Visceral Fat Fattens Carotid ArteriesFriday, January 16, 2009
Regular readers of these pages are by now probably well aware of the fact that increased waist circumference (a rather crude measure of visceral fat) is considered a risk factor for coronary heart disease.
Nevertheless it may be worthwhile pointing out that the coronary artieries are not the only arteries affected – the same is true for peripheral arteries including the carotid vessels.
We are reminded of this by two recent papers in this month’s issue of the International Journal of Obesity.
In the first paper by Kim and colleagues from Pochon CHA University, Korea, common carotid artery intima-media thickness (IMT), waist circumeference (WC) and visceral fat thickness (VFT – measured by ultrasound) were measured in 368 men with type 2 diabetes.
Among the 174 subjects with abdominal obesity (WC >90 cm ), 35 subjects did not have visceral obesity (VFT<47.6 mm). In contrast, among the subjects without abdominal obesity (n=194), 88 patients had visceral obesity. Although there were no differences in age, glucose control, lipid profile and treatment modalities, subjects without abdominal obesity, but who had visceral obesity, had a higher carotid IMT compared with subjects with abdominal obesity, but without visceral obesity.
The authors conclude that in men with established type 2 diabetes, having visceral obesity, regardless of a normal WC, is a risk factor for increased carotid IMT, a measure of atherosclerotic burden.
In the second paper Maher and colleagues from Meath and National Children’s Hospital, Tallaght, Dublin, Ireland, studied 100 never smoking subjects (71 women, 29 men) without vascular events, with normal blood pressure, LDL cholesterol and glucose levels. Subjects underwent vascular measurements (Carotid intima-media thickness (IMT) using duplex ultrasonography, vascular stiffness assessment (Augmentation Index) by applanation tonometry and brachial artery reactivity tests).
Only age, waist-to-height-ratios and BMI were significant correlates of IMT in a multivariate analysis that included age, sex, systolic BP, HDLc and HOMA index. Augmentation Index correlated with age, waist-to-height-ratio and waist circumference, whereas brachial reactivity did not correlate with any anthropometric or metabolic parameters.
The authors concluded that even in in ‘healthy individuals’, anthropometric parameters and metabolic risk factors correlated with each other, but anthropometric parameters were the only significant correlates of carotid IMT.
Both studies together remind us of the importance of fat distribution, particularly the deposition of visceral fat, as a risk factor for cardiovascular risk.