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| Date: 05-15-2015 | HC# 041551-520 |
Re: Palmolein and Olive Oil Have Similar Effects on Endothelial Function in Overweight and Obese Men
Stonehouse
W, Brinkworth GD, Noakes M. Palmolein and olive oil consumed within a high
protein test meal have similar effects on postprandial endothelial function in
overweight and obese men: A randomized controlled trial. Atherosclerosis. 2015;239(1):178-185.
Palmolein
derived from palm (Elaeis guineensis,
Arecaceae) oil is gaining prominence in the food industry
as an alternative to trans fats because it is inherently stabile, resistant to
oxidation, and contains roughly equal amounts of saturated fatty acids (SFAs)
and unsaturated fatty acids (USFAs). However, decreasing dietary intake of SFAs
is considered an important component of coronary heart disease (CHD) risk
reduction. Hence, the authors investigated the effects of palmolein consumption
on endothelial function (a key clinical target for the prevention of CHD) in
comparison to olive (Olea europaea,
Oleaceae) oil which contains mostly USFA (83.4%). As clinical evidence
indicates that the postprandial (after meal) response to dietary SFA may be
dependent on concurrent protein consumption, this randomized, double-blind,
crossover study compared the acute effects of high-fat, high-protein meals
containing either palmolein or olive oil on endothelial function in overweight
and obese men.
Overweight
(body mass index [BMI] of 25-30 kg/m2) and obese (BMI ˃ 30 kg/m2)
men (n = 28, aged 18-65 years) having a stable weight over the previous 3
months participated in this study conducted at the Commonwealth Scientific and Industrial
Research Organisation Nutrition and Health Research Clinic; Adelaide, South
Australia, Australia. Exclusion criteria were the following: systemic medical
conditions or diseases; smoking; history of heavy alcohol consumption; or consumption
during the 3 months prior to the study of nitrates, non-steroidal
anti-inflammatory drugs, or other drugs/supplements that might affect the study
outcomes.
This
was an acute study with 2 sessions separated by a 1-week washout period.
Subjects fasted overnight and then consumed a high-protein, high-fat test meal
prepared at the clinic. The meal consisted of 200 g (raw weight) lean chicken
strips fried in 40 g of the test oil, a slice of fried (with the leftover oil) white
bread, and a 40 g salad. The 2 test oils were palmolein (RBD Palmolein supplied
by the Malaysian Palm Oil Board; Kuala Lumpur, Malaysia), containing 42% SFAs,
47% monounsaturated fatty acids (MUFAs), and 12% polyunsaturated fatty acids
(PUFAs), and Moro Pure Olive Oil 100% pure, produced and packed in Spain for
Conga Foods Pty. Ltd. The ratios of SFA:MUFA:PUFA were 42:47:12 for palmolein
and 17:76:7 for the olive oil. There were no obvious differences in flavor
between the test meals, and they had the same caloric (2791 kJ) and nutritional
composition (40 g protein, 44 g fat, and 21 g carbohydrate).
Brachial
artery flow-mediated dilation (FMD) was measured and blood was drawn at
baseline and 1x/hour for 5 hours after consuming the test meal. The blood samples
were analyzed to determine the concentration of 5 endothelial function markers,
a marker of oxidative stress (nitrotyrosine formation), insulin, glucose, and
triglycerides.
Comparing
the 2 meals, there were no significant differences in postprandial FMD, endothelial
function markers, or metabolic indicators (insulin, glucose, and triglycerides).
Consuming the olive oil meal transiently increased nitrotyrosine concentrations
compared with the palmolein meal 1 hour after consumption (P = 0.002). However,
the area under the curve for plasma nitrotyrosine did not differ between the 2 test
meals, indicating that the transient increase was not clinically significant.
The
authors conclude that in the context of a high-protein meal, palmolein does not
significantly differ from olive oil in terms of its effects on postprandial FMD
or markers of endothelial function in overweight and obese men. The authors acknowledge
that the relevance of these results is limited to overweight and obese men
consuming these 2 oils concurrent with a high-protein meal. They cannot be
generalized to women, normal or underweight males, or persons of either gender
consuming low-protein diets. They also point out that these findings only apply
to palmolein and not to palm oil. Although these preliminary results are
encouraging, longer-duration trials with larger and more diverse study
populations are required to evaluate the chronic effect of palmolein on
endothelial function. Funding for the study was provided by the Malaysian Palm
Oil Board.
—Heather S. Oliff,
PhD
