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FACT OR FICTION: Can Dietary Supplements Enhance Health and Performance?

Santo, Antonio S. Ph.D., R.D., CSSD; Kruskall, Laura J. Ph.D., R.D., CSSD, FACSM

doi: 10.1249/FIT.0b013e318264cae8

LEARNING OBJECTIVE • The reader can expect to learn about updates regarding the dietary supplement regulations established by the U.S. Food and Drug Administration and how to professionally discuss the use of supplements with his or her clients.

It is important for fitness professionals to give accurate, thorough information about dietary supplements. The fitness professional must be critical of the supplement claims and media headlines. FDA regulation and the safety and efficacy of supplements are critical items for discussion

Antonio S. Santo, Ph.D., R.D., CSSD, is an assistant professor at the University of Nevada, Las Vegas. Exercise physiology and sports nutrition are his main educational foci, while his research interest is in the use of nuclear magnetic resonance for detecting lipoprotein particle size and number. He is also a certified Health Fitness Specialist and a professional photographer.

Laura J. Kruskall, Ph.D., R.D., CSSD, FACSM, is the director of Nutrition Sciences at UNLV. Areas of expertise include sports nutrition, weight management, and medical nutrition therapy. Her research interests include body composition, bone density, and energy metabolism. She is a Certified ACSM Health/Fitness Specialist, and is a nutrition consultant for Canyon Ranch Spaclub and Cirque du Soleil in Las Vegas.

The authors declare no conflicts of interest and do not have any financial disclosures.

Disclosure: The authors declare no conflict of interest and do not have any financial disclosures.





A recent breakthrough by scientists has athletes pushing endurance world records. A new supplement, Extreme VO2®, was shown to improve marathon times by 5 minutes! No side effects were reported, and the long-term safety has not been established. Are you interested? How can you get a hold of this new supplement? OK, you figured us out; this is a fictitious report about a supplement that doesn’t exist (yet). However, the initial excitement and hope that you may have experienced are the emotions that makers of dietary supplements would like all their customers to have when purchasing their products. Before you start thinking that this is going to be a piece on bashing the dietary supplement industry, consider this: good marketing can help the consumer feel good about his/her purchase and to help choose one brand over the competitor’s. For example, if you are shopping for a camera, some individuals will tell you that they swear by Nikon cameras over Canon cameras, despite not possessing direct laboratory findings that clearly show superiority. How about Ford versus Chevrolet? I am sure you can think of plenty of other examples where you have been in a place where you need to make a decision about a purchase and perhaps have done so on emotions or anecdotal information rather than genuine facts. So, you see, it’s not unreasonable to suggest that manufacturers of dietary supplements will advertise in a way that negotiates for your emotional confidence in their products. How can you make the best informed decision about the purchase of a dietary supplement and disseminate this to your clients/patients? Let’s take a look at some of the basic elements to accomplish these goals.

1. Establish necessity for supplementation versus experimentation/curiosity.

Photo courtesy of http://www

Photo courtesy of http://www

Nutrition science is a relatively young field of study in comparison with others and subsequently has been subjected to an esoteric “mystique.” Individuals and companies profit greatly from creating an artificial atmosphere where they appear to clandestinely know information that no one else does and they are now willing to share this information with you if you purchase their product, book, and so on. Good marketing strategies make us believe that our food supply is nutritionally inadequate, and the only way to correct our dietary shortcomings is through supplementation. The truth of the matter is that for general health and fitness, a diet that is varied, rich in fruits, vegetables, and whole grains, lean with respect to meats, and consumed in moderation provides us with optimal nutrition. For athletes, supplements may be warranted if they have trouble consuming sufficient and varied foods to meet their nutritional needs. For example, the traveling athlete with several competitive events planned in a short time frame may find it difficult to eat an appropriate amount of food with the necessary nutrients and, therefore, may resort to a meal supplement such as a milkshake to fill the void. Some clinical conditions and special populations (e.g., celiac, cancer, renal, and elderly patients) may benefit from dietary supplementation because of a person’s inability to eat, lack of motivation to eat, or difficulty in moderating nutrients affected by their disease (Table 1). In these situations, it is best to refer the person to a licensed/registered dietitian (RD).



2. Know how dietary supplements are regulated.

Dietary supplements are regulated by the U.S. Food and Drug Administration (FDA) (7). Please see their Web site for a complete description. Some of the key issues include the classification, types of claims, and regulation regarding the ingredients. Supplements are regulated by the FDA as foods, not food additives or drugs. This means that FDA approval is not required before a supplement is placed on the shelf for sale. On the contrary, food additives and drugs undergo rigorous testing before they are approved for sale and use by the FDA.

One of the most confusing aspects about dietary supplements for consumers is the permitted claims. The first category is nutrient-content claims. These are approved by the FDA and may be used for both foods and supplements (Table 2). Examples include terms such as “fat-free” or “excellent source.” A second category is health claims. These also are approved by the FDA and include a statement about the relationship between a nutrient and health-related condition or disease. Examples include the relationship between calcium and osteoporosis, fiber and cardiovascular disease, or folate and neural tube defects. You can get a complete list of FDA-approved nutrient content and health claims on the FDA Web site (7). The third category of claims is called structure-function claims. These are not approved by the FDA. When these claims are used, this disclaimer must be on the label: “This statement has not been evaluated by the FDA. This product is not intended to diagnose, treat, cure, or prevent any disease.” Manufacturers are not allowed to use a disease in these claims; however, it is easy to mislead consumers. For example, labels may include phrases like “promotes healthy blood sugar” or “supports cardiovascular health.” The best thing to teach a client is that if the disclaimer is present, the claim is not approved by the FDA.



Regulation has evolved so that supplements are produced in a quality manner, do not contain contaminants or impurities, and quantities of ingredients are accurate. Although this helps, there are still some things to be cautious about. For example, manufacturers are not required to disclose who should not take the product, what drugs or other products it should not be taken with, or any other warnings. Furthermore, there are no limits on serving sizes on the product. For example, a product can exceed the Dietary Reference Intake (DRI) for a particular vitamin or mineral.

3. Do your homework on the supplement.

If a client inquires about a supplement that is new or vaguely familiar to you, start with the basics and read the Supplement Facts panel first. The panel should tell you the contents of the package, the quantity of active ingredients per serving, and any other ingredients that have been added to the supplements, such as flavorings. The serving size that you’ll see listed is only a suggestion from the manufacturer and may not reflect what’s right for your client or reflective of what any existing scientific evidence (if at all) tells us. Next, what anecdotal claims is your client relaying to you and/or what have you heard about the product? Ponder these claims in relation to the ingredients listed on the Dietary Supplement Label. Is there any possible relationship between the purported claims and the ingredients listed? Once you’ve gathered this information, then you are ready to critically seek the truth.

4. Be critical.

Does the product claim to do it all? This is a big clue that the marketing of the product is attempting to reach a wide audience. If such a product existed, we wouldn’t have the diseases the product claims to alleviate. Understandably, individuals who are stricken with ailments such as heart disease, cancer, or diabetes will often try anything to be cured. The fact of the matter is that no supplement will cure complicated diseases such as these, and there especially isn’t going to be one solution.

We’ve probably all heard a client/patient claim that a friend of a friend tried a particular supplement, and they were cured of cancer! The fact of the matter is that these claims are nearly impossible to demonstrate a cause-and-effect relationship. Moreover, the individual was probably being treated medically and happened to try the supplement concurrently. So, was it the medical treatment or the supplement? More than likely, the medical treatment had a carryover effect and the individual assumed it was the supplement. If dietary supplements cured cancer, then why do incidence rates of the disease continue to increase?

Does the manufacturer claim that you’ll see results in days? Ailments take time to recover from, and no supplement will speed recovery such that symptoms subside in a day or two. However, some supplements may help reduce the severity of symptoms you experience. Please note that the term “in days” is poorly described, which aids manufacturers in avoiding lawsuits. Exactly how many days are we talking about?

Natural or herbal products are better, right? These words are often precariously associated with safety. There are a number of poisonous mushroom varieties that are natural, but if humans were to consume them, they would become violently ill and die. In addition, many of the chemicals used to make prescription medications and over-the-counter drugs are found in nature. These natural substances have potent beneficial effects but also come with unwanted side effects.

The FDA does not regulate the term “natural.” It is important for you to explain that natural does not equate with safety and may not be harmless. Natural products can still be harmful or interact with other supplements or medications. Another consideration is herbal supplements. Many herbal formulas are grown and processed differently than their traditional use. For example, is the active ingredient of a plant in the flower, or root, or stem? If the active ingredient is in the root but the whole plant is ground up and processed, it may not be as effective. So, the next time you see the word “natural” or “herbal,” think twice about what that might mean.

“Satisfaction guaranteed or your money back!” This is an indelible phrase used in marketing that reassures our confidence that this product has to work or the company wouldn’t back the product with such a guarantee. Ask people who have tried to retrieve their hard-earned money, and they’ll tell you that it was nearly impossible. Manufacturers often have a claims department that you have to mail a form to, but you’ll be lucky to hear back from them. As time continues, the lack of response from the manufacturer will frustrate the consumers and they’ll eventually give up. Furthermore, some manufacturers change business addresses and company names so often that it makes it difficult to contact their claims department.

So you want to lose 10 lbs of fat in a week? Here’s the reality: this is not physiologically possible. Because 3 g of water are stored with every gram of muscle glycogen (stored carbohydrate in muscle), when someone restricts their energy intake, muscle glycogen is used for energy and subsequently levels decrease as well as the amount of water weight that was stored with the carbohydrate. Hence, an individual may lose a substantial amount of water weight in a short period of time but may not lose the fat weight they are interested in getting rid of.

There is a conspiracy theory among health professionals. Some individuals claim that medical professionals and the pharmaceutical industry are in collusion and fear homeopathic remedies because of losses in revenue. So let’s put this into perspective: health care professionals want to keep people sick because they stand to profit from it? Let’s presume that there are health care professionals who are this malicious. There are an equal or greater number of health care professionals who are honest, sincere, and philanthropic and would not tolerate such treachery. If you think homeopathic remedies are being suppressed by medical professionals and the pharmaceutical industry, take a look at their net profits; they may just surprise you.

One of the big challenges is to be aware of the possible media or manufacturer misinterpretation when reporting results of scientific studies. If you see a research study discussed on a news program or in an advertisement, it is important for you to get that original research article and make sure you properly interpret the results. Sometimes media persons just report on one line of an abstract that states a parameter increased or decreased as a result of an intervention without looking at the whole picture or the application to a whole population of individuals. Manufacturers often take phrases from legitimate scientific journals and take them out of the context for which they were intended. They will then use these as references to support their claims even though the study had nothing to do with the product they are selling.

5. Research the literature.

So you’ve critiqued the claims but aren’t quite sure what position to take on this supplement. This calls for finding out the hard facts. Google or Wikipedia is next, right? Although you may get satisfaction from instantaneous results from your query, the likelihood of reading material that interprets the scientific literature correctly and provides you with an unbiased and anecdotal-free message is questionable. So where should you seek the truth? It’s always best to acquire your information from the source: the scientific literature. This retains the original message behind the author’s work and leaves no room for subsequent misinterpretation by those not having expertise in the health/fitness field such as the news media and journalists. A database like PubMed (4) places at your fingertips thousands of articles directly from the scientists who collect the data. Additional resources are recommended at the end of this article.

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It is highly likely that as a fitness professional, your clients will ask you questions about many different kinds of supplements. Some questions may be a simple question like, “what do you think about whey protein,” whereas others may be more complex questions about using multiple supplements. You may even face the client who thinks he or she has a wealth of knowledge about a supplement and then seeks your “approval” for its use. Regardless of the extent of the questions, there are some simple guidelines you should follow.

Before discussing what you know about supplements, it is important for you to ask your client some questions (Table 3). When gathering information, remember to remain nonjudgmental throughout the process. Even if you feel a client is being “ridiculous” by taking a supplement (or group of supplements), it is critical for you to be nonbiased. Here are some basic questions you should ask your clients and reasons for asking them. Getting the answers to these questions will help you decide where to begin your conversation.



1. Why are you interested in taking the supplement or why are you taking the supplement?

If you know why they want to take it, you can decide if the product can help them achieve the intended goal. Not all products produce the results claimed.

2. What are you taking and how much are you taking?

Certainly, the name of the product is critical so you can do the research on the product and/or active ingredients. Dose also is important. Many times, clients are taking doses outside of the recommendations or doses that do not match what has been done in research studies.

3. When did you start taking the product(s)?

Sometimes side effects can take time to manifest. It is important to try and correlate any reported unusual symptoms to supplement use.

4. Where did you get information about this supplement or who recommended the supplement to you?

Too often, someone takes a supplement because he or she finds information on a Web site that recommends the product, a friend or relative recommends he or she takes it, or an unqualified health professional recommends it or even sells it. Remember, manufacturers can legally make certain types of claims that seem too good to be true. The average client does not understand the regulation and assumes that if a claim appears on a Web site or bottle, “somebody” regulated this, and it must be true. Furthermore, there are many unqualified health professionals who do not have the scientific training to properly evaluate the efficacy of supplements or even worse, they make a profit by selling the product. Qualified credentialed fitness professionals have a code of ethics to follow, and that usually includes evidence-based practice. The qualified professional would not recommend a product that has not been shown to be efficacious and safe.

Photo courtesy of http://www

Photo courtesy of http://www

5. If taking it, how is it working for you?

Some clients may report that they see no change, whereas others may report undesirable side effects. If they truly feel the product is working, be sure to work closely with your client to see if there could be a placebo effect.

6. Do your physician and pharmacist know you are taking the supplement?

There are so many supplements that may interact with over-the-counter or prescription medications. Many consumers assume that supplements labeled as “natural” or something purchased from a grocery store shelf cannot possibly cause any harm. Physicians and pharmacists can educate patients about any possible harmful interactions.

Before getting into the details about supplements, it is important to understand your role as a fitness professional. If you are unsure of the scientific support for a particular supplement, you must do your own research. It is certainly acceptable to tell a client that there are so many supplements on the market and that you will do some research and get back to him or her. That is preferable to giving limited information. Allow yourself some time to find correct information. A good place to start is the National Institutes of Health Office of Dietary Supplements (ODS) (2,3). In addition to general supplement information and tips on evaluating information on the Internet, this organization provides fact sheets for many popular supplements. This information is credible and reliable. In addition to the Web site, the ODS also has a free app for convenient access on phones and electronic tablets. If you need information on a supplement that has not been reviewed on this site, you may need to search for peer-reviewed journal articles using PubMed (2). If reading the journal articles yourself, make sure you pay attention to the details. For example, if studies were done in animals, are the results applicable to humans? Pay attention to sample sizes, methodology, and accurate statistical analysis and conclusions. A final thing to consider when interpreting research is the concept of statistical significance versus clinical significance. Statistical significance is a concrete methodology that is used to report outcomes of scientific studies. It is important to note that just because a study reported statistical significance in an intervention, the practitioner must think of clinical significance or “are these results important for my client”? For example, if a weight loss supplement study showed that subjects lost significantly more weight from a supplement, but clinically it was only a few pounds and there were harmful side effects, is this clinically significant? Should we recommend a supplement that may result in a few extra pounds of a loss when the side effects could be detrimental? In this case, statistical significance is not the most important factor to consider.

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After doing your research (if needed) and when you are ready to have a discussion with your client, there are a few simple items that must be covered (Table 4). First of all, make sure your client understands how supplements are regulated by the FDA (7). So many consumers have no idea about the category of structure/function claims and believe what they read in the ad or label. Once your client understands the regulation, your role is to provide a comprehensive summary of the scientific literature. Include a discussion on the quantities used in research studies versus what is sold in the commercial supplements, the effectiveness of the supplements (remember to differentiate and educate about statistical and clinical significance), and any issues with side effects or safety of use. You also may include information you may find on Web sites such as Consumerlab (1) or Quackwatch (5). These sites can give you information about problems with products.



Once you give your thorough review on the supplement(s) in question, let the client decide whether or not he or she is going to use the supplement. If you recommend that he or she takes a product and something goes wrong, you may be liable for his or her adverse outcomes.

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The most important thing in educating clients about dietary supplements is to provide information that is thorough, accurate, and certainly evidence based. As health care professionals, it is imperative that we work as a team to help clients/patients in attaining their goals and provide the best evidence-based practice. We should not feel intimidated to reach out to our colleagues with specialties in the areas of resources we need; this is a sign of professional maturity and not of weakness. There are so many supplements on the market that it is difficult for some fitness professionals to keep current on all of the scientific literature. If you feel that your knowledge of supplements is lacking and doing your own research is too time consuming or overwhelming, it is a good idea to refer your client to another professional who has expertise in this area.

The RD has the most extensive training in the area of nutrition and dietetics. In addition, most states currently require a license to practice nutrition and/or dietetics. A Board-Certified Specialist in Sports Dietetics (CSSD) is an RD with additional education and training in sports dietetics. These individuals have in-depth knowledge on macronutrients, micronutrients, and sport/performance-enhancing supplements. To find a CSSD in your area, you can go to the Sports, Cardiovascular, and Wellness Nutrition (SCAN) Web site (6). Lastly, you can always seek out professors of nutrition and dietetics at institutions of higher education. Many of these folks conduct research and are an invaluable resource to getting the hard facts.

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As health care professionals, we must work as a team to provide the evidence-based practice to our patients/clients. We must be critical of all dietary supplements and base our understanding and recommendations on the scientific literature and individual need.

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1. Consumerlab Web site [Internet]: [cited 2012 Mar 13]. Available from:
2. National Center for Complementary and Alternative Medicine (NCCAM) Web site [Internet]: [cited 2012 Mar 13]. Available from:
3. National Institutes of Health Office of Dietary Supplements (ODS) Web site [Internet]: [cited 2012 Mar 13]. Available from:
4. PubMed Web site [Internet]: [cited 2012 Mar 13]. Available from:
5. Quackwatch Web site [Internet]: [cited 2012 March 13]. Available from:
6. Sports, Cardiovascular, and Wellness Nutrition (SCAN) Web site [Internet]: [cited 2012 Mar 13]. Available from:
7. U.S. Food and Drug Administration (FDA) Web site [Internet]: [cited 2012 Mar 13]. Available from: http://
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Recommended Readings

8. Academy of Nutrition and Dietetics (AND) Web site [Internet]: [cited 2012 Mar 13]. Available from:
    9. Physician’s Desk Reference Web site [Internet]: [cited 2012 Mar13]. Available from:
      10. U.S. Pharmacopeial Convention Web site [Internet]: [cited 2012 Mar 13]. Available from:

        Dietary Supplement Regulation; FDA Regulation; Fitness Professional; Health; Performance

        © 2012 American College of Sports Medicine.