Current Developments in Nutrition
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DOI: 10.3945/cdn.116.000257 1
Tricaprylin alone increases plasma ketone response more than coconut oil or other medium chain triglycerides: an acute crossover study in healthy adults Camille Vandenberghe1, 2, Valérie St-Pierre1, 2, Tyler Pierotti3, Mélanie Fortier1, Christian-Alexandre Castellano1, Stephen C Cunnane1, 2,4 1
Research Center on Aging, Sherbrooke, QC, Canada (CV, VSP, MF, CAC, SCC)
Departments of 2Pharmacology and Physiology, and 4Medicine, Université de Sherbrooke, Sherbrooke, QC, Canada (CV, VSP, SCC) 3
Department of Biology-Health Sciences, Bishop’s University, Sherbrooke, QC, Canada
(TP)
Author for correspondence: Stephen Cunnane Research Center on Aging, 1036 Belvedere St. South, Sherbrooke, QC, Canada J1H 4C4 Tel: 1 819 780-2220, ext 45670;
[email protected]
Abbreviations: AcAc, acetoacetate; β-HB, β-hydroxybutyrate; FFA, free fatty acids; CO, coconut oil; MCT, medium chain triglyceride; C8, tricaprylin; C10, tricaprin; AD, Alzheimer’s disease.
Financial support: MCT were provided by Abitec Corporation, Columbus, USA. Financial support from NSERC and Sojecci 2. Trial Registration: NCT 02679222 on ClinicalTrials.gov. Conflict of interest: The authors declare that they have no conflicts interest.
Current Developments in Nutrition
CDN/2016/000257
DOI: 10.3945/cdn.116.000257 2
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ABSTRACT
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Background: Ketones are the brain’s main alternative fuel to glucose. Dietary medium chain
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triglyceride (MCT) supplements increase plasma ketones but their ketogenic efficacy relative to
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coconut oil (CO) is not clear. Objective: To compare the acute ketogenic effect in healthy adults
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of the following test oils: coconut oil (CO; 3% C8, 5% C10), classical MCT oil (C8/C10; 55%
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C8, 35% C10), tricaprylin (>95% C8), tricaprin (>95% C10), or CO mixed 50:50 with C8/C10 or
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C8. Design: In a crossover design, 7 men and 2 women of 34±12 y took two 20 mL doses of the
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test oils prepared as an emulsion in 250 mL of lactose-free skim milk. During the control test
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(CTL), participants received only the milk vehicle. The first test dose was taken with breakfast
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and the second at noon but without lunch. Blood was sampled every 30 min over 8 h for plasma
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acetoacetate and β-hydroxybutyrate analysis. Results: C8 was the most ketogenic test oil with a
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day-long mean of +295±155 µmol/L above CTL. C8 alone induced the highest plasma ketones
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expressed as the areas-under-the-curve (AUC) for 0-4 h and 4-8 h; 780±426 µmol h/L and
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1876±772 µmol h/L, respectively; these values were 813% and 870%, respectively, more than
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CTL (P6.1 mmol/L and glycosylated
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hemoglobin >6.0%), strenuous aerobic exercise more than three times a week, CO allergy,
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untreated hypertension, dyslipidemia, abnormal renal, liver, heart or thyroid function. This
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project is registered on ClinicalTrials.gov (NCT 02679222).
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Test Oils The composition of the CO (President’s Choice®, Toronto, ON, CAN) is shown in Table
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1. The MCT oil was 55% C8, 35% C10 (Captex 355, Abitec, Columbus, OH, USA). The C8 oil
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was 95% pure tricaprylin (Captex 8000, Abitec, Columbus, OH, USA). The C10 oil was 95%
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pure tricaprin (Captex 1000, Abitec, Columbus, OH, USA). A 20 mL dose of each test oil was
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mixed with 250 mL of lactose-free skim milk (Natrel®, Longueuil, QC, CAN) using a blender
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(Magic Bullet©, Los Angeles, CA, USA). CO and C10 are solid at room temperature so they were
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melted in a water bath at 60°C prior to blending into the milk base.
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Experimental design The protocol involved seven separate but identical metabolic study days for each
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participant, hence a repeated/longitudinal measurements design during which the test substances
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were evaluated in random order: vehicle (CTL; 250 mL lactose-free skim milk) or 20 mL of the
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test oils mixed with 250 mL of lactose-free skim milk (CO; C10; C8; C8/C10; CO + C8/C10
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[50:50]; CO + C8 [50:50]) taken twice, once at breakfast and once at mid-day. Participants were
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single blinded and crossed over from one treatment to the next during the trial course. The test
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sequence was determined a priori by the investigator, and the participants were randomized to
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sequences. On each metabolic study day, the participants arrived at 7:30 a.m. after a 12 h
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overnight fast and a minimum of 24 h without alcohol intake. A forearm venous catheter was
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installed and a baseline blood sample (Time 0) withdrawn. Participants then received a standard
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breakfast during which they consumed the test beverage. The breakfast consisted of two pieces of
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toast with raspberry jam, a piece of cheese, and two scrambled eggs. A second dose of the test
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beverage was given alone for lunch, i.e. with no other food (Table 1). Water was available ad
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libitum throughout the study day. Blood samples were taken as baseline (pre-dose) and every 30
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min during 8 h with the first post-dose sample being taken 30 min after the test beverage was
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consumed. Blood samples were centrifuged at 2846 g for 10 min at 4°C and plasma stored at -
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80°C until analyzed.
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Plasma metabolites analyses Plasma β-HB and AcAc were measured by an automated colorimetric assay as previously
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described (9). Briefly, for AcAc, 25 μL of plasma was mixed with 330 μL of fresh reagent (Tris
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buffer, pH 7.0, 100 mmol/L, 20 mmol/L sodium oxamate; 0.15 mmol/L NADH and 1U/mL β-
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hydroxybutyrate dehydrogenase [β-HBDH]). For β-HB, the reagent was Tris buffer (pH 9.0; 20
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mM sodium oxamate, 1 mmol/L NAD, and 1U/mL β-HBDH). Tris, oxamic acid, DL-β-HB
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sodium salt, Li-AcAc standard, and NAD were purchased from Sigma (St. Louis, MO, USA),
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NADH, from Roche (Mannheim, Germany), and β-HBDH from Toyobo (Osaka, Japan). The
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change in absorbance at 340 nm between 15 and 120 s after the addition of the reagent was
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measured on an automated clinical chemistry analyzer (Dimension Xpand Plus; Siemens,
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Deerfield, IL, USA). The assay was calibrated with freshly diluted standards from frozen aliquots
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of a 10 mmol/L standard of Li-AcAc or DL-β-HB sodium salt, which is stable at -20°C for 2 and
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6 months, respectively. Calibrations and quality controls were performed for each assay to ensure
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the precision of the kits (coefficient of variation between tests 5 ± 1 %). Plasma glucose, lactate,
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triglycerides, cholesterol, (Siemens Medical Solutions USA, Inc., Deerfield, IL, USA) and FFA
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(Randox Laboratories Limited, West Virginia, USA) were analysed using commercial kits.
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Glycated hemoglobin was measured by HPLC-723G7, a fully automated high performance liquid
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chromatography instrument-reagent system (Tosoh Bioscience, King of Prussia, PA, USA).
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Statistical analysis All results are given as the mean ± SEM. The sample size calculation was based on a
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previous study in which 8 participants were sufficient to measure a significant difference (β=
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0.80) in plasma ketones after consuming 30 g of MCT oil (9) . We had n=9 for the present study
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in case of a dropout during one of the seven tests. All statistical analyses were carried out using
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SPSS 23.0 software (SPSS Inc., Chicago, IL, USA). Plasma ketone data are all reported in
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relation to Time 0 (baseline). When plasma ketones are given in the plural, this refers to the total
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of AcAc and β-HB combined. The second test dose was given 4 h after the first so the half-day
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periods are reported as 0-4 h and 4-8 h. For total ketones, the areas-under-the-curve (AUC) from
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0-4 h and 4-8 h were calculated according the trapezoid method (11). Since the data were not
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normally distributed (N
