Abstract
Background
It is anecdotally recognized that commercial gym users assume supplements in order to improve performance or health. However, dietary behaviours of people and athletes attending commercial gyms have been poorly studied. The exact amount and frequency of dietary supplements consumption are still needed to be investigated. The main purpose of this study is to understand the quantity and quality of food intake, as well as dietary supplementation in people attending commercial gyms. Secondly to compare the city centre and the suburbs of Palermo, Italy.
Methods
A face-to-face questionnaire was administered to 561 subjects, 207 from the city centre (CC) and 354 from the suburbs (SB) of Palermo, Italy. Frequency of protein supplements use and association with dietary behaviours were investigated. Subsequently, the frequency distribution was used for demographic assessment.
Results
Frequency of protein consumption was similar in both groups (30% for CC and 28.8% for SB). Males show greater consumption percentages than females (30.5% in males and 6.9% in females). Milk and chicken are the most frequently consumed foods. Data show that non-supplement users (NSU) consume significantly more snacks and bakery products than supplement users (SU) (P < 0.001). While, SU consume significantly higher quantities of vegetables, nuts, fresh fish, eggs and canned tuna (P < 0.001). SU consume less low protein food and higher protein foods than NSU. No differences were found between CC and SB.
Conclusions
Protein consumption among commercial gym users is 30% for the CC and 28.8% for the SB. Significant differences were found between CC and SB females, underlining an interesting discrepancy, indicating to dietary supplement industries regarding regional implications. Subjects that use protein supplements also consume larger quantities of high protein food compared to NSU. NSU also eat higher proportions of unhealthy food compared to SU.
Electronic supplementary material
The online version of this article (doi:10.1186/1550-2783-11-30) contains supplementary material, which is available to authorized users.
Introduction
The use of supplements is a generally accepted and widespread practice for a variety of reasons. Health, physical appearance, performance and nutritional purposes are usually the main reasons inducing such consumption [Citation1]. Active individuals use supplements to build muscle, gain strength or prevent future diseases and illnesses [Citation2, Citation3]. The typologies of supplements ingested are related to the age, gender, specific exercise programs and practiced sport [Citation4–Citation6]. Kaufman et al. found that older people were more likely to take multivitamin and mineral supplements, while younger people were more likely to take creatine [Citation4]. Older adults are more likely to use supplements for site-specific health reasons (e.g., bone, heart, eye). Whereas, younger adults are more likely to use products with a short-term effect, either to enhance energy or boost immune function. It has also been reported by Bailey et al. that both men and women use supplements for very specific gender related reasons (e.g., heart and bone health, respectively) [Citation7]. Furthermore, scientific researchers have shown that people have different opinions about the use of supplements [Citation5, Citation6, Citation8–Citation15] and the appropriate food to eat. As reported by Bianco et al. [Citation16] and colleagues [Citation5, Citation6], proteins are the most widely ingested supplements in people attending commercial gyms. Moreover, there is an increased interest in what is considered “proper” nutrition [Citation17–Citation19]. However, gym users might follow dietary regimes that are less or more than optimal [Citation20, Citation21]. According to the nutrition transition model [Citation22], the dietary patterns of a society become more diversified amidst urbanization and higher income levels. This dietary diversity is often associated with an increase in the proportion of fats and sweeteners [Citation23]. Dietary behaviour is in fact a complex phenomenon; food-based approaches are regarded as the long-term strategy for improving nutrition. These require significant efforts and appropriate planning in order to include certain specific macronutrients or supplements in everyday’s diet [Citation24]. Dieting or unhealthy eating practices, (such as eating foods deemed as “bad” by the dieter), may be associated with long-term weight gain [Citation25].
The purpose of this investigation is to understand frequency of food intake of common foods and how this consumption varies between those who use dietary supplements and those who don’t. In addition we are interested in understanding the eventual differences between the city centre and the suburbs of Palermo in resistance trained men and women.
Methods
Participants
Permissions to conduct a survey were obtained from the managers of a representative number of twelve commercial gyms located in the suburbs of Palermo in 2013. We considered suburb gyms (SB) as being located on the outskirts of Palermo (Range from 20 km to 60 km). The gyms were identified by using a database of the CONI register (National Olympic Committee Register for Sport and Fitness Associations). Through this fitness database, a number of 1200 people (20% of the total number) (Age ranging between 13 and 68 years old 26 ± 9 yrs; Females 27 ± 9 yrs, Males 26 ± 9 for the CC and 29 ± 10 yrs, Females 31 ± 10, Males 29 ± 10 for the SB), were randomly selected as potential participants. Only fitness and gym attendees who were taking part in strength training courses (Gym, functional fitness, weightlifting, etc.…) have been selected. All gym and fitness users performing aerobic activities (such as aerobic, spinning, step, circuit training, endurance and cardiovascular programs, etc.…) were excluded. On the basis of these inclusion/exclusion criteria, a total of 354 participants were retained for the present investigation. These subjects were consequently compared with those from our previous study (207 participants), carried out in gyms located in Palermo City (CC) [Citation16].
Questionnaire procedure
In order to evaluate the frequency consumption of protein supplements amongst participants, dietary behaviours and other related information, the questionnaire method was adopted [Citation13] (Additional file 1). The same questionnaire has been administered in commercial gyms of the suburbs of Palermo, Italy. Easy understandable definitions of the supplements were provided to the participants (Common and commercial names of products or substances included within the definition of supplement: product intended to supplement the diet that contains one or more dietary ingredients) [Citation26]. Completion of the questionnaire implied the agreement of respective gym users to participate in the study. According to the Italian regulations, ethical approval was not required for this study. The same investigator using the face-to-face interview method during a period of six months administered the questionnaire.
Food classification
Foods were categorized in accordance to their protein content in three categories: Low, medium and high. We considered low content foods with ≤ 10 g of proteins for 100 g of food, medium those with a protein content between 10 and 20 g every 100 g and finally, high content foods with 20-25 g or above accordingly. The protein content percentage of each food was retrieved from the INRAN database (Istituto Nazionale di Ricerca per gli Alimenti e la Nutrizione; Website: http://nut.entecra.it/646/tabelle_di_composizione_degli_alimenti.html).
Data analysis
Data analysis was performed using the EpiInfo software version 7.0 (CDC, Atlanta, GA, US) and Statistica version 8.0 software for Windows (Tulsa, OK, US). The descriptive analysis was performed by calculating the means and standard deviations. Contingency tables were used to assess frequency distribution of protein consumption solely or stratified by gender, frequency of use and food. Differences were assessed by a two-way ANOVA test and a Bonferroni post-hoc test to compare replicate means by row. The associations between the categorical variables under examination were evaluated using contingency tables. Statistical significance was set at P values ≤ 0.05.
Results
Power analysis showed a statistical power of 0.99 and an effect size of 0.6.
Demographic results
561 questionnaires were analysed after the completion of the investigation. Gender stratification has showed 434 male and 137 female participants. The surveyed population was split between supplement users from the CC and the SB for comparison. The CC group comprised of 80 females and 127 male participants while SB group of 47 females and 307 male participants. The majority of the subjects were aged between 18 and 30 years of age.
Frequency distribution
Participants provided information of the frequency of weekly consumption of both supplements and foods. Notwithstanding the CC and the SB have broadly the same frequency of protein supplement consumption (30% and 28.8%), weekly use however differs between groups (Table ).Male gym users demonstrated greater consumption percentages than females. The survey showed that milk is the most frequently consumed food in all groups (68% of CC and 57.8% of SB of the supplement users vs. 53% of CC and 63% of SB of non-users) followed by chicken ( 48% in CC and 50% in SB for the supplement users vs. 21% in CC and 28% in SB for non-users)(Figures & ).
Data also shows that NSU consumed significantly more snacks and bakery products than SU (P < 0.001). Interestingly, the SU consumed significantly higher quantities of vegetables, nuts, fresh fish, eggs and canned tuna (P < 0.001).
Subsequently a comparison between food categories and protein consumption was assessed (Table ).
SU eat less “low protein foods” and more “high protein foods” respect to NSU.
Discussion
Our major interest was to understand the frequency of common foods and how this consumption varies between SU and NSU in commercial gyms. Secondly, the study focused upon the differences in consumption between the CC and SB of Palermo. Previous studies have shown discrepant rates of supplement intake amongst subjects that exercise in gyms [Citation15, Citation27]. These different findings might be explained by different gyms and people enrolled. Probably an under or over-reported use of such supplements, or an incorrect knowledge of what is considered a supplement may lead to such results [Citation28, Citation29]. Proteins are the most widely consumed supplement in commercial gyms [Citation5, Citation6, Citation16], although association of protein supplements and food consumption is a poorly researched field. It is to date unclear whether those more inclined to supplement also have healthier dietary patterns. The foods that constitute the “healthy” dietary pattern are rich in vitamins, minerals and fibers, which are considered protective against non-transmissible chronic diseases [Citation30]. These dietary patterns usually include skimmed dairy products due to low fat content.
In our study we tried to divide, at the best of our knowledge common foods, in three categories according to their protein content. Interestingly, even though no significant results occurred between our main comparison groups (CC and SB), there were significant statistical differences between those users who took supplements and those who didn’t. Participants who took supplements also ate higher protein content foods in respect to those who did not. Another noteworthy observation is the frequency consumption of bakery goods and snacks. Consumption was relatively high in both groups but significantly higher in those who didn’t use protein supplements. The data presented despite not indicating the exact amount of food ingested during each day, provided some estimate of the protein intake (INRAN database). These preliminary results seem to indicate that the participants which regularly use protein supplements have a “healthier” dietary pattern [Citation31]. However, it‘s still uncertain if the total amount of proteins ingested is higher or lower than mean daily requirements. These results give knowledge to coaches and fitness professionals about the frequency and consumption of protein supplements. Secondly, estimation of quantity and quality of food intake of gym adepts of the city centre and the suburbs of Palermo, Italy.
Conclusion
The results show that in resistance trained men and female gym users, the percentage of those that consume proteins is 30% in the CC and 28.8% in the SB of Palermo, Italy. Generally participants who ingest protein supplements also eat higher protein content foods. Other interesting results regard the NSU which declare a higher consumption of bakery products and snacks (foods recognized as unhealthy) respect to SU. Though, it’s not clear if the total amount of protein intake per day (g/Kg) is adequate to the physiological needs of the gym users, as the SU seem to have high protein intakes while the NSU a noticeably lower percentage. Dietary supplement industries might be interested in these research results and might invest in order to understand why this nutritional behaviour is occurring in suburban females. Further investigations are required to gain a more in-depth understanding of protein supplementation.
Additional file 1:Protein Project questionnaire adopted by Bianco et al. 2014.(PDF 449 KB)
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Download TIFF Image (871.5 KB)Acknowledgements
We are grateful to CONI Sicilia (National Olympic Committee). We also want to thank the participants and the fitness/gym centres managers.
We are in debts with Prof. Giovanni Caramazza (CONI Sicilia President).
We are also grateful to Mr. Ryan Osborn (Erasmus Student from Greenwich University) for his invaluable manuscript syntax and grammar corrections.
Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
All authors have effectively contributed to this work in its different production stages. All authors read and approved the final manuscript.
References
- AljaloudSOIbrahimSAUse of Dietary Supplements among Professional Athletes in Saudi ArabiaJ Nutr Metab20132013 245349 3677665 https://doi.org/10.1155/2013/245349 23762541
- WolfeRRProtein supplements and exerciseAm J Clin Nutr200072 551S 557S 1:CAS:528:DC%2BD3cXlsFyhsL0%3D 10919959
- SundellJHulmiJRossiJ[Whey protein and creatine as nutritional supplements]Duodecim; laaketieteellinen aikakauskirja2011127 700 705 21553504
- KaufmanDWKellyJPRosenbergLAndersonTEMitchellAARecent patterns of medication use in the ambulatory adult population of the United States: the Slone surveyJAMA2002287 337 344 https://doi.org/10.1001/jama.287.3.337 11790213
- MorrisonLJGizisFShorterBPrevalent use of dietary supplements among people who exercise at a commercial gymInt J Sport Nutr Exerc Metab200414 481 492 1:CAS:528:DC%2BD2cXnvFajs7c%3D 15467105
- ScofieldDEUnruhSDietary supplement use among adolescent athletes in central Nebraska and their sources of informationJ Strength Cond Res200620 452 455 16686580
- BaileyRLGahcheJJMillerPEThomasPRDwyerJTWhy US adults use dietary supplementsJAMA2013173 355 361 1:CAS:528:DC%2BC3sXntVaitb8%3D
- ApplegateEEffective nutritional ergogenic aidsInt J Sport Nutr19999 229 239 1:STN:280:DyaK1M3ptVyjtw%3D%3D 10362455
- DodgeJRFordMAPerkoMAFrom ephedra to creatine: Using theory to respond to dietary supplement use in young athletesAm J Health Stud200318 111
- LyleBJMares-PerlmanJAKleinBEKleinRGregerJLSupplement users differ from nonusers in demographic, lifestyle, dietary and health characteristicsJ Nutr1998128 2355 2362 1:CAS:528:DyaK1cXotVOnurY%3D 9868181
- MolineroOMarquezSUse of nutritional supplements in sports: risks, knowledge, and behavioural-related factorsNutr Hosp200924 128 134 1:STN:280:DC%2BD1Mvos1Ojtg%3D%3D 19593480
- EliasonBCKrugerJMarkDRasmannDNDietary supplement users: demographics, product use, and medical system interactionJ Am Board Fam Pract199710 265 271 1:STN:280:DyaK2sznt1ersw%3D%3D 9228621
- EldridgeALSheehanETFood supplement use and related beliefs: Survey of community college studentsJ Nutr Educ199426 259 265 https://doi.org/10.1016/S0022-3182(12)80694-7
- BraunHKoehlerKGeyerHKleinerJMesterJSchanzerWDietary supplement use among elite young German athletesInt J Sport Nutr Exerc Metab200919 97 109 19403956
- ErdmanKAFungTSDoyle-BakerPKVerhoefMJReimerRADietary supplementation of high-performance Canadian athletes by age and genderClin J Sport Med200717 458 464 https://doi.org/10.1097/JSM.0b013e31815aed33 17993788
- BiancoAMamminaCPaoliABellafioreMBattagliaGCaramazzaGPalmaAJemniMProtein supplementation in strength and conditioning adepts: knowledge, dietary behavior and practice in Palermo, ItalyJ Int Soc Sports Nutr20118 25 3267647 1:CAS:528:DC%2BC38Xislanurc%3D https://doi.org/10.1186/1550-2783-8-25 22206347
- GhiasvandRAskariGMalekzadehJHajishafieeMDaneshvarPAkbariFBahreynianMEffects of Six Weeks of beta-alanine Administration on VO(2) max, Time to Exhaustion and Lactate Concentrations in Physical Education StudentsInt J Prev Med20123 559 563 3429803 22973486
- AskariGGhiasvandRKarimianJFeiziAPaknahadZSharifiradGHajishafieiMDoes quercetin and vitamin C improve exercise performance, muscle damage, and body composition in male athletes?J Res Med Sci201217 328 331 3526124 23267392
- GhiasvandRDjalaliMDjazayerySKeshavarzSHosseiniMAskariGJaniNFardadNFatehiFEffect of eicosapentaenoic Acid (EPA) and vitamin e on the blood levels of inflammatory markers, antioxidant enzymes, and lipid peroxidation in Iranian basketball playersIran J Public Health201039 15 21 3468972 1:CAS:528:DC%2BC3cXhtVGksL7I 23112985
- KirchnerEMLewisRDO’ConnorPJBone mineral density and dietary intake of female college gymnastsMed Sci Sports Exerc199527 543 549 1:STN:280:DyaK2MzhtFOjtA%3D%3D https://doi.org/10.1249/00005768-199504000-00012 7791585
- Al-HouraniHMAtoumMFBody composition, nutrient intake and physical activity patterns in young women during RamadanSingap Med J200748 906 910 1:STN:280:DC%2BD2srovVChsw%3D%3D
- PopkinBMThe nutrition transition in low-income countries: an emerging crisisNutr Rev199452 285 298 1:STN:280:DyaK2M%2FnsFGluw%3D%3D https://doi.org/10.1111/j.1753-4887.1994.tb01460.x 7984344
- DrewnowskiAPopkinBMThe nutrition transition: new trends in the global dietNutr Rev199755 31 43 1:STN:280:DyaK2szgtVWjtg%3D%3D https://doi.org/10.1111/j.1753-4887.1997.tb01593.x 9155216
- BhuttaZASalamRAGlobal nutrition epidemiology and trendsAnn Nutr Metab201261 Suppl 1 19 27 1:CAS:528:DC%2BC3sXhsV2ktb0%3D https://doi.org/10.1159/000345167 23343944
- Neumark-SztainerDWallMStoryMStandishARDieting and unhealthy weight control behaviors during adolescence: associations with 10-year changes in body mass indexJ Adolesc Health201250 80 86 3245517 https://doi.org/10.1016/j.jadohealth.2011.05.010 22188838
- Gayle NicholasSDietary Supplement Health and Education ActEncyclopedia of Clinical Pharmacy. Volume null2013 Spain Y.W Taylor & Francis 260 264
- ErdmanKAFungTSReimerRAInfluence of performance level on dietary supplementation in elite Canadian athletesMed Sci Sports Exerc200638 349 356 https://doi.org/10.1249/01.mss.0000187332.92169.e0 16531906
- NieperANutritional supplement practices in UK junior national track and field athletesBr J Sports Med200539 645 649 1725305 1:STN:280:DC%2BD2MvltVOntg%3D%3D https://doi.org/10.1136/bjsm.2004.015842 16118303
- Sundgot-BorgenJBerglundBTorstveitMKNutritional supplements in Norwegian elite athletes–impact of international ranking and advisorsScand J Med Sci Sports200313 138 144 1:STN:280:DC%2BD3s7ivVeqtA%3D%3D https://doi.org/10.1034/j.1600-0838.2003.10288.x 12641646
- LockKPomerleauJCauserLAltmannDRMcKeeMThe global burden of disease attributable to low consumption of fruit and vegetables: implications for the global strategy on dietBull World Health Organ200583 100 108 2623811 15744402
- FingerJDTylleskarTLampertTMensinkGBDietary behaviour and socioeconomic position: the role of physical activity patternsPLoS One20138 e78390 3819390 1:CAS:528:DC%2BC3sXhslGrurnO https://doi.org/10.1371/journal.pone.0078390 24223150
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