What is a Supplement?

Supplements on a blue background

Getty Images / Yulia Renznikov

Sports supplements represent a multi-million dollar industry. Active adults and athletes are often enticed by effective supplement marketing. The promises of enhanced performance among other claims are motivating factors to purchase alternative nutrition to achieve results.

It's estimated that in 2016, the dietary supplement industry garnered more than $40 billion in sales, with sports nutrition supplements accounting for nearly 14%. According to the Office of Dietary Supplements at the National Institutes of Health, athletes, especially elite athletes, are more likely to use dietary supplements and sports nutrition products compared to the general U.S. population.

Despite the popularity of supplements, however, a lack of federal regulation and quality control may mean that unreliable and ineffective products are being used.

What Is a Supplement?

Supplements are considered an addition to an already healthy diet. Active adults or athletes may include supplements to help meet their nutritional needs, improve nutrient deficiencies, enhance athletic performance or achieve personal fitness goals. But without a well-designed nutrition plan in place, supplementation is said to be rarely effective.

Supplement Regulation and Standards

Dietary supplements have been placed in a special food category and not considered drugs. Supplements aren’t required to be submitted to the Food and Drug Administration (FDA) for regulation. Although the FDA has the ability to review ingredients and health claims of supplements, very few are investigated. 

Sport supplement manufacturers are allowed to make health claims with FDA approval as long as the product statements are true and based on scientific evidence. Unfortunately, very few supplements claiming ergogenic benefits are supported by clinical research. This leaves the active adult or athlete without a guarantee of safety, effectiveness, potency or purity of supplements for dietary or ergogenic purposes. 

  • Dietary supplements include vitamins, minerals, amino acids, herbs, botanicals, extracts, or concentrates from plants or foods. They are typically sold as capsules, tablets, liquids, powders or bars and required to be clearly labeled as a dietary supplement. 
  • Ergogenic aids include substances, drugs or techniques used to enhance athletic performance. They can range from acceptable practices of carbohydrate loading to illegal and even unsafe approaches including the use of anabolic-androgenic steroids.

Evaluating the Benefit of Supplements

Supplement use remains controversial and is a personal choice. Common questions asked by active adults, athletes, and sports nutritionists relate to manufacturing and supplement quality. Locating evidence-based research information is highly advised before considering sports foods and supplements.

The International Society of Sports Nutrition (ISSN) recommends evaluating the validity and scientific merit behind supplement claims for enhanced athletic performance. The following questions are suggested:

  •    Does the supplement claim make sense? 
  •    Is there scientific evidence available?
  •    Is the supplement legal or safe?

Supplements are marketed for health and exercise performance based on hypothetical applications gathered from preliminary research. The claims sound promising but often don’t agree with clinical findings. Reliable online references like the Journal of the International Society of Sports Nutrition or the National Library of Medicine's PubMed will help you discern if a supplement is based on sound scientific evidence or not. 

If working with a sports dietitian or specialist, they can be a valuable resource in supplement research interpretation. The information gathered will enable you to make the best decision about taking sports supplements for health and athletic goals. 

How Science Classifies Supplements

Dietary supplements and ergogenic aids are marketed and claim to enhance the diet and athletic performance of an active adult or athlete. Clinical research continues to uncover flaws in these supplement health claims. The International Society of Sports Nutrition (ISSN) has provided a classification for supplements based on clinical research:

  1. Apparently effective: The majority of supplement research studies show safe and effective.
  2. Possibly effective: Initial supplement findings are good, but more research is required to examine the effects on training and athletic performance. 
  3. Too early to tell: Supplement theory makes sense but lacks sufficient research to support using it.
  4. Apparently ineffective: Supplements lack sound scientific evidence and/or research has shown the supplement to be clearly ineffective and/or unsafe. 

The International Society of Sports Nutrition (ISSN) indicates the foundation of a good training program is a sound energy balanced, nutrient-dense diet. If supplements are being considered, the ISSN suggests supplements only from category one (apparently effective).

Any other supplements would be considered experimental. They further discourage supplements in category three (too early to tell) and don’t support athletes taking supplements in category four (apparently ineffective).

Supplement Value of Vitamins and Exercise Performance

Vitamins are organic compounds essential to regulating metabolic processes, energy production, neurological functioning, and protection of our cells. Dietary analysis on active adults or athletes has reported vitamin deficiencies.

Although research shows a possible benefit of taking vitamins for general health, there has been minimal to no ergogenic benefits reported. The following vitamins common to athletes have been researched as proposed nutritional ergogenic aids:

Nutrient Ergogenic Claim Research Findings
Vitamin A May improve sports vision No improvement in athletic performance.
Vitamin D May help prevent bone loss Helps with calcium absorption/co-supplement. Optimal amounts are necessary for regulating immune function, cardiovascular health, growth and repair, muscle health, and strength.
Vitamin E May prevent free radicals Adequate amounts decrease oxidative stress but more research required. Conflicting evidence of high dosing on athletic performance.
Vitamin K May help bone metabolism Adequate amounts are needed for bone metabolism, protein found in muscles and found in cartilage. no improvement in athletic performance beyond adequate amounts.
Thiamin (B1) May improve anaerobic threshold Doesn’t appear to enhance exercise capacity at normal intake.
Riboflavin (B2) May enhance energy availability during exercise Doesn’t appear to enhance exercise capacity at normal intake.
Niacin (B3) May enhance energy metabolism, improve cholesterol and blunt fat stores Shown to decrease cholesterol, triglycerides, and increase HDL, but doesn't appear to enhance exercise capacity at normal intake.
Pyridoxine (B6) May improve lean mass, strength, aerobic capacity and mental focus Well-nourished athletes show no improvement in athletic performance.
Cyano-cobalamin (B12) May increase muscle mass and decrease anxiety No ergogenic effect reported.
Folic acid (folate) May increase red blood cells for better oxygen to muscle and decrease birth defects Found to decrease birth defects in pregnant women, but shown not to enhance athletic performance.
Pantothenic acid May benefit aerobic energy Research reports no enhanced aerobic performance.
Beta-carotene May help exercise-induced muscle damage May help decrease exercise-induced muscle damage, but more research is required for improved athletic performance.
Vitamin C May improve metabolism during exercise Adequate amounts help decrease oxidative stress and maintain immune system after heavy exercise. Vitamin C deficiencies show improvement in VO2 max when returned to adequate levels. High doses may compromise performance.

Supplement Value of Minerals for Athletes

Minerals are inorganic elements essential for metabolic processes, tissue structure and repair, hormone regulation, and neurological function. Research indicates active adults or athletes have been deficient in these important elements.

Mineral deficiency may negatively affect athletic performance and therefore supplementation may be helpful. The following mineral supplements common to athletes have been researched as proposed nutritional ergogenic aids:

Nutrient Ergogenic Claim Research Findings
Boron May promote muscle growth during resistance training No evidence currently exists to support this theory.
Calcium May promote bone growth and fat metabolism Shown to stimulate bone growth taken with vitamin D and may promote fat metabolism. No ergogenic benefit for athletic performance.
Chromium Sold as chromium picolinate and claims to increase lean mass and reduce body fat Recent studies show no improvement in lean mass or reduced body fat.
Iron May help improve aerobic performance shown to only improve aerobic performance in athletes suffering from iron deficiency or anemia.
Magnesium May improve energy metabolism/ATP availability Shown to only improve exercise performance in athletes suffering from magnesium deficiency. Acute changes occurs in moderate to intense exercise and must be considered in replenishing during long bouts of exercise, along with potassium and sodium.
Phosphorus (phosphate salts) May improve energy systems in the body No ergogenic benefits reported alone. paired as sodium phosphate is show to increase maximal oxygen uptake, anaerobic threshold, and improve endurance exercise capacity by 8-10%.
Potassium May help with muscle cramping No ergogenic benefits reported but acute changes occurs in moderate to intense exercise and must be considered in replenishing during long bouts of exercise, along with sodium and magnesium.
Selenium May improve aerobic exercise performance Improvements in aerobic exercise performance have not been demonstrated.
Sodium May help with muscle cramping and reduce risk of hyponatremia Shown to maintain fluid balance during heavy training and prevent hyponatremia. Paired as sodium phosphate is shown to increase maximal oxygen uptake, anaerobic threshold, and improve endurance exercise capacity by 8-10%. Acute changes occurs in moderate to intense exercise and must be considered in replenishing during long bouts of exercise, along with potassium and magnesium.
Vanadyl sulfate (vanadium) May stimulate muscle growth, enhance strength and power Not shown to have any effect on muscle mass, strength or power.
Zinc May reduce upper respiratory tract infections during heavy training Shown to minimize exercise-induced changes to immune function during training.

Water as an Ergogenic Aid for Athletes

Water is considered the most important nutritional ergogenic aid for active adults and athletes. If 2% or more of body weight is lost through sweat, athletic performance may be significantly impaired. Weight loss of 4% or more during exercise may lead to heat illness, heat exhaustion, or more severe adverse health effects.

It is critical for active adults and athletes to implement hydration management during training and competitive events. The International Society of Sports Nutrition (ISSN) recommends:

  • Consuming a sufficient amount of water and sports drinks to maintain fluid balance and hydration throughout the day. Drink at least 500 ml before bedtime, and then another 400-600 ml of water 20-30 minutes before onset of exercise. More may be needed.
  • Athletes should drink 0.5 to 2 liters per hour of fluid in order to offset water loss.
  • Don’t depend on thirst as an indicator to drink water or sports drinks.
  • Athletes should weigh themselves prior to and following exercise.
  • Consume three cups of water for every pound lost during athletic training.
  • Avoid excessive weight loss techniques including sauna sweats, wearing rubber suits, using diuretics, vomiting, or severe dieting.

Educate yourself on proper hydration methods during athletic training. This will help you maintain proper fluid balance and provide a positive exercise experience. 

The Role of Dietary Supplements for Athletes

Dietary supplements can play an important role in an athletic diet. However, they should be viewed as supplements to the diet, not replacements for a good diet. While there are very few supplements backed by scientific evidence to enhance athletic performance, there are some shown to be helpful for exercise and recovery. Whether you’re an active adult, athlete working alone, or have hired a sports nutrition specialist, it’s important to stay current on supplement research.

The following common nutritional supplements have been researched and classified as either: apparently effective, possibly effective, too early to tell, or apparently ineffective: 

Apparently Effective and Generally Safe

Muscle Building Supplements

  • Weight gain powders
  • Creatine
  • Protein
  • Essential amino acids (EAA)

Weight Loss Supplements

  • Low-calorie foods, meal replacement powders (MRPs), ready-to-drink shakes (RTDs)
  • Ephedra, caffeine, and salicin containing thermogenic supplements taken in recommended doses for appropriate populations (ephedra is banned by the FDA)

Performance-Enhancing Supplements

  • Water and sports drinks
  • Carbohydrates
  • Creatine
  • Sodium phosphate
  • Sodium bicarbonate
  • Caffeine
  • B-alanine

Possibly Effective, But More Research Required

Muscle Building Supplements

Weight Loss Supplements

Performance-Enhancing Supplements

  • Post-exercise carbohydrate and protein
  • Essential amino acids (EAA)
  • Branched-chain amino acids (BCAA)
  • HMB
  • Glycerol

Too Early to Tell, and Lacks Sufficient Research

Muscle Building Supplements

Weight Loss Supplements

  • Gymnema Sylvestre, chitosan
  • Phosphatidyl Choline
  • Betaine
  • Coleus forskolin
  • DHEA
  • Psychotropic Nutrients/Herbs

Performance-Enhancing Supplements

  • Medium-chain triglycerides

Apparently Not Effective and/or Unsafe

Muscle Building Supplements

  • Glutamine
  • Smilax
  • Isoflavones
  • Sulfo-polysaccharides (myostatin inhibitors)
  • Boron
  • Chromium
  • Conjugated linoleic acids
  • Gamma oryzanol
  • Prohormones
  • Tribulus Terrestris
  • Vanadyl sulfate (vanadium)

Weight Loss Supplements

  • Calcium Pyruvate
  • Chitosan
  • Chromium (for people who don't have diabetes)
  • HCA
  • L-Carnitine
  • Phosphates
  • Herbal diuretics

Performance-Enhancing Supplements

  • Glutamine
  • Ribose
  • Inosine

General Health Supplements Suggested for Athletes

Maintaining good health for active adults and athletes is essential. It is suggested athletes supplement with a few additional nutrients to stay healthy during intense exercise.

While there is no consensus among health experts as to whether adults should take multivitamins, the American Medical Association recommends a daily low-dose multivitamin to help ensure that adequate levels of nutrients are being met in the diet.

Although not recommended to enhance athletic performance, a multivitamin may be helpful for general health.

A Word From Verywell

Dietary supplements are generally not required for the well-nourished active adult or athlete. Many ergogenic aids are unreliable and should only be considered after careful evaluation of effectiveness, potency, and safety. Extra caution should also be taken because these products are not regulated by FDA. However, sports supplements are here to stay and can play a meaningful role in your training program.

Any supplement under consideration should be backed by chronic clinical studies and clear evidence of their health or ergogenic claims. In other words, become supplement smart for your health and athletic performance and consult a registered dietitian, nutritionist, or your healthcare provider if you have questions.

13 Sources
Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Darla Leal
Darla Leal is a Master Fitness Trainer, freelance writer, and the creator of Stay Healthy Fitness, where she embraces a "fit-over-55" lifestyle.