Postprandial triglycerides across the aging spectrum: A secondary analysis utilizing an abbreviated fat tolerance test.

BACKGROUND & AIMS: Elevated postprandial triglycerides are an independent cardiovascular disease risk factor and observed in older adults. However, differences in postprandial triglycerides across the spectrum of adulthood remain unclear. METHODS AND RESULTS: We performed a secondary analysis of six studies where adults (aged 18-84 years; N = 155) completed an abbreviated fat tolerance test (9 kcal/kg; 70% fat). Differences in postprandial triglycerides were compared in those ≥50 and <50 years and by decade of life, adjusting for sex and BMI. Compared to those <50 years, participants ≥50 years had higher fasting, 4 h, and Δ triglycerides from baseline (p's < 0.05). When examining triglyceride parameters by decade, no differences were observed for fasting triglycerides, but 50 s, 60 s, and 70s-80 s displayed greater 4 h and Δ triglycerides versus 20 s (p's ≤ 0.001). The frequency of adverse postprandial triglyceride responses (i.e., ≥220 mg/dL) was higher in participants ≥50 versus <50 years (p < 0.01), and in 60 s compared to all other decades (p = 0.01). CONCLUSION: Older age was generally associated with higher postprandial triglycerides, with no divergence across the spectrum of older adulthood. In our sample, postprandial triglyceride differences in older and younger adults were driven by those >50 years relative to young adults in their 20 s. REGISTRATION: N/A (secondary analysis).

Cardiorespiratory fitness and submaximal exercise dynamics in normal-weight obesity and metabolically healthy obesity.

PURPOSE: Cardiorespiratory fitness (CRF) is critical for cardiovascular health. Normal-weight obesity (NWO) and metabolically healthy obesity (MHO) may be at increased risk for cardiovascular disease, but a comparison of CRF and submaximal exercise dynamics against rigorously defined low- and high-risk groups is lacking. METHODS: Four groups (N = 40; 10/group) based on body mass index (BMI), body fat %, and metabolic syndrome (MetS) risk factors were recruited: healthy controls (CON; BMI 18.5-24.9 kg/m2, body fat < 25% [M] or < 35% [F], 0-1 risk factors), NWO (BMI 18.5-24.9 kg/m2, body fat ≥ 25% [M] or ≥ 35% [F]), MHO (BMI > 30 kg/m2, body fat ≥ 25% [M] or ≥ 35% [F], 0-1 risk factors), or metabolically unhealthy obesity (MUO; BMI > 30 kg/m2, body fat ≥ 25% [M] or ≥ 35% [F], 2 + risk factors). All participants completed a V ˙ O2peak test on a cycle ergometer. RESULTS: V ˙ O2peak was similarly low in NWO (27.0 ± 4.8 mL/kg/min), MHO (25.4 ± 6.7 mL/kg/min) and MUO (24.6 ± 10.0 mL/kg/min) relative to CON (44.2 ± 11.0 mL/kg/min) when normalized to total body mass (p's < 0.01), and adjusting for fat mass or lean mass did not alter these results. This same differential V ˙ O2 pattern was apparent beginning at 25% of the exercise test (PGroup*Time < 0.01). CONCLUSIONS: NWO and MHO had similar peak and submaximal CRF to MUO, despite some favorable health traits. Our work adds clarity to the notion that excess adiposity hinders CRF across BMI categories. CLINICALTRIALS: gov registration: NCT05008952.

Whole-body bone mineral density and markers of bone homeostasis in adults with normal-weight obesity.

Background: Normal-weight obesity (NWO) describes individuals with a normal body mass index (BMI), but high body fat percent. NWO are at-risk for cardiometabolic diseases, but little is known about their bone health. Methods: Adults (N = 24) were classified as NWO (n = 12; 5M/7F) or low body fat percent controls (Con; n = 12; 6M/6F). Body composition and whole-body bone mineral density (BMD) were assessed using DXA. A serum bioplex assay was performed to examine markers related to bone formation and resorption. Results: In addition to higher body fat percent and visceral fat, NWO had lower whole-body BMD relative to Con (p's < 0.05). Circulating leptin was higher in NWO than Con (p < 0.05). Two biomarkers generally associated with lower bone mass - sclerostin and parathyroid hormone - were higher in NWO compared to Con (p's < 0.05). Conclusion: In this preliminary study, adults with NWO displayed lower whole-body BMD alongside evidence of bone resorption. Impaired bone health may be another subclinical risk factor present in NWO.

Postprandial triglycerides, endothelial function, and inflammatory cytokines as potential candidates for early risk detection in normal-weight obesity.

PROBLEM: Normal-weight obesity (NWO) is associated with increased cardiovascular disease (CVD) risk. However, NWO's clinical presentation is often unremarkable based on common risk factors. We examined whether CVD risk factors not routinely measured clinically including postprandial triglycerides, flow-mediated dilation (FMD), and inflammatory cytokines would be abnormal in NWO, consistent with their future risk. METHODS: Individuals were recruited into 3 groups (n = 10/ group): controls (Con), NWO, and metabolic syndrome (MetS). Con was defined as a normal body mass index (BMI), < 25% (M) or < 35% (F) body fat, and < 1 International Diabetes Federation (IDF) criteria. NWO were above this body fat cutoff while maintaining a normal BMI and MetS was defined per the IDF. Participants underwent an abbreviated fat tolerance test (i.e., difference in fasting and 4 h triglycerides following a high-fat meal [9 kcal/kg; 73% fat)] and fasting and postprandial lipid and glucose metrics, as well as FMD were measured. A T cell cytokine bioplex was also performed using fasting serum. RESULTS: NWO and MetS had similar body fat% and both were higher than Con (p < 0.0001). Despite having similar fasting triglycerides to Con, NWO had 4-hour triglycerides 66% greater than Con, but 46% lower than MetS (p < 0.01). FMD decreased in all groups after the high-fat meal (p < 0.0001). MetS displayed lower fasting FMD than Con, and NWO was similar to both groups (p < 0.05). No group differences were observed with postprandial FMD and the majority of fasting cytokines assessed. However, MetS exhibited higher fasting TNF-α than Con (p < 0.05), and NWO was similar to both groups. CONCLUSIONS: Overall, NWO was associated with higher postprandial triglycerides than Con, but displayed little evidence of impaired vascular health or inflammation.

Comparison of a Standardized High-Fat Meal versus a High-Fat Meal Scaled to Body Mass for Measuring Postprandial Triglycerides: A Randomized Crossover Study.

Post-meal triglycerides are an independent cardiovascular disease (CVD) risk factor, but the ideal high-fat meal formulation has yet to be standardized and is one challenge prohibiting widespread clinical adoption of postprandial triglyceride assessment. Two general approaches often used are giving individuals a high-fat meal scaled to body weight or a standardized high-fat meal containing a set fat bolus. A recent expert panel statement has endorsed the latter, specifying 75 g of fat as an appropriate fat dosage. Despite this recommendation, no study to date has tested whether there is a difference in postprandial triglycerides or if risk classification is affected based on these different approaches. We recruited 16 generally healthy individuals with roughly equal distribution among body mass index (BMI)class (n = 5-6/per BMI category) and sex (n = 2-3 M/F) within each BMI class. Each participant underwent two abbreviated fat tolerance tests separated by ~1 week: one with a scaled to body weight high-fat meal (9 kcal/kg; 70% fat) and a standardized meal containing 75 g of fat (70% fat). Fasting, 4 h, and absolute change in triglycerides across the entire sample and within each BMI category were similar regardless of high-fat meal. Only one participant with obesity had discordant postprandial responses between the fat tolerance tests (i.e., different CVD risk classification). These findings suggest that, within a certain range of fat intake, generally healthy individuals will have a similar postprandial triglyceride response. Considering the greater convenience of utilizing standardized high-fat meals, our data suggest that a standardized high-fat meal may be acceptable for large-scale studies and clinical implementation.

Emulsion droplet crystallinity attenuates early in vitro digestive lipolysis and beta-carotene bioaccessibility.

The impacts of lipid crystallinity on in vitro digestive lipolysis and bioaccessibility of encapsulated (0.1 wt%) beta-carotene (BC) were investigated for a 15 wt% cocoa butter emulsion prepared as crystalline (i.e. solid emulsions, SE & SE-BC) or undercooled (liquid emulsions, LE & LE-BC) droplets at 25 °C. Particle size distributions (D4,3 ∼0.7 µm), morphology (spherical), polymorphism (beta-V), thermal behavior (peak melting ∼30 °C), zeta potential (∼-44 mV) and BC degradation under accelerated lighting conditions were similarly extensive. Following exposure to simulated gastric conditions, duodenal hydrolysis and BC bioaccessibility were lower for SE-BC up to 2 h (P < 0.05). Ultimately, samples with both solid and liquid droplets were hydrolyzed extensively and BC bioaccessibility did not differ (P > 0.05). Therefore, for compositionally equivalent emulsions, lipid droplet solid state delayed digestive lipolysis and bioactive solubilization. These results help to clarify the role of lipid physical state on dietary lipid digestion and bioactive release.