Older adults have an altered chylomicron response to a high-fat meal

Abstract

Ageing is associated with a prolonged and exaggerated postprandial lipaemia. This study aimed to examine the contribution of alterations in chylomicron synthesis, size and lipid composition to increased lipaemia. Healthy older (60-75 years; n 15) and younger (20-25 years; n 15) subjects consumed a high-fat breakfast. Chylomicron dynamics and fatty acid composition were analysed for 5 h in the postprandial state. Plasma TAG levels were elevated following the meal in the older subjects, relative to younger subjects (P < 0·01). For older subjects compared with younger subjects, circulating chylomicron particle size was smaller (P < 0·05), with greater apoB content (P < 0·05) at all postprandial time points. However, total chylomicron TAG concentration between the groups was unaltered post-meal. Compared with younger subjects, the older subjects exhibited a greater proportion of oleic acid in the TAG and phospholipid (PL) fraction (P < 0·05), plus lower proportions of linoleic acid in the TAG fraction of the chylomicrons (P < 0·01). Thus, following the ingestion of a high-fat meal, older individuals demonstrate both smaller, more numerous chylomicrons, with a greater total MUFA and lower PUFA contents. These data suggest that the increased postprandial lipaemia of ageing cannot be attributed to increased chylomicron TAG. Rather, ageing is associated with changes in chylomicron particle size, apoB content and fatty acid composition of the chylomicron TAG and PL fractions.

Comparisons of the Postprandial Inflammatory and Endotoxaemic Responses to Mixed Meals in Young and Older Individuals: A Randomised Trial

“…Older subjects had higher fasting total cholesterol, LDL and HDL ( p < 0.001, p = 0.008, and p < 0.001, respectively; Table 2). Differences in postprandial lipaemia are reported elsewhere [41]. In brief, older participants showed exaggerated and prolonged postprandial elevations of TAG.…”

“…Our results indicate that baseline differences in immune status may be present in healthy older adults, but that any such differences are not associated with differences in the postprandial immune response to a high fat meal. The similarities in immune response between older and younger adults are in spite of exaggerated postprandial lipaemia in these older subjects [41] and suggest that the inflammatory response to a high-fat meal is not exacerbated in older age despite age-related differences in the basal immune profile.…”

“…Sequences were randomly generated using [40] stratified by age group and allocated by concealed envelopes prior to the first visit. The primary outcome of elevated postprandial lipaemia in the elderly has been presented elsewhere [41]. Inflammatory cytokine gene expression, circulating endotoxin, cytokines, and markers of oxidative stress were assessed as secondary outcomes.…”

“…Maximum peak times (T max ) were identified as the nominal sampling time corresponding with peak concentration. Sample size calculations have been described elsewhere for a primary outcome of postprandial lipaemia [41]; these were estimated to detect with 80% power a between-subject TAG incremental AUC (iAUC) difference of 4.77 mmol/L per h [35] with a significance level of p ≤ 0.05. Statistical analyses were conducted with SPSS (IBM, Armonk, NY, USA, version 21).…”

Role of the Enterocyte in Fructose-Induced Hypertriglyceridaemia

“…Therefore, plasma apoB48 concentration serves as a measure of CM particle number (including CMR). However, it must be noted that CM are known to be very heterogeneous in size, with a diameter ranging from 75 to 1200 nm depending on the TG content [62], and may be influenced by several factors, including the amount and type of dietary fat ingested [64,67], age [68], gender [69] or genetic influences [70]. …”