Time to ‘Power-Up’ Esports Performance Nutrition: A Systematic Scoping Review

Highlights

• Early evidence suggests that esport players may have sub-optimal dietary habits that are detrimental to their health, despite believing that diet is important for performance.
• Caffeine may be an effective ergogenic aid in some circumstances but evidence on the benefits of other nutritional supplements is limited.
• More research is needed to understand the optimum diet and use of supplements to aid performance – and whether this varies according to game type.

Introduction

Esports (electronic sports) involves playing video games, such as first-person shooter (FPS), real time strategy (RTS) and multi-player online battle arena (MOBA), in competitive tournaments (1). Tournaments run year-round and are huge commercial and popular events. The International 10 (a Dota 2 tournament) was watched by over 2.74million people (2). Interest in esports is predicted to continue to grow, with the industry expected to be worth $1.87bn by 2025 (3). With this growth has come increased professionalisation of the sport and interest in what drives success (4).

Performance in esports is linked to aspects of cognitive skills such as reaction times, motor skills and visual processing speed (5). Being able to focus for prolonged periods, recover from setbacks and find ‘flow’ (a state of focussed concentration) are also seen as important determinants of success (6). Competitive matches are believed to trigger a sympathetic nervous system response in players, leading to a rise in heart and respiratory rates (7). Maintaining performance over tournaments that can last 8hrs or more requires extensive practice, with esports athletes playing from 5.5hrs-10+hrs a day according to competitive level (4). However, such intense training has also been linked to negative health impacts, such as low bone mineral density, musculoskeletal injuries, sleep disturbances, eye strain and cardiovascular sequalae (8–10). Recognition of these issues, alongside the high rewards for success in esports, has driven an increasing role for the sports sciences in training and competition – including for sports nutrition (11).

It is well documented that overall diet, and some specific nutrients or ergogenic aids (a technique or substance used for the purpose of enhancing performance, i.e. caffeine (12)), may have a role in protecting and enhancing cognitive performance (13, 14). This has been demonstrated in various subgroups of the general population (15,16), including technical and skill-based athletes, military personnel, and pilots (17,18). Moreover, several narrative reviews have highlighted the potential for applying these performance nutrition learnings to esports (19,20). However, relatively little is known about the dietary intake of esports players. There is some evidence that increased duration of recreational videogame playing is linked to higher consumption of sugar-sweetened beverages and snacking, but it is unclear whether this applies to competitive esport athletes (1). A systematic review of health behaviours in esport suggested that players are aware of the benefits of a healthy lifestyle and avoid many of the deleterious behaviours linked to videogaming but did not look at dietary intake and performance (21).

Therefore, there is a need to establish what is known about the diet and nutritional intake of esports athletes and how it may relate to performance. As this is a relatively new area of research, a systematic scoping review is the most appropriate methodology. Systematic scoping reviews are used to methodically map the existing literature in an emerging area, recording the types and range of research, highlighting common themes and identifying potential gaps (23). The results of this review will help guide evidence-based practice and highlight avenues for future research.

Review objective:

The aim of this scoping review is to map the existing evidence on the nutritional intake of esports athletes and how it relates to performance. The secondary objectives are to: i) characterise research in the area to date; ii) highlight research themes, and; iii) identify gaps and potential priorities for future research.

Methods

This review will follow the protocol of the Joanna Briggs Institute (JBI) methodology for scoping reviews (23), based on Arksey and O’Malley’s framework (24). Items will be reported in line with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRIMSA-ScR) (22).

Eligibility criteria:

Population

The scoping review included studies where the participants were characterised as esport or competitive video game players of any level (ie. participating in official matches or tournaments). This included athletes of any gender, age, and nationality. ‘Active’ (ie. motionbased) gaming was excluded due to it not currently being used in any popular esports tournament and the different physiological demands.

Concept

Studies that explored dietary habits, nutritional intake and interventions were considered. This included the use of supplements and ergogenic aids.

Context

The review considered studies in any setting or country that reflect training or competition scenarios.

Types of studies

Original peer reviewed research of any methodology was included. Studies were in English or had translations available. No date limits were set.

Search strategy

An initial limited search was conducted in MEDLINE to identify studies in this area. This was then used to establish a search strategy for MEDLINE (Ovid; 1950- present) and SPORTSDISCUS (EBSCO; 1892-present) using appropriate keywords, wildcards and Boolean operators. The searches were conducted in August 2023. The following keywords were used: ‘Esports’ OR ‘Electronic Sports’ OR ‘competitive video gaming’ OR ‘gamers’ AND ‘nutrition*’ OR ‘intake’ OR ‘diet*’ OR ‘supplements’ OR ‘ergogenic’.

Selection of sources of evidence

Following the search all identified citations were collated and uploaded to ‘REFWORKS V’ (ProQuest) and duplicates removed. Titles and abstracts were screened to determine eligibility. Full texts of the remaining papers were read to determine inclusion. Reasons for exclusion of any full text studies were recorded for reporting. The reference lists of those studies that met the review criteria were then combed to identify any other eligible studies.

Data charting and items

Data was extracted from the included papers into a data extraction tool developed and tested by the author. Data on authors, year, country of study, aim of study, participants (including age, sex, body mass index (BMI), level of esports player, and hours played per week), methodology, outcome measures and key findings were extracted.

Data presentation

Results were summarised in tables (see Tables 1 and 2). These included author, year of publication, study design and key findings.

Results

138 studies were found through the initial searches. 113 of these were excluded based on title. A further 7 were excluded by abstract. 3 were excluded based on the eligibility criteria. The reasons for exclusion are as follows: participants not characterised as esport players or ‘competitive’ gamers (n=2); methodology not in line with scoping review context (doesn’t reflect any esports training or competition scenarios(n=1). 14 studies remained for review. The studies were all published between 2019 and the present day.

Study Characteristics

Participants

Overall, 3154 esports players were included in the studies reviewed with a mean age of 22.7 ± 3.5 years. 92% of participants were male (n=2914) and 8% female (n=290). 6/14 studies only included male participants (27,31,34, 37,38).

There was no common definition of esport player level, however all studies gave an estimate of the number of hours participants spent playing esports per day or week which ranged from >5hrs to 70hrs per week. Four studies (27, 31, 34, 38) defined the level of participants by whether they were a member of a competitive esports team or were receiving regular coaching. One study used a questionnaire developed and trialled by the research team to classify esport player level (26). Three studies asked participants themselves to categorise their playing level via an online questionnaire (28-30). In all other studies the level of esport player was defined by the authors themselves based on their interpretation of hours spent gaming per day/week.

Themes

Following charting of the study data, the following themes were identified: 1) Suboptimal dietary intake; and 2) Impact of nutritional supplements on esports performance. Results relating to these themes are presented below.

1. Suboptimal dietary intake

There were 7 studies which focussed on dietary intake in esports players (25-31) with varying aims. Four studies aimed to describe the diet or health behaviours of participants (28-31); one study sought to compare the gut microbiota, lifestyle and health behaviours of esport athletes with other types of athletes (27); and two explored the link between diet and performance(25,26).

Dietary intake was assessed using a variety of methods: Goulart et al. (26) used an automated 24hr dietary recall software programme to record food intake over 10 days. Kulecka et al. (27) assessed food intake over 3 days using a weighted food diary and remote food photography. Three studies used previously validated questionnaires with two using a food frequency questionnaire (FFQ)(29,30) and one using the PREDIMED questionnaire assessing adherence to a Mediterranean dietary pattern (28). The remaining two studies used self-designed questionnaires with Baumann et al (25) choosing a semi-structured qualitative interview, Rudolf et al. (29) using an ordinal scale for pre-selected food groups.

1.1 Energy and macronutrient intake

Two studies reported on the habitual energy and macronutrient intake of participants. An average total daily energy intake (TDEI) of 1852±698 kcal 2.5g/kg/BM CHO; 0.9g/kg/BM PRO; and 0.9g/kg/BM FAT was reported in a sample of elite esports athletes (n=119), with 66% of participants consumed >10% TDEI from saturated fat (26). Whilst a TEDI of 2155±637kcal was recorded in professional and semi-professional esports athletes with their macronutrient intake reported as 3.37g/kg/BM CHO; 1.34±0.5g/kg/BM PRO; and 1.25±0.48g/kg/BM FAT. The esport athletes in the study also consumed 12% TDEI from saturated fat vs 9.97% in student controls (p<0.05) (27).

The impact of macronutrient profile on performance was considered in three studies (25, 26, 29). Esport athletes who consumed >0.8g/kg/BM/day of protein demonstrated higher gamingrelated cognitive performance (as measured using specialised software) (26). Baumann et al.’s (25) qualitative interviews noted that a diet high in refined carbohydrates and fatty foods was considered detrimental to performance. Finally, Rudolf et al. (29) reported that most participants in their survey believed that ‘balanced nutrition’ had a positive impact on performance (“very positive”: n = 231; 21.7%; “quite positive”: n = 521; 48.9%).

1.2 Fruit and vegetable consumption

Fruit and vegetable consumption was reported in 5 studies (26, 28- 31); Goulart et al’s (26) US based study found that participants consumed an average of 1.1±0.6 portions of vegetables per day and 0.4±0.6 of fruit. Szot et al. (31) meanwhile reported that 67.8% of participants consumed vegetables once a day or less and similarly 66.9% ate fruit once a day or less. Both German studies (29, 30) reported slightly higher average intakes with gamers and esports athletes in their samples consuming 1.7±1.6 servings of vegetables with 0.9±1 fruit per day, and 2.7±1.8 portions fruit and vegetables combined respectively. All 5 studies noted that mean intake by participants failed to meet the relevant national guidelines in their country for consumption with Rudolf et al (29) and Ribeiro et al (28) noting that only 11% and 15.5% of their samples respectively met the 5-a-day recommendation.

Goulart et al. (2023) found that fruit and vegetable intake was significantly correlated with better cognitive performance (r=0.272; p=0.003). Rudolf et al. (29) also noted a non-significant trend for professional esports players to consume more fruit and vegetable portions per day than non-professionals (3.5+2.2 vs. 2.7±1.8 portions a day; p=0.46) but this wasn’t replicated in a similar group-wise comparison by Soffner et al. (30). Soffner et al. (30) noted that both fruit and vegetable consumption were positively associated with self-reported health status (rho=0.19 and 0.14 respectively; both p<0.01)

1.3 Dairy consumption

Three studies reported dairy consumption. Goulart et al. (26) reported an average consumption of 1.4±0.8 cup equivalents of dairy products a day and noted that 95.7% of esport athletes failed to meet the recommended intake of magnesium and 97.4% consumed vitamin D (26). Soffner et al. (30) noted that that esport athletes consumed significantly fewer portions of dairy foods per day than video gamers (0.4±0.6 portions of milk and 0.7±0.4 portions of cheese in esport athletes vs 0.6±0.9 and 0.8±0.4 in video gamers; p<0.01). Intake was also low in Szot et al.’s (31) study with only 36% of participants consuming milk more than once-a-day.

1.4 Fast food consumption

Fast food consumption was reported in three studies (25,30, 31). Szot et al. (31) reported that fast food was consumed once a day or more by 28.3% of their sample. Whilst a comparison between esport athletes and video gamers (30) found that esport athletes consumed significantly more portions per day than video gamers (0.3+0.4 vs 0.2+0.4 portions per day; p<0.01). Intake of fast food was negatively correlated with self-reported health status (rho - 0.12; p<0.01). Fast food consumption was also negatively associated with performance for many of the participants interviewed in the qualitative study (25), with consumption being cited as causing tiredness and poor focus.

1.6 Energy drinks

Four studies reported regular use of energy drinks by esports athletes (25, 28, 30, 31). Energy drinks were reported as being consumed at least once -per day by 26.6% (31) and 40.9% (28) of participants. Soffner et al. (30) noted a mean weekly intake of 0.4±0.9l in their respondents which was positively correlated with video game playing time (rho=0.14; p<0.01) and negatively associated with health status (rho=0.11; p<0.01). Baumann et al. (25) meanwhile reported that 75% of their sample used energy drinks regularly, drinking at least one 500ml bottle at a time. Whilst energy drinks were cited in their study as being useful for ‘staying awake’ they were ultimately believed to harm performance and mood.

CAF=caffeine; PLA=placebo; BP=blood pressure; HR= heart rate; PEBL= Psychology Experiment Building Language cognitive test battery; POMS = Profile of Mood States; PREDIMED = Prevención de Dieta Meditteránea; TMT-A,B = Trail Making Test A and B; PVT=psychomotor vigilance test; LRT = light reaction test

2. Impact of supplements of performance

Seven studies looked at the possible effect of dietary supplements on performance in esports athletes (31-37). A variety of supplements were studied (see table 2): five of which contained caffeine, either alone (33) or in combination with other ingredients (31, 32, 36, 37). Amounts ranged from 40-44mg per dose (equivalent to ~0.6/g/KG/BM) (32) to 270mg (equivalent to ~3.3g/kg/BM) (31). The remaining studies tested a proprietary blend of 1600mg inositol bonded arginine with inositol. Supplement protocols varied in length from 1 to 30 days (33,32 respectively). Only two of the studies attempted to standardise diet preceding the intervention (32,34), the other studies asked participants to either avoid certain foods, dietary supplements or stimulants. One study (32) asked participants to have fasted for 12hours (overnight) prior to testing and one study provided the athletes with a protein bar in addition to the supplement (31).

ASI+I = arginine-bonded inositol; CAF=caffeine; PLA=placebo; BP=blood pressure; HR= heart rate; PEBL= Psychology Experiment Building Language cognitive test battery; POMS = Profile of Mood States; TMT-A,B = Trail Making Test A and B; PVT=psychomotor vigilance test; LRT = light reaction test

2.1 Cognitive performance

The studies reviewed used a variety of cognitive tests to measure performance. Reaction time was measured specifically by all studies except one (36) with most using the Go-No Go Test either in isolation or as part of the PEBL. Two studies also utilised the Light Reaction Test (33,35) and one an online tool (34). Other cognitive tests varied (see table 2).

The studies trialling arginine-bonded inositol demonstrated limited results. Tartar et al. (35) found a reduction in TMT-B errors (visual scanning and psychomotor speed) 15 minutes post supplementation compared to placebo, but these results weren’t replicated by Sowinski et al. (35).

For the supplements containing caffeine, Sainz et al. (34) found that participants taking 3mg/kg/BM caffeine had faster reaction times than PLA (0.19+0.01 vs 0.20+0.01s; p<0.01). Bloomer et al (32); Leonard et al (33), Tartar et al., (37) and Thomas et al. (38). All other studies testing caffeine in combination with other ingredients failed to show significant improvement versus placebo on cognitive performance (32,33,37,38). Some limited within group differences were noted by three of the studies but these were not consistent across time or type of cognitive test (33, 27,38).

2.2 Game-specific performance

This scoping review examined the existing evidence on nutritional intake and performance in esport athletes. Early findings suggest that, whilst esport athletes consider nutrition important for success and wellbeing, they have some sub-optimal dietary habits. These may have a potentially deleterious effect on performance and long-term health. Moreover, whilst the use of energy drinks is widespread, ergogenic supplements in general have failed to demonstrate performance enhancing effects.

The British Esports Federation recommends that players eat a diet that meets the UK EatWell guidelines (39). However, this review found that they are failing to meet guidelines – consuming more fast food and energy drinks than their peers, too much saturated fat and insufficient fruit, vegetables and dairy. This is concerning because these sub-optimal dietary characteristics are linked to an increased risk of adverse health outcomes, including those prevalent in this population, such as mood disturbance, cardiovascular disease, and reduced bone mineral density (9,11). Indeed, although findings were limited to one study, esport athletes who report these sub-optimal habits also have lower self-reported health status (30)). The low intakes of dairy products, vitamin D and magnesium reported are of particular concern. Prolonged periods of sitting and lack of sunlight exposure due to training and competition have been linked to the high prevalence of reduced bone mineral density found in esport athletes (9, 40). Combined dietary and physical activity-based interventions that support athletes to consume a diet that meets their nutritional needs, including the key micronutrients required for bone health, should be considered. This is particularly pressing given bone mass density typically peaks in the early to mid-20s (41) meaning poor habits in current esport athletes may have lifelong consequences.

Conversely, this review found some evidence that esports players believe a balanced diet, low in refined carbohydrates and ‘fatty foods’, may be beneficial to wellbeing and performance (25, 29). More research is needed to substantiate this but the only empirical study to explore this found that esport athletes consuming adequate protein (>0.8g/kg/BM) and higher vegetable intakes perform better in cognitive tests (26). These findings have some support from studies in the general population: both acute and long-term adequate protein intakes have been linked to better working memory function under high task demands (14). This cognitive domain has been shown to relate to performance in certain types of esport games such as RTS (42). More generally, a ‘Mediterranean’ diet (high in fruit, vegetables, lean protein, complex carbohydrates, and healthy fats) is associated with improved cognitive performance in older adults (43). However, evidence on the extent diet could improve game-specific performance in this population is lacking and more work is needed to explore this.

Whilst there is too little research to draw conclusions on the best dietary composition for performance, there is a notable mismatch between what esports athletes are reported to consume and what may be most beneficial for their health and performance. Further research is therefore needed to explore the barriers to healthy eating in this population. None of the studies reviewed directly explored barriers to healthy eating but irregular mealtimes, lack of time and tiredness were described in several of the studies (25;31) These are all factors that have been identified as barriers to healthy eating in young adult men (44). Whilst some elite esports athletes may live in catered facilities with well-planned diets (45), for those at more junior levels there is a need to understand and develop interventions to help them establish healthy eating behaviours that will support their career development.

Research to date suggests that the benefits of supplements on esports performance are uncertain. Arginine-bonded inositol only showed significant results in one of the two studies where acute supplementation reduced errors compared to placebo in the visual scanning element of the TMT (36). Whilst both studies highlighted some within-group results these were inconsistent and, arguably, not meaningful. More research, sufficiently powered, is needed to examine these findings and their applicability to esports game performance.

Most studies tested caffeine, either alone or compounded with other ingredients. Whilst caffeine and energy drinks have been shown to have a positive impact on cognitive skills (46, 47), the studies reviewed reported mixed findings. The four studies that used caffeine in conjunction with other ingredients demonstrated equivocal results. Significant findings were mainly small, within-group effects and in inconsistent cognitive domains. This may be partly due to methodological and conceptual issues.

Doses of caffeine varied from 40mg to 270mg (with no adjustment for body weight) and 2/4 studies did not control for habitual caffeine intake. Participants may have therefore received ineffective doses or already have some degree of tolerance to the ergogenic effects of caffeine.

The only study that reported a clear benefit to game performance used a well-researched dose of caffeine with a clearly defined population and game-specific performance test. Sainz et al. (34) reported that 3mg/kg/BM improved both hit accuracy and reaction times in professional esport athletes playing a FPS under conditions described as ‘stressful’. Caffeine has been found to have most ergogenic benefit during cognitive tasks that involve attention and vigilance, such as FPS-type games where target identification is essential, and in sleep-deprived individuals or stressful conditions (46). Esport games that focus on different skills, such as RTS, may not see the same performance benefits and further research is needed to explore this.

Half of the studies (7/14) in this scoping review were focussed on trialling supplements to improve esports performance. Despite mixed evidence on the efficacy of supplements, there is evidence that esports players not only already use them or know peers who take them (48)) but feel pressure to take them (49).).This study found that energy drinks are habitually consumed by esports players despite some feeling that they were detrimental to wellbeing. This may partly reflect the ubiquity of sports supplements sponsorship and marketing in esports (50). However, it also highlights that the initial reticence of sports science to engage with esports (51) has created a vacuum in which the supplements agenda has flourished whilst performance nutrition foundations have been overlooked.

Limitations

The findings of this scoping review are limited due to several factors. There is a lack of clarity in the literature on what defines an esport athlete and their competitive level. This blurring of descriptors has been noted in previous reviews in this area (1) (and may have confounded results. Work between researchers to establish a consensus on terminology is needed. Secondly, the wide variety of cognitive tests used haven’t been shown to relate to esports performance (52). Game performance measures may be more useful but these need to be title/game specific and what constitutes a meaningful improvement in a competitive setting needs to be established.

Findings from the diet studies will be limited by the methodological and practical difficulties in accurately recording food intake in study populations – it is difficult to control for confounding factors such as participants activity levels, supplement use or behaviour change in response to taking part in a study (53). The study results reported were mainly based on food frequency questionnaires which may be flawed due to participants inability to recall past behaviour accurately (54). One study used a 3-day weighted food diary which is potentially more accurate but is more expensive and burdensome for both participants and researchers. Moreover, only two studies were able to compare intake in esport athletes to that of similar age peers (26,27). The majority of participants in the studies are ‘emerging adults’ (i.e., those between ages 18-25) and previous studies on those in this age group have found similar attitudes and behaviours around food (55) – therefore it is unclear to what extent esport players’ dietary behaviour is distinct compared to others their age.

Conclusions

This scoping review provides an outline of current research into the nutritional intake and performance of esport players. Esports athletes may be failing to consume a diet that meets their nutritional needs, and this has potential consequences for their health and performance. Whilst, ergogenic aids and supplements have been of keen interest, this review found that, to- date, these have failed to show significant game-related performance benefits.

Implications for research

Further research is needed into the optimum diet for esports athletes and strategies for helping them achieve this given the potential barriers to healthy eating and the demands of training. Future study designs should be careful to clearly delineate the level and type of participants and incorporate performance measures that are game-specific and relevant to competitive scenarios.

Implications for practice

Supplements may be popular and promoted to athletes, but it is important to stress that, to date, there is little evidence to support their use. Caffeine may be appropriate for some game- types but should be carefully considered and trialled on an individual basis. Improving the basic diet of esport athletes may not only be beneficial to performance but can also help secure their health, wellbeing and careers for the future.

Acknowledgements

JF helped with study design, quality control and comments on drafts.

Funding and declaration of interests

This work formed part of a post-graduate programme for the first author. There are no conflicts of interest.

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