Abstract
ent de ciency is a common cause of underperformance in endurance athletes, and supplement intake is frequently considered compensatory for vegan and vegetarian athletes speci - cally. This study aimed to investigate the patterns of supplement intake among vegan, vegetarian,
Zurich, 8091 Zurich, Switzerland; thomas.rosemann@usz.ch 11 Medbase St. Gallen Am Vadianplatz, 9001 St. Gallen, Switzerland *Correspondence: beat.knechtle@hispeed.ch; Tel.: +41-(0)-71-226-93-00 Abstract: Nutrient de ciency is a common cause of underperformance in endurance athletes, and supplement intake is frequently considered compensatory for vegan and vegetarian athletes speci - cally. This study aimed to investigate the patterns of supplement intake among vegan, vegetarian, and omnivorous distance (>10 km) runners and its association with age, sex, and race distance. From a total of 317 runners who participated in an online survey, 220 distance runners (mean age: 38.5 years; mean BMI: 21.75 kg/m 2 ) were selected for the nal sample after data clearance and assigned to 100 omnivores, 40 vegetarians, or 80 vegans. Sociodemographic information, racing experience, and patterns of supplement intake, including type, frequency, dosage, etc., were collected using a questionnaire. Macronutrient intake was assessed using a food frequency questionnaire. ANOVA and logistic regression were used for data analysis. The prevalence of supplement intake was 51% for total runners and 72% among vegan runners. Age, sex, and race distance had no signi cant effect on the type of supplement intake (p> 0.05). Compared to omnivores and vegetari- ans, vegan runners reported consuming more vitamin (but not carbohydrate/protein or mineral) supplements (p< 0.05). Vitamin B 12, magnesium, and multivitamin had the most prevalent use amongst micronutrient supplements. This study points to a central role for supplementary nutritional strategies in different groups of distance runners. The present ndings may help future investigations by design to identify speci c requirements of endurance runners when adhering to speci c kinds of diet particularly plant-based diets. Keywords: nutrition; diet; plant-based; supplement; ergogenic aids; supplementation; marathon; half marathon; running; athlete 1. Introduction Plant-based diets are increasingly being followed more for various reasons, including health, performance, ethical, and environmental concerns [1,2]. While the bioavailability of vitamin B12, vitamin D, protein, calcium, iron, iodine, and zinc has been reported to Nutrients2021,13, 2741.
for various reasons, including health, performance, ethical, and environmental concerns [1,2]. While the bioavailability of vitamin B12, vitamin D, protein, calcium, iron, iodine, and zinc has been reported to Nutrients2021,13, 2741.
Nutrients2021,13, 2741 2 of 15 be lower in many consuming plant-based diets compared to diets containing foods from animal sources [2,3], it has been well-documented that plant-based diets typically have higher amounts of carbohydrates and antioxidants [2,4], which can be advantageous for endurance performance [1]. Despite the well-documented bene cial aspects of plant- based diets among different populations, including athletes, there are still some concerns discussed regarding nutrient adequacy of vegan and vegetarian diets for supporting athletic performance, particularly for those who engage in endurance activities [5]. Irrespective of diet type, there is scienti c evidence that indicates endurance runners may not be consuming suf cient nutrients through daily foods to support their athletic needs [6], and this concern might be more critical for endurance athletes who are generally at a higher risk of low energy availability [7] and/or follow speci c kinds of diets, especially when the diet is not planned appropriately [5]. In such a situation, paying careful attention to the optimal intake of supplemental macronutrients and micronutrients has been highly recommended to both vegan and vegetarian athletes [5]. Inadequacy of nutrient intake may be due to avoiding gastrointestinal distress, the inability to manage meal frequencies, and poor nutritional knowledge of food choice such as adhering to non-scienti c regimens (e.g., low-carbohydrate diet) in particular [8,9]. Additionally, competition-related factors (e.g., suppressed appetite and increased anxiety) may limit nutrient intake during consecutive days of pre- and mid-events [8]. While the important crosstalk between diet, metabolic pathways, and VO2max has been well-established in the literature [10], current evidence shows that both elite [11] and recreational [12] endurance athletes are at risk of consuming inadequate dietary intake to meet the requirements of daily training and health. In practice, however, if the well-recognized dietary needs of an endurance athlete could be translated to a well-planned diet, evidence indicates that even ultra-endurance challenges, such as a mountain bike race, can be successfully and healthfully completed by implementing a vegan diet [13]. As a commonly used approach amongst many athletes, dietary supplements are fre- quently consumed to ful ll the nutrient needs and enhance
well-recognized dietary needs of an endurance athlete could be translated to a well-planned diet, evidence indicates that even ultra-endurance challenges, such as a mountain bike race, can be successfully and healthfully completed by implementing a vegan diet [13]. As a commonly used approach amongst many athletes, dietary supplements are fre- quently consumed to ful ll the nutrient needs and enhance physical performance and/or appearance [14]. Although the bene cial effects of many supplements on the promotion of health, prevention of chronic disease, and enhancement of athletic performance remain unclear [14,15], it is well-established that these products signi cantly contribute to the nu- trient requirements of athletes [15,16]. Recreational endurance athletes may have different choices of dietary supplements, which could be associated with their differing goals of engaging in training and competition, compared to elite athletes [17]. In general, careful consideration for a balance between potential bene ts (e.g., contribution to health and performance) and risks (e.g., adverse health effects, distraction, supplement contamination) has been recommended to endurance athletes when using dietary supplements [17]. Although numerous studies demonstrate that the nutrient de ciencies in plant-based diets are generally due to poor planning of regime [1,18], evidence indicates that many vegan and vegetarian athletes frequently use nutritional supplements [5,19], particularly the scienti cally emphasized micronutrients such as vitamin B12, vitamin D, and iron [5,20]. It has been reported that a considerable portion of the daily micronutrient needs of vegan endurance runners comes from micronutrient supplements [20]. This has led to the majority of vegan (but only half of the vegetarian and the omnivorous) endurance runners meeting their nutritional recommendations for many micronutrients [20]. To date, few studies have assessed the nutritional patterns and supplement intake in vegan and vegetarian athletes [21,22]. Despite these issues, and considering the importance of nutritional demands of vegan and vegetarian athletes, patterns of supplement intake among vegan and vegetarian athletes are not yet clear, and current studies investigating the relationship between plant-based diets and nutrient intakes did not discriminate between vegans and vegetarians [23] or different running distances [19,20]. Considering the rising number of athletes adhering to
these issues, and considering the importance of nutritional demands of vegan and vegetarian athletes, patterns of supplement intake among vegan and vegetarian athletes are not yet clear, and current studies investigating the relationship between plant-based diets and nutrient intakes did not discriminate between vegans and vegetarians [23] or different running distances [19,20]. Considering the rising number of athletes adhering to plant-based diets [4,5], and given the limited data investigating the nutritional concerns of vegan and vegetarian endurance athletes, the purpose of this cross-sectional study was to provide a comprehensive pro le of supplement
Nutrients2021,13, 2741 3 of 15 intake among a partially large number of vegan, vegetarian, and omnivorous endurance runners, and assess its association with age, sex, and race distance. 2. Materials and Methods 2.1. Study Design and Ethical Approval The present study was designed as descriptive and cross-sectional and is part of the NURMI (Nutrition and Running High Mileage) study step 2 [24]. Endurance runners in the NURMI study were mainly recruited from German-speaking countries, including Austria, Germany, and Switzerland. The method described subsequently had been introduced in detail previously [21,24,25]. The study protocol was approved by the ethics board of St. Gallen, Switzerland, on 6 May 2015 (EKSG 14/145), with a trial registration number ISRCTN73074080. 2.2. Participants and Experimental Approach Participants completed an online survey within step 2 of the NURMI study, which was available in German and English at completing the questionnaire, participants were provided with a written description of the procedures and gave their informed consent to participate in the study. The questionnaire consisted of several parts, e.g., running training and racing behavior, quality of life, food frequency [26], as well as physical and dietary information, including regular supplement intake (frequency per week, type, amount, specification for nutrient) and estimated percentage of macronutrients. For successful participation in the NURMI study step 2, the following inclusion criteria were required: (1) written informed consent, (2) at least 18 years of age, (3) questionnaire step 2 completed, (4) having a BMI 30 kg/m 2 [27,28], and (5) successful participation in a running event of at least the half-marathon distance in the past two years. However, a total of 79 10-km runners who had not successfully participated in either a half-marathon or a marathon also provided accurate and useful answers with plenty of high-quality data. To avoid an irreversible loss of these valuable data sets, 10-km runners who met the inclusion criteria were included in the study population. 2.3. Data Clearance From a total number of 317 endurance runners, the initial sample of the survey, 72 participants who did not meet the aforementioned general inclusion criteria (e.g., those who did not answer
of high-quality data. To avoid an irreversible loss of these valuable data sets, 10-km runners who met the inclusion criteria were included in the study population. 2.3. Data Clearance From a total number of 317 endurance runners, the initial sample of the survey, 72 participants who did not meet the aforementioned general inclusion criteria (e.g., those who did not answer all essential questions including diet type, age, sex, and race distance) were excluded from the study. As a consequence of the speci c exclusion criteria for the present study, an additional 25 runners were recognized for consuming less than 50% carbohydrates in their dietary intake, which is lower than the minimum amount of recommended level [1,29], and were excluded from the analysis, due to the avoidance of contradictory data in supplement intake [29]. Moreover, the diet types of nine runners were modi ed from vegan or vegetarian to omnivores via applying control questions through the questionnaire. For the purpose of data analysis, participants were assigned into three dietary subgroups, including omnivorous diet (or Western diet, de ned as diets with no restriction on any kind of food), vegetarian diet (de ned as diets devoid of all esh foods but include egg and/or dairy products), and vegan diet (or plant-based diet, de ned as diets devoid of all foods and products from animal sources including meat and processed meat, sh, shell sh and other so-called seafood, animal fats/oils, milk and dairy, eggs, honey, and related byproducts) [2]. Figure current study.
Nutrients2021,13, 2741 4 of 15 Figure 1. Enrollment and categorization of participants by dietary subgroups. CHOcarbohydrates. 2.4. Measures The participants were asked to report their regular supplement intake, in addition to food frequency (unpublished data from our laboratory based on the food frequency ques- tionnaire of the German Health Interview and Examination Survey for Adults (DEGS) with friendly permission of the Robert Koch Institute, Berlin, Germany) [30]. Macronutrient intake of endurance runners was described by the self-reported percentage of daily calories from carbohydrate, protein, and fat. Supplement intake was described by the following items: regular intake; frequency; kind of supplement: carbohydrate/protein (whether separately or in conjugation), minerals, vitamins; brand of supplement (with nutrient that provides the main contribution); amount; other substances; and was linked to age, sex, diet type, and running distance. The latent factors running experience (age. rst.running event, age.run, age. rs t.half-marathon, age. rst.marathon) and racing experience (years.running, com- plete d.half-marathon.number, completed.marathon.number) were derived by using both pooled items de ned by speci c items based on manifest variables. Since the running experience (e.g., number of years of active running, age of rst running event, number of completed races) depends on age, the respective items were operationalized with age (e.g., age-related years of running, age-related number of completed races over half-marathon distance). With this, the respective items (e.g., age-related start of running, completion of rst marathon race) were centered by the median and were z-transformed to a new scale by summarizing the respective items (e.g., years of running, number of completed races over speci c distances). Based on this, the values were categorized considering the two latent factors running experience and racing experience as low (values below 1), medium (values ranging from 1 to +1), and high (values higher +1). 2.5. Statistical Analysis The statistical software R version 4.0.0 (R Foundation for Statistical Computing, Vi- enna, Austria) was used to perform all statistical analyses. Exploratory analysis was performed by descriptive statistics (median and interquartile range (IQR), mean and stan- dard deviation (SD)). Signi cant differences between the types of supplement intake and
higher +1). 2.5. Statistical Analysis The statistical software R version 4.0.0 (R Foundation for Statistical Computing, Vi- enna, Austria) was used to perform all statistical analyses. Exploratory analysis was performed by descriptive statistics (median and interquartile range (IQR), mean and stan- dard deviation (SD)). Signi cant differences between the types of supplement intake and
Nutrients2021,13, 2741 5 of 15 dietary subgroups, age, sex, and race distance were calculated by ANOVA. Logistic re- gression analysis (95% con dence interval (95%-CI)) was used to determine the effect size of the variables (age, sex, diet type, race distance) on intake from kind of supplements (macronutrients, minerals, vitamins) and is displayed as effect plots. Chi-square test ( 2, nominal scale) was used to examine the association between dietary subgroups and age, sex, race distance. Kruskal-Wallis tests (ordinal and metric scale) were approximated by using the t or F distributions or using ordinary least squares and standard errors (SE), and R 2 . Logistic regression analysis (95% con dence interval (95%-CI)) was used to de- termine the effect size of the variables (age, sex, race distance) on intake from kind of supplements (macronutrients, minerals, vitamins) and is displayed as effect plots (95% con dence interval (95%-CI)). The level of statistical signi cance was set atp 0.05. 3. Results From a total number of 317 endurance runners, 220 participants (127 women and 93 men) with a mean age of 38.5 (IQR 18.0) years remained for statistical analysis after a multi-stage data clearance. Germany, Austria, and Switzerland had the majority of endurance runners with 161, 39, and 11 participants, respectively, while 9 participants were from other countries (including Belgium, Brazil, Canada, Italy, Luxemburg, Netherlands, Poland, Spain, and the UK). Based on their race distance, there were a total of 79 10-km runners, 84 half marathoners, and 57 (ultra-)marathoners. In the descriptive characteristics, there was a signi cant difference in absolute values of body weight (F (2, 217)= 6.99,p= 0.001) and BMI (F (2, 217)= 7.32,p< 0.001) but not in body height. In addition, both vegans and vegetarians were signi cantly younger (F (2, 217)= 3.17, p= 0.041) than omnivores. Moreover, there was a signi cant difference between sex and diet type ( 2 (2)= 8.71,p= 0.013), with the majority of vegans and vegetarians being female. No signi cant association was found between the kind of diet and academic quali cation, marital status, country of residence, and race distance (Table). Table 1.Descriptive
(F (2, 217)= 3.17, p= 0.041) than omnivores. Moreover, there was a signi cant difference between sex and diet type ( 2 (2)= 8.71,p= 0.013), with the majority of vegans and vegetarians being female. No signi cant association was found between the kind of diet and academic quali cation, marital status, country of residence, and race distance (Table). Table 1.Descriptive characteristics of participants displayed by dietary subgroups.Total n= 220 Omnivorous n= 100 Vegetarian n= 40 Vegan n= 80 Age (years) 38.5 (IQR 18) 43 (IQR 16.5) 37.5 (IQR 16) 36 (IQR 14.25) Body Weight (kg) 65.0 (IQR 14.4) 68.4 (IQR 15.8) 61 (IQR 8.1) 64.1 (IQR 11) Height (m) 1.7 (IQR 0.1) 1.7 (IQR 0.1) 1.7 (IQR 0.1) 1.7 (IQR 0.1) BMI (kg/m 2 ) 21.75 (IQR 3.44) 22.54 (IQR 3.55) 20.75 (IQR 3.4) 21.32 (IQR 3) Sex Female 127 (58%) 47 (47%) 26 (65%) 54 (68%) Male 93 (42%) 53 (53%) 14 (35%) 26 (32%) Race Distance 10 km 79 (36%) 35 (35%) 12 (30%) 32 (40%) Half marathon 84 (38%) 37 (37%) 19 (48%) 28 (35%) Marathon/Ultra-marathon 57 (26%) 28 (28%) 9 (22%) 20 (25%) Academic Quali cation No quali cation 1 (<1%) 0 (0%) 0 (0%) 1 (1%) Upper secondary 72 (33%) 36 (36%) 16 (40%) 20 (25%) Education/Technical A Levels or equivalent 52 (24%) 26 (26%) 7 (18%) 19 (24%) University/Higher degree 73 (33%) 31 (31%) 13 (32%) 29 (36%) No answer 22 (10%) 7 (7%) 4 (10%) 11 (14%) Marital Status Divorced/Separated 11 (5%) 3 (3%) 1 (2%) 7 (9%) Married/Living with partner 149 (68%) 75 (75%) 23 (57%) 51 (64%) Single 60 (27%) 22 (22%) 16 (40%) 22 (28%) Country of Residence Austria 39 (18%) 21 (21%) 6 (15%) 12 (15%) Germany 161 (73%) 71 (71%) 32 (80%) 58 (72%) Switzerland 11 (5%) 7 (7%) 1 (2%) 3 (4%) Other 9 (4%) 1 (1%) 1 (2%) 7 (9%) BMIbody mass index. IQRinterquartile range.
Description
Investigates supplement intake patterns among different dietary groups of endurance runners.