Study reports that overweight subjects showed signs of vascular dysfunction and recommends that they, in addition to obese individuals, undergo preventative vascular screening to reduce their risk of cardiovascular disease.
Elevated blood pressure, increased inflammation, and oxidative stress contribute to vascular dysfunction of the endothelia, or thin tissues, that surround blood vessels. Micro- and macro- vascular endothelial abnormalities are early markers for arterial stiffness, atherosclerosis, and cardiovascular disease (CVD), and are typically associated with excess fat in individuals classified as obese. However, individuals who are overweight have a 60 percent higher risk of mortality due to CVD than age-matched controls who are lean, suggesting that any excess fat increases future cardiovascular risk. Thus, early detection of functional abnormalities could greatly impact vascular health. A group of researchers from Birmingham, United Kingdom, investigated whether overweight individuals exhibited signs of vascular dysfunction associated with CVD.
Subjects aged 30-55 years were classified according to WHO-defined weight classifications. 100 normal weight (BMI 18.5-24.9 kg/m3) and 100 overweight (BMI 25-29.9 kg/m3) participants were included in the study. Individuals taking medicine for CVD or a related condition were excluded, in addition to smokers and individuals who were classified as obese. All participants were screened for CVD by a physician and underwent general measurements, blood sampling, and micro- and macro-vascular studies that consisted of the examination of ambulatory blood pressure, artery thickness, retinal vascular function, and brachial artery flow-mediated dilation.
The results show that otherwise-healthy overweight subjects show elevated blood pressure, triglyceride, cholesterol, and fasting blood glucose levels compared to lean subjects. Separately or together, these markers are well-known contributors to cardiovascular risk as well as diabetes in adults and children. Triglyceride remnants may cause vascular endothelial damage, and in combination with elevated fasting blood glucose, is a marker for insulin resistance. Overweight individuals also had higher body composition indices (weight, BMI, and fat mass) than controls. Micro-vascular measurements showed impaired retinal vessel function manifested as larger diameter vessels in overweight, but not lean, subjects, and is the first evidence of functional retinal vascular changes in overweight individuals. Reduced retinal vessel dilatory capacity could be due to the increase of molecules involved in vasoconstriction, a known negative effect of higher BMI. In addition, baseline brachial vessel diameter was larger in overweight subjects compared to controls, but no evidence of macrovascular dysfunction was observed.
This study shows for the first time that overweight individuals exhibit micro-vascular functional impairments in addition abnormal circulatory risk markers of cardiovascular risk markers – representing a clinically-relevant weight class that would benefit from early detection and prevention of cardiovascular risk.
Written By: Fiona Wong, PhD