Postprandial lipemia in the elderly involves increased incorporation of ingested fat in plasma free fatty acids and small (S_f20–400) triglyceride-rich lipoproteins

Abstract

In the elderly, the rise in postprandial plasma triglyceride (TG) concentrations is increased, contributing to their increased risk of cardiovascular disease. We sought to determine the incorporation of ingested fat (whipping cream enriched with [1,1,1-13 C]triolein) into plasma lipids during the postprandial period in six healthy elderly (67 Ϯ 1 yr old) and six healthy young (23 Ϯ 2 yr old) subjects. Blood and expired air samples were taken before and at 2-h intervals during the 8-h postprandial period. As expected, the area under the curve of postprandial plasma TG concentrations was larger in the elderly compared with the young subjects (152 Ϯ 38 vs. 66 Ϯ 27 mg·dl Ϫ1 ·h, P Ͻ 0.05). The incorporation of [13 C]oleate in plasma free fatty acids (FFAs) and TG of the small (Sf ϭ 20 -400) triglyceride-rich lipoprotein (TRL) fraction was significantly higher in the elderly compared with the young subjects, resulting in increased postprandial contributions of the ingested lipid to plasma FFAs (41 Ϯ 3 vs. 26 Ϯ 6%, P Ͻ 0.05) and the small TRL fraction (36 Ϯ 5 vs. 21 Ϯ 3%, P Ͻ 0.05) in elderly. Plasma apoB-100 concentration was higher, whereas the rate of oxidation of the ingested lipid was lower (P Ͻ 0.05) in the elderly. We conclude that increased postprandial lipemia in the elderly involves increased contribution of ingested lipid to the plasma small TRLs. This appears to be driven at least in part by increased appearance of the ingested fat as plasma FFA and increased availability of apo B-100 lipoproteins in the elderly. aging; chylomicrons; stable isotope tracers; spillover; very low-density lipoprotein THE ELEVATION IN PLASMA TRIGLYCERIDE (TG) concentrations can last for several hours after fat ingestion, stretch between meals, and result in a major part of lifetime spent in a metabolic state associated with lipemia. The magnitude of postprandial lipemia (PPL) is positively associated with the risk of cardiovascular disease (19,20). It has been documented previously that the magnitude of PPL is increased with aging (4, 5, 9), a phenomenon that places elderly individuals at greater risk for cardiovascular disease compared with their young counterparts.In healthy young individuals, the incremental increase in plasma TG concentrations in the postprandial period is due primarily to the increase in large (S f Ͼ 400) TG-rich lipoprotein (TRL) particles, consisting predominantly of chylomicrons, which result from the absorption of the ingested fat.However, the mechanisms that contribute to the age-associated increase in PPL are poorly understood. This is due in part to the selection of subjects in previous studies that makes conclusions on the effects of aging on PPL problematic as well as the lack of isotopic tracer studies that trace the metabolic fate of ingested fat in the elderly.To elucidate the effects of aging per se on PPL, it is important to control for physiological variables that are not directly linked to aging but are known to modify PPL. Such variables include fasting plasma TG concentrations and fat-free...

Postprandial lipemia as a cardiometabolic risk factor

“…Age Postprandial hypertriglyceridemia is significantly higher in older compared with younger subjects 27,28 . However, the increasing prevalence of pediatric overweight and obesity 29 and the notion that obesity in childhood predicts cardiovascular disease, led the focus of attention to preventive early approaches.…”

Postprandial Spillover of Dietary Lipid into Plasma Is Increased with Moderate Amounts of Ingested Fat and Is Inversely Related to Adiposity in Healthy Older Men3

“…We have shown that after ingestion of a moderate amount of dietary fat (0.7 g · kg body weight 21 ), older men respond with an apparently greater increase in the postprandial plasma FFA concentrations compared with younger men, an effect observed together with greater postprandial spillover of dietary lipid (10). We hypothesized that the postprandial spillover of dietary lipid induced by the ingestion of a moderate amount of dietary fat in older men can be attenuated by lowering the amount of ingested fat.…”

“…Dietary fat was provided in the form of heavy whipping cream: low (LF) and moderate (MF) fat ingestions corresponding to 0.4 and 0.7 g · kg body weight 21 , respectively. Some of the data related to the ingestion of the moderate amount of dietary fat were previously reported (10). Depending on the participantÕs weight, 33-39 g of fat was ingested in the LF trial and 54-65 g was ingested in the MF trial.…”

“…Part of the collected plasma was used for the separation of the chylomicron fraction of the plasma using a density-gradient ultracentrifugation procedure, as we previously described (10). Expired air samples were collected at the 2-h intervals for the determination of the 13 C isotopic enrichment of expired CO 2 .…”

“…Commercially available analytical procedures were used for the determinations of the plasma concentrations of TG (Sigma-Aldrich), FFA, and 3-hydroxybutyrate (3-HB; Wako Chemicals) as well as insulin (ALPCO Diagnostics). For the measurement of 13 Coleate enrichment in plasma lipids, TG from the chylomicron fraction of plasma and plasma FFA were isolated using TLC, as we previously described (10). The 13 C-oleate enrichment of these plasma lipids (i.e., FAME) was determined using GC-MS (Thermo Scientific Trace GC Ultra-DSQ GC-MS system; Thermo Scientific) by selected ion monitoring of m/z 296 and 297 and expressed as tracer:tracee ratio (TTR).…”