Sports Supplements: Buyer Beware?

Posted on 10-04-2018 , by: Nancy Clark , in , , 0 Comments


Definition of Sports supplement: A food, food component, nutrient, or non-food compound that is purposefully ingested in addition to the habitually consumed diet with the aim of achieving a specific health and/or performance benefit.

The global sports nutrition supplement market (including sports foods, drinks and supplements) accounted for $28+ billion in 2016 and, with the help of rigorous advertising, is expected to almost double by 2022. How many of the products are moneymaking ploys marketed to uninformed athletes? Unfortunately, too many.

Due to the plethora of products that have infiltrated gyms, fitness centers and professional sports teams alike, I get questioned by fitness exercisers and aspiring Olympians: Which of these supplements are actually effective?? Hands down, the most effective way to enhance sports performance is via your day-to-day sports diet, coordinated with a consistent training program. Eating the right foods at the right times creates the essential foundation to your success as an athlete.

That said, specific sports supplements could make a minor contribution to small performance improvements for certain elite athletes. If you wonder if the grass is greener on the other side of your sports diet’s fence, here are some facts from the 2018 IOC Consensus Statement: Dietary Supplements and the High-Performance Athlete (1).

  • Supplement use varies across sports. It increases with the athletes’ training level and age, is higher in men than women and is strongly influenced by perceived cultural norms. (For example, “Everyone” on my team takes creatine, so I do, too.)
  • Before making any decisions regarding sports supplements, you want to get a nutritional assessment to be sure your diet supports your performance goals. No amount of supplements will compensate for a lousy diet. To find a local sports dietitian who is a Certified Specialist in Sports Dietetics (CSSD), use the referral network at
  • Despite the ads you see for a zillion sports supplements, very few have strong proof of directly enhancing performance. These include caffeine, creatine, specific buffering agents, and nitrate. Period.
  • Very little research with supplements offers definitive evidence, in part because the research is rarely done with elite athletes under real life conditions. Real life includes 1) multi-day tournaments, competitions or events, 2) “stacking” supplements (such as mixing caffeine and nitrates) and 3) determining if an elite athlete responds the same way to a supplement as does a Division-3 collegiate athlete.

Real life also includes your unique microbiome (the bacteria in your gut that influence your overall health and well-being). We do not yet know how much a microbiome, which varies 80% to 90% between individuals, influences the effectiveness of a sports supplement and contributes to different responses.

Supplements are used for many different reasons.

Here’s a breakdown of supplements by categories.

  1. 1. Supplements used to prevent/treat nutrient deficiency. Nutrients of concern for athletes include iron (to prevent anemia), calcium and vitamin D (for bone health), as well as iodine, folate and B-12 for specific sub-groups of athletes, including vegans and women who might become pregnant. The basic supplement question is: If you are deficient, what led to that deficiency and what dietary changes will you make to resolve the issue so that it doesn’t happen again?
  2. Supplements used to provide energy. Sports drinks, energy drinks, gels, electrolyte replacements, protein supplements, energy bars, and liquid meals are commonly used to help meet energy needs before, during and after exercise. They are a convenient, albeit more expensive alternative to common foods. They aren’t magical or superior to natural food. They are just easy to carry, standardized and eliminate decisions about which foods would offer, let’s say, the “recommended ratio” of carbs, protein and fat.
  3. Supplements that directly improve performance. Caffeine, creatine monohydrate, nitrate, sodium bicarbonate, and possibly beta-alanine are the very few performance enhancing supplements that have adequate support to suggest they may offer a marginal performance gain. If you choose to use them, be sure to test them thoroughly during hard training that mimics the competitive event. Choose a brand that is NSF Certified for Sport to minimize the risk of inadvertent doping due to contamination. Every year, athletes get suspended for failing a drug test after they unknowingly took a supplement with an illegal ingredient…
  4. Supplements that indirectly improve performance. Some supplements claim to enhance performance indirectly by supporting the athlete’s health and limiting illness. “Immune support” supplements that have moderate research to support their health claims include probiotics, vitamin D, and vitamin C. Supplements that lack strong support for their immune-enhancing claims include zinc, glutamine, Echinacea, vitamin E, and fish oil. Tart cherry juice and curcumin show promise

A supplement with strong evidence to indirectly improve performance by helping build muscle is creatine monohydrate. Questionable supplements without strong evidence for athletes include gelatin and HMB.

Adverse effects.

If some supplements are good, would more be better? No, supplements can cause harm. Too much iron can lead to iron overload. Too much caffeine increases anxiety. Supplements are linked to liver toxicity, heart problems and seizures. In the USA in 2015, dietary supplements contributed to about 23,000 emergency department visits. Manufacturers are not required to show safety or assure quality of a supplement. Athletes beware— and try eating better to perform better?


Nancy Clark, MS, RD, CSSD counsels both casual and competitive athletes at her office in Newton, MA (617-795-1875). Her best selling Sports Nutrition Guidebook and food guides for marathoners, cyclists and soccer players offer additional information. They are available at For her popular online workshop, see



Maughan R, Burke L, Dvorak J et al. IOC Consensus Statement: Dietary Supplements and the High-Performance Athlete Intl J Sports Nutr Exerc Metab 2018, 28: 104-125.

Leave a comment