One hundred and one athletes, a 10 km time trial on bike, the same caffeine dose for all: for some, the time improved by 6.8%; for others, it worsened by 13.7%. This trial captures the entire paradox of pre-workout boosters. The caffeine they contain is one of the best-studied supplements in sports, but its response varies from person to person, as do its side effects.
This guide compiles what studies identified via PubMed show about booster ingredients—caffeine, guarana, ginseng, tribulus, and vitamin C—then examines their risks, interactions, and cumulative effects, before offering cautious usage guidelines.
What Works : in a booster, the ingredient with the strongest evidence is caffeine. A synthesis of 21 meta-analyses recognizes its effect on endurance, strength, muscular endurance, and power, with moderate-quality evidence, and sports nutrition experts recommend 3 to 6 mg per kilogram of body weight. Guarana acts mainly through its caffeine content, ginseng shows conflicting results, tribulus has shown no gains in strength or mass in athletes, with no solid evidence of testosterone increase in men, and vitamin C at 1 g per day even diminished certain training adaptations.
What Poses Risks : caffeine raises blood pressure by a few millimeters of mercury, shortens sleep by an average of 45 minutes, and can trigger panic attacks in people with panic disorder at high doses. Reported deaths mainly concern massive intakes of caffeine in tablet or powder form. Always add up the caffeine from coffee, beverages, and supplements.
- Booster or Pre-Workout: What Are We Talking About?
- Caffeine, the Best-Documented Engine
- Genetics and Habit: Why Response Varies
- Guarana: A Plant Source of Caffeine
- Ginseng: Endurance and Fatigue, Conflicting Results
- Tribulus, Strength and Mass: What Trials Show
- Vitamin C: Useful Daily, Not as a Booster
- Blood Pressure, Heart, and Rhythm: Caffeine's Effects
- Sleep, Anxiety, and Digestion
- Who Should Abstain: Interactions and Cumulative Effects
- Severe Cases, Doping, and Contamination
- Using a Booster Safely
- Frequently Asked Questions
Booster or Pre-Workout: What Are We Talking About?
The term booster refers to a product taken around workout time to feel more alert and energized. It is almost always based on a caffeine source, either synthetic or plant-based like guarana, often combined with plants reputed to be tonic and sometimes with vitamin C, in shot, drink or liquid concentrate form.
Pre-workout , on the other hand, is generally a multi-ingredient powder that adds to caffeine beta-alanine, citrulline, creatine or taurine. We analyzed this format ingredient by ingredient in our article onpre-workout and what really works . This guide takes a different angle: energy, plants and, above all, safety.Our Liquid Booster follows this formula: dry acerola extract standardized in vitamin C, ginseng root extract, tribulus fruit extract and guarana seed extract standardized in caffeine, sweetened with acesulfame K and sucralose, with glycerol. No trial has tested this product: the following describes what research shows for each ingredient, at its own doses and in its own populations.
Reading Effect Size
Caffeine, the Best-Documented Engine
A measured effect on endurance, strength and power, ranging from small to medium in size.
11 reviews totaling 21 meta-analyses . These meta-analyses conclude an ergogenic effect, meaning favorable to performance, on aerobic endurance, muscular strength, muscular endurance, power, jumping and speed. For muscular endurance, strength, anaerobic power and aerobic endurance, the quality of evidence is judged moderate; for other criteria, it is weak to very weak. The effect is generally more pronounced for aerobic effort than for anaerobic effort.Two nuances: most studies were conducted in young men, and not all analyses provide a certain direction of effect once the prediction interval is taken into account, which signals the individual variability described below.
For dosage, an expert position statement on sports nutrition published in 2021 recommends
3 to 6 mg per kilogram of body weight , or 210 to 420 mg for a 70 kg person, most often60 minutes before exercise. Very high doses, around 9 mg per kilogram, are accompanied by frequent adverse effects and do not appear necessary. Our guide on caffeine before sport details the calculation and timing of intake. Genetics and Habit: Why Response Varies
Génétique et habitude : pourquoi la réponse varie
The speed at which the body transforms caffeine depends partly on the CYP1A2 gene. A variant of this gene distinguishes fast metabolizers (AA genotype), intermediate (AC) and slow (CC). This is the most well-studied lead to explain why two athletes do not react in the same way.
In 101 male competitive athletes, averaging 25 years old, 4 mg of caffeine per kilogram reduced the time of a 10 km cycling time trial by 3% compared to placebo (17.6 vs 18.1 minutes). In fast metabolizers, the time decreased by 4.8% with 2 mg per kilogram and by 6.8% with 4 mg per kilogram. In slow metabolizers, 4 mg per kilogram increased the time by 13.7%. No effect was observed in intermediate metabolizers.
Guest N, Corey P, Vescovi J, El-Sohemy A. Med Sci Sports Exerc 2018;50(8):1570-1578. DOI : 10.1249/MSS.0000000000001596
In about one hundred male athletes, the same team found on average no effect of 2 or 4 mg per kilogram on grip strength or vertical jump, but 4 mg per kilogram reduced grip strength by 12.8% in slow metabolizers (53 kg vs 61 kg).
Habit counts less than we think. In a trial conducted in 40 trained cyclists, divided according to their daily consumption (58, 143 or 351 mg of caffeine per day on average), 6 mg per kilogram improved a 30-minute time trial by approximately: 29.92 minutes vs 30.81 under placebo. The level of habitual consumption did not modify this gain. Heavy coffee drinkers, however, accumulate more caffeine over the course of the day.
Without genetic testing, the best indicator remains your tolerance to coffee: if a cup makes you nervous or disturbs your sleep, a sports dose of caffeine is likely to work against you.
Guarana: a plant-based source of caffeine
Guarana is a seed originating from Brazil that contains caffeine and other plant compounds. It is presented as a natural sports booster, but natural does not mean caffeine-free: its effect depends primarily on the amount of caffeine it provides.
Eleven endurance athletes received 500 mg of guarana extract containing 130 mg of caffeine, 100 mg of caffeine alone or placebo, before 60 minutes of cycling at fixed load followed by a 15-minute time trial. Work output was higher with guarana than with placebo, 241.4 vs 232.1 kJ, an effect size of 0.18 that the authors consider trivial to small. Caffeine alone differed neither from guarana nor from placebo. The authors cannot say whether guarana provides anything beyond its caffeine content.
Penna EM, Harp A, Hack B, et al. Int J Sport Nutr Exerc Metab 2024;34(1):30-37. DOI : 10.1123/ijsnem.2023-0148
In 27 footballers under 17 years old from a professional club, 3 g of guarana seed powder taken 60 minutes before tests improved neither vertical jump, nor sprint, nor agility; the distance covered in an intermittent running test, however, increased. This trial was conducted on adolescents, a population that sports boosters containing caffeine are not intended for.
The evidence is thin, and guarana counts as a full source of caffeine, with the same precautions.
Ginseng: endurance and fatigue, discordant results
Asian ginseng (Panax ginseng) is traditionally used against fatigue. A review published in 2000 observed improvements in performance especially when several conditions were met: standardized root extracts, more than 8 weeks of intake, more than 1 g of dried root per day or its equivalent, large sample sizes and older participants. Its author was affiliated with a dietary supplement company, an element to keep in mind.
More recently, a meta-analysis of 5 studies and 90 participants found a mean effect of ginseng and its ginsenosides on time to exhaustion (0.58). It covered several plants of the Panax genus, was funded by an industry that employed four of its five authors, and its authors do not exclude imprecision or publication bias. Conversely, a review of 6 trials did not find that Panax ginseng attenuates muscle damage after resistance training.
On fatigue, a meta-analysis of 19 randomized trials does not find a significant decrease in fatigue with ginseng across all studies (−0.36, non-significant). The decrease becomes significant for general fatigue, unrelated to disease (−0.48), and with formulas combining ginseng with other plants, for effects considered small. Ginseng did not increase adverse effects compared to control groups.
Ginseng is not without effect on the body nonetheless. A meta-analysis of 16 trials shows it modestly lowers fasting blood glucose (−0.31 mmol/L), which justifies caution in case of antidiabetic treatment. A review of 19 meta-analyses, of low methodological quality, reports digestive disorders and potential bleeding among its adverse effects, with no serious adverse effect reported.
Our Liquid Booster contains ginseng root extract. If you also take our Red Ginseng (2 capsules provide 200 mg of extract) or our Men's Libido formula, which also contains it, you are accumulating ginseng intake. The Liquid Booster and Red Ginseng are not recommended in case of antidiabetic treatment; if in doubt, consult your doctor or pharmacist.
Tribulus, strength and mass: what the trials show
Tribulus (Tribulus terrestris) is often associated with resistance training and testosterone. The two trials in athletes, however, show no effect on strength or mass compared to placebo.
Twenty-two high-level rugby league players, averaging 19.8 years old, took 450 mg per day of tribulus extract or placebo for 5 weeks of preparation with heavy resistance training. Strength and lean mass increased in both groups, with no difference between them. The urinary testosterone to epitestosterone ratio was not modified.
Rogerson S, Riches CJ, Jennings C, et al. J Strength Cond Res 2007;21(2):348-353. DOI : 10.1519/R-18395.1
An older trial points in the same direction: in 15 men trained in weight training, 3.21 mg of tribulus per kilogram per day for 8 weeks improved neither body composition nor performance compared to placebo.
Regarding testosterone, a systematic review of 11 studies, in humans and animals, concludes that tribulus is ineffective at increasing it in men; an increase only appeared when it was part of a mixture of ingredients. A more recent review of 10 studies and 483 men, at doses of 400 to 750 mg per day for 1 to 3 months, finds the same result: 8 out of 10 studies show no change in androgenic hormones. The two exceptions involved men with low testosterone, with a clinically modest increase. This review focused mainly on erectile function, which improved in 3 of the 5 studies measuring it, with a level of evidence deemed weak. Our article on the tribulus and libido presents this work in detail.
Our Booster liquid contains tribulus fruit extract. Combining it with our Tribulus terrestris (471 mg of extract at 90% saponins) or with our Libido for Men, which contains tribulus and ginseng, amounts to accumulating tribulus. Tribulus terrestris is not recommended during pregnancy and breastfeeding, for minors, in case of a history of breast cancer, and with blood pressure or antidiabetic medication.
For strength, the best-supported ingredient is not a plant but creatine, taken daily for several weeks. A meta-analysis of 23 trials in adults under 50 years old shows that, combined with weight training, it increases strength more than placebo: +4.43 kg on average for the upper body and +11.35 kg for the lower body. Gains were significant in men, not in women, who have been little studied (2 trials and one mixed trial).
Vitamin C: useful daily, not as a booster
Vitamin C is an essential nutrient, often found in boosters in the form of acerola. But a high dose does not improve the workout in trials, and several suggest the opposite.
A review of 12 studies published in 2012 notes that vitamin C above 1 g per day significantly degraded athletic performance in 4 out of 4 studies, and that 4 other studies showed non-significant degradation. Reactive oxygen species produced during exercise also serve as a signal for adaptations, a signal that a high dose of antioxidant could attenuate. The author estimates that approximately 0.2 g per day, provided by five servings of fruits and vegetables, could be sufficient without hindering these adaptations.
In 54 young men and women undergoing 11 weeks of endurance training, 1,000 mg of vitamin C and 235 mg of vitamin E per day did not prevent the increase in VO2max, of 8% as under placebo, nor progress in the shuttle run test (+10% versus +14%). In contrast, markers of new mitochondria formation increased under placebo (+59% and +19%) but not under vitamins (−13% for both).
Paulsen G, Cumming KT, Holden G, et al. J Physiol 2014;592(8):1887-1901. DOI: 10.1113/jphysiol.2013.267419
An older trial conducted in 14 men trained for 8 weeks, of whom 5 received 1 g of vitamin C per day, and supplemented by experiments in rats, concludes that vitamin C hindered endurance capacity and prevented the expression of several mitochondrial biogenesis factors, results that rely largely on rats. With 5 additional supplemented men, the human part does not allow for conclusion alone.
These trials focus on 1 g per day for weeks, sometimes with vitamin E, and say nothing about the amounts provided by diet.
| Ingredient | Dose studied | What the studies show | Level of evidence |
|---|---|---|---|
| Caffeine | 3 to 6 mg per kilogram, 60 minutes before | Effect on endurance, strength, and power; variable response | Moderate, 21 meta-analyses |
| Guarana | 500 mg of extract (130 mg of caffeine); 3 g of seed powder | Trivial to small effect on a time trial | Limited, a few small trials |
| Ginseng | Variable depending on trials | Endurance: 0.58 over 5 studies; fatigue: no overall effect over 19 trials | Weak and discordant |
| Tribulus | 450 mg per day, 5 weeks; 3.21 mg per kilogram, 8 weeks | No gain in strength or mass in athletes; no solid evidence of an increase in testosterone | No demonstrated effect |
| Vitamin C | 1 g per day, several weeks | No improvement in performance; certain adaptations attenuated | No ergogenic effect |
| Creatine (excluding boosters) | 2 to 10 g per day, 4 to 12 weeks | +4.43 kg of upper body strength, +11.35 kg of lower body strength | Solid, 23 trials |
Blood pressure, heart and rhythm: the effects of caffeine
The first effect of caffeine on the cardiovascular system is a rise in blood pressure. A meta-analysis of 17 randomized trials in healthy adults shows that an energy drink (which also contains other ingredients besides caffeine) raises systolic pressure by 4.71 mmHg on average 60 to 80 minutes after consumption (moderate quality evidence) and diastolic pressure by 4.51 mmHg at 120 minutes (low quality). Resting heart rate and QT interval on electrocardiogram were not significantly altered. During exercise, another meta-analysis of 21 trials and 296 adults measures +2.86 beats per minute and +9.02 mmHg of systolic pressure with a caffeinated energy drink, with diastolic pressure remaining comparable.
In people with high blood pressure, 200 to 300 mg of caffeine raised systolic pressure by 8.1 mmHg and diastolic pressure by 5.7 mmHg on average across 5 trials. The increase appeared within an hour of consumption and lasted at least 3 hours. Over 2 weeks, coffee did not increase blood pressure, and 7 cohort studies found no association between habitual coffee consumption and cardiovascular risk in these individuals.
Mesas AE, Leon-Muñoz LM, Rodriguez-Artalejo F, Lopez-Garcia E. Am J Clin Nutr 2011;94(4):1113-1126. DOI: 10.3945/ajcn.111.016667
This acute effect is added to the blood pressure increase caused by exercise, hence the contraindication in cases of high blood pressure or antihypertensive treatment.
On heart rhythm, a randomized trial equipped 100 adults with a continuous electrocardiogram recorder for 14 days, randomly determining each day whether they drank caffeinated coffee or avoided caffeine. Atrial premature beats, the primary endpoint, did not increase significantly (58 versus 53 per day). Ventricular premature beats, premature heartbeats, increased from 102 to 154 per day on average, and nights were 36 minutes shorter on coffee days. In a person with a heart rhythm disorder or heart disease, these findings warrant medical advice before taking caffeine as a supplement.
Sleep, anxiety and digestion
Sleep is the first to suffer from an evening session. A meta-analysis of 24 studies shows that caffeine intake reduces total sleep time by 45 minutes and sleep efficiency by 7%, lengthens time to fall asleep by 9 minutes, and adds 12 minutes of nighttime wakefulness. Deep sleep decreases by 11.4 minutes. The authors calculated a timing to respect before bedtime to avoid losing sleep: at least 8.8 hours for a coffee with 107 mg of caffeine, and at least 13.2 hours for a standard serving of pre-workout at 217.5 mg.
In 128 athletes from 10 studies, caffeine taken before an evening session slightly reduced sleep efficiency (−4.87%, fragile result), with a non-significant trend toward sleeping 32 minutes less; however, athletes consistently reported noticeably disrupted sleep after 3 to 6 mg per kilogram.
In 9 studies involving 237 patients with panic disorder, 51.1% experienced a panic attack after caffeine intake of 400 to 750 mg, none after placebo. In the 6 studies comparing 128 patients to 115 healthy volunteers, 53.9% of patients had an attack, versus 1.7% of volunteers. At these doses, caffeine also increased anxiety in healthy volunteers.
Klevebrant L, Frick A. Gen Hosp Psychiatry 2022;74:22-31. DOI: 10.1016/j.genhosppsych.2021.11.005
These doses, most often 480 mg, are equivalent to approximately five cups of coffee; little is known about lower doses, but caution is warranted for an anxious person.
Digestion is the third point. Many liquid boosters contain polyols, such as glycerol, or sweeteners. A systematic review of 79 studies shows that polyols can cause, depending on the dose, bloating, abdominal discomfort, and a laxative effect, in healthy volunteers as well as in people suffering from irritable bowel syndrome. Our Liquid Booster contains polyols: excess can have a laxative effect, another reason to respect the 10 ml dose.
Who should abstain: interactions and cumulative effects
A systematic review of 381 studies, published in 2017, serves as a reference for caffeine. It concludes that, in healthy adults, consumption up to 400 mg per day is not associated with manifest adverse effects on the heart, behavior, reproduction, or bones; up to 300 mg per day in healthy pregnant women; and that 2.5 mg per kilogram per day remains an appropriate reference in children and adolescents, due to insufficient data. The authors call for better study of more sensitive individuals.
This reference applies to total daily caffeine: coffees, teas, caffeinated beverages, and supplements add up. Our article how many coffees per day helps keep track of this.
| Situation | What studies show | Recommended action |
|---|---|---|
| Hypertension, antihypertensive treatment | +8.1 mmHg systolic after 200 to 300 mg of caffeine, for at least 3 hours | Booster not recommended; medical advice for any caffeine supplementation |
| Arrhythmia, heart disease | Ventricular ectopics of 102 to 154 per day with coffee in 100 adults | Cardiologist's opinion before any use |
| Diabetes, antidiabetic treatment | Ginseng: −0.31 mmol/L fasting blood glucose over 16 trials | Liquid booster, Red Ginseng, and Tribulus terrestris not recommended |
| Panic disorder, anxiety | 51.1% of seizures after 400 to 750 mg in patients | Abstain or seek medical advice |
| Pregnancy, breastfeeding | Reference of 300 mg of caffeine per day, from all sources, during pregnancy | No booster |
| Children and adolescents | Reference of 2.5 mg per kilogram per day, due to lack of data | No booster |
| Antidepressant or stimulant treatment | No interaction study retained; medical precaution, as caffeine adds to other stimulants | Consult your doctor or pharmacist |
Caffeine : add up coffee, tea, caffeinated beverages, guarana and any supplement containing it; a booster should never be added to a pre-workout on the same day. Ginseng and tribulus : our Liquid Booster contains them, as does our Men's Libido formula; our Tribulus terrestris and our Red Ginseng also provide them. Combining them amounts to accumulating these plants. Treatments : antihypertensives and antidiabetics are among the contraindications of the Liquid Booster; for an antidepressant, stimulant, or any long-term treatment, seek the advice of your doctor or pharmacist.
Serious cases, doping and contamination
Serious accidents do exist, but they are rare and mainly concern massive doses. A systematic review identified 92 deaths in which caffeine was the sole identified cause; they more often affected infants, patients with psychiatric disorders and athletes. Serious complications, seizures and arrhythmias, appear from 15 mg of caffeine per liter of plasma. In another review of 51 deaths, caffeine had been taken in tablet or powder form; the author considers it unlikely to reach a toxic dose with beverages alone.
Regarding energy drinks, a review of 43 reports published from 1980 to 2014 describes adverse effects mainly cardiovascular and neurological, primarily in adolescents and young men, which the authors link, without demonstrating it, to caffeine and other stimulants. These reports signal a risk without establishing causality for each case or its frequency.
For athletes subject to anti-doping controls, the main risk is not caffeine but contamination. A systematic review of 44 studies estimates that approximately 9 to 15% of analyzed supplements contained prohibited substances or undeclared pharmacological agents, especially stimulants and anabolic agents. Contamination was most frequent in pre-workouts, weight loss products and muscle-building products.
Use a booster cautiously
The steps below are practical advice, not study results, for healthy adults.
The caffeine content per dose of our liquid Booster is not detailed on its product sheet. If you are sensitive to caffeine or have a risk factor, consult your doctor or pharmacist before using it.
A liquid booster with 4 plants : acerola standardized in vitamin C, ginseng, tribulus and guarana standardized in caffeine, in a 250 ml bottle with red berry flavor. 10 ml in your water bottle, to drink during training.
View the liquid BoosterFor sustained strength over the weeks, also discover our creatine in capsules, to take daily.
Frequently asked questions
What is the difference between a booster and a pre-workout?
A booster focuses on energy, with caffeine and plants, often in liquid form. A pre-workout is generally a multi-ingredient powder that adds beta-alanine, citrulline, creatine or taurine to caffeine. In both cases, caffeine is the ingredient with the best documented immediate effect.
Is a booster dangerous for health?
In a healthy adult who respects the dose and does not combine multiple sources of caffeine, documented side effects include a temporary increase in blood pressure, heart palpitations, nervousness and shortened sleep. Serious cases reported mainly concern massive doses of caffeine in tablets or powder form, or energy drinks in adolescents and young men.
What caffeine dose before exercise?
A position statement by sports nutrition experts recommends 3 to 6 mg per kilogram of body weight, or 210 to 420 mg for 70 kg, most often 60 minutes before exercise. The minimum effective dose could be 2 mg per kilogram. Very high doses, around 9 mg per kilogram, are accompanied by frequent side effects and do not appear necessary.
When to take a booster before training?
Studies on caffeine most often use a dose 60 minutes before exercise. Some liquid boosters are diluted and consumed during the session: follow the product instructions. To protect sleep, a meta-analysis recommends at least 8.8 hours between a coffee and bedtime, and 13.2 hours for a pre-workout dose.
Is guarana an effective natural booster?
Guarana acts mainly through its caffeine content. In a trial with 11 endurance athletes, 500 mg of extract containing 130 mg of caffeine increased work output during a time trial, with a trivial to small effect. In young footballers, it did not improve jumping, sprinting or agility. It counts toward your daily caffeine total.
Does tribulus increase testosterone or strength?
Trials show no gains in strength or muscle mass in athletes, and no solid evidence of increased testosterone in men. In 22 rugby players, 450 mg per day for 5 weeks did not increase strength or lean mass more than placebo. A review of 10 studies and 483 men shows that 8 of 10 studies find no change in androgen hormones.
Does ginseng improve endurance?
Results are inconsistent. A meta-analysis of 5 studies and 90 participants, funded by an industrial company that employed four of its five authors, finds an average effect on time to exhaustion, with a risk of imprecision and publication bias. On fatigue, 19 trials show no significant overall effect, but a reduction in general fatigue.
Can you take a booster in the evening?
Better to avoid it. A meta-analysis of 24 studies shows that caffeine reduces sleep by 45 minutes on average and deep sleep by 11.4 minutes. Reserve boosters for morning or early afternoon sessions.
Who should not take a booster?
Pregnant or nursing women, children and adolescents, people with high blood pressure or suffering from a heart rhythm disorder or heart disease, anxious people or those prone to panic attacks, and those taking antihypertensive or antidiabetic medication. If taking antidepressants or stimulants, seek medical advice.
Can a booster test positive in a doping control?
The main risk comes from contamination: a review of 44 studies estimates that 9 to 15% of analyzed supplements contained banned or undeclared substances, especially stimulants and anabolics, particularly in pre-workouts and weight loss or muscle-building products.
Sources
The studies cited below were identified via PubMed.
- Guest N, Corey P, Vescovi J, El-Sohemy A. Caffeine, CYP1A2 genotype and endurance performance in athletes. Medicine and Science in Sports and Exercise, 2018;50(8):1570-1578. DOI
- Grgic J, Grgic I, Pickering C, et al. Caffeine and exercise performance: an umbrella review of 21 published meta-analyses. British Journal of Sports Medicine, 2020;54(11):681-688. DOI
- Guest NS, VanDusseldorp TA, Nelson MT, et al. Position statement: caffeine and exercise performance. J Int Soc Sports Nutr, 2021;18(1):1. DOI
- Wong O, Marshall K, Sicova M, et al. CYP1A2 genotype modifies the effects of caffeine on muscle strength in competitive male athletes. International Journal of Sport Nutrition and Exercise Metabolism, 2021;31(5):420-426. DOI
- Gonçalves LS, Painelli VS, Yamaguchi G, et al. Dispelling the notion that habitual caffeine consumption alters the performance response to acute caffeine intake. Journal of Applied Physiology, 2017;123(1):213-220. DOI
- Penna EM, Harp A, Hack B, et al. Guarana, but not a low dose of caffeine, improves cycling time trial performance compared to placebo. International Journal of Sport Nutrition and Exercise Metabolism, 2024;34(1):30-37. DOI
- Estrázulas JA, Pereira Dos Santos F, Taborda Machado AJ, et al. Effects of acute guarana intake on soccer player performance: a randomized, crossover, placebo-controlled study. J Am Nutr Assoc, 2024;43(8):671-677. DOI
- Bucci LR. Selected plants and physical performance in humans. American Journal of Clinical Nutrition, 2000;72(2 Suppl):624S-636S. DOI
- Ikeuchi S, Minamida M, Nakamura T, et al. Exploratory systematic review and meta-analysis of Panax genus plant intake on exercise endurance. Nutrients, 2022;14(6):1185. DOI
- Morgans R, Scholten JS, Rhodes D, et al. Effect of Panax ginseng on markers of muscle damage induced by resistance training: systematic review. Journal of Sports Medicine and Physical Fitness, 2024;64(10):1048-1059. DOI
- Li X, Yang M, Zhang YL, et al. Ginseng and ginseng-based formulas against fatigue: systematic review and meta-analysis. Journal of Integrative and Complementary Medicine, 2023;29(8):468-482. DOI
- Shishtar E, Sievenpiper JL, Djedovic V, et al. Effect of ginseng (Panax genus) on glycemic control: systematic review and meta-analysis of randomized trials. PLoS One, 2014;9(9):e107391. DOI
- Li Z, Wang Y, Xu Q, et al. Ginseng and health: umbrella review. Frontiers in Pharmacology, 2023;14:1069268. DOI
- Rogerson S, Riches CJ, Jennings C, et al. Effect of five weeks of tribulus on strength and body composition during preparation of high-level rugby league players. Journal of Strength and Conditioning Research, 2007;21(2):348-353. DOI
- Antonio J, Uelmen J, Rodriguez R, Earnest C. Effects of tribulus on body composition and performance in men trained in resistance training. International Journal of Sport Nutrition and Exercise Metabolism, 2000;10(2):208-215. DOI
- Qureshi A, Naughton DP, Petroczi A. Systematic review on tribulus extract and the origins of its supposed aphrodisiac and performance effects. Journal of Dietary Supplements, 2014;11(1):64-79. DOI
- Vilar Neto JO, de Moraes WMAM, Pinto DV, et al. Effects of tribulus on erectile dysfunction and testosterone in men: systematic review of clinical trials. Nutrients, 2025;17(7):1275. DOI
- Wang Z, Qiu B, Li R, et al. Effects of creatine combined with resistance training on strength gains in adults under 50 years of age: systematic review and meta-analysis. Nutrients, 2024;16(21):3665. DOI
- Braakhuis AJ. Effect of vitamin C supplements on physical performance. Current Sports Medicine Reports, 2012;11(4):180-184. DOI
- Paulsen G, Cumming KT, Holden G, et al. Vitamins C and E impair cellular adaptation to endurance training in humans: a randomized double-blind trial. Journal of Physiology, 2014;592(8):1887-1901. DOI
- Gomez-Cabrera MC, Domenech E, Romagnoli M, et al. Oral vitamin C decreases muscle mitochondrial biogenesis and impairs endurance training adaptations. American Journal of Clinical Nutrition, 2008;87(1):142-149. DOI
- Gualberto PIB, Benvindo VV, Waclawovsky G, Deresz LF. Acute effects of energy drinks on cardiovascular parameters in healthy adults: a systematic review and meta-analysis of randomized trials. Nutrition Reviews, 2024;82(8):1028-1045. DOI
- Grinberg N, Benkhedda K, Barber J, et al. Effects of caffeinated energy drinks on cardiovascular responses to exercise in healthy adults: a systematic review and meta-analysis. Applied Physiology, Nutrition, and Metabolism, 2022;47(6):618-631. DOI
- Mesas AE, Leon-Muñoz LM, Rodriguez-Artalejo F, Lopez-Garcia E. Effect of coffee on blood pressure and cardiovascular disease in hypertensive individuals: a systematic review and meta-analysis. American Journal of Clinical Nutrition, 2011;94(4):1113-1126. DOI
- Marcus GM, Rosenthal DG, Nah G, et al. Acute effects of coffee consumption on the health of adults in daily life. New England Journal of Medicine, 2023;388(12):1092-1100. DOI
- Gardiner C, Weakley J, Burke LM, et al. Effect of caffeine on subsequent sleep: a systematic review and meta-analysis. Sleep Medicine Reviews, 2023;69:101764. DOI
- Kocak A, Georgousopoulou E, Knight-Agarwal CR, et al. Effect of caffeine consumed before late afternoon or evening training or competition on sleep: a systematic review and meta-analysis. Sports, 2025;13(9):317. DOI
- Klevebrant L, Frick A. Effects of caffeine on anxiety and panic attacks in patients with panic disorder: a systematic review and meta-analysis. General Hospital Psychiatry, 2022;74:22-31. DOI
- Lenhart A, Chey WD. Systematic review of the effects of polyols on digestive health and irritable bowel syndrome. Advances in Nutrition, 2017;8(4):587-596. DOI
- Wikoff D, Welsh BT, Henderson R, et al. Systematic review of the potential adverse effects of caffeine in healthy adults, pregnant women, adolescents, and children. Food and Chemical Toxicology, 2017;109(Pt 1):585-648. DOI
- Cappelletti S, Piacentino D, Fineschi V, et al. Caffeine-related deaths: circumstances and at-risk categories. Nutrients, 2018;10(5):611. DOI
- Jones AW. Review of caffeine-related deaths and post-mortem blood concentrations in 51 fatal poisonings. Journal of Analytical Toxicology, 2017;41(3):167-172. DOI
- Ali F, Rehman H, Babayan Z, et al. Energy drinks and their adverse health effects: systematic review of current evidence. Postgraduate Medicine, 2015;127(3):308-322. DOI
- Al-Saad N, Aljaal S, Alessa J, Santhosh ME. Systematic review of undeclared banned substances and pharmacological adulterants in dietary supplements: prevalence, detection and risks in sport. Frontiers in Sports and Active Living, 2026;8:1740663. DOI
