656063

research-article2016
VMJ0010.1177/1358863X16656063Vascular MedicineLane-Cordova et al.

Original Article

Vascular Medicine

High trans but not saturated fat beverage 1­–8

© The Author(s) 2016
Reprints and permissions:
causes an acute reduction in postprandial sagepub.co.uk/journalsPermissions.nav
DOI: 10.1177/1358863X16656063
vascular endothelial function but not vmj.sagepub.com

arterial stiffness in humans

Abbi D Lane-Cordova1, Jordan R Witmer1, Kaitlyn Dubishar1,

Lyndsey E DuBose1, Catherine A Chenard1, Kyle J Siefers1,
Janie E Myers1, Lauren J Points1 and Gary L Pierce1,2,3,4

Abstract
A diet high in trans-fatty acids (TFAs) is associated with a higher risk of cardiovascular disease (CVD) than a diet high
in saturated fatty acids (SFAs), but the mechanisms remain unclear. We hypothesized that a beverage high in TFAs
would cause a larger reduction in postprandial endothelial function and an increase in arterial stiffness, in part from
greater reductions in insulin sensitivity, compared with a beverage high in SFAs. Eleven healthy adults (aged 47±5
years) ingested a warm test beverage (520 kcal, 56 g total fat, 5 g carbohydrate, 1 g protein) high in either TFAs or
SFAs in a randomized cross-over study. Ingestion of the beverage high in TFAs (p<0.01) but not high in SFAs (p=0.49)
decreased endothelial function (brachial artery flow-mediated dilation, mmΔ) at 3–4 hours (p<0.01 for time; p=0.034
for interaction), but did not alter aortic stiffness or carotid β-stiffness. The homeostasis model of insulin resistance
(interaction p=0.062) tended to decrease after SFAs but not TFAs. A beverage high in TFAs but not SFAs results in a
postprandial reduction in endothelial function and a trend for decreased insulin sensitivity, potentially explaining the
higher risk of CVD with a diet high in TFAs.

Keywords
cardiovascular disease, flow-mediated dilation, high-fat diet, pulse wave velocity

Introduction
A diet high in saturated fatty acids (SFAs) and trans-fatty may also be critical in understanding the mechanisms by
acids (TFAs) is associated with increased atherosclerotic which diet contributes to the development of atherosclerotic
cardiovascular disease (CVD) risk, mediated in part from CVD. In this regard, consumption of a high-fat, mixed meal
the development of dyslipidemia, endothelial dysfunc- (high in both SFAs and TFAs as well as carbohydrates)
tion and/or insulin resistance.1–3 However, although SFAs causes a transient postprandial endothelial dysfunction of
and TFAs have similar physical properties,4 their inde- the brachial artery within 3–4 hours,8–12 although several
pendent contribution to CVD risk may differ. Consistent studies report no obvious reduction in endothelial function
with this, prospective studies suggest that a diet high in
TFAs is associated with a higher CVD risk than a diet
with a similar percentage of energy intake from SFAs 1Department of Health and Human Physiology, The University of Iowa,
despite both diets resulting in similar increases in low- Iowa City, IA, USA
density lipoprotein (LDL)-cholesterol.5,6 Moreover, in a 2Fraternal Order of Eagles Diabetes Research Center, The University of

large cohort of Finnish men, chronic TFA consumption Iowa, Iowa City, IA, USA
3Center for Hypertension Research, The University of Iowa, Iowa City,
was associated with an increased risk of coronary death
IA, USA
in multivariate adjusted models in the absence of any 4Abboud Cardiovascular Research Center, The University of Iowa, Iowa

association with intake of SFAs.7 Thus, a diet high in City, IA, USA
TFAs appears to contribute to CVD risk independent of
consumption of SFAs but the mechanisms remain unclear. Corresponding author:
Gary L Pierce, Department of Health and Human Physiology, The
Given that individuals in developed countries spend a University of Iowa, 225 S. Grand Ave, 412 FH, Iowa City, IA 52242,
large proportion of the day in the postprandial state, mecha- USA.
nisms responsible for postprandial vascular dysfunction Email: gary-pierce@uiowa.edu

Downloaded from vmj.sagepub.com at CORNELL UNIV on August 27, 2016

2 Vascular Medicine

Table 1. Subject characteristics (n=11). Table 2. Nutrient composition of test beverages.

Age (years) 47 ± 5 High SFAs High TFAs

Male/female 9/2
Energy (kcal) 520 520
Body mass index (kg/m2) 25.5 ± 0.5
Protein (g) 1.3 1.3
Systolic blood pressure (mmHg) 124 ± 2
Fat (g) 55.8 55.8
Diastolic blood pressure (mmHg) 69 ± 2
total saturated (g) 49.3 13.0
Total cholesterol (mg/dl) 170 ± 13
total monounsaturated (g) 4.4 39.6
Carotid artery IMT (mm) 0.50 ± 0.05
   trans monoenoic (g) 0.1 22.3
Data are mean ± SE. total polyunsaturated (g) 2.0 2.9
IMT, intima–media thickness.    trans polyenoic (g) 0.0 1.2
Carbohydrate (g) 5.4 5.4

following a high-fat meal.13–15 However, these studies are SFAs, saturated fatty acids; TFAs, trans-fatty acids.
often confounded by the use of mixed high-fat meals that
contain both SFAs and TFAs, as well as variable amounts of
carbohydrates, that likely explain these divergent results. disease; smoking within the past year; abnormal findings
Furthermore, data on whether a high-fat, mixed meal alters on screening electrocardiogram (ECG); hormone replace-
postprandial large elastic artery (aorta, carotid) stiffness are ment therapy within the past year. Following an initial
mixed, with studies reporting increases, decreases or no screening visit at the University of Iowa Institute for
change in arterial stiffness.9,16–18 Unfortunately, some of Clinical and Translational Science Clinical Research Unit
these studies were confounded by changes in blood pressure (CRU), subjects were given a food journal and instruction
as well as differing in methods for measuring stiffness; thus, for recording food intake for the day prior to each experi-
it remains unclear whether a single high-fat meal alters post- mental visit. Participants fasted for at least 8 hours prior to
prandial large elastic artery stiffness. each study visit, avoided alcohol the day before, and with-
A previous study reported that 4 weeks of a diet high in held dietary supplements for 2 weeks. They returned to the
TFAs resulted in a reduction in endothelial function and CRU for baseline blood draw and vascular measurements,
high-density lipoprotein (HDL)-cholesterol compared with and were randomized to consume a warm beverage in 10
an isocaloric diet high in SFAs in the absence of differences minutes consisting of one of two isocaloric high-fat bever-
in LDL-cholesterol or triglycerides.19 In contrast, another ages high in either TFAs or SFAs (Supplemental Table 1)
study found that a single isocaloric meal containing ~80 g after baseline measurements were obtained. Vascular meas-
TFAs or SFAs did not decrease postprandial endothelial urements were repeated 3 hours post-ingestion. Blood
function despite a slightly larger increase in circulating tri- draws were repeated at 3 and 4 hours post-ingestion.
glycerides after the TFAs.20 However, the meals contained Because the vascular measurements began at 3 hours and
significant carbohydrate and protein content and subjects required 30–45 minutes to complete. The three visits
were also allowed caffeinated coffee or tea, making deter- occurred within ~1 week of each other in men and post-
mination of the effects of fat alone difficult. Furthermore, menopausal women, and in the early follicular phase 1
there are currently no data on the potential selective effects month apart in premenopausal women, and at the same
on postprandial arterial stiffness of a meal high in TFAs time of day to control for diurnal variation.
compared with SFAs.
Therefore, the purpose of the study was to determine the Test beverages
selective effects of a single beverage high in either TFAs or
SFAs on postprandial endothelial function and arterial stiff- Test beverages were designed to be isocaloric fat loads (520
ness while limiting the confounding effects of carbohydrate kcal, 56 g total fat, 5 g carbohydrate, 1 g protein), high in
and protein. We hypothesized that consuming a beverage either TFAs (42% total fat – partially hydrogenated soybean
high in TFAs (but low in carbohydrates and SFAs) would oil) or SFAs (88% total fat– coconut oil) (Table 2 and
cause a larger reduction in endothelial function and Supplementary Table 2). Fat sources were selected so as to
increases in arterial stiffness compared with a beverage provide the maximal amount of SFAs or TFAs possible from
high in SFAs (and low in carbohydrates and TFAs). one commonly available fat source per beverage. Both bev-
erages were low in carbohydrate and protein in order to pre-
vent a postprandial increase in circulating glucose and
Methods insulin that could potentially confound interpretation of vas-
cular outcomes. The warm beverages consisted of sodium-
Experimental design
free chicken bouillon powder, distilled water, soy lecithin,
We utilized a randomized, cross-over design to test our polysorbate 80 (Supplementary Table 1) and either coconut
hypotheses. Healthy subjects (n=11) between ages 21–65 oil (high SFAs) or partially hydrogenated soybean oil (high
years were recruited from the community using mass TFAs, Supplementary Table 2). Fats were obtained in one
emails and flyers (Table 1). All study procedures were lot, packaged, and analyzed by the supplier (Archer Daniels
approved by the University of Iowa Institutional Review Midland Company, Decatur, IL, USA) for fatty acid compo-
Board (IRB), and all subjects read and signed an IRB- sition (AOCS Official Method Ce 1h-05). Test beverages
approved informed consent document. Exclusion criteria were prepared immediately before serving using the follow-
included: known cardiovascular, metabolic and pulmonary ing process: the fat source was weighed to the nearest gram
Downloaded from vmj.sagepub.com at CORNELL UNIV on August 27, 2016
Lane-Cordova et al. 3

into an opaque, thermal beverage container and microwaved brachial, radial, femoral and carotid artery was performed
until melted. Emulsifiers Lecigran™ 1000P (Cargill, Inc., with a custom transducer and waveforms were signal-aver-
Decatur, IL) and T-MAZ® 80 (BASF Corporation, Florham aged and gated to the ECG R-wave (Noninvasive
Park, NJ) were added to the melted fat and blended with a Hemodynamics Workstation; Cardiovascular Engineering,
hand-held mixer for 45 seconds. Sodium-free chicken bouil- Inc., Norwood, MA, USA) as previously described.23
lon powder (Hormel Foods LLC, Austin, MN) that had been Average systolic and diastolic BPs were used to calibrate
rehydrated with 160°F (71.1°C). Distilled water was slowly the peak and trough of the signal-averaged BP waveform,
added to the beverage container, blending continuously with and BP measurements were read by a single investigator.
the hand mixer and then blended for an additional 60 sec- Carotid-femoral artery pulse wave velocity (PWV) and
onds. Total beverage volume was approximately 1.25 cups. carotid-radial artery PWV were calculated as previously
The beverage container was capped and served to the sub- described.23 Distances from suprasternal notch (SSN) to
ject with instructions to consume within 10 minutes. The carotid was subtracted from SSN to respective pulse record-
beverage container was inspected and weighed after serving ing sites to correct for parallel transmission of the pressure
to verify consumption. pulse in the carotid and aorta. Corrected distances were
divided by respective foot-to-foot time delays to calculate
carotid-femoral PWV.
Vascular endothelial function
Brachial artery flow-mediated dilation (FMD), an index of
Carotid artery β-stiffness
macrovascular endothelial function, was determined using a
12 MHz matrix linear transducer and ultrasound (Logiq 7; The carotid artery was imaged using a 12 MHz matrix linear
GE Healthcare, Milwaukee, WI) as previously described by transducer inferior to the carotid bifurcation. Moving DICOM
our laboratory.21 While supine, the subject positioned his/ images were recorded, and systolic and diastolic diameters of
her arm comfortably on a side table at heart level, and a a 0.5-cm portion of the artery were analyzed offline (Vascular
pediatric cuff was placed on the upper forearm. A segment Analysis Tools 5.5; Medical Imaging Applications, LLC,
of the brachial artery 2–6 cm proximal to the antecubital Coralville, IA, USA) and calibrated with carotid BP wave-
crease was selected for imaging and analysis, and the dis- forms obtained during applanation tonometry measurements,
tance from the crease was recorded in order to select the as previously described.24 Beta was calculated as: [ln(P1/P0)]
same arterial segment for subsequent visits. Baseline dias- / [(D1 − D0)/D0], where P1 = carotid systolic BP, P0 = carotid
tolic ultrasound images and Doppler velocity of the artery diastolic BP, D1 = carotid end-systolic diameter, and D0 =
were acquired in duplex mode (simultaneous B mode and carotid end-diastolic diameter.25 This image was also used to
pulsed Doppler). Reactive hyperemia of the brachial artery measure the intima-media thickness.
was produced by inflating a forearm blood pressure cuff dis-
tal to the antecubital crease to 250 mmHg for 5 minutes and
then rapidly deflating the cuff. ECG-gated end-diastolic
Blood metabolic analyses
ultrasound images and pulsed Doppler of the brachial artery Serum glucose, triglycerides, cholesterol, and insulin con-
were obtained before and continuously for 2 minutes after centrations were measured by the University of Iowa
cuff release. Diameters were analyzed off-line and peak Diagnostic Hospital Laboratory, Department of Pathology.
dilation was determined as the highest diameter post-cuff A commercially available fluorescent assay kit was used to
deflation and expressed as the absolute change (mmΔ) and determine free fatty acid (FFA) serum concentrations (Kit#
percentage change (%Δ) from baseline. 700310; Cayman Chemical, Inc., Ann Arbor, MI, USA).
Shear rate (SR) was calculated as total hyperemic stimu- The homeostatic model of insulin resistance (HOMA-IR)
lus (area under the curve: AUC), as previously described,22 was calculated pre- and post-beverage as (insulin, mU/
by determining the cumulative sum of the SR from cuff ml*glucose, mg/dl)/405.26
deflation up to the peak diameter using the formula:

SR= Velocity*8/diameter
Plasma nitrite/nitrate (NOx) analysis
Plasma samples were collected and stored at −80°C and
Where velocity = mean velocity, 8 is a constant used for then thawed, filtered, and diluted immediately prior to anal-
wide Doppler sample volume, and diameter is the diameter ysis. Total plasma NOx (nitrite + nitrate) was determined as
of the artery during that 4–5 second bin. Peak SR was cal- a readout of nitric oxide (NO) bioavailability with a com-
culated using the velocity in the 4 seconds immediately fol- mercially available colorimetric assay kit (Kit# 780001;
lowing cuff release using the same formula.21 FMD Cayman Chemical, Inc., Ann Arbor, MI, USA), performed
normalized to shear rate AUC was also calculated. according to the manufacturer’s instructions. Samples were
measured in triplicate, and our coefficient of variation was
<5% for these analyses.
Blood pressure and aortic stiffness
After 10 minutes of supine rest, brachial artery blood pres-
Dietary data
sure (BP) was assessed in triplicate using an automated cuff
and auscultatory BP was recorded by an investigator using Nutrient intake during the 24 hours prior to each study visit
a built-in cuff microphone. Arterial tonometry of the was determined from a food record kept by study participants.

Downloaded from vmj.sagepub.com at CORNELL UNIV on August 27, 2016

4 Vascular Medicine

Table 3. Hemodynamic and metabolic variables at baseline (pre) and 3–4 hours postprandial (post) a beverage high in saturated
fatty acids (SFAs) and trans-fatty acids (TFAs).

Pre-SFAs Post-SFAs Pre-TFAs Post-TFAs Interaction p-value

Systolic BP (mmHg) 122 ± 4 123 ± 2 124 ± 5 123 ± 3 0.61
Diastolic BP (mmHg) 69 ± 2 69 ± 2 68 ± 2 69 ± 2 0.58
MAP (mmHg) 87 ± 2 87 ± 2 86 ± 3 87 ± 2 0.99
PP (mmHg) 53 ± 3 54 ± 2 56 ± 4 54 ± 2 0.45
cfPWV (cm*s−1) 693 ± 61 713 ± 49 708 ± 42 677 ± 43 0.16
β-stiffness (U) 9.0 ± 1.1 10.4 ±1.8 8.6 ± 0.6 7.9 ± 1.1 0.16
FFA (mmol/L)a 714 ± 59 884 ± 67 680 ± 84 756 ± 78 0.42
TG (mg/dL) 94 ± 11 97 ± 10 96 ± 15 116 ± 19 0.22
Blood glucose (mg/dl)a 90 ± 2 84 ± 2 88 ± 2 81 ± 2 0.63
Insulin (mU/ml)a 7.6 ± 0.8 5.9 ± 0.7 6.2 ± 0.7 5.8 ± 0.9 0.062
HOMA-IRa 1.7 ± 0.2 1.2 ± 0.1 1.4 ± 0.2 1.2 ± 0.2 0.069

Data are mean ± SE.

BP, blood pressure; MAP, brachial mean arterial pressure; PP, brachial pulse pressure; cfPWV, carotid-femoral pulse wave velocity; β-stiffness, beta stiff-
ness of the common carotid artery; FFA, plasma free fatty acids; TG, serum triglycerides; HOMA-IR, homeostasis model of insulin resistance.
aA significant main effect, p<0.05.

Participants were given a food scale to weigh foods, and were pre- and post-beverage (p > 0.05 for all). There were no sig-
asked to avoid alcohol, fried foods, pizza, ice cream, chips and nificant interactions for these measures between the two
other high-fat foods at dinner and during the evening prior to beverage conditions (Table 3).
testing. Nutrient intake was calculated using the Nutrition
Data System for Research (NDSR) software version 2014
Blood metabolic analyses
(Nutrition Coordinating Center, University of Minnesota,
Minneapolis, MN, USA). Nitrate and nitrite intake were man- Postprandial glucose was reduced across groups (p<0.001)
ually calculated using published data27–29 or values estimated without an interaction effect (p=0.63; Table 3). Insulin was
from published data using standard procedures.30 reduced in the whole cohort with a significant interaction
effect between beverage types (p=0.004 for time and
p=0.01 for interaction effects; Figure 2A). There was a
Statistics strong trend for a reduction in insulin after the SFA bever-
Statistical analysis was performed using SPSS 21 (IBM SPSS age, but not after the TFA beverage (p=0.069 for interac-
Statistics, Armonk, NY, USA). Distribution of variables of tion; Figure 2A). There was also a strong trend for a
interest was evaluated using Kolmogorov-Smirnov tests. decrease in HOMA-IR after the SFA beverage (p<0.05 for
Non-normally distributed variables were log-transformed both), but not the TFA beverage (p=0.062 for interaction
before repeated measures analyses. Effect of time*beverage effect; Figure 2B). Lastly, there was a significant increase
type was evaluated using a repeated measures (2 × 2) in serum FFAs (p=0.03) following the beverages that was
ANOVA. Post-hoc least-significant differences (LSD) tests not different between beverage types (p=0.418 for interac-
were performed to test for differences between beverages if tion; Table 3). Triglycerides were unchanged post-beverage
the interaction was significant, and post-hoc t-tests were per- without an interaction effect (p=0.09 for both).
formed to determine differences following the beverage
within a group. Significance was set at alpha level <0.05. Aortic stiffness and carotid β-stiffness
Carotid-femoral PWV data were obtained in a subset of
Results eight subjects in both beverage conditions. Carotid-femoral
Subjects PWV was unchanged pre- and post-beverage without inter-
action effects (p=0.16 for all; Table 3). Carotid artery
Eleven subjects (M=9/F=2) completed all visits of the β-stiffness data were obtained in a subset of seven subjects
study. Subject characteristics are presented in Table 1. in both beverage conditions. There was no change in carotid
β-stiffness from pre- to post-beverage and no significant
Beverage consumption interaction effect between beverage types (p=0.64 for main
effect of beverage and >0.05 for all; Table 3).
Beverages were consumed by participants with no reports
of adverse effects or complaints about palatability.
Brachial artery FMD
FMD data were obtained in all subjects in all conditions
Blood pressure
and are illustrated in Figures 1A and 1B. There was a sig-
There was no change in brachial mean arterial pressure nificant reduction in absolute FMD (mmΔ) post-beverage
(MAP), systolic BP, diastolic BP, or brachial pulse pressure across conditions (p<0.01 time-effect, with a significant

Downloaded from vmj.sagepub.com at CORNELL UNIV on August 27, 2016

Lane-Cordova et al. 5

Figure 1. Brachial artery flow-mediated dilation (FMD)

response at baseline (pre) and 3 hours after (post) beverage. (A)
Absolute brachial artery FMD (mmΔ); (B) relative brachial artery Figure 2. Plasma insulin concentrations and HOMA-IR at
FMD (%). *p<0.05 signifies a significant main effect; †p<0.05 baseline (pre) and 3 hours after (post) beverage. (A) Plasma
indicates a significant interaction effect; ‡p<0.05 indicates a insulin concentrations; (B) HOMA-IR. *p<0.05 signifies a
decrease from baseline within that beverage type. (TFAs, trans- significant main effect. (TFAs, trans-fat beverage; SFAs, saturated
fat beverage; SFAs, saturated fat beverage.) fat beverage.)

interaction effect between beverage types, p=0.034; all; Table 5). Nitrate and nitrite intake fell within previ-
Figure 1A). The reduction in absolute FMD was signifi- ously reported ranges.31
cantly larger (p<0.05) following the high TFA (p<0.01)
compared with the SFA beverage (p=0.49). There also
was a significant decrease in relative FMD (%Δ) between Discussion
pre- and post-beverage (p=0.014 for main effect), but the The main finding of our study was that consumption of a
interaction effect did not reach significance (p=0.123 for single beverage high in TFAs but not SFAs resulted in a
time*beverage type effect; Figure 1B). Furthermore, there reduction in postprandial brachial artery endothelial func-
was no difference in baseline diameter or between AUC tion within 3–4 hours despite the absence of any group dif-
shear rate up to peak dilation or peak shear rate between ferences in changes in blood pressure or circulating lipids.
conditions before or after the beverage (p>0.30 for all We also found that insulin concentrations and HOMA-IR
comparisons; Table 4). remained elevated 3–4 hours following the high TFA bever-
age despite a time-dependent reduction in glucose. In con-
trast, postprandial insulin and HOMA-IR tended to be
Plasma NOx
reduced following the high SFA beverage over 3–4
Plasma NOx was reduced in the entire cohort post-bever- hours, mirroring the expected time-dependent decrease in
age (p=0.003), with NOx decreasing from 16 ± 5 to 13 ± 5 glucose given the lack of carbohydrate in the beverages.
μM in the TFAs condition and 10 ± 2 to 9 ± 2 μM in the Furthermore, neither beverage – high in TFAs or SFAs –
SFAs condition. There was no significant interaction effect had any effect on postprandial aortic or carotid arterial stiff-
(p=0.68) and the change in NOx was not significant ness. Taken together, these data indicate that the acute
between conditions (p=0.53). effects of a beverage high in TFAs, but not high in SFAs,
have an immediate detrimental effect on vascular endothe-
lial function in the absence of any effect on large elastic
24-Hour dietary record artery stiffness, perhaps in part from a reduction in insulin
There was no difference in the 24-hour record of total sensitivity from a beverage high in TFAs.
kilocalories, fat, carbohydrate, protein, SFAs, TFAs, Our results are in agreement with a previous study by de
nitrate and nitrite intake between conditions (p > 0.40 for Roos et al. (2001)19 who reported that 4 weeks of an

Downloaded from vmj.sagepub.com at CORNELL UNIV on August 27, 2016

6 Vascular Medicine

Table 4. Brachial artery and area under the curve shear rate variables.

SFA TFA p-value

Baseline brachial diameter pre-beverage 3.96 ± 0.25 3.89 ± 0.22 0.84
Baseline brachial diameter 3 hours post-beverage 3.96 ± 0.25 3.91 ± 0.21 0.76
SR AUC pre-beverage 27,935 ± 1616 27,380 ± 2419 0.86
SR AUC 3 hours post-beverage 26,471 ± 3255 34,106 ± 4265 0.17
FMD pre-beverage (mm) 0.14 ± 0.03 0.19 ± 0.02 0.15
FMD pre-beverage (%) 3.9 ± 0.9 4.6 ± 0.9 0.58

Data are mean ± SE.

Baseline brachial diameter pre-beverage = brachial diameter before ingestion of beverage; baseline brachial diameter post-beverage = brachial diam-
eter 3 hours following ingestion of beverage; SR AUC pre-beverage = shear rate area under the curve before ingestion of beverage; SR AUC 3 hours
post-beverage = shear rate area under the curve 3 hours following beverage ingestion; FMD pre-beverage (mm) = absolute flow-mediated dilation
before ingestion of beverage; FMD pre-beverage (%) = percent flow-mediated dilation before ingestion of beverage.

Table 5. Dietary intake 24 hours prior to each experimental because the increase in FFAs were not different between
visit. test beverages. However, the assay for FFAs cannot distin-
Macronutrient SFA TFA guish between SFAs and TFAs, so it is possible that high
circulating TFAs have a direct effect on the vascular wall,
Total kcal 1852 ± 255 1692 ± 144 but this could not be confirmed in our study. In addition,
Total fat (g) 53 ± 11 45 ± 8 blood glucose was also uniformly reduced across both bev-
Total CHO (g) 276 ± 38 249 ± 31 erage conditions, so that the maintenance of baseline insu-
Total protein (g) 82 ± 11 85 ± 11 lin levels following the high-TFA beverage was not caused
Total TFA (g) 1.1 ± 0.2 1.3 ± 0.3 simply by a concomitant maintenance of blood glucose.
Total SFA (g) 13 ± 2 12 ± 3 Consistent with this, fasting insulin concentrations are
Nitrate (mg) 93.9 ± 26.3 89.1 ± 15.5
higher after a 4-week diet high in TFAs compared with
Nitrite (mg) 2.0 ± 0.3 2.1 ± 0.3
monounsaturated fatty acids (MUFAs).32 In contrast, there
Data are mean ± SE. was no difference between diets high in TFAs and SFAs in
Total kcal = total daily kilocalories; total fat = total daily fat grams; total insulin sensitivity after 5 weeks,33 and another study
CHO = total daily carbohydrate grams; total protein = total daily protein reported a similar increase in insulin after 6 weeks of a diet
grams; total TFA = total daily trans-fatty acid grams; total SFA = total
daily saturated fatty acid grams.
high in both TFAs and SFAs compared with MUFAs.34
Furthermore, increased plasma FFA concentrations follow-
ing a high-fat meal cause skeletal muscle insulin resist-
isocaloric high-fat diet that substituted high TFAs for SFAs ance35 and impaired insulin clearance.36 Therefore, in our
resulted in a significant reduction in endothelial function study it is possible that a high-TFA beverage, without the
and HDL-cholesterol in the absence of any changes in confounding effect of SFAs and carbohydrates, caused
LDL-cholesterol and triglycerides. However, the reduc- transient insulin resistance in peripheral tissues, requiring
tions in HDL-cholesterol in their study did not significantly maintenance of insulin concentrations in order to lower cir-
correlate with changes in endothelial function, and circulat- culating glucose over the 3–4-hour postprandial period
ing insulin and glucose concentrations were not reported. compared with SFAs. Alternatively, the TFAs may have
Therefore, the reduction in endothelial function associated caused a reduction in insulin clearance by the liver or
with high TFAs could not be directly attributed to altera- increased insulin secretion by pancreatic β-cells, but addi-
tions in insulin sensitivity or HDL-cholesterol. Our results tional studies are needed to further test these hypotheses.
differ with another study by de Roos et al. (2002)20 who The mechanisms for the acute decrease in endothelial
reported that a single meal high in either TFAs or SFAs did function after the high-TFA beverage but not the high-SFA
not significantly decrease postprandial endothelial func- beverage are unknown. Insulin normally causes activation
tion. The differences between this study and our data could of endothelial NO synthase through a well-characterized
be explained by the high carbohydrate and protein content PI3K/Akt-mediated phosphorylation signaling cascade.37
in the test meals in their study (in the form of a milkshake In contrast, insulin can also activate an ERK-1-mediated
and bread with preserves), and subjects were allowed caf- increase in the endothelin-1 (ET-1) expression in a setting
feinated coffee or tea, which could have influenced vascu- of insulin resistance resulting in enhanced vasoconstrictor
lar assessments. In contrast, our test beverages were very tone and endothelial dysfunction.37 Indeed, experimental
low in carbohydrates, protein and sodium but high in either forearm hyperinsulinemia results in both elevation of ET-1
SFAs or TFAs, thus allowing us to test the independent vasoconstrictor and NO vasodilator pathways, even in indi-
influence of SFAs or TFAs on vascular function. viduals with normal insulin sensitivity and lipid levels,
Previous studies have demonstrated that a diet high in with the NO vasodilator pathway dominating.38 Thus, we
TFAs increases serum FFAs, and that high FFAs can lead to speculated that, in the setting of a beverage high in TFAs,
hyperinsulinemia.32–34 The reduced FMD and sustained vascular NO production would be reduced. However, we
insulin levels following the high-TFA beverage in our study did not find a difference in the effect of the beverage types
do not appear to be caused by increased serum FFAs, on plasma NOx, suggesting that NO availability may not be

Downloaded from vmj.sagepub.com at CORNELL UNIV on August 27, 2016

Lane-Cordova et al. 7

the mechanism by which TFAs caused the reduction in cause a postprandial endothelial dysfunction and blunt the
endothelial function in our study. Thus, we speculate that normal temporal reductions in insulin concentrations
ET-1 vasoconstrictor pathways in the setting of TFA- associated with falling glucose concentrations in the car-
induced insulin resistance may have promoted the develop- bohydrate-fasted state. While a diet high in either TFAs or
ment of endothelial dysfunction, but further studies will be SFAs is associated with increased CVD risk, our data pro-
needed to confirm this possibility. vide potential insight into the long-term effects of a
Lastly, postprandial oxidative stress and inflammation chronic high-TFA diet on cardiovascular and metabolic
have also been reported to be a cause of the transient health in humans.
endothelial dysfunction after a high-fat meal.39 Indeed,
administration of antioxidants (vitamins C and E or Acknowledgements
omega-3 fatty acids) prevented acute endothelial dysfunc- We thank the Archer Daniels Midland Company for providing,
tion following a high-fat meal,9,40 and TFAs directly analyzing, and packaging the fats; Kaitlyn Hemesath, BA who
increase endothelial cell inflammation by increasing assisted with test beverage development; and Greg Peak, BBA
e-selectin, intercellular adhesion molecule 1 (ICAM-1) and who prepared the test beverages.
vascular cell adhesion molecule 1 (VCAM-1), as well as
increasing systemic inflammation.41,42 Therefore, it’s pos- Declaration of conflicting interests
sible that acute TFA ingestion results in enhanced endothe- The authors declared no potential conflicts of interest with respect
lial cell oxidative stress and inflammation contributing to to the research, authorship, and/or publication of this article.
the endothelial dysfunction, but this cannot be determined
from the current study. Funding
The authors disclosed receipt of the following financial support
Limitations for the research, authorship, and/or publication of this article: sup-
ported by National Institutes of Health grants 5T32 HL007638-
Some limitations of our study should be noted. We have a 30, 5T32 HL007121-37 and U54TR001356, and University of
relatively small sample size, but the randomized, cross-over, Iowa Institute for Clinical and Translational Science award 5KL2
repeated-measures design minimizes inter-subject differ- RR24980-5.
ences. However, a larger sample size may have resulted in
significant changes in some of the interactions (e.g. insulin, Supplementary material
HOMA-IR) that approached statistical significance. The fats The supplementary material is available at http://vmj.sagepub.
were not pure sources of SFAs and TFAs, and the TFA bever- com/supplemental
age contained more MUFAs than the SFA beverage. We did
not standardize the evening meal (consumed the night before References
testing), but subjects were asked to consume a low-fat meal 1. Mensink RP, Zock PL, Kester AD, et al. Effects of dietary
the evening before, and the 24-hour dietary record revealed fatty acids and carbohydrates on the ratio of serum total to
no significant differences in caloric or macronutrient intake HDL cholesterol and on serum lipids and apolipoproteins: A
among the subjects between visits. We used HOMA-IR as meta-analysis of 60 controlled trials. Am J Clin Nutr 2003;
an estimate of insulin sensitivity, so our results should be 77: 1146–1155.
confirmed using the ‘gold-standard’ hyperinsulinemic- 2. Willett WC. Dietary fats and coronary heart disease. J Intern
euglycemic clamp. NOx was used as an indirect index of Med 2012; 272: 13–24.
NO bioavailability, but this can be influenced by potential 3. Mozaffarian D, Katan MB, Ascherio A, et al. Trans fatty
differences in dietary nitrate. Furthermore, we did not meas- acids and cardiovascular disease. N Engl J Med 2006; 354:
ure endothelium-independent dilation to sublingual nitro- 1601–1613.
4. Ohlrogge JB, Emken EA, Gulley RM. Human tissue lipids:
glycerin, and therefore it is possible that the TFAs altered the
Occurrence of fatty acid isomers from dietary hydrogenated
vascular smooth muscle function of the brachial artery. oils. J Lipid Res 1981; 22: 955–960.
5. Oomen CM, Ocke MC, Feskens EJ, et al. Association
Conclusion between trans fatty acid intake and 10-year risk of coronary
heart disease in the Zutphen Elderly Study: A prospective
A beverage high in TFAs but low in SFAs and carbohy- population-based study. Lancet 2001; 357: 746–751.
drates resulted in an acute postprandial reduction in 6. Ascherio A, Willett WC. Health effects of trans fatty acids.
endothelial function in healthy adults. In contrast, neither Am J Clin Nutr 1997; 66: 1006S–1010S.
high-fat beverage had any obvious effect on aortic 7. Pietinen P, Ascherio A, Korhonen P, et al. Intake of
stiffness measured by carotid-femoral PWV or carotid fatty acids and risk of coronary heart disease in a cohort
of Finnish men. The Alpha-Tocopherol, Beta-Carotene
artery β-stiffness by high-resolution ultrasonography.
Cancer Prevention Study. Am J Epidemiol 1997; 145:
Furthermore, whereas the high-SFA beverage demon- 876–887.
strated a trend for reductions in insulin concentrations and 8. Gill JM, Al-Mamari A, Ferrell WR, et al. Effects of prior
HOMA-IR 3–4 hours after consumption, insulin concen- moderate exercise on postprandial metabolism and vascular
trations and HOMA-IR were maintained after the high- function in lean and centrally obese men. J Am Coll Cardiol
TFA beverage, suggesting a transient reduction in insulin 2004; 44: 2375–2382.
sensitivity after the high-TFA beverage. These data sup- 9. Fahs CA, Yan H, Ranadive S, et al. The effect of acute fish-oil
port the idea that dietary TFAs more than SFAs selectively supplementation on endothelial function and arterial stiffness

Downloaded from vmj.sagepub.com at CORNELL UNIV on August 27, 2016

8 Vascular Medicine

following a high-fat meal. Appl Physiol Nutr Metab 2010; 35: from fasting plasma glucose and insulin concentrations in
294–302. man. Diabetologia 1985; 28: 412–419.
10. Vogel RA, Corretti MC, Plotnick GD. Effect of a single 27. Hord NG, Tang Y, Bryan NS. Food sources of nitrates and
high-fat meal on endothelial function in healthy subjects. Am nitrites: The physiologic context for potential health benefits.
J Cardiol 1997; 79: 350–354. Am J Clin Nutr 2009; 90: 1–10.
11. Bae JH, Schwemmer M, Lee IK, et al. Postprandial hyper- 28. Griesenbeck JS, Steck MD, Huber JC Jr, et al. Development
triglyceridemia-induced endothelial dysfunction in healthy of estimates of dietary nitrates, nitrites, and nitrosamines for
subjects is independent of lipid oxidation. Int J Cardiol use with the Short Willet Food Frequency Questionnaire.
2003; 87: 259–267. Nutr J 2009; 8: 16.
12. Plotnick GD, Corretti MC, Vogel RA. Effect of antioxi- 29. Food Standards Australia New Zealand. Survey of Nitrates
dant vitamins on the transient impairment of endothelium- and Nitrites in Food and Beverages in Australia. Food
dependent brachial artery vasoactivity following a single Standards Australia and New Zealand. Barton, ACT;
high-fat meal. JAMA 1997; 278: 1682–1686. Wellington: FSANZ.
13. Gokce N, Duffy SJ, Hunter LM, et al. Acute hypertriglyc- 30. Schakel SF, Buzzard IM, Gebhardt SE. Procedures for esti-
eridemia is associated with peripheral vasodilation and mating nutrient values for food composition databases. J
increased basal flow in healthy young adults. Am J Cardiol Food Compost Anal 1997; 9: 385–395.
2001; 88: 153–159. 31. Griesenbeck JS, Brender JD, Sharkey JR, et al. Maternal
14. Raitakari OT, Lai N, Griffiths K, et al. Enhanced peripheral characteristics associated with the dietary intake of nitrates,
vasodilation in humans after a fatty meal. J Am Coll Cardiol nitrites, and nitrosamines in women of child-bearing age: A
2000; 36: 417–422. cross-sectional study. Environ Health 2010; 9: 10.
15. Skilton MR, Lai NT, Griffiths KA, et al. Meal-related 32. Louheranta AM, Turpeinen AK, Vidgren HM, et al. A high-
increases in vascular reactivity are impaired in older and trans fatty acid diet and insulin sensitivity in young healthy
diabetic adults: Insights into roles of aging and insulin in women. Metabolism 1999; 48: 870–875.
vascular flow. Am J Physiol Heart Circ Physiol 2005; 288: 33. Lovejoy JC, Smith SR, Champagne CM, et al. Effects of
H1404–1410. diets enriched in saturated (palmitic), monounsaturated
16. Taylor JL, Curry TB, Matzek LJ, et al. Acute effects of a (oleic), or trans (elaidic) fatty acids on insulin sensitivity and
mixed meal on arterial stiffness and central hemodynamics substrate oxidation in healthy adults. Diabetes Care 2002;
in healthy adults. Am J Hypertens 2014; 27: 331–337. 25: 1283–1288.
17. Lithander FE, Herlihy LK, Walsh DM, et al. Postprandial 34. Christiansen E, Schnider S, Palmvig B, et al. Intake of a
effect of dietary fat quantity and quality on arterial stiffness diet high in trans monounsaturated fatty acids or saturated
and wave reflection: A randomised controlled trial. Nutr J fatty acids. Effects on postprandial insulinemia and glyce-
2013; 12: 93. mia in obese patients with NIDDM. Diabetes Care 1997;
18. Murray T, Yang EY, Brunner G, et al. Postprandial effects 20: 881–887.
on arterial stiffness parameters in healthy young adults. Vasc 35. Szendroedi J, Frossard M, Klein N, et al. Lipid-induced
Med 2015; 20: 501–508. insulin resistance is not mediated by impaired transcapillary
19. De Roos NM, Bots ML, Katan MB. Replacement of dietary transport of insulin and glucose in humans. Diabetes 2012;
saturated fatty acids by trans fatty acids lowers serum HDL 61: 3176–3180.
cholesterol and impairs endothelial function in healthy men and 36. Carpentier A, Mittelman SD, Bergman RN, et al. Prolonged
women. Arterioscler Thromb Vasc Biol 2001; 21: 1233–1237. elevation of plasma free fatty acids impairs pancreatic
20. De Roos NM, Siebelink E, Bots ML, et al. Trans monoun- beta-cell function in obese nondiabetic humans but not
saturated fatty acids and saturated fatty acids have similar in individuals with type 2 diabetes. Diabetes 2000; 49:
effects on postprandial flow-mediated vasodilation. Eur J 399–408.
Clin Nutr 2002; 56: 674–679. 37. Kim JA, Montagnani M, Koh KK, et al. Reciprocal relation-
21. Pierce GL, Eskurza I, Walker AE, et al. Sex specific effects ships between insulin resistance and endothelial dysfunction:
of habitual aerobic exercise on brachial artery flow-mediated Molecular and pathophysiological mechanisms. Circulation
dilation in middle-aged and older adults. Clin Sci (Lond) 2006; 113: 1888–1904.
2011; 120: 13–23. 38. Campia U, Sullivan G, Bryant MB, et al. Insulin impairs
22. Thijssen DH, Black MA, Pyke KE, et al. Assessment of endothelium-dependent vasodilation independent of insulin
flow-mediated dilation in humans: A methodological and sensitivity or lipid profile. Am J Physiol Heart Circ Physiol
physiological guideline. Am J Physiol Heart Circ Physiol 2004; 286: H76–82.
2011; 300: H2–12. 39. Wallace JP, Johnson B, Padilla J, et al. Postprandial lipae-
23. Mitchell GF, Hwang SJ, Vasan RS, et al. Arterial stiffness mia, oxidative stress and endothelial function: A review. Int
and cardiovascular events: The Framingham Heart Study. J Clin Pract 2010; 64: 389–403.
Circulation 2010; 121: 505–511. 40. Nappo F, Loreto M, Giugliano G, et al. Elevated plasma free
24. Pierce GL, Jablonski KL, Walker AE, et al. fatty acid concentrations do not modify cardiac repolariza-
Tetrahydrobiopterin supplementation enhances carotid tion in patients treated by electrolyte-glucose-insulin infu-
artery compliance in healthy older men: A pilot study. Am J sion. J Endocrinol Invest 2002; 25: RC19–22.
Hypertens 2012; 25: 1050–1054. 41. Mozaffarian D, Pischon T, Hankinson SE, et al. Dietary
25. Hirai T, Sasayama S, Kawasaki T, et al. Stiffness of systemic intake of trans fatty acids and systemic inflammation in
arteries in patients with myocardial infarction. A noninva- women. Am J Clin Nutr 2004; 79: 606–612.
sive method to predict severity of coronary atherosclerosis. 42. Baer DJ, Judd JT, Clevidence BA, et al. Dietary fatty acids
Circulation 1989; 80: 78–86. affect plasma markers of inflammation in healthy men fed
26. Matthews DR, Hosker JP, Rudenski AS, et al. Homeostasis controlled diets: A randomized crossover study. Am J Clin
model assessment: Insulin resistance and beta-cell function Nutr 2004; 79: 969–973.

Downloaded from vmj.sagepub.com at CORNELL UNIV on August 27, 2016