Maté Promots Fat Oxidation During Cardio: What's the Intra-Workout Effect From 1 Gram of Ilex Paraguariensis Worth?

Do you want to burn some extra fat during your workouts? Ilex can help. But will it also help you lose body fat?

After the nicotine article a week ago, it's about time to take a look at less "toxic" fat burners. As the case may be, researchers from the Faculty of Health and Wellbeing at the Sheffield Hallam University have just published a paper about the ability of Yerba Maté (Illex Paraguariensis | YM) to augments fat oxidation and energy expenditure during exercise at various submaximal intensities (Alkhatib. 2014).

Now, as a SuppVersity Reader you're well aware that an "augmentation of fatty acid oxidation during exercise", alone, is not worth your heard earned money. The question to keep in mind, when we're going through the results, is thus: Is Ilex Paraguariensis worth using, or is it just worth writing about in a science magazine?
Alright, now that we've set the scene it's about time to take a look at the study design. The study followed a double-blind crossover repeated measures experimental design.

The participants were fourteen healthy adults, seven males and seven females [Mean ± SD: age = 20.8 ± 3.4 yr, height = 171.8 ± 10.0 cm, body mass = 70.4 ± 11.3 kg, body mass index (BMI; in kg/m²) = 23.8 + 0.11]. Participants were assigned randomly to each experimental condition within a period of two weeks.

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Female participants were studied in days 1 to 7 of their menstrual cycle to minimise the influence of cyclical changes in female hormones. All participants were screened prior to the start of the testing in order to determine that they are free from illness and any type of orthopaedic limitation or injury, or chronic disease.

Moreover, none of the subjects consumed ergogenic aids or tons of caffeine regularly (<200 mg/day) - that doesn't mean they never drank more coffee, but they had to abstain from more than 1.5 cups of coffee, tons of energy drinks caffeine containing soft drinks or medications.

A very reasonable request, if you want to measure significant effects from Ilex Paraguariensis which contains 1.5% (according to Alkhatib. 2014) caffeine and roughly 0.12% theobromine (according to Reginatto. 1999).

The tests & supplements

All participants reported to the Physiology Laboratory on two separate occasions following 10 hrs overnight fast, and each testing session (between 07:00am and 10:00am) was separated by at least three days within two weeks period.

During each visit participants ingested either 1000 mg (2× 500 mg capsule) YM or hydroxypropyl methylcellulose placebo empty capsules (PLC). Two capsules with similar coatings of either YM and PLC capsules were placed within an empty water cup and taken in the same way with a 100 ml of water. The YM capsules contained a standardized ground YM leaves (batch number 0422009/2012) with a natural content of approximately 1.5% caffeine (Rio Trading Company, Brighton, United Kingdom).
Immediately following the ingestion of supplement or placebo, participants rested for 60 minutes in a semi-recumbent position in quiet laboratory condition. For the estimation of FAO and CHO at rest and during exercise, breath by breath cardiorespiratory measurements included oxygen uptake ( ) 2 VO , carbon dioxide production, and respiratory exchange ratio (RER), using an online gas analyzer (Metalyzer Cortex 3B, Leipzig, Germany).

The exercise protocol & its consequences

All participants followed the same incremental exercise assessment using an electromagnetically braked cycling ergometer (Schoberer Rad Messtechnik, SRM, Ergo, Julich, Germany). The ergometer was calibrated before use and similar cycling positions were applied in both tests for each participant, which included adjusting the handlebar and saddle height and distance, crank length and toe clip positions during the first visit and re-apply the same position in the following visit.

The cycling protocol consisted of three-minute incremental stages that were initiated at and increased by 0.5 W/kg body mass. Participants cycled at 60–70 rpm throughout the whole test until volitional exhaustion defined as meeting the at least two of 2 peak VO2 termination criteria: RER value > 1.1, heart rate within 10 beats/min of age predicted maximum heart-rate, or achieving levelling-off of VO2 Peak power (P_peak). Similar verbal encouragement was provided to all participants throughout the exercise tests. All tests were followed by a sufficient cool down for at least 20 min, in which participants consumed at least 200 ml of water, and instructed to stay hydrated and consume at least 2 litres of water during the day of the test.
Interestingly, following the 60 min rest after YM ingestion, no significant difference was found for either resting blood lactate contentration (1.4 ± 0.32 vs. 1.5 ± 0.30 mmol/l) or resting respiratory exchange ratio (0.82 ± 0.08 vs. 0.81 ± 0.05) for PLC vs. YM respectively.

In other words: After the workout there were no measurable difference between the active and placebo treatment. The latter cannot be said of the RER during workouts, though.

Figure 1: Significant decreased RER and higher fatty oxidation rates - two sides of the same fat burning coin and evidence that the ingestion of the YM supplement lead to significant increases in fatty oxidation (Alkhatib. 2014)

As you can see in Figure 1 the effects of the Ilex supplements were significant - statistical significant, but also practically relevant? Probably not. The increase in fatty oxidation was after all paid for with an increase in glucose oxidation (see Figure 2).

Figure 2: The glucose usage during workouts decreases, obviously this leads to greater increases in lactate levels, whether it's pro-weight loss is questionable, though. If anything it could increase the time to fatigue (Alkhatib. 2014)

The net energy expenditure, the one thing that really counts, was thus identical. For someone who has to get rid of tons of fat in his blood. The increase in RER may be relevant. For someone who is fit and well-trained, it's not really important if he or she burns fat or glucose during the workout - why else would HIIT work so well for losing fat - specifically in lean athletic individuals? Well, the answer is easy: It burns glucose and will thus increase GLUT-4 expression insulin sensitivity and, in the end, also fatty oxidation - to replete the depleted energy stores.
References:

• Godfrey, R. J., et al. "A–Z of nutritional supplements: dietary supplements, sports nutrition foods and ergogenic aids for health and performance: Part 45." British journal of sports medicine 47.10 (2013): 659-660.
• Pang, Jisook, Youngshim Choi, and Taesun Park. "Ilex paraguariensis extract ameliorates obesity induced by high-fat diet: Potential role of AMPK in the visceral adipose tissue." Archives of biochemistry and biophysics 476.2 (2008): 178-185.
• Reginatto, Flavio Henrique, et al. "Methylxanthines accumulation in Ilex species-caffeine and theobromine in erva-mate (Ilex paraguariensis) and other Ilex species." Journal of the Brazilian Chemical Society 10.6 (1999): 443-446.