Research provides the evidence, that the best way to improve health, prevent disease, optimize healing and enhance performance, is to, whenever possible, eat a balanced diet consisting of whole food. Nevertheless, use of dietary supplements is common among the U.S. adult population; over 40% used supplements in 1988-1994 and 50% in 2003-2006 (NHANES data). There is an overwhelming number of dietary supplements and ergogenic aids available and the multibillion-dollar supplement industry continues to grow every year.


In 1994, under the Dietary Supplement Health Education Act, the Federal Government deregulated the supplement industry, allowing supplement manufacturers to make claims regarding the effect of products on structure/function of the body as long as they do not claim to diagnose, mitigate, treat or prevent a specific disease. As long as a special supplement label indicates the active ingredients and the entire ingredients list is provided, claims for enhance performance can be made, valid or not. Although manufacturers are required by the FDA to analyze the identity, purity and strength of all of their products’ ingredients, they are not required to demonstrate the safety and efficacy of their products. 

So what are Registered Dieticians to do?  First and foremost, our job is to evaluate our client’s diet to determine what, if any, nutrients they may be lacking and to educate them on choosing and preparing foods that offer the nutrients they need.  Regardless of the reasons why a client is supplementing or thinking about supplementing, i.e. whether it is based on need determined by a dietary analysis or a desire to gain a competitive edge in sport, our job is to provide a thorough evaluation of the supplements/ergogenic aids in question. A complete evaluation should include the following list of questions:

  1. What claims are being made regarding the benefits of the supplement?
  2. Is it regulated by the FDA?
  3. Has there been any independent scientific research conducted on this product?
  4. Does it contain more than 100% o the RDA?
  5. Is it safe?
  6. Is it effective?
  7. Is it free of contaminants?
  8. Are there any potential food-drug interactions?
  9. Can I get the same effect from eating a healthy diet?
  10. What is the cost?
  11. How is the dosage determined for the individual?
  12. Will it cause an athlete to test positive for a banned substance?

 Dietary supplements/ergogenic aids are no substitute for genetic make-up, years of training and optimum nutrition. While each individual is responsible for the dietary supplements/ergogenic aids they ingest and the subsequent consequences, it is important that RDs keep an open mind and provide recommendations that are based on both thorough evaluations of the scientific literature and the needs of the individual.


Caffeine:  Caffeine is widely used as an ergogenic aid. It has been shown to enhance endurance performance in runners, cyclists and cross-country skiers (Ganio 2009) and mask mental and physical fatigue due to its effect on the central nervous system (Burke 2008). When used in moderation, i.e. less than 300 mg/d, caffeine does not cause dehydration or electrolyte imbalance (Armstrong 2002, 2005, 2007, IOM 2002). Caffeine can be ergolytic rather than ergogenic (Sillivent 2012) and even dangerous when used in excess or in combination with stimulants or alcohol or other unregulated herbals. Potential side effects of caffeine can be anxiety, jitteriness, rapid heartbeat, gastrointestinal distress and insomnia.


Creatine: Creatine is the most commonly used ergogenic aid to build muscle and enhance recovery (Williams 2006). Creatine has been shown to be effective in repeated short bursts of high intensity activity in sports that derive energy primarily from ATP-creatine phosphate energy system, such as sprinting and weight lifting but not for endurance sports such as distance running (Branch 2003). Its most common side-effects include weight gain, cramping, nausea and diarrhea (Juhn 1998). It is generally considered safe (recent studies do not show any adverse effects in healthy adults from creatine supplementation) although there are anecdotal reports of dehydration, muscle tears and kidney damage (Kreider 2003, Mayhew 2002).


Protein and Amino Acid Supplements: Current evidence indicates that protein and amino acid supplements are no more or no less effective than food when energy is adequate for gaining lean body mass (Phillips 2007, Tipton 2007).There is not a strong body of evidence documenting that additional dietary protein is needed by healthy adults who undertake endurance or resistance exercise, hence there are few times an RD would recommend protein intake greater than the DRI. Having said that, protein is often taken in excess of the RDA to maintain optimum physical performance. 


Recent studies have shown that protein turnover may become more efficient in response to endurance exercise training (Dunford 2006, Burke 2006). Nitrogen balance studies suggest that dietary protein intake necessary to support nitrogen balance in endurance athletes ranges from 1.2-14 g/kg/d (Dunford 2006, Tipton 2007). Resistance and endurance exercise, particularly in the early phase of strength training when the most significant gains in muscle size occurs, may necessitate protein intake in excess of the RDA because additional protein, essential amino acids in particular, is needed along with sufficient energy to support muscle growth (Phillips 2007, Tipton 2007). The amount of protein needed to maintain muscle mass may be lower for individuals who routinely resistance train due to more efficient protein utilization (Phillips 2007, Tipton 2007). Recommended protein intakes for strength trained athletes range from approximately 1.2 - 1.7 g/kg/d (Philips 2007, Burke 2006).


Research has shown that intact, high quality proteins such as whey, casein or soy, consumed in close proximity to strength and endurance exercise, can be effectively used for the maintenance, repair and synthesis of skeletal muscle proteins in response to training (Tipton 2007, Hartman 2001). However, protein or amino acid supplementation has not been shown to positively influence athletic performance (Bemben 2010, Ivy 2003, van Essen 2006). Consequently, recommendations regarding protein supplementation are conservative and directed primarily at optimizing the training response to and the recovery period following exercise. 


In the case of vegetarians, although most are able to meet or exceed recommendations for total protein intake, their diets often provide less protein than those of non-vegetarians (Tipton 2007). Therefore, some individuals may need more protein to meet training and competition needs. For individuals who avoid all animal proteins, protein quality is a potential concern as their diets may be limited in lysine, threonine, tryptophan and methionine (Tipton 2007).


Vitamins and Minerals:  Exercise stresses many of the metabolic pathways where micronutrients are required, and exercise training may increase micronutrient needs. Routine exercise may also increase the turnover and loss of these micronutrients. As a result, increased intakes of micronutrients may be required to cover increased needs for building, repair and maintenance of lean body mass in athletes. While supplements have the potential to fill dietary gaps, they may also increase intakes above ULs. Unless nutrient deficiencies are present, multivitamins/minerals have not been shown to improve athletic performance or prevent chronic disease.


Omega-3 Fatty Acid Supplements:  Omega-3 fatty acids are being used to improve athletic performance. While promising for use in athletes with exercise-induced bronchoconstriction due to asthma, they have not otherwise been shown to improve performance (Mickleborough 2006).