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Capsaicin and evodiamine ingestion does not augment energy expenditure and fat oxidation at rest or after moderately-intense exercise Neil A. Schwarz, Mike Spillane, Paul La Bounty, Peter W. Grandjean, Brian Leutholtz, Darryn S. Willoughby⁎ Department of Health, Human Performance, and Recreation, Baylor University, Box 97313, Waco, TX 76798, USA
ARTI CLE I NFO
A BS TRACT
Article history:
Capsaicin and evodiamine are 2 thermogenic agents recognized for their ability to stimulate
Received 17 May 2013
the sympathetic nervous system. We hypothesized that both capsaicin and evodiamine
Revised 12 August 2013
would be effective at increasing thermogenesis and lipid oxidation during rest and exercise.
Accepted 13 August 2013
In a randomized, cross-over design, 11 men ingested 500 mg of cayenne pepper (1.25 mg capsaicin), 500 mg evodiamine, or placebo at rest following 30 minutes of energy
Keywords:
expenditure assessment using open-circuit spirometry. Energy expenditure was assessed
Thermogenesis
again prior to commencing approximately 30 minutes of treadmill exercise at 65% peak
Humans
oxygen consumption. Energy expenditure was assessed for another 30 minutes of the post-
Catecholamines
exercise period. Heart rate, blood pressure, core temperature, and venous blood samples
Fatty acids
were obtained 30 minutes before supplement ingestion, 1 hour after supplement ingestion,
Triglycerides
immediately post-exercise, and 45 minutes post-exercise. Serum markers of lipid oxidation
Capsaicin
(glycerol, free fatty acids, glucose, epinephrine, and norepinephrine) were determined
Energy expenditure
spectrophotometrically with enzyme-linked immunosorbent assay. Two-way analyses of
Evodiamine
variance with repeated measures were performed for each dependent variable (P ≤ .05) with Supplement and Test as main effects. Statistical analyses revealed significant main effects for Test for hemodynamics, energy expenditure, serum catecholamines, and markers of fat oxidation immediately post-exercise (P < .05). No significant interactions between Supplement and Test were noted for any criterion variable (P > .05). These results suggest that acute ingestion of 500 mg of cayenne (1.25 mg capsaicin) or evodiamine is not effective at inducing thermogenesis and increasing fat oxidation at rest or during exercise in men. © 2013 Elsevier Inc. All rights reserved.
1.
Introduction
Dietary weight loss supplements are growing in popularity as a means to enhance weight loss efforts in the United States.
The majority of these products supposedly contain special agents that possess thermogenic capabilities which are alleged to increase the body’s metabolism. Capsaicin and evodiamine are herbal compounds that can be found in a
Abbreviations: 45PE, 45 minutes post-exercise; ATP, adenosine tri-phosphate; FFA, free fatty acids; GERD, gastroesophageal reflux disease; IPE, immediate post-exercise; PE, pre-exercise; PS, pre-supplement; REE, resting energy expenditure; RER, respiratory exchange ratio; TRPV1, transient receptor potential channel vanilloid subfamily member 1; VO2peak, peak oxygen consumption. ⁎ Corresponding author. Department of Health, Human Performance, and Recreation, Baylor University, 1312 South 5th Street, Waco, TX 76798. Tel.: +1 254 710 3504; fax: +1 254 710 3527. E-mail address: [email protected] (D.S. Willoughby). 0271-5317/$ – see front matter © 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.nutres.2013.08.007
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number of over-the-counter weight loss products due to their potential capabilities of increasing metabolic activity. Capsaicin (Capsicum frutescens), which is the active, pungent component of chili peppers, works to speed up the body’s metabolism by provoking the activity of the sympathetic nervous system [1]. Capsaicin is considered to be a vanilloid receptor agonist, specifically of transient receptor potential channel vanilloid subfamily member 1 (TRPV1) [2,3]. The TRPV1 is a receptor located on primary sensory neurons, and is activated by various ligands as well as natural irritants [3,4]. Activation of TRPV1 by capsaicin ultimately leads to an increase in blood pressure, body temperature, and heart rate shortly after ingestion [5,6]. Additionally, ingestion of capsaicin stimulates sustained fat oxidation for adults after weight loss when compared to a placebo group [7]. Energy expenditure has also been observed to rise above basal after acute ingestion of capsaicin in multiple studies [7-11]; however, this is not a consistent finding [12-14]. In rats, capsaicin increases swimming endurance through the increase of fatty acid utilization due to enhanced adrenaline secretion caused by capsaicin [15]. Despite evidence implicating its possible effectiveness, the characteristic pungency of capsaicin may hinder its use as an anti-obesity agent in some individuals. Acute administration of capsaicin induces esophageal and gastric symptoms of heartburn in healthy individuals and gastroesophageal reflux disease (GERD) patients [16]. Acute capsaicin ingestion also hastens the time to peak heartburn symptoms and leads to greater acid reflux [17,18]. Chronic ingestion of chili peppers containing capsaicin induces GERD symptoms in otherwise healthy individuals suggesting the esophageal and gastric symptoms associated with acute capsaicin ingestion do not subside with chronic administration [19]. Furthering the problem is the positive association between obesity and the risk for GERD symptoms which may contraindicate use of capsaicin in this population [20,21]. Because of these observations, there has been an effort to identify non-pungent vanilloids capable of activating TRPV1. Evodiamine, regarded as a “hot nature” herb in Chinese medicine, is extracted from the fruit of Evodia rutaecarpa and has no perceptible taste or pungency [22]. Like capsaicin, evodiamine is a TRPV1 agonist with demonstrable antiobesity effects. In rats, evodiamine induced heat loss and heat production while also stimulating the utilization of stored food energy at a rate like that of capsaicin [22]. However, when evodia was ingested by women daily at 3 g (6.75 mg evodiamine) for 8 weeks consecutively, weight loss was not significantly more than attained with a placebo [23]. Since evodiamine has been demonstrated to be less potent than capsaicin [24], it is possible that the 6.75 mg dose of evodiamine provided in the previous study [23] was too low to elicit a thermogenic response. Although some research has been conducted in order to identify the effects of evodiamine, nothing has yet been empirically established. In fact, compared to the numerous experiments conducted to analyze the effects of capsaicin, research is limited. Non-pungent evodiamine may be a viable alternative to capsaicin, which is intolerable in some individuals, for inducing lipid oxidation and thermogenesis via TRPV1 stimulation. Most data available for capsaicin and evodiamine
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with regard to weight loss and thermogenesis have been exclusively focused on long-term use with little data available regarding the acute effects of ingesting these herbs. Many, but not all, studies of capsaicin employ doses that may not be realistic due to its pungency. However, because evodiamine has no pungency associated with its ingestion, high doses of this extract may be tolerated well. The purpose of this study was to investigate the effects a single 500 mg dose of cayenne (equivalent to 1.25 mg of capsaicin) and a single dose of 500 mg of evodiamine (100% pure evodiamine extract) had on hemodynamics, energy expenditure, and lipid oxidation at rest and after moderateintensity exercise. We hypothesized that both supplements would acutely increase thermogenesis and lipid oxidation during rest and exercise, and that supplementation with evodiamine would lead to effects equal to or greater than those observed with capsaicin because of the higher dose administered. To test this hypothesis, hemodynamics, energy expenditure, and serum markers of lipid oxidation (glucose, triglycerides, free fatty acids, and glycerol) were measured at rest, 30 minutes after supplement ingestion, and after a single bout of moderate-intensity exercise equivalent to an energy expenditure of 500 kilocalories. This approach was based on the premise that after ingesting the supplement, hemodynamics, energy expenditure, and lipid oxidation may be affected compared to before ingesting the supplement and that an additive effect of supplementation with exercise may exist.
2.
Methods and materials
2.1.
Experimental approach
In a randomized, uniform-balanced, cross-over design, participants performed 3 separate testing sessions involving a resting and endurance exercise component after ingesting 500 mg of either placebo, cayenne pepper (1.25 mg capsaicin), or evodiamine. The mean (SD) duration between each testing session was 13 ± 7 days (Fig.).
2.2.
Participants
Eleven apparently healthy and active men between the ages of 18 to 30 years participated in the double-blind study. Enrollment was open to men of all ethnicities. Only participants who were considered as low to moderate risk for cardiovascular disease and had no contraindications to exercise as outlined by the American College of Sports Medicine, who had not consumed any nutritional supplements other than vitamins, and who had never been involved in any weight loss regimen in the last 6 months were allowed to participate. There were no exclusionary criteria regarding exercise habits or body weight. All eligible participants were cleared for participation by passing a mandatory medical screening and provided written informed consent by signing university-approved informed consent documents and approval was granted by the Institutional Review Board for Human Subjects. Additionally, all experimental procedures involved in the study conformed to the ethical consideration of the Helsinki Code.
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Fig. – An illustration of the experimental protocol for each of the 3 testing sessions.
2.3. Baseline assessments of body composition and peak oxygen consumption Total body mass (kg) was determined on a standard dual beam balance scale (Detecto, Webb City, MO, USA). Percent body fat, fat mass, and fat-free mass, were determined using dualenergy x-ray absorptiometry (Hologic Discovery Series W, Waltham, MA, USA) based on our previous guidelines [25]. Baseline hemodynamic measurements at rest were completed. Heart rate was determined by palpation of the radial artery for 15 seconds using standard procedures. Blood pressure was assessed in the supine position after resting for 5 minutes by manual auscultation of the brachial artery using a stethoscope and mercurial sphygmomanometer. Participants then performed a graded exercise test on a treadmill ergometer (Quinton, Seattle, WA, USA) employing the Bruce protocol [26] to determine peak oxygen consumption (VO2peak). Oxygen consumption was measured every 15 seconds via an opencircuit sampling system (Parvo Medics, Provo, UT, USA).
2.4.
Core body temperature
On the evening before each of the three testing sessions, participants ingested a silicon-coated pill (CorTemp, HQ Inc, Palmetto, FL, USA). This pill is a sensor that is commonly used to monitor core body temperature in laboratory and field settings [27-31]. This pill was used as the sensor for determining core temperatures during each of the 3 testing sessions. The sensor is designed to be ingested easily and voided with normal bowel movements within 48 hours [27,32].
2.5.
Supplementation protocol
Participants orally ingested one capsule (500 mg) of a supplement containing either cellulose placebo (Nutricology, Alameda, CA, USA), cayenne pepper (40,000 heat units, 1.25 mg capsaicin [Nutrition for Optimal Wellness, Bloomingdale, IL, USA]), or evodiamine (Vital Pharmaceuticals, Weston, FL, USA). Both the researchers and participants were blinded to the supplement being administered. The capsules from each of the three supplements were identical in size, shape, color, and texture. An individual not connected to the study was responsible for coding the supplements, and the coding was revealed after analysis of all samples. Studies with evodiamine supplementation in humans are scarce and, as a result,
there appears to be no recommended dose. A dose of 500 mg for evodiamine, approximately 74 times the dose used by Kim et al [23] in their study (6.75 mg evodiamine), was decided upon based on pilot testing in our lab. The dose of capsaicin (500 mg cayenne pepper, 1.25 mg capsaicin) was based on the manufacturer’s recommended dose and was considered to be representative of a realistic dose for chronic ingestion.
2.6.
Testing protocol
In a randomized, cross-over fashion, participants participated in 3 separate testing sessions. An illustration of the testing protocol can be seen in Fig. At each session, participants reported to the laboratory after an 8-hour fast. After baseline heart rate, blood pressure, and core body temperature were determined, a blood sample was obtained from the antecubital vein. Participants then underwent a 30-minute presupplement, rest period in which their energy expenditure was determined by way of open-circuit spirometry using the Parvo Medics 2400 TrueMax Metabolic Measurement System (Sandy, UT, USA), based on our previous guidelines [33]. This time point was defined as pre-supplement (PS). At the end of this period, participants ingested the supplement and relaxed for thirty minutes to allow time for absorption. Thirty minutes after supplement ingestion, participants then underwent a second 30-minute post-supplement rest period in which energy expenditure continued to be assessed. At the end of this time, heart rate, blood pressure, core body temperature, and blood was obtained immediately prior to participants engaging in a bout of aerobic exercise. This time point was defined as pre-exercise (PE). Next for the exercise portion of the study, participants performed a standardized five-minute warm-up on the treadmill at 2 mph and 2% grade, then speed and grade were adjusted to elicit the appropriate intensity for each condition (determined from the maximal graded exercise test completed during the baseline assessments). Heart rate and respiratory gas analysis values were checked at five minute intervals throughout the exercise session to verify intensity (65% of their VO2peak) and estimate energy expenditure. If necessary, the treadmill speed and grade was adjusted throughout the exercise session to maintain the appropriate intensity. Based on a previous study [34], the exercise bout was standardized to an energy expenditure of 500 kilocalories. Caloric expenditure was estimated by multiplying a standard caloric equivalent of 5 kcal/L of oxygen consumed by the
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corresponding absolute rate of oxygen consumption (L/min). Exercise duration was determined by dividing 500 kcal by the estimated rate of caloric expenditure, and the exercise bout terminated upon each participant expending 500 kcal. Heart rate, blood pressure, core body temperature, and blood samples were obtained immediately following exercise. This time point was defined as immediate post-exercise (IPE). Following sample collection, participants rested for 30 minutes while continuing to have their resting energy expenditure assessed. At the end of the post-exercise energy expenditure assessment, heart rate, blood pressure, core body temperature, and blood samples were obtained. This time point was defined as 45 minutes post-exercise (45PE). Additionally, at the conclusion of each testing session, participants completed a supplement side-effect questionnaire, and were told to report any possible side effects from supplementation.
2.7. Assessment of serum glycerol, fatty acids, triglycerides, and catecholamines Serum glycerol and fatty acid content was determined spectrophotometrically using the free glycerol determination kit (Sigma Aldrich, St. Louis, MO, USA) and glycerol standard (Sigma Aldrich, St. Louis, MO) at a wavelength of 490 nm. Serum free fatty acids (#K612-100, Bio Vision, Mountain View, CA, USA) and triglycerides (#K622-100, Biovision, Mountain View, CA, USA) were determined spectrophotometrically at a wavelength of 570 nm against known standard curves. Serum epinephrine and norepinephrine were determined with enzyme immunoassay (#17-BCTHU-E02, Alpco, Salem, NH) performed at 450 nm wavelength against known standard curves. All assays were performed in duplicate with a microplate reader (xMark, Bio-Rad, Hercules, CA, USA) and data analysis was performed using microplate data-reduction software (Microplate Manager, Bio-Rad, Hercules, CA, USA). These procedures are similar to those employed in previous studies [35,36].
2.8.
Dietary analysis
Participants were required to record their dietary intake for three consecutive days leading up to each of the three testing sessions. The participants’ diets were not standardized and they were asked not to change their dietary habits during the course of the study. The three-day dietary records were evaluated with the Food Processor dietary assessment software program (ESHA Research, Ogden, UT, USA) to determine the average daily macronutrient consumption of fat, carbohydrate, and protein in the diet for the duration of the study.
2.9.
Statistical analyses
Statistical analyses were performed by utilizing separate 3 × 4 (Supplement × Test) factorial analyses of variance (ANOVA) with repeated measures for each criterion variable. Significant between-group differences were determined involving the Tukey post hoc test. However, to protect against type I error, the conservative Hunyh-Feldt Epsilon correction factor was used to evaluate observed within-group F-ratios. All statistical
procedures were performed using SPSS 19.0 software and a probability level of P < .05 was adopted throughout.
3.
Results
3.1.
Baseline entry data
Table 1 presents baseline entry data for participants. A total of 11 (10 white, non-Hispanic; 1 Asian) active, apparently healthy men participated in this study.
3.2. Dietary intake, exercise duration, and supplement side-effects Dietary intake was calculated from the dietary recalls performed three days prior to each exercise session. No significant differences were detected between testing sessions for total calories and grams of carbohydrates, fats, and protein (Table 2). The mean (SD) duration for all 3 exercise sessions was 42.58 ±5.20 minutes, with no significant difference between sessions (P > .05). No side effects were reported for placebo, capsaicin, or evodiamine.
3.3.
Hemodynamics and core body temperature
There were significant main effects for Test as a result of exercise intervention for heart rate (P < .001), systolic blood pressure (P < .001), and core temperature (P < .001), but not diastolic blood pressure. Post hoc analysis indicated that heart rate was significantly greater at IPE and 45PE compared to PS and PE as seen in Table 3. Furthermore, systolic blood pressure was significantly greater at PE and IPE compared to PS. Core body temperature was significantly greater at IPE compared to PS, PE, and 45PE. No significant main effects existed for Supplement for heart rate, systolic blood pressure, diastolic blood pressure, and core temperature. Additionally, there were no significant interactions between Supplement and Test for heart rate, systolic blood pressure, diastolic blood pressure, or core temperature indicating there to be no significant differences between the three supplements for each test (Table 3).
Table 1 – Descriptive data for baseline participant entry variables Age (y) Height (cm) Body weight (kg) Body mass index (kg/m2) Heart Rate (bpm) Systolic blood pressure (mmHg) Diastolic blood pressure (mmHg) Peak VO2 max (mL/kg per minute) Max RER (VO2/O2) Body fat (%) Lean mass (kg) Fat mass (kg) Values are means ± SD (n = 11).
20 ± 2 179 88.3 27.1 61 114.7 70.0 49.5 1.26 19.4 61.3 17.3
± ± ± ± ± ± ± ± ± ± ±
6 22.6 5.7 10 7.6 7.5 10.4 0.03 8.9 9.6 12.7
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Table 2 – Dietary variables determined three days prior to each supplement session Variable
Placebo
Total calories (kcal/d) Carbohydrates (g/d) Fats (g/d) Protein (g/d)
2149.9 295.7 82.5 82.5
± ± ± ±
743.0 110.5 36.6 8.6
Evodiamine 2549.2 ± 320.2 ± 99.4 ± 95.8 ±
Capsaicin
891.5 132.6 35.7 32.4
2361.1 295.1 91.1 91.8
± ± ± ±
Supplement (P < .05)
711.7 95.0 36.1 27.8
0.500 0.841 0.555 0.531
Values are means ± SD (n = 11). Values were analyzed by two-way ANOVA with repeated measures.
3.4. Respiratory exchange ratio and resting energy expenditure There were significant main effects for Test as a result of exercise intervention for respiratory exchange ratio (RER; P < .001) and resting energy expenditure (REE; p = .001). Post-hoc analysis indicated that RER was significantly greater at IPE compared to PE, PS, and 45PE. In addition, PE was greater than 45PE. For REE, 45PE was greater than PE and PS. No significant main effects existed for Supplement for RER or REE. There were no significant interactions between Supplement and Test for RER or REE indicating there to be no significant differences between the three supplements for each test (Table 4).
3.5. Serum glucose, triglycerides, glycerol, and free fatty acid levels While statistical analyses revealed no significant main effects for Test for glucose and triglycerides, analyses did demonstrate there to be significant main effects for Test as a result of exercise for free fatty acids (p= .001) and glycerol (P < .001). Post hoc analysis indicated that free fatty acids were significantly greater at PE, IPE, and 45PE compared to PS. Glycerol was also significantly greater PE, IPE, and 45PE compared to PS, and was also greater at IPE compared to PE. No significant main effects existed for Supplement for glucose, triglycerides, free fatty
acids, or glycerol. Results demonstrated no significant interactions between Supplement and Test for glucose, triglycerides, free fatty acids, or glycerol indicating there to be no significant differences between the three supplements for each test (Table 5).
3.6.
Serum epinephrine and norepinephrine
For epinephrine (P < .001) and norepinephrine (P < .001), there were significant main effects for Test resulting from the exercise intervention. Post hoc analysis indicated that epinephrine was significantly greater at IPE and 45PE compared to PS and PE. In addition, epinephrine at IPE was greater than 45PE. For norepinephrine, PE, IPE, and 45PE were significantly greater than PS. At IPE, norepinephrine was also greater than 45PE. No significant main effects for Supplement for epinephrine or norepinephrine were observed. There were no significant interactions between Supplement and Test for epinephrine or norepinephrine indicating there to be no significant differences between the three supplements for each test (Table 6).
4.
Discussion
The purpose of this study was to observe the effects that capsaicin and evodiamine had on hemodynamics, energy
Table 3 – Hemodynamics and core body temperature at each test point for the three supplement sessions Supplement
Placebo Evodiamine Capsaicin Placebo Evodiamine Capsaicin Placebo Evodiamine Capsaicin Placebo Evodiamine Capsaicin
PS
PE
Heart rate (bpm) 56.6 ± 6.7 50.6 ± 4.1 54.9 ± 5.1 53.7 ± 6.5 52.6 ± 4.3 53.1 ± 6.0 Systolic blood pressure (mmHg) 109.4 ± 8.1 112.0 ± 7.7 106.3 ± 10.2 111.1 ± 8.8 112.1 ± 8.0 115.1 ± 9.3 Diastolic blood pressure (mmHg) 69.1 ± 10.1 70.0 ± 7.8 70.0 ± 7.3 74.0 ± 6.6 69.1 ± 8.9 74.0 ± 6.3 Core body temperature (°C) 36.79 ± 0.30 36.51 ± 0.26 36.74 ± 0.34 36.51 ± 0.16 36.86 ± 0.39 36.56 ± 0.22
IPE
45PE
171.7 ± 11.7 168.71 ± 7.8 170.0 ± 5.5
82.3 ± 12.4 78.3 ± 13.4 77.4 ± 14.2
128.9 ± 12.6 129.4 ± 12.1 124.6 ± 6.9
109.7 ± 9.2 109.4 ± 10.9 105.7 ± 18.8
70.6 ± 8.6 71.1 ± 6.1 68.3 ± 7.6
68.6 ± 8.5 69.7 ± 7.4 67.7 ± 7.7
38.11 ± 0.55 38.03 ± 0.34 38.11 ± 0.55
36.92 ± 0.22 36.95 ± 0.22 37.03 ± 0.55
Supplement (P < .05)
Test (P .05)
Supplement × test (P < .05)
.952
< .001 a
.975
.889
< .001 b
.904
.316
.130
.901
.481
< .001 c
.994
Values are means ± SD (n = 11). Values were analyzed by two-way ANOVA with repeated measures and Tukey post hoc test. a IPE > PS; 45PE > PS; IPE > PE; IPE > 45PE. b PE > PS; IPE > PS; IPE > PE; PE > 45PE. c IPE > PS; IPE > PE; IPE > 45PE.
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Table 4 – Respiratory exchange ratio and resting energy expenditure at each test point for the three supplement sessions Supplement
Placebo Evodiamine Capsaicin Placebo Evodiamine Capsaicin
PS
PE
IPE c
Respiratory exchange ratio (VCO2/VO2) 0.79 ± 0.05 0.80 ± 0.04 0.90 ± 0.03 0.79 ± 0.04 0.79 ± 0.04 0.91 ± 0.01 0.80 ± 0.04 0.79 ± 0.04 0.90 ± 0.02 Resting energy expenditure (kcal/d) 1859.6 ± 261.8 1856.3 ± 260.5 1822.8 ± 281.5 1823.0 ± 253.1 1781.9 ± 306.5 1832.8 ± 298.9 -
45PE
Supplement (P < .05)
Test (P < .05)
Supplement × Test (P < .05)
.909
< .001 a
.663
.970
.001 b
.966
0.75 ± 0.06 0.76 ± 0.05 0.75 ± 0.07 2049.7 ± 324.0 2070.5 ± 299.5 2105.6 ± 404.0
Values are means ± SD (n = 11). Values were analyzed by two-way ANOVA with repeated measures and Tukey post hoc test. a IPE > PS; IPE > PE; IPE > 45PE; PE > 45PE. b 45PE > PS; 45PE > PE. c No resting energy expenditure measurement for this time point.
expenditure, and markers of lipid oxidation while at rest and after a single bout of moderate-intensity exercise. We observed an increase in all variables due to exercise intervention; however, our hypothesis was not supported. At the dose ingested, no significant differences were observed between supplements and placebo-control conditions indicating them to be ineffective at acutely increasing energy expenditure and lipid oxidation during rest and after a single bout of moderateintensity aerobic exercise. Aerobic exercise is a valuable tool to reduce obesity and retain lean mass, especially when combined with a calorierestricted diet [37]. Aerobic exercise increases adenosine triphosphate (ATP) production in order to meet the energy needs associated with increased cardiac and skeletal muscle contraction rate and force [38]. In order to reach the goal of increased ATP synthesis, exercise-onset withdrawal of the parasympathetic nervous system along with stimulation of the sympathetic nervous system is necessary [39]. Activation of the sympathetic nervous system plays an important role in the increase of hemodynamics and fuel utilization via the
release of catecholamines from the sympathetic nerve endings and adrenal medulla during exercise [40]. Norepinephrine increases heart rate, and subsequently blood pressure, to assist in the delivery of oxygen and fuel substrate needed by muscle tissue for the increased rate of ATP synthesis. Epinephrine strongly enhances the rate of glycogenolysis and of lipolysis and appearance of free fatty acids (FFA) in the blood stream via activation of β-adrenergic receptors in muscle and adipose tissue, respectively [40,41]. Additionally, due to the inefficiency of humans to produce and harness ATP energy, only about 25% of energy found in fuel substrates is used to form ATP and the rest is lost as heat, thus increasing core body temperature [42]. Catecholamine levels remain elevated for a period of time following exercise further increasing metabolic rate into the postexercise period [41]. In the current study, an aerobic exercise workload of 500 kcal increased catecholamine levels substantially, and they remain elevated at the 45PE test point. Accordingly, heart rate and systolic blood pressure were significantly increased IPE
Table 5 – Serum levels of markers of lipid oxidation at each test point for the 3 supplement sessions Variable
Placebo Evodiamine Capsaicin Placebo Evodiamine Capsaicin Placebo Evodiamine Capsaicin Placebo Evodiamine Capsaicin
PS
PE
Glucose (mg/dL) 82.0 ± 27.2 88.1 ± 86.7 ± 19.5 87.1 ± 90.9 ± 21.4 94.8 ± Triglycerides (mg/dL) 49.9 ± 43.9 38.0 ± 40.8 ± 22.9 43.6 ± 50.4 ± 41.7 54.2 ± Free Fatty Acids (nmol) 0.15 ± 0.13 0.26 ± 0.19 ± 0.16 0.25 ± 0.11 ± 0.06 0.21 ± Glycerol (μg/mL) 8.7 ± 5.2 11.5 ± 8.4 ± 4.1 12.2 ± 7.1 ± 4.7 12.4 ±
IPE
45PE
21.2 17.6 26.5
92.5 ± 20.3 98.1 ± 35.7 94.7 ± 33.7
93.3 ± 16.8 83.6 ± 21.5 92.3 ± 23.4
23.2 35.9 49.8
59.4 ± 39.0 61.4 ± 45.2 64.6 ± 52.5
50.6 ± 31.5 51.6 ± 29.2 41.1 ± 35.7
0.26 0.17 0.12
0.41 ± 0.19 0.27 ± 0.12 0.31 ± 0.19
0.25 ± 0.20 0.25 ± 0.20 0.24 ± 0.19
6.5 8.4 8.1
16.5 ± 6.9 20.6 ± 10.3 17.7 ± 6.0
12.2 ± 4.8 13.3 ± 7.6 16.9 ± 6.5
Supplement (P < .05)
Test (P < .05)
Supplement × Test (P < .05)
.640
.555
.933
.944
.586
.776
.403
.001 a
.735
.572
< .001 b
.646
Values are means ± SD (n = 11). Values were analyzed by two-way ANOVA with repeated measures and Tukey post hoc test. a PE > PS; IPE > PS; 45PE > PS. b PE > PS; IPE > PS; 45PE > PS; IPE > PE.
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Table 6 – Serum levels of epinephrine and norepinephrine at each test point for the three supplement sessions Variable
Placebo Evodiamine Capsaicin Placebo Evodiamine Capsaicin
PS
PE
Epinephrine (ng/mL) 305.76 ± 359.97 540.06 332.50 ± 198.80 360.00 416.56 ± 288.64 400.26 Norepinephrine (ng/mL) 156.48 ± 97.08 246.63 112.97 ± 65.56 226.02 164.22 ± 113.22 259.86
± 700.74 ± 275.51 ± 307.67 ± 135.52 ± 77.87 ± 196.84
IPE
1606.30 ± 1639.37 1424.10 ± 977.24 1017.00 ± 829.69 283.01 ± 135.82 273.52 ± 81.62 317.81 ± 267.11
45PE
Supplement (P < .05)
Test (P < .05)
Supplement × Test (P < .05)
.470
< .001 a
0.848
.678
< .001 b
.981
848.91 ± 750.89 736.50 ± 424.71 661.07 ± 666.08 198.06 ± 96.72 207.48 ± 92.55 184.60 ± 131.70
Values are means ± SD (n = 11). Values were analyzed by two-way ANOVA with repeated measures and Tukey post hoc test. a IPE > PS; 45PE > PS; IPE > PE; 45PE > PE; IPE > 45PE. b PE > PS; IPE > PS; 45PE > PS; IPE > 45PE.
with heart rate staying elevated at 45PE. Systolic blood pressure returned to below resting levels at 45PE, as expected. Diastolic pressure remained relatively consistent throughout. Serum FFA and glycerol levels rose after supplement ingestion along with norepinephrine; however, no difference was seen between capsaicin, evodiamine, and placebo. Serum FFA and glycerol concentrations rose even more as a result of the exercise session; although, only significantly more than observed PE for glycerol. Serum FFA and glycerol levels remained elevated above baseline at 45PE, yet not at a higher concentration than observed PE. As expected, RER increased significantly during the exercise testing session as a result of increased glucose utilization with values returning to significantly below baseline at 45PE. Energy expenditure was also significantly increased at 45PE. Taken together, increased energy expenditure with a reduced RER and FFA serum concentration suggests an increase in FFA uptake and utilization for ATP production at 45PE. Core temperature was significantly higher IPE returning to baseline by the 45PE test. Our study investigated whether TRPV1 agonists, capsaicin and evodiamine, could augment the effect of exercise on hemodynamics and lipid oxidation. As noted, no significant differences were observed between capsaicin, evodiamine, and placebo for any test point. Since capsaicin may have undesirable side effects, our goal was to determine if capsaicin could induce acute alterations in metabolic activity at a low dose that may be well-tolerated by individuals for a prolonged period of time. Our results indicated that 1.25 mg of capsaicin was insufficient to induce acute changes in the variables of hemodynamics, energy expenditure, and lipid oxidation measured. Furthermore, capsaicin did not augment the metabolic shift associated with aerobic exercise. Our results are consistent with a recent meta-analysis which revealed that doses below 7 mg of capsaicin are ineffective at increasing energy expenditure and lipid oxidation. However, results of one previous study suggest that delivery method of capsaicin may be important [36], as this study demonstrated that a dose of 2 mg of capsaicinoids, when delivered as encapsulated beadlets, was more effective than a placebo at increasing blood FFA and glycerol concentration. Evodiamine is a TRPV1 agonist purported to have similar anti-obesity properties as capsaicin. Evodiamine is an attractive anti-obesity agent because it does not possess the
pungent quality associated with capsaicin which may allow for the use of much higher dosages [22]. Although shown to be a successful therapy for lipid oxidation in rodents [22], Kim et al. [23] demonstrated that daily ingestion of 6.75 mg of evodiamine for 8 weeks did not induce weight loss or increase resting metabolic rate in a group of premenopausal women when compared to placebo ingestion. Evodiamine has been demonstrated to be 3-fold and 19-fold weaker for binding to the TRPV1 receptor and for induction of calcium uptake, respectively, than that of capsaicin [24]. Therefore, it is conceivable that a much higher dose than 6.75 mg of evodiamine is needed in order to elicit an anti-obesity effect. In agreement with this hypothesis are the findings, including those of the current study, that the more-potent capsaicin is not effective at increasing energy expenditure or lipid oxidation when used at dosages similar to (
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Capsaicin and evodiamine ingestion does not augment energy expenditure and fat oxidation at rest or after moderately-intense exercise Neil A. Schwarz, Mike Spillane, Paul La Bounty, Peter W. Grandjean, Brian Leutholtz, Darryn S. Willoughby⁎ Department of Health, Human Performance, and Recreation, Baylor University, Box 97313, Waco, TX 76798, USA
ARTI CLE I NFO
A BS TRACT
Article history:
Capsaicin and evodiamine are 2 thermogenic agents recognized for their ability to stimulate
Received 17 May 2013
the sympathetic nervous system. We hypothesized that both capsaicin and evodiamine
Revised 12 August 2013
would be effective at increasing thermogenesis and lipid oxidation during rest and exercise.
Accepted 13 August 2013
In a randomized, cross-over design, 11 men ingested 500 mg of cayenne pepper (1.25 mg capsaicin), 500 mg evodiamine, or placebo at rest following 30 minutes of energy
Keywords:
expenditure assessment using open-circuit spirometry. Energy expenditure was assessed
Thermogenesis
again prior to commencing approximately 30 minutes of treadmill exercise at 65% peak
Humans
oxygen consumption. Energy expenditure was assessed for another 30 minutes of the post-
Catecholamines
exercise period. Heart rate, blood pressure, core temperature, and venous blood samples
Fatty acids
were obtained 30 minutes before supplement ingestion, 1 hour after supplement ingestion,
Triglycerides
immediately post-exercise, and 45 minutes post-exercise. Serum markers of lipid oxidation
Capsaicin
(glycerol, free fatty acids, glucose, epinephrine, and norepinephrine) were determined
Energy expenditure
spectrophotometrically with enzyme-linked immunosorbent assay. Two-way analyses of
Evodiamine
variance with repeated measures were performed for each dependent variable (P ≤ .05) with Supplement and Test as main effects. Statistical analyses revealed significant main effects for Test for hemodynamics, energy expenditure, serum catecholamines, and markers of fat oxidation immediately post-exercise (P < .05). No significant interactions between Supplement and Test were noted for any criterion variable (P > .05). These results suggest that acute ingestion of 500 mg of cayenne (1.25 mg capsaicin) or evodiamine is not effective at inducing thermogenesis and increasing fat oxidation at rest or during exercise in men. © 2013 Elsevier Inc. All rights reserved.
1.
Introduction
Dietary weight loss supplements are growing in popularity as a means to enhance weight loss efforts in the United States.
The majority of these products supposedly contain special agents that possess thermogenic capabilities which are alleged to increase the body’s metabolism. Capsaicin and evodiamine are herbal compounds that can be found in a
Abbreviations: 45PE, 45 minutes post-exercise; ATP, adenosine tri-phosphate; FFA, free fatty acids; GERD, gastroesophageal reflux disease; IPE, immediate post-exercise; PE, pre-exercise; PS, pre-supplement; REE, resting energy expenditure; RER, respiratory exchange ratio; TRPV1, transient receptor potential channel vanilloid subfamily member 1; VO2peak, peak oxygen consumption. ⁎ Corresponding author. Department of Health, Human Performance, and Recreation, Baylor University, 1312 South 5th Street, Waco, TX 76798. Tel.: +1 254 710 3504; fax: +1 254 710 3527. E-mail address: [email protected] (D.S. Willoughby). 0271-5317/$ – see front matter © 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.nutres.2013.08.007
N U T RI TI O N R ES E A RC H 3 3 (2 0 1 3) 1 03 4–1 0 42
number of over-the-counter weight loss products due to their potential capabilities of increasing metabolic activity. Capsaicin (Capsicum frutescens), which is the active, pungent component of chili peppers, works to speed up the body’s metabolism by provoking the activity of the sympathetic nervous system [1]. Capsaicin is considered to be a vanilloid receptor agonist, specifically of transient receptor potential channel vanilloid subfamily member 1 (TRPV1) [2,3]. The TRPV1 is a receptor located on primary sensory neurons, and is activated by various ligands as well as natural irritants [3,4]. Activation of TRPV1 by capsaicin ultimately leads to an increase in blood pressure, body temperature, and heart rate shortly after ingestion [5,6]. Additionally, ingestion of capsaicin stimulates sustained fat oxidation for adults after weight loss when compared to a placebo group [7]. Energy expenditure has also been observed to rise above basal after acute ingestion of capsaicin in multiple studies [7-11]; however, this is not a consistent finding [12-14]. In rats, capsaicin increases swimming endurance through the increase of fatty acid utilization due to enhanced adrenaline secretion caused by capsaicin [15]. Despite evidence implicating its possible effectiveness, the characteristic pungency of capsaicin may hinder its use as an anti-obesity agent in some individuals. Acute administration of capsaicin induces esophageal and gastric symptoms of heartburn in healthy individuals and gastroesophageal reflux disease (GERD) patients [16]. Acute capsaicin ingestion also hastens the time to peak heartburn symptoms and leads to greater acid reflux [17,18]. Chronic ingestion of chili peppers containing capsaicin induces GERD symptoms in otherwise healthy individuals suggesting the esophageal and gastric symptoms associated with acute capsaicin ingestion do not subside with chronic administration [19]. Furthering the problem is the positive association between obesity and the risk for GERD symptoms which may contraindicate use of capsaicin in this population [20,21]. Because of these observations, there has been an effort to identify non-pungent vanilloids capable of activating TRPV1. Evodiamine, regarded as a “hot nature” herb in Chinese medicine, is extracted from the fruit of Evodia rutaecarpa and has no perceptible taste or pungency [22]. Like capsaicin, evodiamine is a TRPV1 agonist with demonstrable antiobesity effects. In rats, evodiamine induced heat loss and heat production while also stimulating the utilization of stored food energy at a rate like that of capsaicin [22]. However, when evodia was ingested by women daily at 3 g (6.75 mg evodiamine) for 8 weeks consecutively, weight loss was not significantly more than attained with a placebo [23]. Since evodiamine has been demonstrated to be less potent than capsaicin [24], it is possible that the 6.75 mg dose of evodiamine provided in the previous study [23] was too low to elicit a thermogenic response. Although some research has been conducted in order to identify the effects of evodiamine, nothing has yet been empirically established. In fact, compared to the numerous experiments conducted to analyze the effects of capsaicin, research is limited. Non-pungent evodiamine may be a viable alternative to capsaicin, which is intolerable in some individuals, for inducing lipid oxidation and thermogenesis via TRPV1 stimulation. Most data available for capsaicin and evodiamine
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with regard to weight loss and thermogenesis have been exclusively focused on long-term use with little data available regarding the acute effects of ingesting these herbs. Many, but not all, studies of capsaicin employ doses that may not be realistic due to its pungency. However, because evodiamine has no pungency associated with its ingestion, high doses of this extract may be tolerated well. The purpose of this study was to investigate the effects a single 500 mg dose of cayenne (equivalent to 1.25 mg of capsaicin) and a single dose of 500 mg of evodiamine (100% pure evodiamine extract) had on hemodynamics, energy expenditure, and lipid oxidation at rest and after moderateintensity exercise. We hypothesized that both supplements would acutely increase thermogenesis and lipid oxidation during rest and exercise, and that supplementation with evodiamine would lead to effects equal to or greater than those observed with capsaicin because of the higher dose administered. To test this hypothesis, hemodynamics, energy expenditure, and serum markers of lipid oxidation (glucose, triglycerides, free fatty acids, and glycerol) were measured at rest, 30 minutes after supplement ingestion, and after a single bout of moderate-intensity exercise equivalent to an energy expenditure of 500 kilocalories. This approach was based on the premise that after ingesting the supplement, hemodynamics, energy expenditure, and lipid oxidation may be affected compared to before ingesting the supplement and that an additive effect of supplementation with exercise may exist.
2.
Methods and materials
2.1.
Experimental approach
In a randomized, uniform-balanced, cross-over design, participants performed 3 separate testing sessions involving a resting and endurance exercise component after ingesting 500 mg of either placebo, cayenne pepper (1.25 mg capsaicin), or evodiamine. The mean (SD) duration between each testing session was 13 ± 7 days (Fig.).
2.2.
Participants
Eleven apparently healthy and active men between the ages of 18 to 30 years participated in the double-blind study. Enrollment was open to men of all ethnicities. Only participants who were considered as low to moderate risk for cardiovascular disease and had no contraindications to exercise as outlined by the American College of Sports Medicine, who had not consumed any nutritional supplements other than vitamins, and who had never been involved in any weight loss regimen in the last 6 months were allowed to participate. There were no exclusionary criteria regarding exercise habits or body weight. All eligible participants were cleared for participation by passing a mandatory medical screening and provided written informed consent by signing university-approved informed consent documents and approval was granted by the Institutional Review Board for Human Subjects. Additionally, all experimental procedures involved in the study conformed to the ethical consideration of the Helsinki Code.
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Fig. – An illustration of the experimental protocol for each of the 3 testing sessions.
2.3. Baseline assessments of body composition and peak oxygen consumption Total body mass (kg) was determined on a standard dual beam balance scale (Detecto, Webb City, MO, USA). Percent body fat, fat mass, and fat-free mass, were determined using dualenergy x-ray absorptiometry (Hologic Discovery Series W, Waltham, MA, USA) based on our previous guidelines [25]. Baseline hemodynamic measurements at rest were completed. Heart rate was determined by palpation of the radial artery for 15 seconds using standard procedures. Blood pressure was assessed in the supine position after resting for 5 minutes by manual auscultation of the brachial artery using a stethoscope and mercurial sphygmomanometer. Participants then performed a graded exercise test on a treadmill ergometer (Quinton, Seattle, WA, USA) employing the Bruce protocol [26] to determine peak oxygen consumption (VO2peak). Oxygen consumption was measured every 15 seconds via an opencircuit sampling system (Parvo Medics, Provo, UT, USA).
2.4.
Core body temperature
On the evening before each of the three testing sessions, participants ingested a silicon-coated pill (CorTemp, HQ Inc, Palmetto, FL, USA). This pill is a sensor that is commonly used to monitor core body temperature in laboratory and field settings [27-31]. This pill was used as the sensor for determining core temperatures during each of the 3 testing sessions. The sensor is designed to be ingested easily and voided with normal bowel movements within 48 hours [27,32].
2.5.
Supplementation protocol
Participants orally ingested one capsule (500 mg) of a supplement containing either cellulose placebo (Nutricology, Alameda, CA, USA), cayenne pepper (40,000 heat units, 1.25 mg capsaicin [Nutrition for Optimal Wellness, Bloomingdale, IL, USA]), or evodiamine (Vital Pharmaceuticals, Weston, FL, USA). Both the researchers and participants were blinded to the supplement being administered. The capsules from each of the three supplements were identical in size, shape, color, and texture. An individual not connected to the study was responsible for coding the supplements, and the coding was revealed after analysis of all samples. Studies with evodiamine supplementation in humans are scarce and, as a result,
there appears to be no recommended dose. A dose of 500 mg for evodiamine, approximately 74 times the dose used by Kim et al [23] in their study (6.75 mg evodiamine), was decided upon based on pilot testing in our lab. The dose of capsaicin (500 mg cayenne pepper, 1.25 mg capsaicin) was based on the manufacturer’s recommended dose and was considered to be representative of a realistic dose for chronic ingestion.
2.6.
Testing protocol
In a randomized, cross-over fashion, participants participated in 3 separate testing sessions. An illustration of the testing protocol can be seen in Fig. At each session, participants reported to the laboratory after an 8-hour fast. After baseline heart rate, blood pressure, and core body temperature were determined, a blood sample was obtained from the antecubital vein. Participants then underwent a 30-minute presupplement, rest period in which their energy expenditure was determined by way of open-circuit spirometry using the Parvo Medics 2400 TrueMax Metabolic Measurement System (Sandy, UT, USA), based on our previous guidelines [33]. This time point was defined as pre-supplement (PS). At the end of this period, participants ingested the supplement and relaxed for thirty minutes to allow time for absorption. Thirty minutes after supplement ingestion, participants then underwent a second 30-minute post-supplement rest period in which energy expenditure continued to be assessed. At the end of this time, heart rate, blood pressure, core body temperature, and blood was obtained immediately prior to participants engaging in a bout of aerobic exercise. This time point was defined as pre-exercise (PE). Next for the exercise portion of the study, participants performed a standardized five-minute warm-up on the treadmill at 2 mph and 2% grade, then speed and grade were adjusted to elicit the appropriate intensity for each condition (determined from the maximal graded exercise test completed during the baseline assessments). Heart rate and respiratory gas analysis values were checked at five minute intervals throughout the exercise session to verify intensity (65% of their VO2peak) and estimate energy expenditure. If necessary, the treadmill speed and grade was adjusted throughout the exercise session to maintain the appropriate intensity. Based on a previous study [34], the exercise bout was standardized to an energy expenditure of 500 kilocalories. Caloric expenditure was estimated by multiplying a standard caloric equivalent of 5 kcal/L of oxygen consumed by the
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corresponding absolute rate of oxygen consumption (L/min). Exercise duration was determined by dividing 500 kcal by the estimated rate of caloric expenditure, and the exercise bout terminated upon each participant expending 500 kcal. Heart rate, blood pressure, core body temperature, and blood samples were obtained immediately following exercise. This time point was defined as immediate post-exercise (IPE). Following sample collection, participants rested for 30 minutes while continuing to have their resting energy expenditure assessed. At the end of the post-exercise energy expenditure assessment, heart rate, blood pressure, core body temperature, and blood samples were obtained. This time point was defined as 45 minutes post-exercise (45PE). Additionally, at the conclusion of each testing session, participants completed a supplement side-effect questionnaire, and were told to report any possible side effects from supplementation.
2.7. Assessment of serum glycerol, fatty acids, triglycerides, and catecholamines Serum glycerol and fatty acid content was determined spectrophotometrically using the free glycerol determination kit (Sigma Aldrich, St. Louis, MO, USA) and glycerol standard (Sigma Aldrich, St. Louis, MO) at a wavelength of 490 nm. Serum free fatty acids (#K612-100, Bio Vision, Mountain View, CA, USA) and triglycerides (#K622-100, Biovision, Mountain View, CA, USA) were determined spectrophotometrically at a wavelength of 570 nm against known standard curves. Serum epinephrine and norepinephrine were determined with enzyme immunoassay (#17-BCTHU-E02, Alpco, Salem, NH) performed at 450 nm wavelength against known standard curves. All assays were performed in duplicate with a microplate reader (xMark, Bio-Rad, Hercules, CA, USA) and data analysis was performed using microplate data-reduction software (Microplate Manager, Bio-Rad, Hercules, CA, USA). These procedures are similar to those employed in previous studies [35,36].
2.8.
Dietary analysis
Participants were required to record their dietary intake for three consecutive days leading up to each of the three testing sessions. The participants’ diets were not standardized and they were asked not to change their dietary habits during the course of the study. The three-day dietary records were evaluated with the Food Processor dietary assessment software program (ESHA Research, Ogden, UT, USA) to determine the average daily macronutrient consumption of fat, carbohydrate, and protein in the diet for the duration of the study.
2.9.
Statistical analyses
Statistical analyses were performed by utilizing separate 3 × 4 (Supplement × Test) factorial analyses of variance (ANOVA) with repeated measures for each criterion variable. Significant between-group differences were determined involving the Tukey post hoc test. However, to protect against type I error, the conservative Hunyh-Feldt Epsilon correction factor was used to evaluate observed within-group F-ratios. All statistical
procedures were performed using SPSS 19.0 software and a probability level of P < .05 was adopted throughout.
3.
Results
3.1.
Baseline entry data
Table 1 presents baseline entry data for participants. A total of 11 (10 white, non-Hispanic; 1 Asian) active, apparently healthy men participated in this study.
3.2. Dietary intake, exercise duration, and supplement side-effects Dietary intake was calculated from the dietary recalls performed three days prior to each exercise session. No significant differences were detected between testing sessions for total calories and grams of carbohydrates, fats, and protein (Table 2). The mean (SD) duration for all 3 exercise sessions was 42.58 ±5.20 minutes, with no significant difference between sessions (P > .05). No side effects were reported for placebo, capsaicin, or evodiamine.
3.3.
Hemodynamics and core body temperature
There were significant main effects for Test as a result of exercise intervention for heart rate (P < .001), systolic blood pressure (P < .001), and core temperature (P < .001), but not diastolic blood pressure. Post hoc analysis indicated that heart rate was significantly greater at IPE and 45PE compared to PS and PE as seen in Table 3. Furthermore, systolic blood pressure was significantly greater at PE and IPE compared to PS. Core body temperature was significantly greater at IPE compared to PS, PE, and 45PE. No significant main effects existed for Supplement for heart rate, systolic blood pressure, diastolic blood pressure, and core temperature. Additionally, there were no significant interactions between Supplement and Test for heart rate, systolic blood pressure, diastolic blood pressure, or core temperature indicating there to be no significant differences between the three supplements for each test (Table 3).
Table 1 – Descriptive data for baseline participant entry variables Age (y) Height (cm) Body weight (kg) Body mass index (kg/m2) Heart Rate (bpm) Systolic blood pressure (mmHg) Diastolic blood pressure (mmHg) Peak VO2 max (mL/kg per minute) Max RER (VO2/O2) Body fat (%) Lean mass (kg) Fat mass (kg) Values are means ± SD (n = 11).
20 ± 2 179 88.3 27.1 61 114.7 70.0 49.5 1.26 19.4 61.3 17.3
± ± ± ± ± ± ± ± ± ± ±
6 22.6 5.7 10 7.6 7.5 10.4 0.03 8.9 9.6 12.7
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Table 2 – Dietary variables determined three days prior to each supplement session Variable
Placebo
Total calories (kcal/d) Carbohydrates (g/d) Fats (g/d) Protein (g/d)
2149.9 295.7 82.5 82.5
± ± ± ±
743.0 110.5 36.6 8.6
Evodiamine 2549.2 ± 320.2 ± 99.4 ± 95.8 ±
Capsaicin
891.5 132.6 35.7 32.4
2361.1 295.1 91.1 91.8
± ± ± ±
Supplement (P < .05)
711.7 95.0 36.1 27.8
0.500 0.841 0.555 0.531
Values are means ± SD (n = 11). Values were analyzed by two-way ANOVA with repeated measures.
3.4. Respiratory exchange ratio and resting energy expenditure There were significant main effects for Test as a result of exercise intervention for respiratory exchange ratio (RER; P < .001) and resting energy expenditure (REE; p = .001). Post-hoc analysis indicated that RER was significantly greater at IPE compared to PE, PS, and 45PE. In addition, PE was greater than 45PE. For REE, 45PE was greater than PE and PS. No significant main effects existed for Supplement for RER or REE. There were no significant interactions between Supplement and Test for RER or REE indicating there to be no significant differences between the three supplements for each test (Table 4).
3.5. Serum glucose, triglycerides, glycerol, and free fatty acid levels While statistical analyses revealed no significant main effects for Test for glucose and triglycerides, analyses did demonstrate there to be significant main effects for Test as a result of exercise for free fatty acids (p= .001) and glycerol (P < .001). Post hoc analysis indicated that free fatty acids were significantly greater at PE, IPE, and 45PE compared to PS. Glycerol was also significantly greater PE, IPE, and 45PE compared to PS, and was also greater at IPE compared to PE. No significant main effects existed for Supplement for glucose, triglycerides, free fatty
acids, or glycerol. Results demonstrated no significant interactions between Supplement and Test for glucose, triglycerides, free fatty acids, or glycerol indicating there to be no significant differences between the three supplements for each test (Table 5).
3.6.
Serum epinephrine and norepinephrine
For epinephrine (P < .001) and norepinephrine (P < .001), there were significant main effects for Test resulting from the exercise intervention. Post hoc analysis indicated that epinephrine was significantly greater at IPE and 45PE compared to PS and PE. In addition, epinephrine at IPE was greater than 45PE. For norepinephrine, PE, IPE, and 45PE were significantly greater than PS. At IPE, norepinephrine was also greater than 45PE. No significant main effects for Supplement for epinephrine or norepinephrine were observed. There were no significant interactions between Supplement and Test for epinephrine or norepinephrine indicating there to be no significant differences between the three supplements for each test (Table 6).
4.
Discussion
The purpose of this study was to observe the effects that capsaicin and evodiamine had on hemodynamics, energy
Table 3 – Hemodynamics and core body temperature at each test point for the three supplement sessions Supplement
Placebo Evodiamine Capsaicin Placebo Evodiamine Capsaicin Placebo Evodiamine Capsaicin Placebo Evodiamine Capsaicin
PS
PE
Heart rate (bpm) 56.6 ± 6.7 50.6 ± 4.1 54.9 ± 5.1 53.7 ± 6.5 52.6 ± 4.3 53.1 ± 6.0 Systolic blood pressure (mmHg) 109.4 ± 8.1 112.0 ± 7.7 106.3 ± 10.2 111.1 ± 8.8 112.1 ± 8.0 115.1 ± 9.3 Diastolic blood pressure (mmHg) 69.1 ± 10.1 70.0 ± 7.8 70.0 ± 7.3 74.0 ± 6.6 69.1 ± 8.9 74.0 ± 6.3 Core body temperature (°C) 36.79 ± 0.30 36.51 ± 0.26 36.74 ± 0.34 36.51 ± 0.16 36.86 ± 0.39 36.56 ± 0.22
IPE
45PE
171.7 ± 11.7 168.71 ± 7.8 170.0 ± 5.5
82.3 ± 12.4 78.3 ± 13.4 77.4 ± 14.2
128.9 ± 12.6 129.4 ± 12.1 124.6 ± 6.9
109.7 ± 9.2 109.4 ± 10.9 105.7 ± 18.8
70.6 ± 8.6 71.1 ± 6.1 68.3 ± 7.6
68.6 ± 8.5 69.7 ± 7.4 67.7 ± 7.7
38.11 ± 0.55 38.03 ± 0.34 38.11 ± 0.55
36.92 ± 0.22 36.95 ± 0.22 37.03 ± 0.55
Supplement (P < .05)
Test (P .05)
Supplement × test (P < .05)
.952
< .001 a
.975
.889
< .001 b
.904
.316
.130
.901
.481
< .001 c
.994
Values are means ± SD (n = 11). Values were analyzed by two-way ANOVA with repeated measures and Tukey post hoc test. a IPE > PS; 45PE > PS; IPE > PE; IPE > 45PE. b PE > PS; IPE > PS; IPE > PE; PE > 45PE. c IPE > PS; IPE > PE; IPE > 45PE.
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Table 4 – Respiratory exchange ratio and resting energy expenditure at each test point for the three supplement sessions Supplement
Placebo Evodiamine Capsaicin Placebo Evodiamine Capsaicin
PS
PE
IPE c
Respiratory exchange ratio (VCO2/VO2) 0.79 ± 0.05 0.80 ± 0.04 0.90 ± 0.03 0.79 ± 0.04 0.79 ± 0.04 0.91 ± 0.01 0.80 ± 0.04 0.79 ± 0.04 0.90 ± 0.02 Resting energy expenditure (kcal/d) 1859.6 ± 261.8 1856.3 ± 260.5 1822.8 ± 281.5 1823.0 ± 253.1 1781.9 ± 306.5 1832.8 ± 298.9 -
45PE
Supplement (P < .05)
Test (P < .05)
Supplement × Test (P < .05)
.909
< .001 a
.663
.970
.001 b
.966
0.75 ± 0.06 0.76 ± 0.05 0.75 ± 0.07 2049.7 ± 324.0 2070.5 ± 299.5 2105.6 ± 404.0
Values are means ± SD (n = 11). Values were analyzed by two-way ANOVA with repeated measures and Tukey post hoc test. a IPE > PS; IPE > PE; IPE > 45PE; PE > 45PE. b 45PE > PS; 45PE > PE. c No resting energy expenditure measurement for this time point.
expenditure, and markers of lipid oxidation while at rest and after a single bout of moderate-intensity exercise. We observed an increase in all variables due to exercise intervention; however, our hypothesis was not supported. At the dose ingested, no significant differences were observed between supplements and placebo-control conditions indicating them to be ineffective at acutely increasing energy expenditure and lipid oxidation during rest and after a single bout of moderateintensity aerobic exercise. Aerobic exercise is a valuable tool to reduce obesity and retain lean mass, especially when combined with a calorierestricted diet [37]. Aerobic exercise increases adenosine triphosphate (ATP) production in order to meet the energy needs associated with increased cardiac and skeletal muscle contraction rate and force [38]. In order to reach the goal of increased ATP synthesis, exercise-onset withdrawal of the parasympathetic nervous system along with stimulation of the sympathetic nervous system is necessary [39]. Activation of the sympathetic nervous system plays an important role in the increase of hemodynamics and fuel utilization via the
release of catecholamines from the sympathetic nerve endings and adrenal medulla during exercise [40]. Norepinephrine increases heart rate, and subsequently blood pressure, to assist in the delivery of oxygen and fuel substrate needed by muscle tissue for the increased rate of ATP synthesis. Epinephrine strongly enhances the rate of glycogenolysis and of lipolysis and appearance of free fatty acids (FFA) in the blood stream via activation of β-adrenergic receptors in muscle and adipose tissue, respectively [40,41]. Additionally, due to the inefficiency of humans to produce and harness ATP energy, only about 25% of energy found in fuel substrates is used to form ATP and the rest is lost as heat, thus increasing core body temperature [42]. Catecholamine levels remain elevated for a period of time following exercise further increasing metabolic rate into the postexercise period [41]. In the current study, an aerobic exercise workload of 500 kcal increased catecholamine levels substantially, and they remain elevated at the 45PE test point. Accordingly, heart rate and systolic blood pressure were significantly increased IPE
Table 5 – Serum levels of markers of lipid oxidation at each test point for the 3 supplement sessions Variable
Placebo Evodiamine Capsaicin Placebo Evodiamine Capsaicin Placebo Evodiamine Capsaicin Placebo Evodiamine Capsaicin
PS
PE
Glucose (mg/dL) 82.0 ± 27.2 88.1 ± 86.7 ± 19.5 87.1 ± 90.9 ± 21.4 94.8 ± Triglycerides (mg/dL) 49.9 ± 43.9 38.0 ± 40.8 ± 22.9 43.6 ± 50.4 ± 41.7 54.2 ± Free Fatty Acids (nmol) 0.15 ± 0.13 0.26 ± 0.19 ± 0.16 0.25 ± 0.11 ± 0.06 0.21 ± Glycerol (μg/mL) 8.7 ± 5.2 11.5 ± 8.4 ± 4.1 12.2 ± 7.1 ± 4.7 12.4 ±
IPE
45PE
21.2 17.6 26.5
92.5 ± 20.3 98.1 ± 35.7 94.7 ± 33.7
93.3 ± 16.8 83.6 ± 21.5 92.3 ± 23.4
23.2 35.9 49.8
59.4 ± 39.0 61.4 ± 45.2 64.6 ± 52.5
50.6 ± 31.5 51.6 ± 29.2 41.1 ± 35.7
0.26 0.17 0.12
0.41 ± 0.19 0.27 ± 0.12 0.31 ± 0.19
0.25 ± 0.20 0.25 ± 0.20 0.24 ± 0.19
6.5 8.4 8.1
16.5 ± 6.9 20.6 ± 10.3 17.7 ± 6.0
12.2 ± 4.8 13.3 ± 7.6 16.9 ± 6.5
Supplement (P < .05)
Test (P < .05)
Supplement × Test (P < .05)
.640
.555
.933
.944
.586
.776
.403
.001 a
.735
.572
< .001 b
.646
Values are means ± SD (n = 11). Values were analyzed by two-way ANOVA with repeated measures and Tukey post hoc test. a PE > PS; IPE > PS; 45PE > PS. b PE > PS; IPE > PS; 45PE > PS; IPE > PE.
1040
N U T RI TI O N R ES E A RC H 3 3 (2 0 1 3) 1 03 4–1 04 2
Table 6 – Serum levels of epinephrine and norepinephrine at each test point for the three supplement sessions Variable
Placebo Evodiamine Capsaicin Placebo Evodiamine Capsaicin
PS
PE
Epinephrine (ng/mL) 305.76 ± 359.97 540.06 332.50 ± 198.80 360.00 416.56 ± 288.64 400.26 Norepinephrine (ng/mL) 156.48 ± 97.08 246.63 112.97 ± 65.56 226.02 164.22 ± 113.22 259.86
± 700.74 ± 275.51 ± 307.67 ± 135.52 ± 77.87 ± 196.84
IPE
1606.30 ± 1639.37 1424.10 ± 977.24 1017.00 ± 829.69 283.01 ± 135.82 273.52 ± 81.62 317.81 ± 267.11
45PE
Supplement (P < .05)
Test (P < .05)
Supplement × Test (P < .05)
.470
< .001 a
0.848
.678
< .001 b
.981
848.91 ± 750.89 736.50 ± 424.71 661.07 ± 666.08 198.06 ± 96.72 207.48 ± 92.55 184.60 ± 131.70
Values are means ± SD (n = 11). Values were analyzed by two-way ANOVA with repeated measures and Tukey post hoc test. a IPE > PS; 45PE > PS; IPE > PE; 45PE > PE; IPE > 45PE. b PE > PS; IPE > PS; 45PE > PS; IPE > 45PE.
with heart rate staying elevated at 45PE. Systolic blood pressure returned to below resting levels at 45PE, as expected. Diastolic pressure remained relatively consistent throughout. Serum FFA and glycerol levels rose after supplement ingestion along with norepinephrine; however, no difference was seen between capsaicin, evodiamine, and placebo. Serum FFA and glycerol concentrations rose even more as a result of the exercise session; although, only significantly more than observed PE for glycerol. Serum FFA and glycerol levels remained elevated above baseline at 45PE, yet not at a higher concentration than observed PE. As expected, RER increased significantly during the exercise testing session as a result of increased glucose utilization with values returning to significantly below baseline at 45PE. Energy expenditure was also significantly increased at 45PE. Taken together, increased energy expenditure with a reduced RER and FFA serum concentration suggests an increase in FFA uptake and utilization for ATP production at 45PE. Core temperature was significantly higher IPE returning to baseline by the 45PE test. Our study investigated whether TRPV1 agonists, capsaicin and evodiamine, could augment the effect of exercise on hemodynamics and lipid oxidation. As noted, no significant differences were observed between capsaicin, evodiamine, and placebo for any test point. Since capsaicin may have undesirable side effects, our goal was to determine if capsaicin could induce acute alterations in metabolic activity at a low dose that may be well-tolerated by individuals for a prolonged period of time. Our results indicated that 1.25 mg of capsaicin was insufficient to induce acute changes in the variables of hemodynamics, energy expenditure, and lipid oxidation measured. Furthermore, capsaicin did not augment the metabolic shift associated with aerobic exercise. Our results are consistent with a recent meta-analysis which revealed that doses below 7 mg of capsaicin are ineffective at increasing energy expenditure and lipid oxidation. However, results of one previous study suggest that delivery method of capsaicin may be important [36], as this study demonstrated that a dose of 2 mg of capsaicinoids, when delivered as encapsulated beadlets, was more effective than a placebo at increasing blood FFA and glycerol concentration. Evodiamine is a TRPV1 agonist purported to have similar anti-obesity properties as capsaicin. Evodiamine is an attractive anti-obesity agent because it does not possess the
pungent quality associated with capsaicin which may allow for the use of much higher dosages [22]. Although shown to be a successful therapy for lipid oxidation in rodents [22], Kim et al. [23] demonstrated that daily ingestion of 6.75 mg of evodiamine for 8 weeks did not induce weight loss or increase resting metabolic rate in a group of premenopausal women when compared to placebo ingestion. Evodiamine has been demonstrated to be 3-fold and 19-fold weaker for binding to the TRPV1 receptor and for induction of calcium uptake, respectively, than that of capsaicin [24]. Therefore, it is conceivable that a much higher dose than 6.75 mg of evodiamine is needed in order to elicit an anti-obesity effect. In agreement with this hypothesis are the findings, including those of the current study, that the more-potent capsaicin is not effective at increasing energy expenditure or lipid oxidation when used at dosages similar to (
