January 2025 Issue
Supplements for Athletes
By Dana Angelo White, MS, RD, ATC
Today’s Dietitian
Vol. 27 No. 1 P. 14
An Updated Guide for Safety and Efficacy
Making sense of dietary supplements (DS) and knowing how and when to recommend them can be a complicated matter for all dietitians. Navigating loose regulatory standards, proper dosing guidelines, and reducing the risk of side effects and interactions is a big job, yet incredibly necessary for providing quality care. Clinicians who work with athletes may experience additional concerns over banned substance violations and doping. High school athletes who aspire to play at the next level should also carefully consider the DS they choose.
With an ever-increasing number of athletes taking DS, and in large amounts, there is good reason for concern and a need for dietitians to be educated. Influence by peers, social media, and coaches perpetuates misinformation about DS, which may increase the risks. To help mitigate dangers, a qualified sports dietitian is needed to develop protocols for safety, compliance, and performance enhancement.1 There is a time for safe supplement use but also times when it is best to pass.
Evaluation of Dietary Supplements
DS are only subject to minor regulatory mandates. The Dietary Supplement Health and Education Act, passed in 1994, set standards that are still followed today. These guidelines indicate that DS are subject to investigation after products go to market. This leaves plenty of opportunity for products to be poorly produced, contaminated, and intentionally or unintentionally adulterated. While there are some companies taking extra steps to ensure quality and label accuracy, it is not required or closely monitored under the Dietary Supplement Health and Education Act.2
Due to the current landscape of poor regulation, it is all too common for readily available products with undisclosed ingredients to negatively impact athlete safety. A study published in 2022 determined that nearly 30% of over 3,100 supplements tested contained undeclared ingredients that put athletes at risk for doping violations.3
Due to these risks, dietitians are encouraged to rely heavily on DS that have undergone third-party testing. There are several organizations that independently test DS to evaluate them for label accuracy and the presence of banned substances. The organizations commonly used by sports dietitians include NSF Certified for Sport, Informed Sport and Informed Choice, and USP Verified. Recommending products that have undergone third-party testing can help ensure label accuracy and increase safety, but it does not mean that they are appropriate for any athlete to use, that is where clinical expertise comes in. These organizations can also be utilized for supplement selection. Databases allow users to search by product to look up a particular product, check a DS brand, or seek out a desired tested product.
Be aware that a brand may have numerous items in its product line that have undergone third-party testing but also several products that have not; verification does not stretch across every item in a brand catalog.
While not directly related to third-party testing, the Australian Institute of Sport does extensive research and categorizes supplements by an “ABCD classification system” that groups products by level of evidence and safe use indications for athletes. Supplements in Group A include electrolyte products, vitamin D, and iron; Group D includes stimulants and hormone boosters.
See https://www.ais.gov.au/nutrition/supplements for complete lists.
Supplement Hit List
Supplement use among athletes is high—between 40% and 100% of athletes report typically using DS.4 Some of the most popular DS are not well-studied, and those that do have evidence to support their effectiveness are not appropriate for everyone. Christina Weidman, MS, RDN, CSSD, LDN, advanced clinical dietitian for Northwestern Athletics, highlights the importance of customizing care when making DS recommendations. “Being able to dial it in based on an athlete’s level of training and performance goals can make these supplements worthwhile. Taking these products without great direction usually leads to spending a lot of money on something that probably won’t work,” Weidman says.
Evidence-Based Sports Supplements
There are several supplements that may be beneficial to athletes. Here are six DS with evidence to back them up, recommended by experts.
Creatine
Creatine monohydrate is one of the most well-researched DS available to athletes and there is a large body of evidence supporting safety and efficacy when used appropriately in 5 g daily doses of creatine monohydrate.5 Creatine supplementation increases levels of muscle creatine to produce more muscle energy via phosphocreatine resynthesis. As with many DS, the majority of scientific evidence on creatine involves male subjects; however, there is a growing body of research looking at the positive effects of creatine in females as it relates to supporting muscle, brain, and bone health as well.6 Tavis Piattoly, MS, RD, LDN, cofounder of My Sports Dietitian and the Eat 2 Win Nutrition app, emphasizes that creatine is underutilized. “I don’t believe we see enough athletes using it, especially at the youth level, because there is a lack of understanding of the benefits among those in the medical community who are not familiar with how safe and effective creatine is for a variety of outcomes.”
Beta-Alanine
Beta-alanine may increase concentrations of carnosine in muscle tissue, which helps to buffer pH levels and delay the onset of fatigue occurring in skeletal muscle during strenuous exercise.7 Dosing and administration for beta-alanine requires careful calculations7 but often approaches 65 mg/kg body weight every three to four hours daily. Beta-alanine is a common ingredient in protein powders and preworkout supplements, but dosages and administration are often not aligned with clinical recommendations.
Omega-3
Omega-3 supplements made from fish oil are commonly recommended for athletes with limited dietary intake from whole food sources. Dose recommendations are inconsistent, but several studies support potential benefits and safety with doses up to 5 g per day.8 The role of omega-3s in injury prevention and treatment is also being investigated. Piattoly points out that many athletes can benefit, as omega-3s “reduce inflammation and protect the brain from trauma. We have a lot of evidence that shows higher blood levels of omega-3 reduce inflammation, muscle soreness, and enhance recovery. One of the essential omega-3 fats, DHA, makes up 25% of the brain’s fatty acid composition and numerous studies show DHA supplementation can reduce neuroinflammation in the brain and speed recovery time.”
Magnesium
It seems like every athlete is asking about magnesium. “We have studies indicating between 42% to 90% of athletes were magnesium deficient,” Piattoly says. This mineral plays a central role in muscle function and there are magnesium DS in several forms with varying absorption capacities and side effects. Magnesium is often marketed to enhance sleep and support stress reduction, but more research is needed on how to properly administer magnesium to help athletes in these areas. There is conflicting data on the most effective forms and doses, but a review published in 2017 found that supplementation may improve energy metabolism and performance parameters in aerobic and anaerobic activities.9 Magnesium citrate may be more bioavailable than magnesium oxide, which may also cause more gastrointestinal side effects.10 Magnesium citrate may be superior to magnesium glycinate in impacting levels in the brain, blood, and muscle.11
Vitamin D
Vitamin D insufficiency and deficiency are very common in athletes.12 Specific guidelines for athletes have not yet been established, but needs may approach as high as 10,000 IU per day to correct low levels. Blood values must be determined to properly dose supplementation and prevent toxicity.13
Iron
Much like vitamin D, iron status must be monitored to determine proper dosing, using a variety of biochemical status markers, including serum ferritin and hemoglobin, hematocrit, and mean corpuscular volume.14 Dosing of iron, available forms, and protocols for supplementation may vary based on athletes’ needs and tolerance, with doses ranging from 40 to 400 mg daily .15 Ferrous salts such as ferrous sulfate are better absorbed than ferric preparations, and heme iron products may carry a lower risk of gastrointestinal side effects.16
Beetroot
Beetroot juice as a method for nitrate supplementation has gained considerable popularity, and a growing body of evidence supports its effectiveness in increasing nitric oxide bioavailability and exercise capacity, though the effects may be lessened in highly trained athletes. It should also be noted that ideal dosing should occur two to three hours before activity for benefits to be seen.13
Overhyped Sports Supplements
Supplement trends continue to influence athletes of all ages. Experts agree that there are several DS that lack scientific evidence and are not worth the hype that surrounds them.
Calming and Sleep Products
Athletes are drawn to products that promise to provide sleep and stress reduction and are easily influenced by the large number of products on the market. “I’ve found that sleep and calming supplements have been the most improperly used products, especially in my population of collegiate athletes who hold dual responsibilities as full-time students and high-performing athletes,” Weidman says. “Many times, these athletes are using caffeinated energy drinks or supplements to overcome sleep deprivation, but then need something to help them come down and relax for sleep. … These products usually contain melatonin, magnesium, l-theanine, chamomile, or a combination of these ingredients. When it comes to melatonin, I find that all products on the market are well above the therapeutic dose and may not be having the impact desired.”
High-Dose Micronutrients
Many athletes take in high doses of vitamins and minerals via DS that are far beyond their needs and more than the upper limit, therefore increasing the risks of toxic effects. Floris Wardenaar, assistant professor in nutrition at the Arizona State University College of Health Solutions, cautions against high-dose vitamins and minerals exceeding the tolerable upper intake level. “Low micronutrient intake in athletes can result in deficiencies affecting health and performance, in particular when this occurs for longer periods of time, but the actual number of deficiencies is relatively low. More importantly, with some exceptions such as vitamin D and iron, in general, very high doses of vitamins and minerals are not needed to remove these deficiencies, and finally, high intakes without having a deficiency will not lead to improvement in performance.”18
Preworkouts
One of the most popular DS that sports dietitians are concerned about are preworkouts. While there is no one-size-fits-all product, these types of products include various stimulants and are very appealing to athletes with hectic schedules. “Many of the active ingredients (such as caffeine, creatine, and beta-alanine) are not in the right dosage to provide a performance-enhancing benefit, but the marketing, especially to young athletes, is so strong that many athletes feel quite loyal to their product,” Weidman says. “These preworkouts also tend to contain large amounts of stimulants, like caffeine, which could be providing the anticipated performance benefits, but it is something that some drug-tested athletes need to be careful with since it can be banned at certain levels of competitions.”
According to Wardenaar, 20% of high school athletes and 17% of collegiate Division 1 athletes report the use of preworkout supplements and call out the dangers of the lack of transparency about the ingredients. “Preworkout supplements often contain ‘propriety blends,’ which is a concern for supplement safety. Preworkout supplements have been associated with contaminations related to banned substances; therefore I would strongly advocate against the use of preworkout supplements,” Piattoly says.
The combination of stimulants and other ingredients can impact cardiovascular function. As Piattoly points out, the dangers can be life threatening. “One of the primary reasons is individuals are looking for an energy boost and these products are designed to increase mental and physical alertness by stimulating the central nervous system. My biggest concern with these products is they usually contain multiple stimulants in addition to caffeine. When combined with intense exercise or training, it’s a potential recipe for setting off an arrhythmia (ie, irregular heartbeat), which could be fatal.”
Greens Powders
Many athletes are drawn to greens powders as a replacement for eating fruits and vegetables. Dietitians understand vegetable powders cannot replace food, plus these expensive concoctions also contain a long list of other supplemental ingredients. There is little research about the benefits of greens powder for athletic performance, and much of the existing research is funded by the supplement manufacturers. “Most of the popular commercial brands selling greens products are not transparent with their supplement facts panels and use a proprietary blend of ingredients, which is a big red flag,” Piattoly warns. “I have seen some brands who have done a great job formulating a greens powder and being transparent with the label and using dosages of specific ingredients that provide a benefit to someone’s health, the majority of brands do not.”
HMB
Beta-hydroxy-beta-methylbutyrate (HMB) is a metabolite of the branched-chain amino acid leucine that is promoted to enhance muscle building while decreasing fat mass, but there is a lack of evidence to support these claims in human subjects. A robust meta-analysis published in 2020 concluded that, overall, the effects of using HMB to change body composition are not significant.18 Common dosage recommendations an average of 3 g of HMB per day, but athletes would see more substantial improvements in muscle growth by focusing on sources of leucine from dietary protein.13
Branched-Chain Amino Acids
Supplementing isolated branched-chain amino acids (leucine, isoleucine, and valine) is a common interest for athletes interested in muscle growth, but the solid evidence is lacking. Leucine is a vital amino acid in the mTOR pathway for muscle protein synthesis, but leucine’s effectiveness relies on balance from other essential amino acids. The current available research suggests that branched-chain amino acids are most effective when consumed in conjunction with all the essential amino acids via high quality protein foods.19
Additional Considerations for High School Athletes
High school athletes are very interested in DS use and report regular consumption of energy drinks and sports drinks, believing they are healthy options. Weidman encourages these athletes to focus on the fundamentals. “My best advice for high school athletes is that supplements won’t fix poor eating patterns, skipping out on sleep, or even genetics that haven’t kicked in yet when thinking about gaining weight and mass. As a high school athlete, you should be thinking about the foundation of your performance nutrition first, such as not skipping meals, eating regular snacks, and making sure to sip on fluids all day long. Then, if you are still interested in supplementation, work with a qualified individual, such as a sports dietitian, who can help you navigate low risk options.”
High school athletes are also bombarded with product recommendations from a variety of sources, and while intentions may be good, there are several unqualified people that may be selling DS. “Avoid multilevel marketing brands being sold by family, friends, coaches, or others, as in many cases they are typically overpriced, poorly formulated, and not third-party certified,” Piattoly cautions. “Even those that are certified for sport rarely have an ingredient profile that aligns with the science to initiate a beneficial effect.”
No matter what the age or skill level of the athlete, best practices indicate to leave DS recommendations to the experts. Wardenaar highlights the need for a tailored approach: “Products that can support or enhance sports performance should be used best only with an individualized and event-specific protocol with the expert guidance of a registered sports dietitian.”
— Dana Angelo White, MS, RD, ATC, is a dual registered dietitian nutritionist and certified athletic trainer with over 20 years of clinical experience. She is a media dietitian, cookbook author and full-time professor and sports RDN at Quinnipiac University in Hamden, Connecticut.
References
1. Lambert V, Carbuhn A, Culp A, Ketterly J, Twombley B, White D. Interassociation consensus statement on sports nutrition models for the provision of nutrition services from registered dietitian nutritionists in collegiate athletics. J Athl Train. 2022;57(8):717-732.
2. Starr RR. Too little, too late: ineffective regulation of dietary supplements in the United States. Am J Public Health. 2015;105(3):478-485.
3. Kozhuharov VR, Ivanov K, Ivanova S. Dietary supplements as source of unintentional doping. Biomed Res Int. 2022;8387271.
4. Garthe I, Maughan RJ. Athletes and supplements: prevalence and perspectives. Int J Sport Nutr Exerc Metab. 2018;28(2):126-138.
5. Kreider RB, Kalman DS, Antonio J, et al. International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine. J Int Soc Sports Nutr. 2017;14:18.
6. Smith-Ryan AE, Cabre HE, Eckerson JM, Candow DG. Creatine supplementation in women's health: a lifespan perspective. Nutrients. 2021;13(3):877.
7. Saunders B, Elliott-Sale K, Artioli GG, et al. β-alanine supplementation to improve exercise capacity and performance: a systematic review and meta-analysis. Br J Sports Med. 2017;51(8):658-669.
8. Thielecke F, Blannin A. Omega-3 fatty acids for sport performance-are they equally beneficial for athletes and amateurs? A narrative review. Nutrients. 2020;12(12):3712.
9. Zhang Y, Xun P, Wang R, Mao L, He K. Can magnesium enhance exercise performance? Nutrients. 2017;9(9):946.
10. Blancquaert L, Vervaet C, Derave W. Predicting and testing bioavailability of magnesium supplements. Nutrients. 2019;11(7):1663.
11. Ates M, Kizildag S, Yuksel O, et al. Dose-dependent absorption profile of different magnesium compounds. Biol Trace Elem Res. 2019;192(2):244-251.
12. Sale C, Elliott-Sale KJ. Nutrition and athlete bone health. Sports Med. 2019;49(Suppl 2):139-151.
13. Maughan RJ, Burke LM, Dvorak J, et al. IOC consensus statement: dietary supplements and the high-performance athlete. Br J Sports Med. 2018;52(7):439-455.
14. Larson-Meyer DE, Woolf K, Burke L. Assessment of nutrient status in athletes and the need for supplementation. Int J Sport Nutr Exerc Metab. 2018;28(2):139-158.
15. Pedlar CR, Brugnara C, Bruinvels G, Burden R. Iron balance and iron supplementation for the female athlete: a practical approach. Eur J Sport Sci. 2018;18(2):295-305.
16. DellaValle DM. Iron supplementation for female athletes. Curr Sports Med Rep. 2013;12(4):234-239.
17. Wardenaar F, Brinkmans N, Ceelen I, et al. Micronutrient intakes in 553 Dutch elite and sub-elite athletes: prevalence of low and high intakes in users and non-users of nutritional supplements. Nutrients. 2017;9(2):142.
18. Jakubowski JS, Nunes EA, Teixeira FJ, et al. Supplementation with the leucine metabolite β-hydroxy-β-methylbutyrate (HMB) does not improve resistance exercise-induced changes in body composition or strength in young subjects: a systematic review and meta-analysis. Nutrients. 2022;12(5):1523.
19. Jackman SR, Witard OC, Philp A, Wallis GA, Baar K, Tipton KD. Branched-chain amino acid ingestion stimulates muscle myofibrillar protein synthesis following resistance exercise in humans. Front Physiol. 2017;8:390.