The repeatability of the abbreviated (4-h) Oral Fat Tolerance Test and influence of prior acute aerobic exercise

Are There Interindividual Responses of Cardiovascular Disease Risk Markers to Acute Exercise? A Replicate Crossover Trial

PURPOSE

Using a replicated crossover design, we quantified the response heterogeneity of postprandial cardiovascular disease risk marker responses to acute exercise.

METHODS

Twenty men (mean (SD) age, 26 (6) yr; body mass index, 23.9 (2.4) kg·m -2 ) completed four 2-d conditions (two control, two exercise) in randomized orders. On days 1 and 2, participants rested and consumed two high-fat meals over 9 h. Participants ran for 60 min (61 (7)% of peak oxygen uptake) on day 1 (6.5 to 7.5 h) of both exercise conditions. Time-averaged total area under the curve (TAUC) for triacylglycerol, glucose, and insulin were calculated from 11 venous blood samples on day 2. Arterial stiffness and blood pressure responses were calculated from measurements at baseline on day 1 and at 2.5 h on day 2. Consistency of individual differences was explored by correlating the two replicates of control-adjusted exercise responses for each outcome. Within-participant covariate-adjusted linear mixed models quantified participant-by-condition interactions and individual response SDs.

RESULTS

Acute exercise reduced mean TAUC-triacylglycerol (-0.27 mmol·L -1 ·h; Cohen's d = 0.29, P = 0.017) and TAUC-insulin (-25 pmol·L -1 ·h; Cohen's d = 0.35, P = 0.022) versus control, but led to negligible changes in TAUC-glucose and the vascular outcomes (Cohen's d ≤ 0.36, P ≥ 0.106). Small-to-moderate, but nonsignificant, correlations were observed between the two response replicates ( r = -0.42 to 0.15, P ≥ 0.066). We did not detect any individual response heterogeneity. All participant-by-condition interactions were P ≥ 0.137, and all individual response SDs were small with wide 95% confidence intervals overlapping zero.

CONCLUSIONS

Large trial-to-trial within-subject variability inhibited detection of consistent interindividual variability in postprandial metabolic and vascular responses to acute exercise.

Assessing Insulin Sensitivity and Postprandial Triglyceridemic Response Phenotypes With a Mixed Macronutrient Tolerance Test

The use of meal challenge tests to assess postprandial responses in carbohydrate and fat metabolism is well established in clinical nutrition research. However, challenge meal compositions and protocols remain a variable. Here, we validated a mixed macronutrient tolerance test (MMTT), containing 56-g palm oil, 59-g sucrose, and 26-g egg white protein for the parallel determination of insulin sensitivity and postprandial triglyceridemia in clinically healthy subjects. The MMTT was administered in two study populations. In one, women with overweight/obese BMIs (n = 43) involved in an 8-week dietary intervention were administered oral glucose tolerance tests (OGTTs) and MMTTs within 2 days of each other after 0, 2, and 8 weeks of the dietary intervention. In the other, 340 men and women between 18 and 64 years of age, with BMI from 18–40 kg/m2, completed the MMTT as part of a broad nutritional phenotyping effort. Postprandial blood collected at 0, 0.5, 3, and 6 h was used to measure glucose, insulin, and clinical lipid panels. The MMTT postprandial insulin-dependent glucose disposal was evaluated by using the Matsuda Index algorithm and the 0- and 3 h blood insulin and glucose measures. The resulting MMTT insulin sensitivity index (ISIMMTT) was strongly correlated (r = 0.77, p < 0.001) with the OGTT-dependent 2 h composite Matsuda index (ISIComposite), being related by the following equation: Log (ISIComposite) = [0.8751 x Log(ISIMMTT)] –0.2115. An area under the triglyceride excursion curve >11.15 mg/mL h–1 calculated from the 0, 3, and 6 h blood draws established mild-to-moderate triglyceridemia in agreement with ∼20% greater prevalence of hypertriglyceridemia than fasting indications. We also demonstrated that the product of the 0 to 3 h and 3 to 6 h triglyceride rate of change as a function of the triglyceride incremental area under the curve optimally stratified subjects by postprandial response patterns. Notably, ∼2% of the population showed minimal triglyceride appearance by 6 h, while ∼25% had increasing triglycerides through 6 h. Ultimately, using three blood draws, the MMTT allowed for the simultaneous determination of insulin sensitivity and postprandial triglyceridemia in individuals without clinically diagnosed disease.

Clinical Trial Registration

[https://clinicaltrials.gov/], identifier [NCT02298725; NCT02367287].

The reliability of an abbreviated fat tolerance test: A comparison to the oral glucose tolerance test

BACKGROUND & AIMS

Postprandial lipemia (PPL) is predictive of cardiovascular disease risk, but the current method for assessing PPL is a burdensome process. Recently, the validity of an abbreviated fat tolerance test (AFTT) has been demonstrated. As a continuation of this research, the purpose of this study was to determine the reliability of the AFTT and compare it to the reliability of the oral glucose tolerance test (OGTT).

METHODS

In this randomized crossover trial, 20 healthy adults (10 male and 10 female) completed 2 AFTTs and 2 OGTTs, each separated by a 1-week washout. For the AFTT, triglycerides (TG) were measured at baseline and 4 h post-consumption of a high-fat meal, during which time participants were able to leave the lab. For the OGTT, we measured blood glucose at baseline and 2 h post-consumption of a 75-g pure glucose solution, and participants remained in the lab. To determine reliability, we calculated within-subject coefficient of variation (WCV) and intraclass correlation coefficient (ICC).

RESULTS

The mean 4-h TG WCV for the AFTT was 12.6%, while the mean 2-h glucose WCV for the OGTT was 10.5%. ICC values for 4-h TG and TG change were 0.79 and 0.71, respectively, while ICC values for 2-h glucose and glucose change were 0.66 and 0.56, respectively.

CONCLUSIONS

Based on WCV and ICC, the TG response to an AFTT was similarly reliable to the glucose response to an OGTT in our sample of healthy adults, supporting the AFTT's potential as a standard clinical test for determining PPL. However, reliability of the AFTT needs to be further tested in individuals at greater risk for cardiometabolic disease.

Efficacy of Polyphenols in the Management of Dyslipidemia: A Focus on Clinical Studies

Polyphenols (PLPs), phytochemicals found in a wide range of plant-based foods, have gained extensive attention in view of their antioxidant, anti-inflammatory, immunomodulatory and several additional beneficial activities. The health-promoting effects noted in animal models of various non-communicable diseases explain the growing interest in these molecules. In particular, in vitro and animal studies reported an attenuation of lipid disorders in response to PLPs. However, despite promising preclinical investigations, the effectiveness of PLPs in human dyslipidemia (DLP) is less clear and necessitates revision of available literature. Therefore, the present review analyzes the role of PLPs in managing clinical DLP, notably by dissecting their potential in ameliorating lipid/lipoprotein metabolism and alleviating hyperlipidemia, both postprandially and in long-term interventions. To this end, PubMed was used for article search. The search terms included polyphenols, lipids, triglycerides, cholesterol, LDL-cholesterol and /or HDL-cholesterol. The critical examination of the trials published to date illustrates certain benefits on blood lipids along with co-morbidities in participant’s health status. However, inconsistent results document significant research gaps, potentially owing to study heterogeneity and lack of rigor in establishing PLP bioavailability during supplementation. This underlines the need for further efforts in order to elucidate and support a potential role of PLPs in fighting DLP.

Hypertriglyceridaemia-associated acute pancreatitis: diagnosis and impact on severity

BACKGROUND

The level of hypertriglyceridaemia (HTG) at which the risk of acute pancreatitis (AP) increases and the impact of HTG on AP attributable to other aetiologies remains unclear.

METHODS

We compared clinical outcomes of patients admitted within 48 h of the onset of abdominal pain from a first episode of AP and admission serum triglyceride levels of either <5.65 mmol/l (<500 mg/dl) or ≥5.65 to <11.3 mmol/l (moderate HTG) or ≥11.3 mmol/l (≥1000 mg/dl, severe HTG).

RESULTS

Among a cohort of 1,233 patients with AP there were significant progressive increases in all major deleterious clinical outcomes including mortality (all P_trend < 0.05) that were directly dependent on admission triglyceride levels. Outcomes were improved by earlier presentation (<24 h compared to 24-48 h from abdominal pain onset). Patients with severe HTG and a concomitant aetiology (n = 68) had significantly more persistent organ failure, pancreatic necrosis and longer hospital stays (P < 0.05) than those with severe HTG alone (n = 206).

CONCLUSIONS

There appears to be an association between HTG grade and the severity of AP. Severe HTG significantly increased the severity of AP, over AP attributable to other aetiologies. Moderate as well as severe HTG can be used as a criterion for the diagnosis of HTG-associated AP.

Validity of an Abbreviated, Clinically Feasible Test for Postprandial Lipemia in Healthy Adults: A Randomized Cross-Over Study

BACKGROUND

A large post-meal triglyceride (TG) response is an independent risk factor for cardiovascular disease, but postprandial lipemia assessments are not clinically practical in their current form. Therefore, we assessed the validity of an abbreviated, clinically feasible protocol in measuring postprandial lipemia.

METHOD

Eighteen healthy adults (8 male and 10 female) completed 3 high-fat meal trials in random order: (1) a Standard in Lab (SL) protocol wherein blood draws (to determine TG) were made from a catheter at baseline and hourly for 6 h; (2) an Abbreviated in Lab (AL) protocol in which participants remained in the laboratory but blood draws were only made at baseline and 4 h post-meal; and (3) an Abbreviated with Freedom (AF) protocol in which participants vacated the laboratory between the meal and the 4-h blood draw.

RESULTS

TG increase from baseline was very similar (p = 0.93) across the 3 trials (SL: 68.5 ± 62.7 mg/dL; AL: 71.1 ± 58.0 mg/dL; AF: 66.7 ± 46.4 mg/dL), as were 4-h TG levels (SL: 144.6 ± 84.2 mg/dL; AL: 171.4 ± 88.2 mg/dL; AF: 157.7 ± 76.7 mg/dL; p = 0.49). Similarly, total and incremental area under the curve (AUC) were not significantly different across the trials (p = 0.12 and 0.91, respectively).

CONCLUSION

The TG results of the clinically feasible, abbreviated protocol were similar to those of the more exhaustive standard protocol. The AF protocol could be a valid and feasible clinical tool for measurement of postprandial lipemia and assessment of cardiovascular risk, although studies in larger and more diverse cohorts are needed.

Hemodilution is not the only reason of difference: Comparison of fasting and non-fasting lipoproteins in paired samples

INTRODUCTION

Low-density lipoprotein cholesterol (LDL) is an important risk factor for cardiovascular disease (CVD) and generally measured after 8-12 h fasting. However, some recent studies have pointed that non-fasting lipoproteins, especially LDL concentrations, are better indicators for demonstrating CVD risk and atherosclerosis. They asserted that nutrition is a negligible factor on changes in lipoprotein concentrations and claimed this difference as a result of hemodilution effect, caused from fluid intake and can be eliminated by applying some adjustments. We aimed to compare the fasting and non-fasting LDL values of the same individuals and discuss whether non-fasting and fasting LDL results can be used in place of each other, directly or after applying hemodilution correction models.

MATERIAL AND METHODS

Fasting and non-fasting blood samples of 248 apparently healthy participants were collected. Lipid panel tests, albumin and hemoglobin levels were studied in each sample. Results were evaluated in seven different models which were recommended to correct the hemodilution effect on fasting and non-fasting lipid concentrations of the same individual. Concordance of fasting and non-fasting risk group of the individual were calculated according to the National Cholesterol Education Program classification.

RESULTS

Fasting and non-fasting LDL and non-high density lipoprotein cholesterol (non-HDL) concentrations were significantly different in every model (p < 0.001). Concordance results of fasting and non-fasting LDL and non-HDL risk groups were 63.8% and 77.9% respectively.

CONCLUSIONS

Our results demonstrated that fasting and non-fasting LDL and non-HDL concentrations could not be used in place of each other even when the results were adjusted for elimination of the hemodilution effect.