Nutritional and exercise lifestyle strategies are primary tools for weight and fat loss to prevent major health risks and lifestyle diseases such as obesity, diabetes, and cardiovascular disease. The effectiveness of healthy lifestyle strategies can be maximized with a variety of nutritional aids in the form of functional foods and naturally available herbal ingredients [1
Yerba Maté (YM), the plant Ilex paraguariensis
, is traditionally consumed in many South American regions, but its popularity is increasing in North America, Europe, and other regions worldwide [3
]. Several anti-atherogenic and weight-loss properties have been associated with the regular consumption of YM [4
], including anti-oxidation, vasodilation, reduction in blood lipids, and other anti-mutagenic and anti-glycation benefits [5
]. These health properties have been attributed to several naturally-present bioactive ingredients, which have been detected in YM including polyphenols and caffeoyl derivatives (caffeic acid, chlorogenic acid, 3,4-Dicaffeoylquinic acid, 4,5-Dicaffeoylquinic acid and 3,5-Dicaffeoylquinic acid), phytosterols, saponins, some amino acids, vitamins, and minerals [4
]. Metabolic functions of YM components are thought to be responsible for reductions in serum cholesterol, serum triglycerides, and glucose concentrations; and an improved glycemic control and lipid profile in in high-fat fed mice [7
], reduced body fat mass, and distribution and reduced waist to hip ratio in humans, all shown following YM ingestion [10
Recent findings have also indicated that YM metabolic properties may be combined with positive psychomotor and appetite control effects, which complement the YM fat-loss promoting properties. Such effects include suppressed appetite through an increased expression of glucagon-like peptide-1 (GLP-1) and delayed gastric emptying, as seen in mice studies [12
], and increased ghrelin up to 4.2-fold in rat models following YM ingestion [14
A trend towards increased satiety, reduced hunger, and improved mood state has also been found using visual analogue scale in human participants who ingested YM combined with other fat-loss ingredients [15
]. The reported psychomotor effects include improved total mood disturbance score [15
], increased focus, alertness and energy, and decreased fatigue in habitual caffeine consumers [16
]. Modifying behavioral factors of mood state and appetite control is considered essential for effective weight-loss lifestyle interventions [17
]. Consequently, indications of the positive YM effects combined with exercise on those outcomes should be further investigated, especially given the known positive effects of exercise on mood state and mental health [20
Along with the nutritional metabolic weight and fat-loss benefits, exercise is known to stimulate fat metabolism, and reverse associated metabolic health risks. YM effects on thermogenesis has been suggested to promote fat-loss by influencing indirect calorimetry measures such as energy expenditure (EE), fatty acid oxidation (FAO), and respiratory exchange ratio (RER) in resting healthy obese participants [21
]. However, little is known about such YM metabolic effects during exercise. Our recent work has shown that YM favors FAO as a fuel source during exercise, when either ingested as a single ingredient [22
] or combined with other fat-loss compounds in a multi-ingredient supplement [15
]. In Alkhatib, 2014 it was found that 1 g of YM can induce an over 20% increase in FAO at the exercise intensity range of 40–70% of peak oxygen uptake (
), which is considered to be within the low-to-moderate exercise intensity domain [22
]. This intensity range of exercise corresponds to maximal fat oxidation (Fatmax) intensity, defined as the exercise intensity where FAO becomes maximal, and the crossover point (COP), defined as the power output when the energy expenditure derived from carbohydrates (CHO) fuels predominates over that from FAO fuels [23
]. Performing exercise at individually determined Fatmax or COP intensities has been shown to induce favorable metabolic outcomes, such as enhanced FAO ability, improved insulin sensitivity, and enhanced vascular function [25
]. However, to date no study has tested whether the exercise-induced metabolic effects at those effective exercise intensities (i.e., COP intensities) could be augmented with YM ingestion.
Given our recent promising findings of YM acute effects on FAO during exercise intensities in the COP range [15
], and the YM weight-loss postulated effects on satiety and mood state [13
], our study is important to test whether and how YM affects FAO, satiety, and mood state during prolonged exercise at individuals’ COP intensities. This study aims to test the hypothesis that YM ingestion combined with steady state exercise at the COP intensities augments FAO, and improves the measures of satiety and mood state.
In this experiment, YM increased FAO during prolonged steady-state exercise and induced positive psychomotor mood state and satiety during and after exercise without affecting the exercise RPE.
Augmented FAO was approximately 23% higher in YM compared with PLC during 30 min of steady-state low-to-moderate intensity exercise corresponding to individuals’ COP intensity (Figure 1
). This increase is comparable with 24% increase found during low to moderate exercise intensities determined using an incremental protocol in our previous study [22
]. The present study extended previous findings by determining COP individually, and demonstrated that YM ingestion is effective in enhancing the impact of FAO at the targeted COP exercise intensities. Targeting such intensities with exercise training enhances fat metabolism, and associated “fat-loss” metabolic health outcomes including increased insulin sensitivity [25
], enhanced lipolysis and ability to oxidize lipids [32
], and microvascular activity [26
]. Therefore, YM augments such metabolic outcomes when combined with prolonged exercise at such given fat-loss intensities.
Previous studies in human participants have shown promising effects of YM ingestion on metabolic rate and RER acutely [21
], and after 12 weeks of ingestion, on blood lipid metabolites in healthy obese participants [11
]. However, these metabolic effects were only tested at rest. YM was also administered, with various metabolic efficacy, in various doses of ≈1 g of proprietary multi-ingredient thermogenic blends containing weight-loss ingredients such as YM and green tea extracts, caffeine anhydrous, guarana, yohimbine HCI, capsicum, ginger and bitter orange extracts, and other proprietary blends [16
]. In two separate studies conducted previously, we tested the exercise-dependent effects on FAO at various intensities with 1 g YM [22
] or when YM combined with a proprietary thermogenic blend of 1.5 g dose [15
]. Both studies used mixed gender samples and showed an augmented FAO during low-to-moderate intensity exercise of 24% and 26% in YM compared with PLC. This is close to the 23% found for FAO in this cohort of female participants, using a higher ingestion dose of 2 g (Figure 1
). The 38%
intensity used in this study is less than intensities (40–70%) [22
] and 44%
] used in those two previous studies, but demonstrated almost equal % difference in FAO, which suggests that supplementing a higher dosage of 2 g could be more effective at higher intensities, and merits further investigation. Such intensity effects of the higher dosage used in the present study could also be attributed to the no significant difference found in the TEE (Figure 3
). All three studies used sufficient amounts of resting time of 1–3 h following ingestion and prior to exercise, which is considered sufficient to induce the YM thermogenic effects at rest [21
] and during exercise [22
]. Other available studies to compare our findings with during exercise are limited to herbs which share some similar active ingredients to YM, especially green tea [4
]. For example, Gahreman et al. (2015) [35
] combined green tea with intermittent exercise and showed an increased FAO, plasma glycerol, and plasma catecholamines at rest and post exercise compared with placebo in healthy active female participants of similar characteristics to the present study. Another study by Hodgson et al. (2013) [36
] found that a drink containing 1.2 g of green tea affected the metabolic profile (3-β-hydroxybutyrate, pyruvate, lactate and alanine concentrations) at rest and during 60 min of exercise at 56%
compared with placebo. However, both studies used higher intensities which promotes CHO metabolism, than the COP intensity of 38%
used in the present protocol.
It is likely that active YM thermogenic ingredients work in synergy to promote lipolysis and augment FAO during exercise. The metabolic effects include adrengenic effects and stimulated central nervous system associated with caffeine, anti-lipolytic, and hypocholesterolemic properties in chlorogenic acids (mono- and di-caffeolquinic acids) hydroxycinnamic acids (caffeic acid, quinic acid) and triterpenic saponins, and other minerals and vitamins [5
]. Anti-oxidant compounds in YM such as flavonoids and polypheonols are common in other herbal teas and may affect nitric oxide levels, which have been shown to be effective in inducing vasodialatory effects [37
] when combined with exercise [27
]. Anti-oxidant compounds of YM have been recently attributed to accelerating muscle strength recovery 24 h after exercise, suggesting that YM favored the concentration of blood antioxidant compounds [39
]. Therefore, YM active ingredients may have played a synergetic role in the metabolic effects found during exercise. However, further research is required to assess active ingredients of YM capsules and analyze their bioavailability following ingestion.
Favorable psychomotor effects on mood state and satiety are often expected outcomes of fat and weight-loss supplementation protocols. However, several negative side effects were reported for common thermogenic supplements containing caffeine including jitteriness, mood swings, and headache [40
]. It is suggested that these effects can be reduced with YM ingested with other ingredients compared with caffeine [22
]. The present study found an improvement in almost all measures of POMS and VAS (Table 1
). In particular, there was an increased focus (p
= 0.022), energy (p
= 0.008) and concentration (p
= 0.003) in the YM treatment compared with PLC, which was combined with no effects on fatigue scores. Interestingly, the RPE score was not different (Figure 5
), suggesting that the positive psychomotor YM effects had no negative effects on the perception of effort and fatigue during exercise, which is important when considering adherence to prescribed exercise for weight loss and sport performance outcomes.
There was also a reduction in appetite VAS measures, especially for hunger (p
= 0.019) and prospective eating (p
= 0.022), (Table 1
) following the YM ingestion compared with PLC. These YM appetite control effects are reported in humans for the first time, considering previous positive effects reported in animal models [13
], and the recent report of appetite suppression following exercise in trained female participants [41
]. The reduced VAS appetite scores are also in line with previous results found when YM was combined with other multi-ingredients before and after moderate exercise at Fatmax intensities at 43%
, which is slightly higher than COP intensities of 38%
to the present COP intensities [22
]. Nonetheless, it is suggested that irrespective of the intensity differences, exercise suppresses appetite hormones (GLP-1, PYY3-36, and acylated ghrelin) and VAS scores in trained women [41
]. It has also been reported that exercise combined with satiety-inducing compounds is effective in reducing energy intake in active females [42
]. This suggests that YM effects on satiety and mood state may be dependent on augmented metabolism during exercise. Perhaps, exercise combined with YM is most effective in appetite control and improved mood state after performing exercise, which is important for designing lifestyle interventions and weight-loss adherence.
HR response is a standard measurement for exercise intensity and training cardiovascular adaptations, but it was not significantly affected by YM ingestion (Figure 5
). Cardiovascular benefits for YM consumption have been reported using more sensitive biomarkers such as detecting an increase in vascular endothelium-dependent vasorelaxing activity in rats [43
]. Such microvascular measurements have been shown to be sensitive to the exercise-dependent effects in human lifestyle interventions [26
]. Perhaps HR monitoring is insufficient to detect vascular responses associated with combining YM ingestion with exercise, and future research could determine more sensitive macro- and microvascular health effects associated with YM ingestion during exercise, especially when combined with detecting YM metabolic effects found in the present study.
Although there was not significance for all variables, the significant increase in FAO is mathematically accounted for by combined non-significant reductions in glucose oxidation and non-significant elevated TEE for YM (Figure 3
). The estimates are approximately 0.35 kcal/min greater FAO, and 0.23 reduced CHO with 0.14 kcal/min greater TEE, and with a corresponding significant YM on the calculated total AUC for FAO, CHO, and TEE (p
< 0.001). It is unclear whether there are additional YM effects on glucose and adipose tissue levels not determined in this study [45
]. We used indirect calorimetry methodology to estimate metabolic variables, so perhaps future studies could use different techniques to estimate YM effects on different body compartments, tissues, and metabolites by including in vitro and muscle biopsy methods.
With respect to the gender-specific effects on metabolism, females’ FAO during exercise is known to be higher compared to men [46
], possibly due to higher total body fat percentage, fitness level, and exercise modality [47
]. The BF% data indicated all females who took part were at the lower BF% percentile, indicating that they were physically active, with higher
of 38 mL/kg/min, which is higher than 32 mL/kg/min measured for a mixed gender cohort in a previous similarly designed study [18
]. The study’s participants completed their tests within the same week and reported to be within the same menstrual cycle phase. Some authors suggested that the luteal phase of the menstrual cycle is associated with increased lipid oxidation compared with the follicular phase [48
], but no differences were reported by others during prolonged moderate exercise between luteal and follicular phases [46
]. All participants within the present study repeated their assessments within the same phase of the cycle, so it is unlikely that menstrual cycle affected the metabolic variables. Nevertheless, gender differences’ effects on the combined YM and exercise-induced fat oxidation response needs further investigation.