceral fat); as a result of dietary education did not reach statistical significance. The average decrease in WC achieved in our study population was around 3%. Although traditionally recommended weight loss target to improve health is around 5%, recent evidence suggests that a fall in body weight as small as 1 kg can improve health if this achieves permanent change in the person’s weight trajectory [20, 21]. More importantly, some preliminary observations suggest that nutrition interventions such as calorie-restriction, Mediterranean diet and garlic extract administration may increase adiponectin concentrations [11]. A preliminary feasibility study in 32 normal and overweight subjects randomized to 12-week alternate day fasting or a control group eating ad libitum revealed reduced total body weight and fat mass coupled with increased plasma adiponectin in the intervention group compared with the control group [12]. In another study weight and visceral fat mass reduction in severely obese patients following bariatric surgery resulted in increased serum adiponectin levels with no significant correlations between changes in adiponectin and body mass index and visceral fat measured using waist circumference [13]. A recent long-term weight reduction trial, using 4 different dietary intervention approaches reported increased adiponectin levels and improved fat distribution and lipid metabolism independent of weight change [22]. This study highlights the potential benefits of manipulating adiponectin levels through dietary modifications in obese patients.
More research is needed to elucidate the mechanisms and potential pathways for increasing adiponectin in different populations and more importantly its potential benefit in the treatment and prevention of obesity associated metabolic diseases such as type 2 diabetes .
An important limitation of the study was the reduced numbers of subjects at follow up visits. This was because some subjects refused to provide blood samples. Another limitation was the lack of a control group and the open design. Nevertheless, body composition measurements were performed digitally and printed on a sheet to minimize observer error. Biochemical analyses were also carried out by a laboratory technician not involved in the recruitment, dietary education or outcome data collection.
