Cardiovascular and metabolic control in obese children and adolescents

Abstract

Childhood obesity is an emerging risk factor for disease and mortality worldwide. Thecardiovascular consequences and prevention thereof need to be further investigated. Exerciseand weight loss are well examined and effective in the prevention of cardiovascular risk, butwarrant well motivated patients with strong social support. The benefits of a diet rich inmarine essential (n-3) fatty acids on cardiovascular risk in adults such as prevention ofarrhythmias, lowering blood pressure and heart rate, decreasing platelet aggregation andlowering triglyceride levels are well known.The aims of this thesis were to characterize the vascular changes and cardiac autonomicfunction in obese children compared to lean subjects and to test whether supplementation withn-3 fatty acids may improve the vascular and metabolic risk profile in obese adolescents.Very high resolution ultrasound, pulse wave velocity measurements, baroreceptor sensitivitymeasurements and exercise tests were performed in order to characterize vascular changesand autonomic control in obese compared to lean children and adolescents. Supplementationwith 1,2 g/day of n-3 fatty acids was tested in a randomized, placebo-controlled trial with adouble-blind, cross-over design. Blood samples and anthropometric measurements were takenbefore the start of treatment and after each 3 month treatment period. At the end of eachtreatment period, muscle and adipose tissue biopsies were obtained; insulin sensitivity andvascular function were tested.Obese children show increased intimal wall thickness in radial artery, increased vasculardiameter in peripheral arteries and decreased pulse wave velocity compared to lean subjects.Obese children and adolescents also show cardiac autonomic dysfunction in terms ofdecreased baroreceptor sensitivity, decreased maximal exercise heart rate and greater heartrate increase during the first minute of exercise, indicating moderate cardiac autonomicdysfunction. After 3 months supplementation with marine fatty acids, n-3 fatty acid content ofphospholipids in serum, skeletal muscle and adipose tissue increased. Vascular functionmeasured as vasodilatory response to hyperaemia was improved, and the number oflymphocytes and monocytes was lowered. In females, insulin sensitivity and glucosetolerance improved after n-3 fatty acid supplementation.In conclusion, obese children show signs of increased risk for cardiovascular disease in termsof increased intimal wall thickness and cardiac autonomic dysfunction. It is possible tomodify this increased risk in obese adolescents by supplementing with n-3 fatty acids, whichimproves vascular function, decreases subclinical inflammation and improves insulinsensitivity.