Nutrient Adequacy in Endurance Athletes

roper nutrition is critical for optimal performance in endurance athletes. However, it is unclear if endurance athletes are meeting all their energy and nutrient needs. We examined if endurance athletes are meeting their nutritional requirements and if this differed by sex. Ninety- ve endurance athletes (n = 95; 50.5% men; 34.9 12.9 y) participated in the study. Dietary intake was evaluated using the 24 h dietary recall method. Energy and nutrient intakes were calculated using the ESHA Food Processor Diet Analysis Software and compared against reference nutrient intakes. Endurance athletes did not consume the recommended amount of energy (76.8% of athletes), carbohydrates (95.8%), linoleic acid (75.8%), -linolenic acid (ALA) (77.9%), eicosatetraenoic and docosahexaenoic acid (96.8%), dietary ber (49.5%), vitamins D (93.7%), E (71.6%), and K (54.7%), folate (54.7%), pantothenic acid (70.5%), biotin (83.2%), manganese (58.9%), magnesium (56.8%), chromium (91.6%), molybdenum (93.7%), choline

and compared against reference nutrient intakes. Endurance athletes did not consume the recommended amount of energy (76.8% of athletes), carbohydrates (95.8%), linoleic acid (75.8%), -linolenic acid (ALA) (77.9%), eicosatetraenoic and docosahexaenoic acid (96.8%), dietary ber (49.5%), vitamins D (93.7%), E (71.6%), and K (54.7%), folate (54.7%), pantothenic acid (70.5%), biotin (83.2%), manganese (58.9%), magnesium (56.8%), chromium (91.6%), molybdenum (93.7%), choline (85.3%), and potassium (56.8%), and consumed too much saturated fat (50.5%) and sodium (94.7%) than recommended. Fisher's Exact test showed that the requirements for dietary ber (70.8% vs. 27.7%), ALA (87.5% vs. 68.1%), and total water (70.8% vs. 44.7%) were not met by more men versus women (p< 0.05). The needs for protein (70.2% vs. 25%) and vitamin B12 (46.8% vs. 22.9%) were not met by more women compared to men (p< 0.05). These ndings need to be con rmed by a larger study. Keywords:nutrient intakes; endurance athletes; nutrient adequacy macronutrients; micronutrients 1. Introduction Nutrition is one of the key factors in achieving optimal training, performance, recovery, injury prevention, and health among endurance athletes [1,2]. More speci cally, endurance athletes train at high volumes which may increase susceptibility to fatigue and muscle damage, negatively impacting performance [3]. To mitigate the effects of prolonged or rigorous training, athletes rely on nutrition to aid in recovery and maintaining health [4]. Studies have also shown that prolonged inadequate energy and nutrient intakes can lead to increased risk for overtraining syndrome (i.e., when training exceeds the ability to recover), infectious diseases, and stress fractures [5–7]. Other health issues related to prolonged inadequate energy balance or relative energy de ciency in sport include complications impacting the gastrointestinal, endocrine, reproductive, skeletal, renal, cardiovascular, and central nervous systems [8]. Despite the importance of proper nutrition, previous studies have shown that many athletes do not achieve adequate energy, macronutrient, and micronutrient intakes [9]. Cross-sectional studies have consistently found that a high percentage of athletes do not meet the recommendations for energy and some macronutrient intakes. Inade- quate energy intake has been found in U.S. female collegiate cross-country and lacrosse Int. J. Environ. Res. Public Health2023,20, 5469.

have shown that many athletes do not achieve adequate energy, macronutrient, and micronutrient intakes [9]. Cross-sectional studies have consistently found that a high percentage of athletes do not meet the recommendations for energy and some macronutrient intakes. Inade- quate energy intake has been found in U.S. female collegiate cross-country and lacrosse Int. J. Environ. Res. Public Health2023,20, 5469.

Int. J. Environ. Res. Public Health2023,20, 5469 2 of 15 athletes [10,11], elite Brazilian athletes [12], and South Asian athletes [13]. In addition, several studies from different countries have shown that athletes do not get enough car- bohydrates [9,14–17], protein [1,18], dietary ber, and essential fatty acids such as linoleic acid, alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) [6,16]. Moreover, female athletes are less likely to meet the recommended amount of dietary ber, possibly because they consume fewer calories than men [16]. In contrast to these ndings multiple studies have found that many athletes consume more total fat than the recommended amount (20–35% energy) [15,16,19]. Besides inadequate consumption of several macronutrients, many athletes have reported inadequate intakes of thiamin, ribo avin, niacin, vitamin B6, vitamin B12, pantothenic acid, biotin, folate, vitamins A, C, D, E, and K, potassium, calcium, zinc, phosphorus, manganese, chromium, molybdenum, selenium, and magnesium [9,16,18–26]. Further, female athletes are less likely to meet the recommendations for iron intake compared to male athletes [9,16,18,20,27] and female athletes may have lower intakes of vitamin B12[28]. Although inadequate nutrient intakes and the impact of this on athletes have been noted, there are several limitations in the current literature. For example, a majority of the studies that examined macronutrient and micronutrient intakes were conducted in elite athletes from a mix of various types of sports [6,9,11,12,15,18,20–22,26]. The few studies that examined nutrient intakes in endurance athletes only, primarily focused on macronutrients [10,17]. and a few micronutrients [16,19,23]. Additionally, there were even fewer studies in endurance athletes examining essential fatty acids such as linoleic acid and ALA [16]. Further, examining essential fatty acids intakes in endurance athletes is critical because they aid in body weight maintenance and reduce in ammation [29–31]. To address gaps in the previous literature, the primary aim of this study was to determine if endurance athletes are meeting their requirements for a comprehensive set of macronutrients including essential fatty acids and micronutrient intakes. Capturing this information is of critical importance given that adequate nourishment is needed for optimizing training, performance, injury prevention, injury recovery, and

ammation [29–31]. To address gaps in the previous literature, the primary aim of this study was to determine if endurance athletes are meeting their requirements for a comprehensive set of macronutrients including essential fatty acids and micronutrient intakes. Capturing this information is of critical importance given that adequate nourishment is needed for optimizing training, performance, injury prevention, injury recovery, and health among endurance athletes [4]. The secondary aim of this study was to compare nutrient adequacy by sex. Based on previous literature, we hypothesized that the majority of endurance athletes will not meet the nutrient requirements and that fewer female athletes will meet the recommendations compared to male athletes. 2. Materials and Methods 2.1. Participants A total of 95 (women: 47, men: 48) endurance athletes were recruited by emailing iers to endurance sports clubs and linking them to their social media groups, posting iers on campus and sport stores in the Dallas–Fort Worth metroplex, and by word of mouth. The endurance athletes were Tier 2: trained/developmental or above based on the criteria from McKay and colleagues [32]. The criteria for Tier 2 training involves training at the local level, exercising 3 days per week, identify with a speci c sport, train with the purpose to complete, have limited skill or development [32]. About 80% of the athletes lived in Texas and the remainder were from other states within the U.S. Inclusion criteria included individuals competing in and/or training for recreational competitive endurance- based sports (e.g., cycling, running, rowing, triathlon, and/or swimming). The exclusion criteria included individuals under 18 years old and those who did not self-identify as an endurance athlete or participate in training activities for endurance-based sports. This study was approved by the Institutional Review Board and each participant read and signed an approved informed consent form. Data collection began in January 2021 and ended in May 2022. 2.2. Procedures Athletes who were eligible to participate were sent an electronic informed consent document which they signed and returned to the research team via email. Following

read and signed an approved informed consent form. Data collection began in January 2021 and ended in May 2022. 2.2. Procedures Athletes who were eligible to participate were sent an electronic informed consent document which they signed and returned to the research team via email. Following

Int. J. Environ. Res. Public Health2023,20, 5469 3 of 15 this, a phone interview was scheduled with each participant to collect information on demographics, anthropometry, dietary intake, health information, and medication and supplement use. Each member of the research team was trained by one of the authors (KM) on how to collect the study data prior to conducting the interviews. 2.3. Measurements 2.3.1. Demographics, Anthropometry, Type of Sport, and Health History Demographic, anthropometric, type of sport, and health history were collected via questionnaire. Demographic information included age, sex (male and female), ethnicity (Hispanic and non-Hispanic), race (White and other including Black/African American, Asian, American Indian/Alaska Native, Native Hawaiian/Other Paci c Islander, and multiracial), and education (high school diploma or lower, some college, college degree, and graduate degree or higher). Self-reported height (m) and weight (kg) were used to calculate body mass index (BMI) (kg/m 2 ). Type of sport included categories such as cycling, running, rowing, swimming, and triathlon. Health history included questions regarding the participant having any chronic health condition. Additionally, the participants were asked if they used any medications, supplements, were vegetarian, currently smoked, or consumed alcohol. 2.3.2. Dietary Intake Assessment Dietary recalls were collected using a multiple-pass 24 h dietary recall method, a validated measure [33,34]. The 24 h dietary recall was collected only after rst verifying with the participant that the intake on the previous day was representative of their usual intake. The interview was re-scheduled for another day if the intake on the previous day was reported by the participant not to be similar to their usual intake. During the multiple-pass 24 h recall, participants were asked to remember and report, in detail, the type and amount of all the foods and beverages that they had consumed on the previous day. The multiple-pass 24 h recall method consisted of ve steps [34]. In the rst step, the participants provided a list of all of the foods and beverages they consumed. During the second step, participants were asked if they consumed any foods from the commonly forgotten list such as beverages, snacks, fruits, vegetables, and breads.

had consumed on the previous day. The multiple-pass 24 h recall method consisted of ve steps [34]. In the rst step, the participants provided a list of all of the foods and beverages they consumed. During the second step, participants were asked if they consumed any foods from the commonly forgotten list such as beverages, snacks, fruits, vegetables, and breads. In the third step, participants were asked about the time and occasion they consumed the foods. During the fourth step, participants provided details about the amounts of food they consumed. Participants were asked to determine portion sizes using tablespoons, teaspoons, cups, pounds, ounces, grams, or slices. The participants were encouraged to provide brand names for processed food, restaurant names if they ate out, and recipes for the food they prepared at home. In the fth step, the researcher asked additional questions about how the food was prepared and foods that the participant might have missed such as snacks or beverages. Energy and nutrient intake were determined using ESHA's Food Processor Diet Analysis Software Version 11.11 (Salem, OR, USA). The ESHA's Food Processor Diet Analysis software provides detailed reports on macronutrient and micronutrient intakes. The software database consisted of over 1900 food sources such as the USDA Standard Reference database, USDA FoodData Central Brands, and manufacturer's data. Further, the software database has more than 146,000 ingredients, recipes, and restaurant food brands. 2.3.3. Dietary Nutritional Adequacy The dietary nutritional adequacy was determined by calculating the percentages of participants who had nutrient intakes below the recommended standards set by the by the Institute of Medicine (IOM) [35], American College of Sports Medicine (ACSM) [36], the Dietary Guidelines for Americans (DGA) [37], or the American Heart Association (AHA) [38]. The ACSM recommendations for athletes were used for assessing dietary fat, protein, and carbohydrate adequacy [36]. Estimated Average Requirements (EAR) a Dietary Reference Intake (DRI), set by the IOM, and used to assess the nutrient adequacy of a group

were used for assessing dietary fat, protein, and carbohydrate adequacy [36]. Estimated Average Requirements (EAR) a Dietary Reference Intake (DRI), set by the IOM, and used to assess the nutrient adequacy of a group

Int. J. Environ. Res. Public Health2023,20, 5469 4 of 15 of individuals, were used to assess adequacy for omega 3 fatty acid, omega 6 fatty acid, vitamins A, C, D, E, B6, and B12, thiamin, ribo avin, niacin, folate, calcium, copper, iron, magnesium, phosphorus, selenium, molybdenum, and zinc [39–44]. Adequate intake (AI), another DRI, was used for the nutrients that did not have an EAR to determine the number of participants who had inadequate intakes of linoleic acid, ALA, total dietary ber, vitamin K, pantothenic acid, biotin, manganese, chromium, choline, potassium, sodium, and total water [35,40,42,45]. Estimated energy requirement (EER), a DRI, was used to determine energy needs [46]. Percent energy from saturated fat was assessed using the 2020–2025 DGA [37]. The AHA guidelines were used to determine the number of participants who did not meet the recommendations for EPA, DHA, and dietary cholesterol [38]. 2.4. Statistical Analysis Categorical variables (i.e., race, ethnicity, education, endurance sport, smoking status, alcohol consumption, vegetarian status, chronic conditions, medication use, and supple- ment use) were presented as percentages and continuous variables (age and BMI) as mean standard deviation. Energy, macronutrient, and micronutrient intakes were presented in medians (25th and 75th percentiles) due to skewed distributions. Differences by sex for categorical variables were determined using Fisher's Exact test and continuous variables by Wilcoxon Rank-Sum test. Since nutrient variables had skewed distributions, the Wilcoxon Rank-Sum tests were used to compare energy, macronutrient, and micronutrient intakes by sex. Nutrient adequacy was determined by calculating the proportion of athletes with inadequate nutrient intakes in comparison to the reference values. Fisher's Exact test was used to compare the proportion of female and male endurance athletes that did not meet the energy, macronutrient and micronutrient requirements. Similar comparisons were made by type of sport and whether or not they had a health condition, and no differences were found. These data were not reported in the paper. Data were analyzed using IBM SPSS version 29 (Armonk, NY, USA). Alpha level was set at 0.05. 3. Results 3.1. Participant Characteristics Participant characteristics for the total sample are presented in Table standard deviation

by type of sport and whether or not they had a health condition, and no differences were found. These data were not reported in the paper. Data were analyzed using IBM SPSS version 29 (Armonk, NY, USA). Alpha level was set at 0.05. 3. Results 3.1. Participant Characteristics Participant characteristics for the total sample are presented in Table standard deviation for age and BMI were 34.9 12.9 y and 23.6 3.84 kg/m 2 , respectively. Slightly more than half (50.5%) of the participants were male, 91.6% were white, 83.2% were non- Hispanic, 71.5% had a bachelor's or graduate degree, 49.5% were runners, 24.2% were triathletes, 18.9% were cyclists, 5.3% were rowers, and 2.1% were swimmers. None of the participants smoked, 66.3% consumed alcohol, 7.4% were vegetarian, 64.2% had a chronic condition, 36.8% were on medications, and 49.5% used supplements. None of the participant characteristics were different by sex. Table 1.Participant characteristics of endurance athletes. Variables Total Sample (n = 95) Female (n = 47) Male (n = 48) p* Age (y) 34.9 12.9 33.5 11.0 36.2 14.5 0.49 BMI (kg/m 2 ) 23.6 3.84 23.0 2.81 24.2 4.59 0.12 Race White 87 (91.6) 41 (87.2) 46 (95.8) 0.16 Other 8 (8.4) 6 (12.8) 2 (4.2) Ethnicity Hispanic 17 (16.8) 4 (8.6) 12 (25.0) 0.09 Non-Hispanic 79 (83.2) 43 (91.4) 36 (75.0)

Int. J. Environ. Res. Public Health2023,20, 5469 5 of 15 Table 1.Cont. Variables Total Sample (n = 95) Female (n = 47) Male (n = 48) p* Education High school 2 (2.1) 0 (0.0) 2 (4.2) 0.51 Some college 25 (26.4) 10 (21.3) 15 (31.2) Bachelor's degree 31 (32.6) 16 (34.0) 15 (31.3) Graduate degree 37 (38.9) 21 (44.7) 16 (33.3) Endurance Sport Cycling 18 (18.9) 6 (12.8) 12 (25.0) 0.27 Running 47 (49.5) 24 (51.1) 23 (47.9) Triathlon 23 (24.2) 14 (29.8) 9 (18.7) Swimming 2 (2.0) 0 (0.0) 2 (4.2) Rowing 5 (5.3) 3 (6.3) 2 (4.2) Smoking Yes 0 (0.0) 0 (0.0) 0 (0.0) 1 No 95 (100.0) 47 (100.0) 48 (100.0) Alcohol Consumption Yes 63 (66.3) 34 (72.3) 29 (60.4) 0.28 No 32 (33.7) 13 (27.7) 19 (39.6) Vegetarian Yes 7 (7.4) 6 (12.8) 1 (2.1) 0.06 No 88 (92.6) 41 (87.2) 47 (97.9) Chronic Condition Yes 61 (64.2) 30 (63.8) 31 (64.5) 1 No 34 (35.8) 17 (36.2) 17 (35.4) Medication Use Yes 35 (36.8) 19 (40.4) 16 (33.3) 0.51 No 60 (63.2) 28 (59.6) 32 (66.7) Supplement Use Yes 47 (49.5) 24 (51.1) 23 (47.9) 0.84 No 48 (50.5) 23 (48.9) 25 (52.1) Abbreviations: BMI, Body mass index. Categorical variables are presented as number and percent of subjects and continuous variables as mean standard deviation. * Fisher's Exact test was used to compare the categorical variables and a Wilcoxon Rank-Sum test was used to compare the continuous variables between the female and male participants. 3.2. Energy and Macronutrient Intakes Energy and dietary macronutrient intakes are presented in Table. Male endurance athletes consumed signi cantly more energy (median difference (MD): 541 kcal/d; p 0.0001), and dietary cholesterol (MD: 152 mg/d;p< 0.01) compared to female en- durance athletes. Table 2.Energy and dietary macronutrient intakes of female and male endurance athletes.Nutrient Total Sample (n = 95) Female (n = 47) Male (n = 48) p* Energy (kcal) 2283 (1655–2826) 1998 (1475–2441) 2539 (1996–3246) 0.0001 Protein (% energy) 18.9 (14.6–23.5) 18.6 (15.0–22.9) 18.9 (14.5–24.3) 0.88 Carbohydrate (% energy)43.4 (33.7–57.1) 43.0 (34.8–56.3) 46.4 (33.0–62.2) 0.95 Total fat (% energy)

This study examines the nutritional requirements of endurance athletes and differences by sex.