October 2018 Issue
CPE Monthly: Nutritional Supplements and Male Athletes
By Natalie Robertello, MS, RDN, CSSD, CDN
Vol. 20, No. 10, P. 48
Suggested CDR Learning Codes: 3100, 4060, 4170
Suggested CDR Performance Indicators: 8.2.1, 8.3.6, 10.4.1, 10.4.5
CPE Level 2
The sports world is full of strong and competitive individuals. Athletes not only want to perform their best but also to win. The use of nutritional strategies has gained popularity among athletes who want to gain a competitive edge. As nutrition experts, RDs know most athletes can meet their dietary needs through food alone. However, with the ever-growing popularity of dietary supplements, athletes may feel supplements can improve their health and performance.
While a large portion of the population uses dietary supplements, evidence suggests that use is higher among athletes compared with nonathletes, and more so in elite vs amateur athletes.1-6
This continuing education course discusses the use of dietary supplements by male athletes and reviews the latest research to help RDs guide athletes about whether supplementation is warranted.
Growth of the Supplement Industry
Interest in supplements appears to have hit an all-time high. Advertisements in fitness magazines and on the internet and television suggest there's a supplement for every health or performance concern, contributing to a significantly increased use of dietary supplements during the past several years. In 2011, the supplement industry surpassed $30 billion in revenue, demonstrating a $2 billion growth over the year. Of the supplements on the market, two categories outperformed the others—sports nutrition supplements and meal replacements—both of which reported double-digit growth in 2011.7 Additional data throughout 2014 show a continued growth trend of dietary supplements, with sports supplements and meal replacements showing the largest growth over several years.8
Defining a Dietary Supplement
According to Congress's Dietary Supplement Health and Education Act of 1994 (DSHEA), dietary supplements are defined as "a product taken by mouth that contains a 'dietary ingredient' intended to supplement the diet." DSHEA classifies dietary ingredients to include "vitamins, minerals, herbs or other botanicals, amino acids, and substances (eg, enzymes, organ tissues, glandular, and metabolites)." Dietary supplements also may comprise extracts or concentrates from plants or foods.9,10 Meal replacements, sports gels and bars, vitamins, and minerals are considered dietary supplements, some with potential ergogenic effects. Ergogenic aids can be defined as any training or psychological technique, mechanical device, nutritional practice, or pharmacologic agent that can help improve exercise performance capacity or enhance physical strength.10 This course discusses the use and efficacy of sports supplements, including supplements with potential ergogenic effects, in the male athlete.
Regulation of Supplements
Before 1994, dietary supplements were regulated in the same fashion as prescription drugs under the Food, Drug and Cosmetics Act. With a growing interest in and use of dietary supplements by the public, the FDA saw a need to develop regulations specifically tailored to dietary supplements, which led to the creation of the DSHEA of 1994.10 With this act, supplements were to be classified as food, allowing continued consumer access to dietary supplements, but with specific labeling requirements and regulatory framework. These new regulations called for a "Supplement Facts" section similar to the Nutrition Facts label found on food; the development of Good Manufacturing Practices for dietary supplements, which ensures that supplements are manufactured in a consistent manner that meets quality standards; and clarification on structure/function claims, which allows the manufacturer to comment on a supplement's potential general health benefits but prevents them from making claims that the supplement can cure or prevent any disease.
According to the regulations, manufacturers can state that the supplement addresses a nutrient deficiency, supports health, or reduces risk of developing a health problem, but also must follow this with the following disclaimer: "This statement has not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease."11 A limitation of the DSHEA is that, unlike before the act, manufacturers don't have to prove that the supplement is safe and effective when putting the product on the market.10-12 If a supplement on the market is found to be unsafe, only then can the FDA take action against the manufacturer. The goal of DSHEA was to ensure legitimate manufacture, sale, and use of supplements while enforcing the law against illegal products and practices.
Sports Association and Agency Regulations
Per the FDA, most dietary supplements on the market appear to have clean records. However, there's desire for further regulation, given the number of supplements on the market and lack of FDA regulation to verify ingredients and dosages in dietary supplements.9
Professional and collegiate sporting associates use strict policies to reduce doping and provide a safe environment for athletes. Use of performance-enhancing drugs is one of the most concerning issues faced in the world of athletics.13 The World Anti-Doping Agency (WADA) and the National Collegiate Athletic Association (NCAA) have regulations in place that prohibit athletes from using specific substances. A supplement is considered for prohibition if medical or antidoping research shows it enhances or has the potential to enhance sports performance, represents an actual or potential health risk to the athlete, or violates the spirit of the sport. Prohibited substances include hormones, anabolic agents, diuretics, stimulants, cannabinoids, glucocorticoids, and narcotics.14,15 The list of prohibited substances for Olympic sports appears on the US Anti-Doping Agency (USADA) website (www.usada.org/substances/prohibited-list/athlete-guide), while banned substances for collegiate sports appear on the NCAA's website (www.ncaa.org/2017-18-ncaa-banned-drugs-list).
USADA's prohibited list is updated annually by a committee of international scientists that meets three times per year to make revisions, which thereafter are sent to WADA's Medical and Research committee for further evaluation before being finalized. WADA has a monitoring system in place to ensure compliance with its established list. USADA holds the right to drug test Olympic athletes via blood or urine samples 365 days per year on a random basis.16 USADA doesn't oversee NCAA and professional non-Olympic sport drug testing; drug testing is managed by the professional associations (National Football League, National Hockey League, etc) and their member schools or teams. Drug testing within the NCAA is handled by The National Center for Drug Free Sport, Inc. and often occurs on a random basis, though institutions often are notified one to two days before testing.17 No supplements are approved as "safe" by the NCAA. NCAA recommends athletes check with their medical staff before considering a supplement. Further information regarding the regulations and drug testing can be found at www.ncaa.org/sport-science-institute/ncaa-drug-testing-program.
While there are blatant cases of doping, some athletes may experience accidental doping due to contamination of dietary supplements on the market.18,19 Investigation into dietary supplements on the market have revealed that some contained prohibited substances such as ephedrine, caffeine, methylenedioxymethamphetamine, and sibutramine that weren't declared on their labels.20 With the potential for inadvertent doping, NCAA and WADA warn athletes to use dietary supplements at their own risk. Even if intake isn't intentional, the NCAA and WADA will take action against athletes who test positive for banned substances, with punishment ranging from suspension to being banned from the sport.
Who Uses Supplements and Why
Among the male and female athlete population, it's clear that men use more supplements compared with women.3-6,21-25 Research suggests that men choose supplements that favor the enhancement of muscle mass and strength more frequently than they use supplements to enhance overall health.26,27 Reasons for supplement use vary by age and competition level.28 External and internal motivators influence athletes' decisions to use supplements, including a desire for improvement in overall health and wellness, increased energy, protection of bones and joints, improvement in muscular strength, immune support, reduction in body fat, and increase in lean muscle mass, as well as a need to compensate for a poor diet.1,4,23 Dietary supplement use among elite athletes ranges from 65% to 87.5%, reporting use to prevent nutritional deficiencies and maintain overall health.4,6 Younger adolescent and collegiate athletes use dietary supplements at rates from 22.3% to 71%, with reported reasoning for use to improve strength and performance.4,29,30 Moreover, athletes report that their decision to take supplements often stems from recommendations by coaches, family, friends, retailers, and internet articles, rather than from suggestions by sports dietitians and other sports-related professionals,1,3,25,29 with the exception of elite athletes, who more often seek help and recommendations from health professionals.30
Supplements Commonly Used by Male Athletes
Popular supplements athletes report taking include multivitamin/minerals, vitamin C, calcium, iron, ergogenic aids such as creatine and caffeine, and sports foods such as meal replacement protein supplements and protein bars.4,23,29 Among male adolescent and collegiate athletes, dietary supplements such as multivitamins and minerals were reported as the most used supplement by male adolescent athletes (as high as 64%);29,31,32 use of sports supplements such as creatine and caffeine also was noted. Creatine use was reported among 16% to 37% of adolescent male athletes, and caffeine 16% to 26%.25,31 Male collegiate athletes have reported taking 1.8±1.2 supplements each, usually including multivitamins, protein, creatine, vitamin C, caffeine, and glutamine.29,33 The most used supplements reported by elite male athletes include multivitamins and minerals, followed by protein, creatine, sports drinks, and caffeine.1,24,30 Additional performance supplements that have increased in use in recent years include bicarbonate, beta-alanine, and branched-chain amino acids (BCAAs),33 popular for their potential ergogenic effects.
Efficacy and Safety of Commonly Used Supplements
For most of the many supplements available, there's little quality research to support their efficacy and safety. Of the performance-enhancing supplements male athletes commonly use, there's well-documented research about the performance-enhancing ability of creatine, caffeine, beta-alanine, and sodium bicarbonate. Studies of glutamine and BCAAs, however, have produced mixed results concerning their ability to improve performance. The Academy of Nutrition and Dietetics' and the American College of Sports Medicine's latest position paper on Nutrition and Athletic Performance,34 as well as the supplement classification system from the Australian Institute of Sport, are excellent resources for reviewing the safety and efficacy of popular supplements used by male athletes.
Creatine is produced endogenously and stored predominately within skeletal muscle but also is found in small amounts within the liver, kidneys, and brain.35 For meat-eating athletes, creatine can be obtained through diet; however, for vegetarians and vegans, the absence of meat in their diets results in lower resting creatine levels.35 Reported benefits of creatine supplementation include improved strength, increased anaerobic power output, and reduced fatigue after short bouts of high-intensity exercise.36,37
Yáñez-Silva and colleagues studied short-term (14-day) low-dose creatine intake in male youth soccer athletes. Increased peak power and mean output were observed in athletes given 0.03 g/kg/day when compared with a placebo.36 Law and colleagues studied larger doses over a shorter period of time. Trained males were given 20 g creatine daily, (4-g doses five times per day) and were assessed at both two and five days of supplementation. Subjects at day five showed significant improvement in average anaerobic power and squat strength; two days of supplementation with creatine didn't show increased power or strength.37 Athletes participating in sports such as football or those involving short-distance running (eg, sprinting and soccer) may benefit from its use, while long-distance runners or those engaging in endurance-related sports wouldn't see significant performance benefits.
A "loading period" has long been recommended to obtain performance benefits from creatine. This includes a 20-g creatine monohydrate dosage, given daily and split into 5-g doses four times per day for two to five days, followed by a maintenance dose of 3 to 5 g/day.36-38 However, studies have demonstrated ergogenic benefits with 3 to 6 g/day over a 28-day period without the loading phase.36,38,39
There's potential for athletes to be "nonresponders," meaning they don't gain performance benefits from creatine supplementation; this often is the case in athletes with sufficient base creatine stores before supplementation.36
Acute weight gain has been reported (0.6 to 1 kg) in all "responding" users during the loading phase due to an increase in intracellular water caused by creatine supplementation.34,38,40
Overall, creatine appears to be safe for adults, with the exception of occasional reports of cramping.36 However, its safety and efficacy haven't been established in athletes aged 18 or younger.34,36
Caffeine is found naturally in a variety of foods and beverages, including chocolate, tea, and coffee. Caffeine is thought to alter central nervous system function with its ability to act as an adenosine-receptor antagonist.40 The binding of adenosine inhibits the release of neurotransmitters, reducing arousal and activity.41 A dose of 1 to 5 mg/kg caffeine has demonstrated ergogenic effects.34,41,42 Jenkins and colleagues demonstrated a 4% increase in performance when cyclists were administered 2 to 4 mg/kg caffeine 60 minutes before a short, high-intensity bike ride compared with those receiving a placebo.42 Beyond an increase in power output, a reduction in perceived exertion and fatigue also has been noted as a potential benefit of caffeine supplementation. Azevedo and colleagues found a 14% increase in endurance performance compared with placebo when 5 mg/kg caffeine was administered to subjects at the point of mental fatigue, which was assessed using a cognitive test.41 While individuals react differently to caffeine, some side effects noted included tremors, anxiety, and increased heart rate.40,42 Collegiate athletes should be aware there's a potential risk of doping with caffeine supplementation; urinary concentration exceeding 15 mcg/mL will result in a positive drug test for an athlete.34
Beta-alanine is a naturally occurring amino acid in the body that's been found to delay the onset of muscle fatigue and improve endurance.34,43 As exercise intensity increases, the body begins to rely on anaerobic metabolism for energy. As a byproduct of anaerobic metabolism, H+ ions are produced, reducing muscle pH. Marinescu and colleagues examined athletes' pH and lactic acid levels throughout a water polo match; they found the average pH among participants decreased from 7.402 preexercise to 7.339 in the fourth quarter, and lactic acid increased from 1.7 preexercise to 6.2 in the fourth quarter.44
Beta-alanine is important for the production of carnosine, which acts to buffer H+ ions and reduce fatigue. Research has shown that 4 to 6.4 g/day of beta-alanine increases intramuscular carnosine concentration by 30% to 80%.45,46 Derave and colleagues found an increase in muscle carnitine concentration with supplementation of 4.8 g/day beta-alanine in 400-m sprinters but didn't note increased overall performance. Average time to complete the 400-m sprint was 51.44 ± 1.57 seconds.46 Howe and colleagues studied the effect of 4.5 g/day of beta-alanine supplementation on power output and fatigue. Cyclists performed a four-minute high-intensity cycle after four weeks of beta-alanine supplementation. Power output was increased 44% in those getting the supplement compared with those who received the placebo, and fatigue was significantly reduced.47 These two studies are consistent with the recommendation from the Academy of Nutrition and Dietetics and American College of Sports Medicine that beta-alanine would best benefit athletes involved in high-intensity exercise lasting 60 to 240 seconds.34
Sodium bicarbonate has been studied as an ergogenic aid for its ability to reduce fatigue during high-intensity exercise. Similar to beta-alanine, sodium bicarbonate works as a buffering agent, reducing acid buildup in working muscle. A dosage of 0.3 to 0.5 g/kg of sodium bicarbonate has been shown to elicit performance-enhancing benefits in well-trained athletes. Krustrup and colleagues found a 14% increase in performance among highly trained athletes given supplementation compared with those receiving no supplementation. Athletes completed repeated bouts of 20-m runs at progressively faster speeds with each bout. A total dosage of 0.4 g/kg sodium bicarbonate was split and taken at 90, 80, 70, 60, and 50 minutes before exercise. Blood pH and bicarbonate concentration overall was higher in the sodium bicarbonate group. Blood pH before exercise was, on average, 7.37 in both groups; increased in the sodium bicarbonate group (average 7.44) and decreased in the nonsupplement group (average 7.32) before exercise; and decreased in both groups postexercise (7.19 in sodium bicarbonate group and 7.09 in nonsupplement group). In addition, lactate concentrations were higher in the group receiving supplementation, while the rate of perceived exertion was lower.48
Some studies have failed to show performance improvements with supplementation; however, it's believed that well-trained athletes will benefit most from sodium bicarbonate supplementation.49 Sodium bicarbonate appears to be useful in high-intensity activity lasting one to seven minutes, such as repeated bouts of sprints. Most studies agree that a dose of 200 to 300 mg/kg of body weight produces benefits, and that dose should be taken 60 to 90 minutes before exercise.48,50 A notable side effect of sodium bicarbonate is diarrhea; therefore, taking it too close to exercise can be problematic for some athletes.49 Athletes who experience this side effect may want to consider taking sodium bicarbonate 180 minutes rather than 60 to 90 minutes before exercise.51
Glutamine is a nonessential amino acid that's plentiful in the diet via protein-rich foods. Glutamine has been researched for its potential ergogenic effects in promoting recovery postexercise. Lower concentrations of glutamine have been found in the athletic population, and it's been hypothesized that lower glutamine levels could impair immune function.52 There's insufficient evidence that oral glutamine supplementation aids in muscle recovery postexercise. Legault and colleagues found that muscle soreness and strength loss were reduced with 0.3 g/kg/day L-glutamine supplementation given 60 minutes pre-exercise and immediately postexercise. Supplementation with L-glutamine compared with placebo showed greater peak torque recovery and reduced perceived muscle soreness.53 In contrast, Rahmani Nia and colleagues found no significant reduction in quadriceps muscle damage with supplementation of 0.1 g/kg three days per week for four weeks before exercise, but did find a reduction in delayed-onset muscle soreness.54 At this time, there's no research-supported recommendations for glutamine supplementation for muscle recovery postworkout in the athletic population.52,55
BCAAs comprise the essential amino acids leucine, isoleucine, and valine. These essential amino acids are found in a variety of protein-rich foods, including eggs, chicken, and beef. Athletes often choose to use BCAAs to improve strength, power, and endurance. BCAAs are thought to stimulate muscle protein synthesis, attenuate muscle protein degradation, and reduce muscle soreness postworkout.56,57 However, research is mixed regarding their ability to enhance performance by reducing muscle degradation.56-58 Kephart and colleagues failed to demonstrate an improvement in one repetition max (maximum amount of weight that can be contracted in one contraction) performance in a group taking a mixed BCAA-carbohydrate supplement containing 3 g leucine, 1 g isoleucine, and 2 g valine compared with the group given only carbohydrate (Powerade) when ingested immediately postexercise.58 Furthermore, reduction in perceived muscle soreness wasn't observed. Like Kephart and colleagues, Howatson and researchers couldn't demonstrate improved vertical jump performance; however, in contrast, they observed reduction in perceived muscle soreness 24 and 48 hours postexercise in the BCAA group compared with the placebo group. BCAAs were administered twice per day, morning and evening, consisting of 2 g leucine, 1 g isoleucine, and 1 g valine.56
In opposition to both of these studies, Kirby and colleagues found that when subjects were given 2.5 g/kg leucine 30 minutes before exercise, immediately preexercise, immediately postexercise, and pre-posttest, isometric force output was significantly greater than that of individuals in the placebo group; however, there was no improvement in jump. Moreover, no reduction in perceived muscle soreness was observed.57 Differences among these studies are the timing and dose of the BCAAs. Dosage recommendations range from 5 to 20 g/day with at least 2 to 3 g leucine.56-58 Recommendations for timing of supplemental BCAA remains to be determined.
Deciphering the Data
The nature of much of the available research limits its ability to detect a consistent and truthful trend on athlete supplement use; sample sizes often are small, and data are based on self-reported usage. Due to the variation in reported supplement use, it's difficult to give an accurate percentage of male athletes who use supplements. However, several observations can be made about the use of dietary supplements.
Young athletes often struggle with making optimal food choices to get the nutrients they need for peak performance. This may in part be due to lack of nutrition knowledge derived from credible sources, which can hamper training ability. In athletes who consume a well-balanced diet, dietary supplements aren't necessary. Exceptions to this include athletes who aren't meeting their calorie needs, have a nutrient deficiency, or want to improve performance with the use of ergogenic aids. Meal replacement beverages and/or protein supplements offer a convenient option to athletes with busy schedules; however, these athletes may miss out on additional key nutrients from whole foods if they heavily rely on these supplements on a regular basis.
It's apparent that overuse of supplements can occur among young athletes due to lack of education. Staff sports RDs can help young athletes by addressing individual needs and creating sport-specific dietary strategies to maximize performance. Dietary supplements and ergogenic aids have a place if needed, but proper education and supervision are essential.
Putting It Into Practice
Since diet is crucial for enhancing training and performance, the role of RDs is to assess athletes' diets and educate them about the appropriate foods for obtaining the necessary calories and macro- and micronutrients for their sports training. It's important to be aware of athletes' needs, taking into consideration their sport, athletic level, and age. For example, young male athletes, both at the high school and collegiate level, are more susceptible to deficiencies in zinc, B vitamins, calcium, and protein.59
Athletes, especially at the high school and collegiate levels, have misconceptions about the efficacy of dietary supplements.28 Petróczi and colleagues surveyed athletes' reasons for taking various supplements and found these athletes believed that both creatine and protein supplementation will help them to "maintain strength."60 These fallacies largely can be attributed not only to inexpert sources of information but also to misleading advertisements and poor regulation of supplements. Nutrition education on dietary supplements is lacking within high school and collegiate level athletics; only 14% to 29% of athletes report talking with RDs about the decision to use dietary supplements.6,25,28 Therefore, RDs shouldn't dismiss their clients' desire to take supplements; if their questions aren't adequately addressed, they may get information from less credible sources, which can put them at risk. Taking the time to understand the rationale behind the desire to supplement not only will help build rapport with athletes but also could provide RDs with information that will help them address their clients' concerns. Your first step should be to complete a nutrition assessment.
A food diary also may be necessary to further assess the usual diet of the athlete. Ask clients to complete a three-day food journal including two weekdays and one weekend day. This will help to better assess their diet through training, competition, and rest. Included in your assessment should be questions regarding the client's desire to use particular supplements, such as, "What are your goals in taking that supplement?" or "How do you think this supplement will benefit you?" Using the most up-to-date scientific evidence, discuss the efficacy and safety of the supplement(s) with the athlete. Reference the pros and cons, including the specific benefits and side effects. This is vital to helping clients understand whether the supplement can truly benefit them in the way they hope or whether adjustments to diet alone will help to improve performance.
If athletes are considering a trial of a supplement to assess its potential benefits, it's the RD's duty to ensure they proceed safely. Once again, referencing evidence-based research is essential. Using the classification system developed by the Australian Institute of Sport (www.ausport.gov.au/ais/nutrition/supplements/classification) and/or the International Society of Sports Nutrition can help RDs quickly reference supplements that have proven efficacy and safety.10 Supplements that are banned, fall into the C or D categories per the Australian Institute of Sport, or are listed in category III or IV per the International Society of Sports Nutrition should be strongly discouraged. Before supplementation, consider the legality, efficacy, and safety of the product. Is the marketing claim in line with the research/analysis of the supplement? Is there science-based research that supports the supplement? Research studies should mimic real-life situations and events. For example, they should analyze an athletic population rather than a sedentary population.
Determine whether the supplement is legal by referencing the WADA and NCAA lists of prohibited substances. Resource pages are provided on their websites to help athletes make educated decisions.15,61 They can be found at www.usada.org/substances/supplement-411; www.ncaa.org/2016-17-ncaa-banned-drugs-list; and www.drugfreesport.com/services/rec-overview.asp. Furthermore, guide athletes to seek products from companies that abide by Good Manufacturing Practices and are verified for quality by third-party testing companies such as NSF International, Informed-Choice, US Pharmacopeia, and Consumer Lab.10 These third-party testing agencies don't guarantee supplements as banned substance-free but do reduce risk of using contaminated and unsafe products. An additional safeguard is using the Drug-Free Sport database. Drug-Free Sport has a risk level ranking system for dietary supplements, denoting whether a supplement is considered safe, risky, or banned based on its ingredients.
— Natalie Robertello, MS, RDN, CSSD, CDN, of Buffalo, New York, is a consultant dietitian and owns a sports-nutrition focused private practice.
After completing this continuing education course, nutrition professionals should be better able to:
1. Determine at least two reasons athletes should be cautious of dietary supplements.
2. Distinguish three methods for assessing the safety and efficacy of dietary supplements.
3. Evaluate the available research on dietary supplements.
4. Provide informed recommendations about nutritional supplementation to male athletes.
5. Identify five prohibited substances per the World Anti-Doping Agency and the National Collegiate Athletic Association.
CPE Monthly Examination
1. Which of the following is a major limitation of the Dietary Supplement and Health Education Act of 1994?
a. Manufacturers are allowed to make general health claims.
b. Manufacturers aren't required to provide evidence-based research or have their product evaluated by the FDA before putting a supplement on the market.
c. It developed Good Manufacturing Practices for only certain dietary supplements.
d. Dietary supplements are regulated in the same fashion as food and drugs.
2. Which of the following is the best way for consumers to ensure the safety and quality of a supplement?
a. Read the supplement label.
b. Check supplements via third-party testing companies.
c. Purchase the most expensive brand.
d. Use supplements with a proprietary blend.
3. Which of the following is a banned substance per the World Anti-Doping Agency and National Collegiate Athletic Association?
b. Branched-chain amino acids
d. Sodium bicarbonate
4. Generally speaking, which of the following would be best to consume postworkout?
a. Protein shake
d. Chocolate milk and piece of fruit
5. What dosage of caffeine has demonstrated ergogenic effects?
a. 3 mg/kg of body weight
b. 5 mg/kg of body weight
c. 7 mg/kg of body weight
d. 9 mg/kg of body weight
6. For which of the following athletes would creatine supplementation be most appropriate?
a. 20-year-old long-distance runner
b. 18-year-old sprinter
c. 25-year-old football player
d. 30-year-old triathlete
7. What's the first step you should take in determining whether a dietary supplement can benefit an athlete?
a. Review the literature on the supplement.
b. Complete a dietary assessment.
c. Discourage the use of supplements.
d. Make a recommendation on appropriate dosage.
8. Which of the following is an ideal way to assess typical dietary intake of an athlete?
a. Food frequency questionnaire
b. 24-hour recall
c. Three-day food log
d. Seven-day food log
9. Which of the following supplements appears to be most popular among male adolescent athletes?
a. Multivitamin/mineral supplement
b. Vitamin C
10. What guideline should you give an athlete to aid in choosing a safe supplement?
a. Choose supplements deemed "natural."
b. Choose supplements that have been tested by a third-party agency, such as NSF International.
c. Choose supplements recommended by teammates, coaches, or vitamin/mineral stores.
d. Choose supplements deemed as a "collegiate" formula.
1. Braun H, Koehler K, Geyer H, Kleiner J, Mester J, Schanzer W. Dietary supplement use among young elite young German athletes. Int J Sport Nutr Exerc Metab. 2009;19(1):97-109.
2. Huang HY, Caballaro B, Chang S, et al. The efficacy and safety of multivitamin and mineral supplement use to prevent cancer and chronic disease in adults: a systematic review for a National Institutes of Health State-of-the-Science Conference. Ann Intern Med. 2006;145(5):372-385.
3. Erdman KA, Fung TS, Reimer RA. Influence of performance level on dietary supplementation in elite Canadian athletes. Med Sci Sports Exerc. 2006;38(2):349-356.
4. Maughan RJ, Greenhaff PL, Hespel P. Dietary supplements for athletes: emerging trends and recurring themes. J Sports Sci. 2011;29(Suppl 1):S57-S66.
5. Tscholl P, Alonso JM, Dollé G, Junge A, Dvorak J. The use of drugs and nutritional supplements in top-level track and field athletes. Am J Sports Med. 2010;38(1):133-140.
6. Huang SH, Johnson K, Pipe AL. The use of dietary supplements and medications by Canadian athletes at the Atlanta and Sydney Olympic Games. Clin J Sport Med. 2006;16(1):27-33.
7. Nutrition Business Journal's Supplement Business Report 2012. New Hope Network website. http://www.newhope.com/research-and-insights/supplement-business-report. Published September 5, 2012. Accessed August 19, 2018.
8. 2015 NBJ Supplement Business Report: a tough year for supplements by the numbers. New Hope Network website. http://www.newhope.com/managing-your-business/2015-nbj-supplement-business-report-tough-year-supplements-numbers. Published June 1, 2015. Accessed August 19, 2018.
9. FDA 101: dietary supplements. US Food and Drug Administration website. http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm050803.htm. Updated November 6, 2017. Accessed August 19, 2018.
10. Kreider RB, Wilborn CD, Taylor L, et al. ISSN exercise & sport nutrition review: research & recommendations. J Int Soc Sports Nutr. 2010;7:7.
11. Frequently asked questions (FAQ). National Institutes of Health, Office of Dietary Supplements website. https://ods.od.nih.gov/Health_Information/ODS_Frequently_Asked_Questions.aspx. Updated July 1, 2013. Accessed August 19, 2018.
12. Milestones in U.S. food and drug law history. US Food and Drug Administration website. https://www.fda.gov/ForConsumers/ConsumerUpdates/ucm2007256.htm. Updated February 1, 2018. Accessed August 19, 2018.
13. US Anti-Doping Agency. Values and ethics — concern about PEDs. NCAA website. http://www.ncaa.org/sites/default/files/table4_0.jpg. Accessed August 19, 2018.
14. WADA Prohibited List. US Anti-Doping Agency website. https://www.usada.org/wp-content/uploads/wada-2018-prohibited-list-en.pdf
15. 2017-18 NCAA Banned Drugs List. NCAA website. http://www.ncaa.org/2017-18-ncaa-banned-drugs-list
16. Frequently asked questions. US Anti-Doping Agency website. http://www.usada.org/resources/faq/. Accessed August 19, 2018.
17. Frequently asked questions about drug testing. NCAA website. http://www.ncaa.org/health-and-safety/policy/frequently-asked-questions-about-drug-testing. Accessed August 19, 2018.
18. Outram S, Stewart B. Doping through supplement use: a review of available empirical data. Int J Sport Nutr Exerc Metab. 2015;25(1):54-59.
19. Petroczi A, Taylor G, Naughton DP. Mission impossible? Regulatory and enforcement issues to ensure safety of dietary supplements. Food Chem Toxicol. 2011;49(2):393-402.
20. Geyer H, Parr MK, Koehler K, Mareck U, Schänzer W, Thevis M. Nutritional supplements cross-contaminated and faked with doping substances. J Mass Spectrom. 2008;43(7):892-902.
21. Godo JR, Graves BS, O'Kroy JA, Hecht S. Influences of dietary supplement use in South Florida adolescent athletes. Am J Health Stud. 2006;21(1-2):91-98.
22. Grossbard J, Hummer J, LaBrie J, Pederson E, Neighbors C. Is substance use a team sport? Attraction to team, perceived norms, and alcohol and marijuana use among male and female intercollegiate athletes. J Appl Sport Psychol. 2009;21(3):247-261.
23. McDowall JA. Supplement use by young athletes. J Sports Sci Med. 2007;6(3):337-342.
24. Heikkinen A, Alaranta A, Helenius I, Vasankari T. Use of dietary supplements in Olympic athletes is decreasing: a follow-up study between 2002 and 2009. J Int Soc Sports Nutr. 2011;8(1):1.
25. Scofield DE, Unruh S. Dietary supplement use among adolescent athletes in central Nebraska and their sources of information. J Strength Cond Res. 2006;20(2):452-455.
26. Lun V, Erdman KA, Fung TS, et al. Dietary supplement practices in Canadian high-performance athletes. Int J Sport Nutr Exerc Metab. 2012;22(1):31-37.
27. Giraldi G, Unim B, Masala D, Miccoli S, La Torre G. Knowledge, attitudes and behaviors on doping and supplements in young football players in Italy. Public Health. 2015;129(7):1007-1009.
28. Kiertscher E, DiMarco NM. Use and rationale for taking nutritional supplements among collegiate athletes at risk for nutrient deficiencies. Perform Enhanc Health. 2013;2(1):24-29.
29. Darvishi L, Askari G, Hariri M, et al. The use of nutritional supplements among collegiate male athletes. Int J Prev Med. 2013;4(Suppl 1):S68-S72.
30. Dascombe BJ, Karunaratna M, Cartoon J, Fergie B, Goodman C. Nutritional supplementation habits and perceptions of elite athletes within a state-based sporting institution. J Sci Med Sport. 2010;13(2):274-280.
31. Knapik JJ, Steelman RA, Hoedebecke SS, Austin KG, Farina EK, Lieberman HR. Prevalence of dietary supplement use by athletes: a systematic review and meta-analysis. Sports Med. 2016;46(1):103-123.
32. Stuntz CP, Edwards JC, Kaye M. Individual and social predictors of performance-enhancing and dietary supplement use among male NCAA division III athletes. J Issues Intercollegiate Athl. 2014;2014:187-206.
33. Brown-Riggs C. Ergogenic aids — competitive edge or hidden danger? Today's Dietitian. 2013;15(4):24-29.
34. Thomas DT, Erdman KA, Burke LM. Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: nutrition and athletic performance. J Acad Nutr Diet. 2016;116(3):501-528.
35. Cooper R, Naclerio F, Allgrove J, Jimenez A. Creatine supplementation with specific view to exercise/sports performance: an update. J Int Soc Sports Nutr. 2012;9(1):33.
36. Yáñez-Silva A, Buzzachera CF, Piçarro IDC, et al. Effect of low dose, short-term creatine supplementation on muscle power output in elite youth soccer players. J Int Soc Sports Nutr. 2017;14:5.
37. Law YL, Ong WS, GillianYap TL, Lim SC, Von Chia E. Effects of two and five days of creatine loading on muscular strength and anaerobic power in trained athletes. J Strength Cond Res. 2007;23(3):906-914.
38. Buford TW, Kreider RB, Stout JR, et al. International Society of Sports Nutrition position stand: creatine supplementation and exercise. J Int Soc Sports Nutr. 2007;4:6.
39. Hicker RC, Dyck DJ, Sklar J, Hatley H, Byrd P. Effect of 28 days of creatine ingestion on muscle metabolism and performance of a simulated cycling road race. J Int Soc Sports Nutr. 2010;7:26.
40. Tarnopolsky MA. Caffeine and creatine use in sport. Ann Nutr Metab. 2010;57(Suppl 2):1-8.
41. Azevedo R, Silva-Cavalcante MD, Gualano B, Lima-Silva AE, Bertuzzi R. Effects of caffeine ingestion on endurance performance in mentally fatigued individuals. Eur J Appl Physiol. 2016;116(11-12):2293-2303.
42. Jenkins NT, Trilk JL, Singhal A, O'Connor PJ, Cureton KJ. Ergogenic effects of low doses of caffeine on cycling performance. Int J Sport Nutr Exerc Metab. 2008;18(3):328-342.
43. Seher CL. Sports nutrition: beta-alanine supplements. Today's Dietitian. 2012;14(7):20-21.
44. Marinescu G, Ticala D, Radulescu A. Metabolic cost of the effort specific to water polo game, based on the relationship between pH and lactic acid concentrations in junior III. Sci Mov Health. 2015;15(2):419-424.
45. Baguet A, Bourgois J, Vanhee L, Achten E, Derave W. Important role of muscle carnosine in rowing performance. J Appl Physiol (1985). 2010;109(4):1096-1101.
46. Derave W, Ozdemir M, Harris R, et al. Beta-alanine supplementation augments in muscle carnosine content and attenuates fatigue during repeated isokinetic contraction bouts in trained sprinters. J Appl Physiol (1985). 2007;103(5):1736-1743.
47. Howe ST, Bellinger PM, Driller MW, Shing CM, Fell JW. The effect of beta-alanine supplementation on isokinetic force and cycling performance in highly trained cyclists. Int J Sport Nutr Exerc Metab. 2013;23(6):562-570.
48. Krustrup P, Ermidis G, Mohr M. Sodium bicarbonate intake improves high-intensity intermittent exercise performance in trained young men. J Int Soc Sports Nutr. 2015;12:25.
49. Carr AJ, Slater GJ, Gore CJ, Dawson B, Burke LM. Effect of sodium bicarbonate on [HCO3-], pH, and gastrointestinal symptoms. Int J Sport Nutr Exerc Metab. 2011;21(3):189-194.
50. Burke LM. Practical considerations for bicarbonate loading and sports performance. Nestle Nutr Inst Workshop Ser. 2013;75:15-26.
51. Siegler JC, Marshall PW, Bray J, Towlson C. Sodium bicarbonate supplementation and ingestion timing: does it matter? J Strength Cond Res. 2012;26(7):1953-1958.
52. Gleeson M. Dosing and efficacy of glutamine supplementation in human exercise and sport training. J Nutr. 2008;138(10):2045S-2049S.
53. Legault Z, Bagnall N, Kimmerly DS. The influence of oral L-glutamine supplementation on muscle strength recovery and soreness following unilateral knee extension eccentric exercise. Int J Sport Nutr Exerc Metab. 2015;25(5):417-426.
54. Rahmani Nia F, Farzaneh E, Damirchi A, Shamsi Majlan A. Effect of L-glutamine supplementation on electromyographic activity of the quadriceps muscle injured by eccentric exercise. Iran J Basic Med Sci. 2013;16(6):808-812.
55. Walsh NP, Gleeson M, Pyne DB, et al. Position statement. Part two: maintaining immune health. Exerc Immunol Rev. 2011;17:64-103.
56. Howatson G, Hoad M, Goodall S, Tallent J, Bell PG, French DN. Exercise-induced muscle damage is reduced in resistance-trained males by branched chain amino acids: a randomized, double-blind, placebo controlled study. J Int Soc Sports Nutr. 2012;9:20.
57. Kirby TJ, Triplett NT, Haines TL, Skinner JW, Fairbrother KR, McBride JM. Effect of leucine supplementation on indices of muscle damage following drop jumps and resistance exercise. Amino Acids. 2012;42(5):1987-1996.
58. Kephart WC, Mumford PW, McCloskey AE, et al. Post-exercise branched chain amino acid supplementation does not affect recovery markers following three consecutive high intensity resistance training bouts compared to carbohydrate supplementation. J Int Soc Sports Nutr. 2016;13:30.
59. Smith JW, Holmes M, McAllister MJ. Nutritional considerations for performance in young athletes. J Sports Med (Hindawi Publ Corp). 2015;2015:734649.
60. Petróczi A, Naughton DP, Pearce G, Bailey R, Bloodworth A, McNamee M. Nutritional supplement use by elite young UK athletes: fallacies of advice regarding efficacy. J Int Soc Sports Nutr. 2008;5:22.
61. Supplement 411: realize, recognize, reduce. US Anti-Doping Agency website. http://www.usada.org/substances/supplement-411/. Accessed August 19, 2018.