Context Bile acids (BA) are known for their role in intestinal lipid absorption and can also play a role as signaling molecules to control energy metabolism. Prior evidence suggests that... Show moreContext Bile acids (BA) are known for their role in intestinal lipid absorption and can also play a role as signaling molecules to control energy metabolism. Prior evidence suggests that alterations in circulating BA levels and in the pool of circulating BA are linked to an increased risk of obesity and a higher incidence of type 2 diabetes in middle-aged adults. Objective We aimed to investigate the association between plasma levels of BA with cardiometabolic risk factors in a cohort of well-phenotyped, relatively healthy young adults. Methods Body composition, brown adipose tissue, serum classical cardiometabolic risk factors, and a set of 8 plasma BA (including glyco-conjugated forms) in 136 young adults (age 22.1 +/- 2.2 years, 67% women) were measured. Results Plasma levels of chenodeoxycholic acid (CDCA) and glycoursodeoxycholic acid (GUDCA) were higher in men than in women, although these differences disappeared after adjusting for body fat percentage. Furthermore, cholic acid (CA), CDCA, deoxycholic acid (DCA), and glycodeoxycholic acid (GDCA) levels were positively, yet weakly associated, with lean body mass (LBM) levels, while GDCA and glycolithocholic acid (GLCA) levels were negatively associated with F-18-fluorodeoxyglucose uptake by brown adipose tissue. Interestingly, glycocholic acid (GCA), glycochenodeoxycholic acid (GCDCA), and GUDCA were positively associated with glucose and insulin serum levels, HOMA index, low-density lipoprotein cholesterol, tumor necrosis factor alpha, interleukin (IL)-2, and IL-8 levels, but negatively associated with high-density lipoprotein cholesterol, ApoA1, and adiponectin levels, yet these significant correlations partially disappeared after the inclusion of LBM as a confounder. Conclusion Our findings indicate that plasma levels of BA might be sex dependent and are associated with cardiometabolic and inflammatory risk factors in young and relatively healthy adults. Show less
The role of lifestyle behaviors on neck adipose tissue (NAT), a fat depot that appears to be involved in the pathogenesis of different cardiometabolic diseases and in inflammatory status, is... Show moreThe role of lifestyle behaviors on neck adipose tissue (NAT), a fat depot that appears to be involved in the pathogenesis of different cardiometabolic diseases and in inflammatory status, is unknown. In this cross-sectional and exploratory study, the authors examined the relationship between sedentary time and physical activity (PA) with neck adiposity in young adults. A total of 134 subjects (69% women, 23 +/- 2 years) were enrolled. The time spent in sedentary behavior and PA of different intensity were objectively measured for 7 consecutive days (24 hr/day), using a wrist (nondominant)-worn accelerometer. The NAT volume was assessed using computed tomography, and the compartmental (subcutaneous, intermuscular, and perivertebral) and total NAT volumes were determined at the level of vertebra C5. Anthropometric indicators and body composition (by dual-energy X-ray absorptiometry) were determined. The time spent in light physical activity and moderate physical activity (MPA) and the overall PA were inversely associated with the intermuscular NAT volume in men, as were the MPA and overall PA with total NAT volume (all ps <= .04). Sedentary time was directly related to the total NAT volume (p = .04). An opposite trend was observed in women, finding a direct relationship of MPA with the subcutaneous NAT; of light physical activity, MPA, and overall PA with the perivertebral NAT; and of light physical activity with total NAT volumes (all ps <= .05). The observed associations were weak, and after adjusting for multiplicity, the results became nonsignificant (p > .05). These findings suggest that the specific characteristics of PA (time and intensity) might have sex-dependent implications in the accumulation of NAT. Show less
The present study examines whether the daily rhythm of distal skin temperature (DST) is associated with brown adipose tissue (BAT) metabolism as determined by F-18-fluorodeoxyglucose (F-18-FDG)... Show moreThe present study examines whether the daily rhythm of distal skin temperature (DST) is associated with brown adipose tissue (BAT) metabolism as determined by F-18-fluorodeoxyglucose (F-18-FDG) uptake in young adults. Using a wireless thermometer (iButton) worn on the nondominant wrist, DST was measured in 77 subjects (26% male; age 22 +/- 2 years; body mass index 25.2 +/- 4.8 kg/m(2)) for 7 consecutive days. The temperatures to which they were habitually exposed over the day were also recorded. The interday stability of DST was calculated from the collected data, along with the intraday variability and relative amplitude; the mean temperature of the 5 and 10 consecutive hours with the maximum and minimum DST values, respectively; and when these hours occurred. Following exposure to cold, BAT volume and mean and peak standardized F-18-FDG uptake (SUVmean and SUVpeak) were determined for each subject via static F-18-FDG positron emission tomography/computed tomography scanning. Relative amplitude and the time at which the 10 consecutive hours of minimum DST values occurred were positively associated with BAT volume, SUVmean, and SUVpeak (p <= 0.02), whereas the mean DST of that period was inversely associated with the latter BAT variables (p <= 0.01). The interday stability and intraday variability of the DST were also associated (directly and inversely, respectively) with BAT SUVpeak (p <= 0.02 for both). All of these associations disappeared, however, when the analyses were adjusted for the ambient temperature to which the subjects were habitually exposed. Thus, the relationship between the daily rhythm of DST and BAT activity estimated by F-18-FDG uptake is masked by environmental and likely behavioral factors. Of note is that those participants exposed to the lowest ambient temperature showed 3 to 5 times more BAT volume and activity compared with subjects who were exposed to a warmer ambient temperature. Show less
