Dietary Supplements for Improving Athletic Performance?

Dietary Supplements for Improving Athletic Performance?

To be a successful competitive athlete at any level, proper training and genetics play a very significant role.  After that, proper nutrition and supplements can play an important role as well.  However, there’s an enormous information gap between marketing claims made by supplement manufacturers and published, original scientific research studies.  To find out the latest available information, you can spend days or weeks reviewing articles on Medline or simply continue reading this article.

For competitive athletes, the difference between winning and losing isn’t just the difference between a gold or silver medal, it can also mean the difference of hundreds of thousands or possibly millions of dollars in endorsement contracts.  Since your genetics are out of your control, what you can do to perform better is limited to training, equipment, and proper nutrition.  Staying up-to-date on the latest advances in sports supplements and nutrition can be a time-consuming endeavor.

In the Journal of the International Society of Sports Nutrition, they recently published their review and recommendations of nutritional supplement use for athletes.  This review is a 5-year update to their lead paper published in 2004.  Included in this review are their specific recommendations about nutritional intake as well as the evidence for the safety and efficacy of various potentially ergogenic or performance-enhancing vitamins and dietary supplements.  I’ll provide a brief overview of these recommendations while including other recently reviewed supplements that I’ve added to their classification

Nutritional guidelines from the ISSN:

Energy intake:

  • For people participating in 30-40 minutes of exercise three times per week, they can meet their nutritional requirements following a normal diet of 1800-2400 kcals/day.
  • For athletes involved in moderately intense exercise (2-3 hours per day, 5-6 days per week), their caloric demands may approach 50-80 kcal/kg/day.


  • Individuals in general fitness programs can typically meet their demands with a diet consisting of 45-55% CHO [3-5 grams/kg/day].
  • For athletes during moderate intense periods of training (as above), these demands can reach 55-65% carbohydrate ([5-8 grams/kg/day].

Protein intake:

There has been considerable debate regarding protein needs of athletes . Initially, it was recommended that athletes do not need to ingest more than the RDA for protein (i.e., 0.8 to 1.0 g/kg/d for children, adolescents and adults). However, research over the last decade has indicated that athletes engaged in intense training need to ingest about two times the RDA of protein in their diet (1.5 to 2.0 g/kg/d) in order to maintain protein balance . If an insufficient amount of protein is obtained from the diet, an athlete will maintain a negative nitrogen balance, which can increase protein catabolism and slow recovery.

  • Exercising individuals need approximately 1.4 to 2.0 grams of protein per kilogram of body weight per day.
  • Concerns that protein intake within this range is unhealthy are unfounded in healthy, exercising individuals.
  • An attempt should be made to obtain protein requirements from whole foods, but supplemental protein is a safe and convenient method of ingesting high quality dietary protein.
  • The timing of protein intake in the time period encompassing the exercise session has several benefits including improved recovery and greater gains in fat free mass.Protein residues such as branched chain amino acids have been shown to be beneficial for the exercising individual, including increasing the rates of protein synthesis, decreasing the rate of protein degradation, and possibly aiding in recovery from exercise.

I’ve often been asked by people who were concerned about the safety of consuming protein in greater quantities than the RDA about the risk of kidney damage or other side effects.  For those with medical conditions, particularly renal or kidney impairment, this clearly would not be safe.  However, for healthy, young athletes, there really isn’t any substantial evidence that consuming 1.5-2.0 g/kg/d of protein carries a health risk.

Fat Intake:

  • The ISSN recommends that dietary fat intake is similar or slightly greater than for non-athletes–particularly essential fatty acids.
  • This amounts to approximately 30% of their total dietary caloric intake.
  • The ISSN cites research that suggests that high-fat diets maintain circulating testosterone levels better than low fat diets.
  • For athletes attempting to reduce their body fat, they recommend 0.5-1.0 g/kg/day.


  • Once-daily, a low-dose multivitamin to promote general health
  • Antioxidants, Vitamin C, E, and beta carotene
    • Vitamin E – may decrease exercise-induced oxidative stress.
    • Vitamin C – 500mg after training may reduce respiratory infections.


Phosphate salts:

Recent well-controlled research studies reported that sodium phosphate supplementation (4 g/d for 3 d) improved the oxygen energy system in endurance tasks.


During the first several days of intense training in the heat, a greater amount of sodium is lost in sweat. Additionally, prolonged ultraendurance exercise may decrease sodium levels leading to hyponatremia. Increasing salt availability during heavy training in the heat has been shown to help maintain fluid balance and prevent hyponatremia.

Ergogenic Aids:

What is the most important nutritional ergogenic aid for athletes?


  • Exercise performance can be significantly impaired when 2% or more of body weight is lost through sweat.
  • The normal sweat rate of athletes ranges from 0.5 to 2.0 L/h depending on temperature, humidity, exercise intensity, and their sweat response to exercise.
  • This means that in order to maintain fluid balance and prevent dehydration, athletes need to ingest 0.5 to 2 L/h of fluid in order to offset weight loss.
  • This requires frequent ingestion of 6-8 oz of cold water or a GES (glucose electrolyte solution) sports drink every 5 to 15-min during exercise.

Dietary Supplements and Athletes

Convenience supplements:

These include meal replacement powders, energy bars, and energy gels.  Convenience supplements comprise 50-75% of dietary supplement sales.  As the ISSN recommends, I agree that they should be used to improve the dietary availability of macronutrients, not as a replacement for a good diet.

Muscle Building Supplements

Apparently effective:

1. Creatine monohydrate

  • “Creatine monohydrate is the most effective ergogenic nutritional supplement currently available to athletes in terms of increasing high-intensity exercise capacity and lean body mass during training.”
  • “Creatine monohydrate supplementation is not only safe but possibly beneficial in regard to preventing injury and/or management of select medical conditions when taken within recommended guidelines.”

2. Protein

3.  Essential Amino Acids

  • Ingest 3-6 grams of essential amino acids prior to and/or following exercise to increase muscle mass.

5. Cold Beverages

Possibly effective:

  1. β-hydroxy β-methylbutyrate (HMB)
  2. Branched Chain Amino Acids (BCAA)
  3. L-Arginine 

Too early to tell:

  1. α-ketoglutarate (α-KG)
  2. α-Ketoisocaproate (KIC)
  3. Ecdysterones
  4. Growth Hormone Releasing Peptides (GHRP) and Secretagogues
  5. Ornithine-α-ketoglutarate (OKG)
  6. Zinc/Magnesium Aspartate (ZMA)

Apparently ineffective:

  1. Glutamine
  2. Smilax officinalis (SO)
  3. Isoflavones
  4. Sulfo-Polysaccharides (Myostatin Inhibitors)
  5. Boron
  6. Chromium
  7. Conjugated Linoleic Acids (CLA)
  8. Gamma Oryzanol (Ferulic Acid)
  9. Prohormones
  10. Tribulus terrestris
  11. Vanadyl Sulfate (Vanadium)
  12. Energy Drinks

Weight Loss Supplements

Apparently Effective:

  1. Low Calorie Diet Foods & Supplements
  2. Ephedra, Caffeine

Possibly Effective:

  1. High fiber diet
  2. Calcium
  3. Green Tea Extract
  4. Conjugated Linoleic Acids (CLA)
  5. Green Coffee Bean Extract
  6. Raspberry Ketones

Too Early to Tell:

  1. Gymnema Sylvestre
  2. Phosphatidyl Choline (Lecithin)
  3. Betaine
  4. Coleus Forskohlii (Forskolin)
  5. Dehydroepiandrosterone (DHEA) and 7-Keto DHEA
  6. Psychotropic Nutrients/Herbs
    1. St. John’s Wort
    2. Kava
    3. Ginkgo Biloba
    4. Ginseng
    5. L-Tyrosine

Apparently Ineffective:

  1. Calcium Pyruvate
  2. Chitosan
  3. Chromium
  4. Garcinia cambogia
  5. l-carnitine
  6. phosphates
  7. herbal diuretics

Performance Enhancement Supplements:

Apparently Effective:

  1. Water and sports drinks
  2. Carbohydrate
  3. Creatine
  4. Sodium phosphate
  5. Sodium bicarbonate (baking soda)
  6. Caffeine
  7. Β-alanine

Possibly Effective:

  1. Post-Exercise Carbohydrate and Protein
  2. Essential Amino Acids (EAA)
  3. Branched Chain Amino Acids (BCAA)
  4. β-HMB
  5. Glycerol
  6. L-Arginine 
  7. Beetroot Juice
  8. Leucine – here, and here
  9. Glycine Propionyl l-carnitine
  10. Arginine and Grape Seed Extract
  11. Roseroot
  12. Quercetin

Too Early to Tell:

  1. Medium-chain triglycerides

Apparently Ineffective:

  1. Glutamine
  2. Ribose
  3. Inosine

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