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The impact of nutrition education on nutrition knowledge and adherence to the Mediterranean Diet in adolescent competitive swimmers
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ARTICLE IN PRESS Journal of Science and Medicine in Sport xxx (2016) xxx–xxx
Contents lists available at ScienceDirect
Journal of Science and Medicine in Sport journal homepage: www.elsevier.com/locate/jsams
Original research
The impact of nutrition education on nutrition knowledge and adherence to the Mediterranean Diet in adolescent competitive swimmers Elena Philippou a,∗ , Nicos Middleton b , Constantinos Pistos c , Eleni Andreou a , Michael Petrou d a
Department of Life and Health Sciences, University of Nicosia (UNIC), Cyprus Department of Nursing, School of Health Sciences, Cyprus University of Technology, Cyprus c Department of Chemistry, West Chester University, United States d Centre for Leisure, Tourism & Sport Research & Development, UNIC, Cyprus b
a r t i c l e
i n f o
Article history: Received 30 March 2016 Received in revised form 19 August 2016 Accepted 22 August 2016 Available online xxx Keywords: KIDMED Index Athlete education Adolescent athlete Parental education
a b s t r a c t Objectives: Nutrition education of adolescent competitive swimmers is under-studied although their diet and nutrition knowledge are generally poor. This study aimed to assess the impact of nutrition education on nutrition knowledge and adherence to the Mediterranean Diet (MD) and explore the effect of parental education on the swimmers’ MD adherence. Design: A pre–post measurement interventional study was carried out. Methods: A half-day nutrition education session was delivered for the swimmers and a separate session for their parents. At baseline and 6-weeks post-workshop, a short nutrition knowledge assessment of food sources of nutrients and the MD composition as well as adherence to the MD using the KIDMED Index were undertaken. The swimmers’ parents also completed the KIDMED Index to evaluate the swimmers’ diet. Results: Thirty-four competitive swimmers (age: 15.2 ± 1.5 yr, 23 males) and 22 of their parents participated in the study. There was an improvement in MD adherence with 47% having good adherence post-intervention vs 21% at baseline (p < 0.01) and an increase in the KIDMED Index score (median [interquartile range]: 5.0 [4.0–7.0] vs 7.0 [7.0–9.0]; p < 0.01)). There was also an increase in the swimmers’ nutrition knowledge assessment score (median [IQR]: 7.0 [5.0–8.0] vs 7.0 [6.0–8.0], p < 0.05)), and a trend for a lower score post-intervention in swimmers whose parents did not participate compared to those whose parents participated (6.0 [6.0–7.8] vs 7.0 [7.0–8.0], p = 0.063). Conclusions: The intervention improved adherence to the MD and increased nutrition knowledge. The findings support parental participation in nutrition education. © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.
1. Introduction Adoption of healthy eating by adolescent athletes is imperative in order to meet their nutritional needs, promote health and enhance sport performance.1,2 Although the importance of ongoing nutrition education of young athletes, coaches and parents is highlighted by sports organisations internationally,2–4 nutrition education in adolescent athletes and specifically swimmers is not well-studied. Nevertheless, the need to educate athletes is evident
∗ Corresponding author. E-mail addresses: [email protected], [email protected] (E. Philippou).
as shown in a sample of elite athletes, a large proportion of whom aged ≤18 years old, who scored poorly on the ‘sources of nutrients’ section of a questionnaire compared with non-athlete controls.5 Furthermore, a systematic review of nutrition knowledge in competitive, recreational or elite athletes over the age of 13 found that although athletes’ nutrition knowledge was equal to or better than that of non-athletes, it was lower than that of non-athlete comparison groups.6 It is of note, however, that the comparison groups included nutrition students possibly skewing the results of the study.6 A number of studies have shown that adherence of athletes to dietary recommendations was poor, while intake of important micronutrients was insufficient.7,8 One of the strategies to improve adolescent swimmers’ diet may be through enhancement of their nutrition knowledge. As
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Please cite this article in press as: Philippou E, et al. The impact of nutrition education on nutrition knowledge and adherence to the Mediterranean Diet in adolescent competitive swimmers. J Sci Med Sport (2016), http://dx.doi.org/10.1016/j.jsams.2016.08.023
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noted by the International Journal of Sport Nutrition and Exercise Performance Consensus Statement on ‘Nutrition for Swimming’, this should be achieved through a carefully designed nutrition education program aiming to progressively develop nutrition knowledge.9 Previous research in children showed that multicomponent nutrition interventions with parental involvement were the most successful in improving dietary habits.10 Such nutrition education programs are under-studied among adolescent athletes however, with only some exceptions producing mixed results.11,12 The Mediterranean Diet (MD) is widely acknowledged as one of the healthiest dietary patterns for degenerative disease prevention.13 It is in line with recommendations on nutrition for athletic performance, where it is suggested to increase the consumption of whole grains and cereals, beans, and legumes, consume five or more daily servings of fruits and vegetables and lean cuts of meats.1 Additionally, the MD is based on carbohydrate-rich foods which would be expected to enhance athletic performance aiding both performance and recovery.14 Thus, the MD may be used by adolescent athletes as a basis for dietary planning, taking into account the individual athlete’s characteristics such as energy and nutrient requirements and athletic goals and ensuring that specific sports recommendations e.g., fluid intake are also adhered to. With the above in mind, an intervention study was designed aiming to assess the impact of a nutrition workshop on nutrition knowledge and adherence to the MD in adolescent competitive swimmers and explore the effect of parental education on the athletes’ adherence to MD. It was hypothesized that nutrition education would be beneficial on knowledge and adherence to the MD and that parental involvement would result in further benefits to the assessed outcomes.
2. Methods A pre–post measurement interventional study was carried out among young adolescent swimmers. All (n = 65, 62% male) members of the six swimming clubs in two cities in Cyprus meeting the following criteria were invited to participate: age 13–19 years old; training 5 or more times a week for at least one year and having competed at the national level at least once. Exclusion criteria were acute disease (such as a cold or a flu virus), use of medication (e.g., antibiotics) or documented eating disorder. Invitation took place through separate meetings with each club’s members during which the study was explained and an information sheet was provided. Participation in the study was voluntary. Swimmers were asked to attend the study centre twice, at baseline and 6 weeks after the workshop. At the baseline visit, a half-day educational session was provided by study dietitians (EP and EA) and a medical doctor (MP) specializing in sports medicine. The educational session consisted of interactive lectures designed to cover nutrition-related issues for this population group on the topics of: MD, sports nutrition for adolescent swimmers and use and misuse of dietary supplements in sports. The material used was based on available nutrition guidelines and recommendations for young athletes1,2,4 and the known benefits of the MD.13 The educational material had been customized and adapted from material previously piloted in talks and seminars to groups of athletes of similar ages and their parents which did not include a formal assessment (unpublished data). An educational guided supermarket tour was also organized, where swimmers were instructed on reading food labels. While guided supermarket tours are commonly built in multicomponent nutrition intervention programmes aiming general or specific population groups,15 to our knowledge, they have not been previously used in nutrition education of athletes. All lecture and workshop material was given to the swimmers.
At baseline and post-intervention, adherence to the MD was assessed using the KIDMED Index which is a validated tool evaluating the adequacy of MD dietary patterns in children and youth and consists of 16 questions evaluated by a score of +1 or −1, totaling to a maximum score of 12.16 Adherence to the MD is described as poor (score: 0–3), medium (score: 4–7) or good (score: 8–12). A short assessment of nutrition knowledge relating to the topics covered during the nutrition education session took place at baseline and post-intervention. The assessment had been pilot tested to assess understanding in athletes of similar ages (unpublished data). Swimmers were asked to record foods that are important sources of macronutrients (carbohydrate, protein, fat and dietary fibre) and micronutrients (Vitamins A, C, E, calcium and iron) (nine questions) and to identify the correct definition of the MD out of 4 possible answers (one question). The correct answers to this short knowledge test were summed up with a maximum possible score of 10. Additionally, at baseline and post-intervention, swimmers were asked whether they check the following information on food labels: energy, total fat, saturated fat, sugar, dietary fibre, salt/sodium and list of ingredients before shopping or eating a product. Responses were recorded on a 5-point scale of ‘always’, ‘often’, ‘sometimes’, ‘rarely’, ‘never’ or ‘don’t shop’. The swimmers’ parents or guardians were asked to attend a 2-h interactive educational session (held during the same week as the baseline visit) where they were presented with an outline of the topics explained to the swimmers and received written educational material. Parents were also asked to complete the KIDMED Index to assess their child’s adherence to the MD, at baseline and post-intervention. Demographic characteristics were collected from the swimmers and their parents using separate self-completed questionnaires. The study was approved by the Cyprus National Bioethics Committee (EEBK/2012/27) and conducted according to the guidelines laid down in the Declaration of Helsinki. Written informed consent was signed by swimmers and both their parents/guardians before participation and a separate written informed consent was signed by the parents who participated in the parental education session. The study was carried out between January–March 2013. Categorical data are presented as number and percentages, and continuous data are presented as median [interquartile range, IQR]. The possible answers: ‘always’, ‘often’, ‘sometimes’, ‘rarely and ‘never’ were grouped into only three, these being: ‘always/often’, ‘sometimes’ and ‘rarely/never’ and comparison between baseline and post-intervention was done using Wilcoxon tests. McNemar’s test was used to compare categorical data and Mann–Whitney U test to assess differences between males and females and compare swimmers whose parents participated and those whose parents did not participate. Data was analyzed using the Statistical Software Package for the Social Sciences Version 21.0 (IBM Corp, Armonk, NY, 2012) with a p-value of <0.05 considered statistically significant.
3. Results A total of 37 out of 65 invited swimmers (57% response rate) participated in the study (male = 23; female = 14). Three (all females) were excluded because of reported acute illness and use of medication which resulted in changes in their usual food intake. The swimmers’ demographic characteristics are shown in Table 1 and the parents’ demographic characteristics can be found in online Supplementary material Table 1S. The swimmers trained in swimming on average 5.8 ± 0.4 days/week for 122.5 ± 6.1 min. Out of the 22 parents who participated, two did not provide a complete questionnaire post-intervention and thus were not included in the analysis. Tables 2 and 3 show the KIDMED Index scores as well as the percentages with positive answers to each of the 16 components
Please cite this article in press as: Philippou E, et al. The impact of nutrition education on nutrition knowledge and adherence to the Mediterranean Diet in adolescent competitive swimmers. J Sci Med Sport (2016), http://dx.doi.org/10.1016/j.jsams.2016.08.023
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E. Philippou et al. / Journal of Science and Medicine in Sport xxx (2016) xxx–xxx Table 1 Demographic characteristics of the swimmers. All (n = 34) n
%
Gender Males Females
23 11
68 32
Area of residence Urban Rural
21 13
62 38
Body weight classification (IOTF) Underweight Normal weight Overweight
0 26 8
0 77 24
Age (yr)a
15.2 ± 1.5
IOTF: International Obesity Task Force. a Showing mean ± standard deviation.
of the Index. There was a significant change in the KIDMED Index between baseline and post-intervention with a shift toward a better adherence to the MD both in the whole sample and in the two genders separately (in all cases p < 0.01). The proportion of swimmers classified as having good adherence to MD post-intervention was 47% in the overall sample (vs 21% at baseline), 52% in males (vs 30%) and 36% in females (vs 0%). A comparison between baseline and post-intervention in the individual components of the KIDMED score (Table 3) showed that the largest change was observed in the ‘consumption of sweets several times a week’ where a signif-
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icant reduction was recorded over the study period (56% vs 38%; p = 0.031). While not statistically significant in the gender-specific analysis, this change was observed in both males (61% vs 44%) and females (46% vs 27%). Much smaller and non-statistically significant increases were observed in some items such as increased consumption of yoghurt and/or cheese (24% vs 35%) and nuts (29% vs 38%). No significant changes were observed in most of the individual components of the KIDMED with the exception of an increase in the ‘use of olive oil at home’ among males (65% vs 87%, p = 0.063). Comparison of the results of the KIDMED Index score between swimmers whose parents participated (median: 5.5 IQR: [4.8–7.3] vs 7.5 [7.0–9.0]; p = 0.002) and those whose parents did not participate (4.5 [3.3–7.0] vs 7.0 [7.0–8.0]; p = 0.007) showed that there was an increase in the score in both groups between baseline and post-intervention. There was no significant difference between the groups either at baseline or post-intervention or in the change in KIDMED score over the study period. A comparison of the KIDMED Index score calculated from the answers of the parents (n = 20) to the score of the swimmers themselves showed that although both scores increased significantly between baseline and post-intervention (parents’ answers: 6.0 [4.3–7.8] vs 7.0 [6.0–7.8], p = 0.028 vs swimmers’ answers: 5.5 [4.3–7.8] vs 7.5 [7.0–9.0], p = 0.002), the parents’ scores for the swimmers were significantly lower than those of the swimmers themselves post-intervention (p = 0.007). Additionally, there was a non-significant trend for a difference between the change in KIDMED score over the study period reported by the parents for the swimmers (1.0 [−0.8 to 2.0]) compared to that reported by the swimmers themselves (2.0 [1.0–3.0] (p = 0.054)).
Table 2 KIDMED Index score results and overall adherence to the Mediterranean Diet of all swimmers and of males and females separately. KIDMED Index score
Mean ± SD Median [IQR]
All (n = 34)
Males (n = 23)
p-Value*
Females (n = 11)
Baseline
Post-intervention
Baseline
Post-intervention
Baseline
Post-intervention
All
Males
Females
5.7 ± 2.1 5.0 [4.0–7.0]
7.6 ± 1.7 7.0 [7.0–9.0]
6.0 ± 3.0 6.0 [4.0–8.0]
7.6 ± 1.8 8.0 [7.0–9.0]
5.0 ± 1.4 5.0 [4.0–7.0]
7.6 ± 1.6 7.0 [7.0–9.0]
<0.000
0.002
0.005
17 52 30
4 44 52
9 91 0
0 64 36
Adherence to the MD diet assessed by KIDMED (%) Poor (≤3) Medium (4–7) Good (≥8) *
15 65 21
3 50 47
p-Value comparing results at baseline and post-intervention by Wilcoxon ranked test.
Table 3 Results of the individual components of the KIDMED Index. KIDMED Index questions
All (n = 34) Baseline (%)
Post-intervention (%)
Baseline (%)
Post-intervention (%)
Baseline (%)
Post-intervention (%)
Fruit or fruit juice daily Second serving of fruit daily Fresh or cooked vegetables daily Fresh or cooked vegetables >1/day Regular fish consumption (at least 2–3 times/week) >1/week fast-food restaurant Pulses >1/week Pasta or rice almost daily (≥5/week) Cereal or cereal product for breakfast Regular nut consumption (at least 2–3/week) Use of olive oil at home No breakfast Dairy product for breakfast Commercially baked goods or pastries for breakfast Two yoghurts and/or 40 g of cheese daily Sweets and candy several times a day
91 47 47 15 27 3 74 29 85 29 71 6 94 6 24 56
85 47 35 21 24 6 71 50 88 38 82 3 97 12 35 38*
91 52 48 17 39 0 65 39 87 39 65** 4 96 9 35 61
83 52 39 22 22 4 61 61 91 44 87 4 100 13 48 44
91 36 46 9 0 9 91 9 82 9 82 9 91 0 0 46
91 36 27 18 27 9 91 27 82 27 73 0 91 9 9 27
* **
Males (n = 23)
Females (n = 11)
p-Value <0.05. p-Value = 0.063 when comparing results at baseline and post-intervention by McNemar’s test.
Please cite this article in press as: Philippou E, et al. The impact of nutrition education on nutrition knowledge and adherence to the Mediterranean Diet in adolescent competitive swimmers. J Sci Med Sport (2016), http://dx.doi.org/10.1016/j.jsams.2016.08.023
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The nutrition knowledge score increased significantly in the whole sample from a median [IQR] of 7.0 [5.0–8.0] at baseline to 7.0 [6.0–8.0] post-intervention (p = 0.034). Nevertheless, it appeared that this increase was mainly driven by males with scores 7.0 [5.0–7.0] vs 7.0 [6.0–8.0], (p = 0.059). At baseline, the score of the swimmers whose parents participated did not differ from the score of those whose parents did not participate (7.0 [6.0–8.0] vs 7.0 [2.8–7.0]). Post-intervention, however, there was a trend for the score of those whose parents did not participate (6.0 [6.0–7.8]) to be lower than that whose parents participated (7.0 [7.0–8.0] (p = 0.063)). There was no difference between the change in nutrition knowledge score over the study period (post-intervention—baseline score) between those whose parents participated (0.0 [0.0–1.0]) compared to those whose parents did not participate (1.0 [2.0]). With regards to checking nutrition labels by swimmers who reported that they shop (n = 24), there was an increase in the frequency of checking food labels for energy (baseline vs postintervention: never/rarely 58.3% vs 33.3%, sometimes: 20.8% vs 25.0% and always/most times: 20.8% vs 41.7%; p = 0.010), fat (never/rarely 79.2% vs 50.0%, sometimes 8.3% vs 29.2% and always/most times: 12.5% vs 20.8%; p = 0.054), sugar (never/rarely: 73.9% vs 54.2%, sometimes: 17.4% vs 29.2%, always/most times: 8.7% vs 16.7%; p = 0.053) and list of ingredients (never/rarely: 60.9% vs 33.3%, sometimes: 21.7% vs 29.2% and always/most times: 17.4% vs 37.5%; p = 0.022) but not saturated fat, dietary fat or salt content.
4. Discussion Overall, the intervention resulted in a significant improvement in the swimmers’ adherence to the MD, an important finding since the MD is related to higher nutritional quality and reduced disease risk.13 The intervention also resulted in improvements in the swimmers’ understanding of food labels and increases in nutrition knowledge of food sources of macro- and micronutrients and the definition of the MD. These nutrition skills are paramount to a swimmer’s ability to turn knowledge into practice.9 The question of whether nutrition education improves dietary intake was recently addressed and significant but weak associations were found between nutrition knowledge and some aspect of dietary intake, most often being increased consumption of fruit and vegetables in studies in athletes.17 In a study of adolescents, poor nutrition knowledge was associated with low adherence to the MD18 while actual MD knowledge was the only significant predictor of MD adherence among Greek adolescents.19 In this study, the KIDMED Index was used to assess adherence to the MD.16 This tool is widely used in cross-sectional studies among the general children population16,20 but with a few exceptions e.g., adolescent football players,21 it has not been used in athlete populations. Here, it was shown that the tool may prove to be useful for sports dietitians and coaches when assessing diet. Based on the breakdown of the answers to the KIDMED Index, the increase in adherence to the MD over the study period did not appear to reflect large changes in overall practices. The largest change was observed in the reduction in the intake of sweets and use of more olive oil, at least in males. Reducing sweets is important since they provide only ‘empty calories’, possibly displace healthy snacks, increase the risk of dental caries and maybe associated with an increased body weight.22 Olive oil is a rich source of polyphenols and other antioxidants23 which may contribute to protection against the exercise-induced oxidative stress, something that may best be done through whole foods rather than supplements.24 Moreover, a higher adherence to the MD is indicative of an overall healthier diet as shown in a study assessing younger children.20
The current study also showed that provision of nutrition education in an interactive way including a supermarket tour can have positive effects on some aspects of nutrition knowledge. This is important since swimmers of this age or slightly older have a positive attitude toward nutrition education but nevertheless lack knowledge of nutrition with implications on their food choices.25,26 In the general population of children, it has been shown that the most successful ways to improve dietary habits are multicomponent nutrition interventions with parental involvement.10 Interestingly though, increasing nutrition knowledge does not always translate into healthier eating habits,17 possibly since many other factors such as taste preferences, convenience, skill in shopping, label reading and food preparation, cultural factors and family habits also influence intake to different extents.27 In adolescent athletes, research on nutrition education is scarce and results are mixed. In adolescent hockey players, nutrition education provided as part of a hockey camp did not effectively improve nutrition knowledge11 while an educational program in adolescent ballet dancers, with the use of a DVD lecture series was effective in both improving knowledge and self-reported dietary intake12 suggesting that innovative ways of delivering nutrition-related messages may be necessary. Further research is thus warranted to address the most effective nutrition education programs including the mode of delivering, specifically in adolescent athletes. The important role of parental participation in nutrition education programs10 was supported by our findings, since there was a trend for a lower score in knowledge in those whose parents did not participate. It is of note, however, that swimmers and their parents’ dietary assessment was not always in agreement, with swimmers appearing to generally assess themselves more favorably. This has also been shown before in younger children28 with no parent–child dyad providing the same answers to all questions. It is thus recommended that self-assessment by adolescents as well as parental assessment pre- and post an intervention could be used to check agreement between the two. This is the first study to assess adherence to the MD following nutrition education in adolescent swimmers. The workshop design is of importance since it was innovative and interactive. Additionally, evaluation of MD adherence was done using a validated tool. This is also the first study to assess the impact of parental participation on nutrition education of young swimmers. Other strengths include the fact that parents were also educated on their children’s diets, all participants had similar swimming training and a number of different tools were used for assessment. Additionally, it can be speculated that the delivery of the nutrition education to a small group of athletes might have enhanced its effectiveness, something that warrants to be addressed in future research. On the other hand, the small sample size precluded the inclusion of a control group and made evaluation of the effect of the intervention in terms of gender and parental participation difficult. Furthermore, since participation was on a voluntary basis, the results may be biased by those participating having a high interest in nutrition. The results might not be generalizable to all adolescent competitive swimmers due to the specific demographic characteristics of the studied population. It is also of note that the responsiveness of the test score to change in a before–after study of nutrition education may not suggest a generalized change in nutrition knowledge among the athletes but specific improvement with regards to the topics covered. It is suggested that future studies use validated sports nutrition questionnaires such as that of Zinn et al.29 in addition to assessment of nutrition knowledge related to the specific topics covered. Furthermore, although the KIDMED Index has been validated for use in children,16 it has not been validated for use by parents assessing their child’s diet, something that may be useful to do in future research due to the inconsistencies seen between parent–child dyad’s answers. Finally, the use of a biomarker of a
Please cite this article in press as: Philippou E, et al. The impact of nutrition education on nutrition knowledge and adherence to the Mediterranean Diet in adolescent competitive swimmers. J Sci Med Sport (2016), http://dx.doi.org/10.1016/j.jsams.2016.08.023
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component of the MD e.g., tyrosol for olive oil intake30 could have enabled some validation of the KIDMED Index scores. 5. Conclusion In conclusion, the study showed that aspects of nutrition knowledge and adherence to the MD can be improved in adolescent competitive swimmers by an interactive nutrition education workshop and that parental participation appears to be an important component in enhancing observed benefits. Further research is needed to address whether the nutrition education workshop can be scaled up to larger population groups or athletes of other sports, ways to enhance nutrition education and assess the impact of the findings on sports performance. Practical implications • Nutrition education of adolescent competitive swimmers is imperative both for their health and sports performance. • Use of interactive methods in nutrition education including a supermarket tour can help adolescent competitive swimmers to improve their nutrition knowledge and consume a diet closer to the Mediterranean Diet. • Educating the swimmers’ parents may be more beneficial than educating only the swimmers. Acknowledgments This work was funded by internal funding. Special thanks are addressed to the swimmers and their parents for their time and commitment. Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.jsams.2016.08. 023. References 1. American Dietetic Association. Position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine: nutrition and athletic performance. J Am Diet Assoc 2009; 109:509–527. 2. Desbrow B, McCormack J, Burke LM et al. Sports dietitians Australia position statement: sports nutrition for the adolescent athlete. Int J Sport Nutr Exerc Metab 2014; 24(5):570–584. 3. Meyer F, O’Connor H, Shirreffs SM. Nutrition for the young athlete. J Sports Sci 2007; 25(Suppl. 1):S73–S82. 4. Mountjoy M, Armstrong N, Bizzini L et al. IOC consensus statement on training the elite child athlete. Clin J Sport Med 2008; 18:122–123. 5. Spendlove JK, Heaney SE, Gifford JA et al. Evaluation of general nutrition knowledge in elite Australian athletes. Br J Nutr 2012; 107:1872–1880. 6. Heaney S, O’Connor H, Michael S et al. Nutrition knowledge in athletes: a systematic review. Int J Sport Nutr Exerc Metab 2011; 21:248–261.
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7. de Sousa EF, Da Costa THM, Nogueira JAD et al. Assessment of nutrient and water intake among adolescents from sports federations in the federal district, Brazil. Br J Nutr 2008; 99:1275–1283. 8. Martinez S, Pasquarelli BN, Romaquera D et al. Anthropometric characteristics and nutritional profile of young amateur swimmers. J Strength Cond Res 2011; 25:1126–1133. 9. Shaw G, Boyd KT, Burke LM et al. Nutrition for swimming. Int J Sport Nutr Exerc Metab 2014; 24:360–372. 10. Evans CE, Christian MS, Cleghorn CL et al. Systematic review and meta-analysis of school-based interventions to improve daily fruit and vegetable intake in children aged 5 to 12 y. Am J Clin Nutr 2012; 96:889–901. 11. Reading KJ, McCargar LJ, Marriage BJ. Adolescent and young adult male hockey players: nutrition knowledge and education. Can J Diet Pract Res 1999; 60:166–169. 12. Doyle-Lucas AF, Davy BM. Development and evaluation of an educational intervention program for pre-professional adolescent ballet dancers: nutrition for optimal performance. J Dance Med Sci 2011; 15:65–75. 13. Sofi F, Macchi C, Abbate R et al. Mediterranean diet and health status: an updated meta-analysis and a proposal for a literature-based adherence score. Public Health Nutr 2013:1–14. 14. Costill DL, Flynn MG, Kirwan JP et al. Effects of repeated days of intensified training on muscle glycogen and swimming performance. Med Sci Sports Exerc 1988; 20:249–254. 15. Escaron AL, Meinen AM, Nitzke SA et al. Supermarket and grocery store-based interventions to promote healthful food choices and eating practices: a systematic review. Prev Chronic Dis 2013; 10:E50. 16. Serra-Majem L, Ribas L, Ngo J et al. Food, youth and the Mediterranean diet in Spain. Development of KIDMED, Mediterranean diet quality index in children and adolescents. Public Health Nutr 2004; 7:931–935. 17. Spronk I, Kullen C, Burdon C et al. Relationship between nutrition knowledge and dietary intake. Br J Nutr 2014; 111:1713–1726. 18. Sahingoz SA, Sanlier N. Compliance with Mediterranean diet quality index (KIDMED) and nutrition knowledge levels in adolescents. A case study from Turkey. Appetite 2011; 57:272–277. 19. Tsartsali PK, Thompson JL, Jago R. Increased knowledge predicts greater adherence to the Mediterranean diet in Greek adolescents. Public Health Nutr 2009; 12:208–213. 20. Lazarou C, Panagiotakos DB, Matalas AL. Level of adherence to the Mediterranean diet among children from Cyprus: the CYKIDS study. Public Health Nutr 2009; 12:991–1000. 21. Torun NT, Yildiz Y. Assessment of nutritional status of 10–14 years old adolescents using Mediterranean diet quality index (KIDMED). Proc Soc Behav Sci 2013; 106:512–518. 22. World Health Organization, Guideline: sugars intake for adults and children. Geneva, 2015. Ref Type: Report. 23. Visioli F, Galli C. Biological properties of olive oil phytochemicals. Crit Rev Food Sci Nutr 2002; 42:209–221. 24. Yavari A, Javadi M, Mirmiran P et al. Exercise-induced oxidative stress and dietary antioxidants. Asian J Sports Med 2015; 6:e24898. 25. Hoogenboom BJ, Morris J, Morris C et al. Nutritional knowledge and eating behaviors of female, collegiate swimmers. N Am J Sports Phys Ther 2009; 4:139–148. 26. Webb MC, Beckford SE. Nutritional knowledge and attitudes of adolescent swimmers in Trinidad and Tobago. J Nutr Metab 2014; 2014:506434. 27. Nestle M, Wing R, Birch L et al. Behavioral and social influences on food choice. Nutr Rev 1998; 56:S50–S64. 28. Thorn JE, DeLellis N, Chandler JP et al. Parent and child self-reports of dietary behaviors, physical activity, and screen time. J Pediatr 2013; 162:557–561. 29. Zinn C, Schofield G, Wall C. Development of a psychometrically valid and reliable sports nutrition knowledge questionnaire. J Sci Med Sport 2005; 8:346–351. 30. Miro-Casas E, Covas MI, Fito M et al. Tyrosol and hydroxytyrosol are absorbed from moderate and sustained doses of virgin olive oil in humans. Eur J Clin Nutr 2003; 57:186–190.
Please cite this article in press as: Philippou E, et al. The impact of nutrition education on nutrition knowledge and adherence to the Mediterranean Diet in adolescent competitive swimmers. J Sci Med Sport (2016), http://dx.doi.org/10.1016/j.jsams.2016.08.023
ARTICLE IN PRESS Journal of Science and Medicine in Sport xxx (2016) xxx–xxx
Contents lists available at ScienceDirect
Journal of Science and Medicine in Sport journal homepage: www.elsevier.com/locate/jsams
Original research
The impact of nutrition education on nutrition knowledge and adherence to the Mediterranean Diet in adolescent competitive swimmers Elena Philippou a,∗ , Nicos Middleton b , Constantinos Pistos c , Eleni Andreou a , Michael Petrou d a
Department of Life and Health Sciences, University of Nicosia (UNIC), Cyprus Department of Nursing, School of Health Sciences, Cyprus University of Technology, Cyprus c Department of Chemistry, West Chester University, United States d Centre for Leisure, Tourism & Sport Research & Development, UNIC, Cyprus b
a r t i c l e
i n f o
Article history: Received 30 March 2016 Received in revised form 19 August 2016 Accepted 22 August 2016 Available online xxx Keywords: KIDMED Index Athlete education Adolescent athlete Parental education
a b s t r a c t Objectives: Nutrition education of adolescent competitive swimmers is under-studied although their diet and nutrition knowledge are generally poor. This study aimed to assess the impact of nutrition education on nutrition knowledge and adherence to the Mediterranean Diet (MD) and explore the effect of parental education on the swimmers’ MD adherence. Design: A pre–post measurement interventional study was carried out. Methods: A half-day nutrition education session was delivered for the swimmers and a separate session for their parents. At baseline and 6-weeks post-workshop, a short nutrition knowledge assessment of food sources of nutrients and the MD composition as well as adherence to the MD using the KIDMED Index were undertaken. The swimmers’ parents also completed the KIDMED Index to evaluate the swimmers’ diet. Results: Thirty-four competitive swimmers (age: 15.2 ± 1.5 yr, 23 males) and 22 of their parents participated in the study. There was an improvement in MD adherence with 47% having good adherence post-intervention vs 21% at baseline (p < 0.01) and an increase in the KIDMED Index score (median [interquartile range]: 5.0 [4.0–7.0] vs 7.0 [7.0–9.0]; p < 0.01)). There was also an increase in the swimmers’ nutrition knowledge assessment score (median [IQR]: 7.0 [5.0–8.0] vs 7.0 [6.0–8.0], p < 0.05)), and a trend for a lower score post-intervention in swimmers whose parents did not participate compared to those whose parents participated (6.0 [6.0–7.8] vs 7.0 [7.0–8.0], p = 0.063). Conclusions: The intervention improved adherence to the MD and increased nutrition knowledge. The findings support parental participation in nutrition education. © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.
1. Introduction Adoption of healthy eating by adolescent athletes is imperative in order to meet their nutritional needs, promote health and enhance sport performance.1,2 Although the importance of ongoing nutrition education of young athletes, coaches and parents is highlighted by sports organisations internationally,2–4 nutrition education in adolescent athletes and specifically swimmers is not well-studied. Nevertheless, the need to educate athletes is evident
∗ Corresponding author. E-mail addresses: [email protected], [email protected] (E. Philippou).
as shown in a sample of elite athletes, a large proportion of whom aged ≤18 years old, who scored poorly on the ‘sources of nutrients’ section of a questionnaire compared with non-athlete controls.5 Furthermore, a systematic review of nutrition knowledge in competitive, recreational or elite athletes over the age of 13 found that although athletes’ nutrition knowledge was equal to or better than that of non-athletes, it was lower than that of non-athlete comparison groups.6 It is of note, however, that the comparison groups included nutrition students possibly skewing the results of the study.6 A number of studies have shown that adherence of athletes to dietary recommendations was poor, while intake of important micronutrients was insufficient.7,8 One of the strategies to improve adolescent swimmers’ diet may be through enhancement of their nutrition knowledge. As
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Please cite this article in press as: Philippou E, et al. The impact of nutrition education on nutrition knowledge and adherence to the Mediterranean Diet in adolescent competitive swimmers. J Sci Med Sport (2016), http://dx.doi.org/10.1016/j.jsams.2016.08.023
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noted by the International Journal of Sport Nutrition and Exercise Performance Consensus Statement on ‘Nutrition for Swimming’, this should be achieved through a carefully designed nutrition education program aiming to progressively develop nutrition knowledge.9 Previous research in children showed that multicomponent nutrition interventions with parental involvement were the most successful in improving dietary habits.10 Such nutrition education programs are under-studied among adolescent athletes however, with only some exceptions producing mixed results.11,12 The Mediterranean Diet (MD) is widely acknowledged as one of the healthiest dietary patterns for degenerative disease prevention.13 It is in line with recommendations on nutrition for athletic performance, where it is suggested to increase the consumption of whole grains and cereals, beans, and legumes, consume five or more daily servings of fruits and vegetables and lean cuts of meats.1 Additionally, the MD is based on carbohydrate-rich foods which would be expected to enhance athletic performance aiding both performance and recovery.14 Thus, the MD may be used by adolescent athletes as a basis for dietary planning, taking into account the individual athlete’s characteristics such as energy and nutrient requirements and athletic goals and ensuring that specific sports recommendations e.g., fluid intake are also adhered to. With the above in mind, an intervention study was designed aiming to assess the impact of a nutrition workshop on nutrition knowledge and adherence to the MD in adolescent competitive swimmers and explore the effect of parental education on the athletes’ adherence to MD. It was hypothesized that nutrition education would be beneficial on knowledge and adherence to the MD and that parental involvement would result in further benefits to the assessed outcomes.
2. Methods A pre–post measurement interventional study was carried out among young adolescent swimmers. All (n = 65, 62% male) members of the six swimming clubs in two cities in Cyprus meeting the following criteria were invited to participate: age 13–19 years old; training 5 or more times a week for at least one year and having competed at the national level at least once. Exclusion criteria were acute disease (such as a cold or a flu virus), use of medication (e.g., antibiotics) or documented eating disorder. Invitation took place through separate meetings with each club’s members during which the study was explained and an information sheet was provided. Participation in the study was voluntary. Swimmers were asked to attend the study centre twice, at baseline and 6 weeks after the workshop. At the baseline visit, a half-day educational session was provided by study dietitians (EP and EA) and a medical doctor (MP) specializing in sports medicine. The educational session consisted of interactive lectures designed to cover nutrition-related issues for this population group on the topics of: MD, sports nutrition for adolescent swimmers and use and misuse of dietary supplements in sports. The material used was based on available nutrition guidelines and recommendations for young athletes1,2,4 and the known benefits of the MD.13 The educational material had been customized and adapted from material previously piloted in talks and seminars to groups of athletes of similar ages and their parents which did not include a formal assessment (unpublished data). An educational guided supermarket tour was also organized, where swimmers were instructed on reading food labels. While guided supermarket tours are commonly built in multicomponent nutrition intervention programmes aiming general or specific population groups,15 to our knowledge, they have not been previously used in nutrition education of athletes. All lecture and workshop material was given to the swimmers.
At baseline and post-intervention, adherence to the MD was assessed using the KIDMED Index which is a validated tool evaluating the adequacy of MD dietary patterns in children and youth and consists of 16 questions evaluated by a score of +1 or −1, totaling to a maximum score of 12.16 Adherence to the MD is described as poor (score: 0–3), medium (score: 4–7) or good (score: 8–12). A short assessment of nutrition knowledge relating to the topics covered during the nutrition education session took place at baseline and post-intervention. The assessment had been pilot tested to assess understanding in athletes of similar ages (unpublished data). Swimmers were asked to record foods that are important sources of macronutrients (carbohydrate, protein, fat and dietary fibre) and micronutrients (Vitamins A, C, E, calcium and iron) (nine questions) and to identify the correct definition of the MD out of 4 possible answers (one question). The correct answers to this short knowledge test were summed up with a maximum possible score of 10. Additionally, at baseline and post-intervention, swimmers were asked whether they check the following information on food labels: energy, total fat, saturated fat, sugar, dietary fibre, salt/sodium and list of ingredients before shopping or eating a product. Responses were recorded on a 5-point scale of ‘always’, ‘often’, ‘sometimes’, ‘rarely’, ‘never’ or ‘don’t shop’. The swimmers’ parents or guardians were asked to attend a 2-h interactive educational session (held during the same week as the baseline visit) where they were presented with an outline of the topics explained to the swimmers and received written educational material. Parents were also asked to complete the KIDMED Index to assess their child’s adherence to the MD, at baseline and post-intervention. Demographic characteristics were collected from the swimmers and their parents using separate self-completed questionnaires. The study was approved by the Cyprus National Bioethics Committee (EEBK/2012/27) and conducted according to the guidelines laid down in the Declaration of Helsinki. Written informed consent was signed by swimmers and both their parents/guardians before participation and a separate written informed consent was signed by the parents who participated in the parental education session. The study was carried out between January–March 2013. Categorical data are presented as number and percentages, and continuous data are presented as median [interquartile range, IQR]. The possible answers: ‘always’, ‘often’, ‘sometimes’, ‘rarely and ‘never’ were grouped into only three, these being: ‘always/often’, ‘sometimes’ and ‘rarely/never’ and comparison between baseline and post-intervention was done using Wilcoxon tests. McNemar’s test was used to compare categorical data and Mann–Whitney U test to assess differences between males and females and compare swimmers whose parents participated and those whose parents did not participate. Data was analyzed using the Statistical Software Package for the Social Sciences Version 21.0 (IBM Corp, Armonk, NY, 2012) with a p-value of <0.05 considered statistically significant.
3. Results A total of 37 out of 65 invited swimmers (57% response rate) participated in the study (male = 23; female = 14). Three (all females) were excluded because of reported acute illness and use of medication which resulted in changes in their usual food intake. The swimmers’ demographic characteristics are shown in Table 1 and the parents’ demographic characteristics can be found in online Supplementary material Table 1S. The swimmers trained in swimming on average 5.8 ± 0.4 days/week for 122.5 ± 6.1 min. Out of the 22 parents who participated, two did not provide a complete questionnaire post-intervention and thus were not included in the analysis. Tables 2 and 3 show the KIDMED Index scores as well as the percentages with positive answers to each of the 16 components
Please cite this article in press as: Philippou E, et al. The impact of nutrition education on nutrition knowledge and adherence to the Mediterranean Diet in adolescent competitive swimmers. J Sci Med Sport (2016), http://dx.doi.org/10.1016/j.jsams.2016.08.023
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E. Philippou et al. / Journal of Science and Medicine in Sport xxx (2016) xxx–xxx Table 1 Demographic characteristics of the swimmers. All (n = 34) n
%
Gender Males Females
23 11
68 32
Area of residence Urban Rural
21 13
62 38
Body weight classification (IOTF) Underweight Normal weight Overweight
0 26 8
0 77 24
Age (yr)a
15.2 ± 1.5
IOTF: International Obesity Task Force. a Showing mean ± standard deviation.
of the Index. There was a significant change in the KIDMED Index between baseline and post-intervention with a shift toward a better adherence to the MD both in the whole sample and in the two genders separately (in all cases p < 0.01). The proportion of swimmers classified as having good adherence to MD post-intervention was 47% in the overall sample (vs 21% at baseline), 52% in males (vs 30%) and 36% in females (vs 0%). A comparison between baseline and post-intervention in the individual components of the KIDMED score (Table 3) showed that the largest change was observed in the ‘consumption of sweets several times a week’ where a signif-
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icant reduction was recorded over the study period (56% vs 38%; p = 0.031). While not statistically significant in the gender-specific analysis, this change was observed in both males (61% vs 44%) and females (46% vs 27%). Much smaller and non-statistically significant increases were observed in some items such as increased consumption of yoghurt and/or cheese (24% vs 35%) and nuts (29% vs 38%). No significant changes were observed in most of the individual components of the KIDMED with the exception of an increase in the ‘use of olive oil at home’ among males (65% vs 87%, p = 0.063). Comparison of the results of the KIDMED Index score between swimmers whose parents participated (median: 5.5 IQR: [4.8–7.3] vs 7.5 [7.0–9.0]; p = 0.002) and those whose parents did not participate (4.5 [3.3–7.0] vs 7.0 [7.0–8.0]; p = 0.007) showed that there was an increase in the score in both groups between baseline and post-intervention. There was no significant difference between the groups either at baseline or post-intervention or in the change in KIDMED score over the study period. A comparison of the KIDMED Index score calculated from the answers of the parents (n = 20) to the score of the swimmers themselves showed that although both scores increased significantly between baseline and post-intervention (parents’ answers: 6.0 [4.3–7.8] vs 7.0 [6.0–7.8], p = 0.028 vs swimmers’ answers: 5.5 [4.3–7.8] vs 7.5 [7.0–9.0], p = 0.002), the parents’ scores for the swimmers were significantly lower than those of the swimmers themselves post-intervention (p = 0.007). Additionally, there was a non-significant trend for a difference between the change in KIDMED score over the study period reported by the parents for the swimmers (1.0 [−0.8 to 2.0]) compared to that reported by the swimmers themselves (2.0 [1.0–3.0] (p = 0.054)).
Table 2 KIDMED Index score results and overall adherence to the Mediterranean Diet of all swimmers and of males and females separately. KIDMED Index score
Mean ± SD Median [IQR]
All (n = 34)
Males (n = 23)
p-Value*
Females (n = 11)
Baseline
Post-intervention
Baseline
Post-intervention
Baseline
Post-intervention
All
Males
Females
5.7 ± 2.1 5.0 [4.0–7.0]
7.6 ± 1.7 7.0 [7.0–9.0]
6.0 ± 3.0 6.0 [4.0–8.0]
7.6 ± 1.8 8.0 [7.0–9.0]
5.0 ± 1.4 5.0 [4.0–7.0]
7.6 ± 1.6 7.0 [7.0–9.0]
<0.000
0.002
0.005
17 52 30
4 44 52
9 91 0
0 64 36
Adherence to the MD diet assessed by KIDMED (%) Poor (≤3) Medium (4–7) Good (≥8) *
15 65 21
3 50 47
p-Value comparing results at baseline and post-intervention by Wilcoxon ranked test.
Table 3 Results of the individual components of the KIDMED Index. KIDMED Index questions
All (n = 34) Baseline (%)
Post-intervention (%)
Baseline (%)
Post-intervention (%)
Baseline (%)
Post-intervention (%)
Fruit or fruit juice daily Second serving of fruit daily Fresh or cooked vegetables daily Fresh or cooked vegetables >1/day Regular fish consumption (at least 2–3 times/week) >1/week fast-food restaurant Pulses >1/week Pasta or rice almost daily (≥5/week) Cereal or cereal product for breakfast Regular nut consumption (at least 2–3/week) Use of olive oil at home No breakfast Dairy product for breakfast Commercially baked goods or pastries for breakfast Two yoghurts and/or 40 g of cheese daily Sweets and candy several times a day
91 47 47 15 27 3 74 29 85 29 71 6 94 6 24 56
85 47 35 21 24 6 71 50 88 38 82 3 97 12 35 38*
91 52 48 17 39 0 65 39 87 39 65** 4 96 9 35 61
83 52 39 22 22 4 61 61 91 44 87 4 100 13 48 44
91 36 46 9 0 9 91 9 82 9 82 9 91 0 0 46
91 36 27 18 27 9 91 27 82 27 73 0 91 9 9 27
* **
Males (n = 23)
Females (n = 11)
p-Value <0.05. p-Value = 0.063 when comparing results at baseline and post-intervention by McNemar’s test.
Please cite this article in press as: Philippou E, et al. The impact of nutrition education on nutrition knowledge and adherence to the Mediterranean Diet in adolescent competitive swimmers. J Sci Med Sport (2016), http://dx.doi.org/10.1016/j.jsams.2016.08.023
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The nutrition knowledge score increased significantly in the whole sample from a median [IQR] of 7.0 [5.0–8.0] at baseline to 7.0 [6.0–8.0] post-intervention (p = 0.034). Nevertheless, it appeared that this increase was mainly driven by males with scores 7.0 [5.0–7.0] vs 7.0 [6.0–8.0], (p = 0.059). At baseline, the score of the swimmers whose parents participated did not differ from the score of those whose parents did not participate (7.0 [6.0–8.0] vs 7.0 [2.8–7.0]). Post-intervention, however, there was a trend for the score of those whose parents did not participate (6.0 [6.0–7.8]) to be lower than that whose parents participated (7.0 [7.0–8.0] (p = 0.063)). There was no difference between the change in nutrition knowledge score over the study period (post-intervention—baseline score) between those whose parents participated (0.0 [0.0–1.0]) compared to those whose parents did not participate (1.0 [2.0]). With regards to checking nutrition labels by swimmers who reported that they shop (n = 24), there was an increase in the frequency of checking food labels for energy (baseline vs postintervention: never/rarely 58.3% vs 33.3%, sometimes: 20.8% vs 25.0% and always/most times: 20.8% vs 41.7%; p = 0.010), fat (never/rarely 79.2% vs 50.0%, sometimes 8.3% vs 29.2% and always/most times: 12.5% vs 20.8%; p = 0.054), sugar (never/rarely: 73.9% vs 54.2%, sometimes: 17.4% vs 29.2%, always/most times: 8.7% vs 16.7%; p = 0.053) and list of ingredients (never/rarely: 60.9% vs 33.3%, sometimes: 21.7% vs 29.2% and always/most times: 17.4% vs 37.5%; p = 0.022) but not saturated fat, dietary fat or salt content.
4. Discussion Overall, the intervention resulted in a significant improvement in the swimmers’ adherence to the MD, an important finding since the MD is related to higher nutritional quality and reduced disease risk.13 The intervention also resulted in improvements in the swimmers’ understanding of food labels and increases in nutrition knowledge of food sources of macro- and micronutrients and the definition of the MD. These nutrition skills are paramount to a swimmer’s ability to turn knowledge into practice.9 The question of whether nutrition education improves dietary intake was recently addressed and significant but weak associations were found between nutrition knowledge and some aspect of dietary intake, most often being increased consumption of fruit and vegetables in studies in athletes.17 In a study of adolescents, poor nutrition knowledge was associated with low adherence to the MD18 while actual MD knowledge was the only significant predictor of MD adherence among Greek adolescents.19 In this study, the KIDMED Index was used to assess adherence to the MD.16 This tool is widely used in cross-sectional studies among the general children population16,20 but with a few exceptions e.g., adolescent football players,21 it has not been used in athlete populations. Here, it was shown that the tool may prove to be useful for sports dietitians and coaches when assessing diet. Based on the breakdown of the answers to the KIDMED Index, the increase in adherence to the MD over the study period did not appear to reflect large changes in overall practices. The largest change was observed in the reduction in the intake of sweets and use of more olive oil, at least in males. Reducing sweets is important since they provide only ‘empty calories’, possibly displace healthy snacks, increase the risk of dental caries and maybe associated with an increased body weight.22 Olive oil is a rich source of polyphenols and other antioxidants23 which may contribute to protection against the exercise-induced oxidative stress, something that may best be done through whole foods rather than supplements.24 Moreover, a higher adherence to the MD is indicative of an overall healthier diet as shown in a study assessing younger children.20
The current study also showed that provision of nutrition education in an interactive way including a supermarket tour can have positive effects on some aspects of nutrition knowledge. This is important since swimmers of this age or slightly older have a positive attitude toward nutrition education but nevertheless lack knowledge of nutrition with implications on their food choices.25,26 In the general population of children, it has been shown that the most successful ways to improve dietary habits are multicomponent nutrition interventions with parental involvement.10 Interestingly though, increasing nutrition knowledge does not always translate into healthier eating habits,17 possibly since many other factors such as taste preferences, convenience, skill in shopping, label reading and food preparation, cultural factors and family habits also influence intake to different extents.27 In adolescent athletes, research on nutrition education is scarce and results are mixed. In adolescent hockey players, nutrition education provided as part of a hockey camp did not effectively improve nutrition knowledge11 while an educational program in adolescent ballet dancers, with the use of a DVD lecture series was effective in both improving knowledge and self-reported dietary intake12 suggesting that innovative ways of delivering nutrition-related messages may be necessary. Further research is thus warranted to address the most effective nutrition education programs including the mode of delivering, specifically in adolescent athletes. The important role of parental participation in nutrition education programs10 was supported by our findings, since there was a trend for a lower score in knowledge in those whose parents did not participate. It is of note, however, that swimmers and their parents’ dietary assessment was not always in agreement, with swimmers appearing to generally assess themselves more favorably. This has also been shown before in younger children28 with no parent–child dyad providing the same answers to all questions. It is thus recommended that self-assessment by adolescents as well as parental assessment pre- and post an intervention could be used to check agreement between the two. This is the first study to assess adherence to the MD following nutrition education in adolescent swimmers. The workshop design is of importance since it was innovative and interactive. Additionally, evaluation of MD adherence was done using a validated tool. This is also the first study to assess the impact of parental participation on nutrition education of young swimmers. Other strengths include the fact that parents were also educated on their children’s diets, all participants had similar swimming training and a number of different tools were used for assessment. Additionally, it can be speculated that the delivery of the nutrition education to a small group of athletes might have enhanced its effectiveness, something that warrants to be addressed in future research. On the other hand, the small sample size precluded the inclusion of a control group and made evaluation of the effect of the intervention in terms of gender and parental participation difficult. Furthermore, since participation was on a voluntary basis, the results may be biased by those participating having a high interest in nutrition. The results might not be generalizable to all adolescent competitive swimmers due to the specific demographic characteristics of the studied population. It is also of note that the responsiveness of the test score to change in a before–after study of nutrition education may not suggest a generalized change in nutrition knowledge among the athletes but specific improvement with regards to the topics covered. It is suggested that future studies use validated sports nutrition questionnaires such as that of Zinn et al.29 in addition to assessment of nutrition knowledge related to the specific topics covered. Furthermore, although the KIDMED Index has been validated for use in children,16 it has not been validated for use by parents assessing their child’s diet, something that may be useful to do in future research due to the inconsistencies seen between parent–child dyad’s answers. Finally, the use of a biomarker of a
Please cite this article in press as: Philippou E, et al. The impact of nutrition education on nutrition knowledge and adherence to the Mediterranean Diet in adolescent competitive swimmers. J Sci Med Sport (2016), http://dx.doi.org/10.1016/j.jsams.2016.08.023
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component of the MD e.g., tyrosol for olive oil intake30 could have enabled some validation of the KIDMED Index scores. 5. Conclusion In conclusion, the study showed that aspects of nutrition knowledge and adherence to the MD can be improved in adolescent competitive swimmers by an interactive nutrition education workshop and that parental participation appears to be an important component in enhancing observed benefits. Further research is needed to address whether the nutrition education workshop can be scaled up to larger population groups or athletes of other sports, ways to enhance nutrition education and assess the impact of the findings on sports performance. Practical implications • Nutrition education of adolescent competitive swimmers is imperative both for their health and sports performance. • Use of interactive methods in nutrition education including a supermarket tour can help adolescent competitive swimmers to improve their nutrition knowledge and consume a diet closer to the Mediterranean Diet. • Educating the swimmers’ parents may be more beneficial than educating only the swimmers. Acknowledgments This work was funded by internal funding. Special thanks are addressed to the swimmers and their parents for their time and commitment. Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.jsams.2016.08. 023. References 1. American Dietetic Association. Position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine: nutrition and athletic performance. J Am Diet Assoc 2009; 109:509–527. 2. Desbrow B, McCormack J, Burke LM et al. Sports dietitians Australia position statement: sports nutrition for the adolescent athlete. Int J Sport Nutr Exerc Metab 2014; 24(5):570–584. 3. Meyer F, O’Connor H, Shirreffs SM. Nutrition for the young athlete. J Sports Sci 2007; 25(Suppl. 1):S73–S82. 4. Mountjoy M, Armstrong N, Bizzini L et al. IOC consensus statement on training the elite child athlete. Clin J Sport Med 2008; 18:122–123. 5. Spendlove JK, Heaney SE, Gifford JA et al. Evaluation of general nutrition knowledge in elite Australian athletes. Br J Nutr 2012; 107:1872–1880. 6. Heaney S, O’Connor H, Michael S et al. Nutrition knowledge in athletes: a systematic review. Int J Sport Nutr Exerc Metab 2011; 21:248–261.
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7. de Sousa EF, Da Costa THM, Nogueira JAD et al. Assessment of nutrient and water intake among adolescents from sports federations in the federal district, Brazil. Br J Nutr 2008; 99:1275–1283. 8. Martinez S, Pasquarelli BN, Romaquera D et al. Anthropometric characteristics and nutritional profile of young amateur swimmers. J Strength Cond Res 2011; 25:1126–1133. 9. Shaw G, Boyd KT, Burke LM et al. Nutrition for swimming. Int J Sport Nutr Exerc Metab 2014; 24:360–372. 10. Evans CE, Christian MS, Cleghorn CL et al. Systematic review and meta-analysis of school-based interventions to improve daily fruit and vegetable intake in children aged 5 to 12 y. Am J Clin Nutr 2012; 96:889–901. 11. Reading KJ, McCargar LJ, Marriage BJ. Adolescent and young adult male hockey players: nutrition knowledge and education. Can J Diet Pract Res 1999; 60:166–169. 12. Doyle-Lucas AF, Davy BM. Development and evaluation of an educational intervention program for pre-professional adolescent ballet dancers: nutrition for optimal performance. J Dance Med Sci 2011; 15:65–75. 13. Sofi F, Macchi C, Abbate R et al. Mediterranean diet and health status: an updated meta-analysis and a proposal for a literature-based adherence score. Public Health Nutr 2013:1–14. 14. Costill DL, Flynn MG, Kirwan JP et al. Effects of repeated days of intensified training on muscle glycogen and swimming performance. Med Sci Sports Exerc 1988; 20:249–254. 15. Escaron AL, Meinen AM, Nitzke SA et al. Supermarket and grocery store-based interventions to promote healthful food choices and eating practices: a systematic review. Prev Chronic Dis 2013; 10:E50. 16. Serra-Majem L, Ribas L, Ngo J et al. Food, youth and the Mediterranean diet in Spain. Development of KIDMED, Mediterranean diet quality index in children and adolescents. Public Health Nutr 2004; 7:931–935. 17. Spronk I, Kullen C, Burdon C et al. Relationship between nutrition knowledge and dietary intake. Br J Nutr 2014; 111:1713–1726. 18. Sahingoz SA, Sanlier N. Compliance with Mediterranean diet quality index (KIDMED) and nutrition knowledge levels in adolescents. A case study from Turkey. Appetite 2011; 57:272–277. 19. Tsartsali PK, Thompson JL, Jago R. Increased knowledge predicts greater adherence to the Mediterranean diet in Greek adolescents. Public Health Nutr 2009; 12:208–213. 20. Lazarou C, Panagiotakos DB, Matalas AL. Level of adherence to the Mediterranean diet among children from Cyprus: the CYKIDS study. Public Health Nutr 2009; 12:991–1000. 21. Torun NT, Yildiz Y. Assessment of nutritional status of 10–14 years old adolescents using Mediterranean diet quality index (KIDMED). Proc Soc Behav Sci 2013; 106:512–518. 22. World Health Organization, Guideline: sugars intake for adults and children. Geneva, 2015. Ref Type: Report. 23. Visioli F, Galli C. Biological properties of olive oil phytochemicals. Crit Rev Food Sci Nutr 2002; 42:209–221. 24. Yavari A, Javadi M, Mirmiran P et al. Exercise-induced oxidative stress and dietary antioxidants. Asian J Sports Med 2015; 6:e24898. 25. Hoogenboom BJ, Morris J, Morris C et al. Nutritional knowledge and eating behaviors of female, collegiate swimmers. N Am J Sports Phys Ther 2009; 4:139–148. 26. Webb MC, Beckford SE. Nutritional knowledge and attitudes of adolescent swimmers in Trinidad and Tobago. J Nutr Metab 2014; 2014:506434. 27. Nestle M, Wing R, Birch L et al. Behavioral and social influences on food choice. Nutr Rev 1998; 56:S50–S64. 28. Thorn JE, DeLellis N, Chandler JP et al. Parent and child self-reports of dietary behaviors, physical activity, and screen time. J Pediatr 2013; 162:557–561. 29. Zinn C, Schofield G, Wall C. Development of a psychometrically valid and reliable sports nutrition knowledge questionnaire. J Sci Med Sport 2005; 8:346–351. 30. Miro-Casas E, Covas MI, Fito M et al. Tyrosol and hydroxytyrosol are absorbed from moderate and sustained doses of virgin olive oil in humans. Eur J Clin Nutr 2003; 57:186–190.
Please cite this article in press as: Philippou E, et al. The impact of nutrition education on nutrition knowledge and adherence to the Mediterranean Diet in adolescent competitive swimmers. J Sci Med Sport (2016), http://dx.doi.org/10.1016/j.jsams.2016.08.023