Evaluating Dietary Supplements

Christopher R. Mohr, PhD, RD

The manufacture and sale of dietary supplements is an $18+ billion per year industry. Sorting through the advertisements and associated claims for the 29,000-plus dietary supplements available can be difficult and confusing. This is particularly true considering there is a great deal of misinformation that make many supplements look like miracles.

But, considering the supplement market is a big one, it’s important for trainers to educate themselves on how to intelligently evaluate dietary supplements. Clients are surely asking questions about them and you may have questions yourself. What supplements work? Which do not? Are they safe?

Who should use what and do they need anything at all? When clients ask about product x, you will be able to inform them as to how they should go about evaluating the product first before buying. Here are six guidelines and recommendations on how to evaluate any dietary supplements on the market.

1. Are there legitimate physiological mechanisms associated with the supplement?

The purpose of an ergogenic aid is to enhance performance in one way or another, whether it is to allow athletes to lift more weight, lose fat, run faster, or increase endurance. When evaluating the product, ask yourself, “Is it possible for the supplement to enhance the pathway from point A to point B?”

For example, creatine phosphate is useful in energy reactions to regenerate ATP, the body’s “energy currency.” It therefore makes sense that this dietary supplement may in fact be beneficial in some situations. The next step is to consider whether the supplement in question is necessary for the reaction to occur, may enhance the speed of the reaction, or will do nothing to change what normally goes on in the body. How can you tell this?

Well, it takes a little background research and reading. It can get tricky because very often it makes sense that a product may in fact work if, for example, it’s primary ingredient is a major part of a pathway in the body, but that often doesn’t mean consuming excess will improve anything.

2. Is this product useful for the intended sport?

Certain supplements are designed for high-intensity, short-duration events, such as weight lifting or sprinting. Others are designed to increase endurance, while some are purported to enhance weight loss.

Therefore, depending on the sport one is involved in, certain supplements should not even be considered. Again using creatine as the example, it appears that it is not beneficial for long-duration, endurance-type activities, such as marathons. Using such a supplement to train or compete in these types of events would be nothing more than a waste of money.

On the other hand, when the body needs quick bursts of energy, such as pushing a lineman off the line during a football game, creatine may increase the ability to regenerate ATP, which is used in these quick reactions.

3. Are there scientific, placebo-controlled studies to support or refute the claims being made for the supplement? Have the results been duplicated?

Dietary supplements are being developed, improved, and launched practically every single day. Unfortunately, well-conducted scientific studies take much longer than this, and in the meantime athletes are being drawn to them through crafty marketing and expensive advertisements.

Dietary supplements do not have to endure the same rigor as pharmaceutical agents. However, some supplements have had a number of safety and efficacy studies conducted on them. Such studies are published in peer reviewed, scientific journals. It is also important to find out if the research has been duplicated.

If one study was conducted in the laboratory of the company that produces the supplement, and there has never been any follow-up research conducted, you should be hesitant about putting too much faith in their claims. Access to thousands of well-respected journals can be found for free on PubMed, a resource of the National Library of Medicine at www.pubmed.gov.

And don’t always fall for the fancy graphs that are boldly stated in the pages of magazines with the ads; look at the fine print and, if there is some reference provided for the study, follow up to determine the results of the study. It’s very simple to take something out of context to make it fit the bill.

Here’s a perfect example. In the early 1990’s, the supplement boron was included in a lot of supplements because of a cited study that showed consuming boron increased testosterone levels. Taking that for face value, it seems worthwhile to therefore consume boron.

However, if you checked out the actual study itself that was repeatedly cited in the popular media, you found out that boron did in fact increase testosterone levels; however, this increase occurred in postmenopausal rats! I can guarantee that most folks taking this are not postmenopausal; whether they are rats or not is an entirely different story, though. Moral of the story—always read the fine print!

4. Is there adequate safety data on the particular dietary supplement?

The importance of long-term health can be difficult to get across to young, otherwise healthy athletes. However, it’s vital to stress the safety concern that’s associated with dietary supplements.

If the athlete’s goal is to gain lean body mass, and the supplement he or she is taking will do so at the expense of curtailing his or her adult life, it’s too high a price to pay.

This caution is obviously a bit extreme, but excess stress on the kidneys, liver, and other organs SHOULD BE a concern with some supplements. Winning at all costs is not what you want to emphasize to clients. You have to weigh the risk to benefit ratio of all products with each individual client.

5. What is the source of information regarding the dietary supplement?

Did the athlete hear about the dietary supplement in question from a friend, coach, magazine, etc.? Remember that most mainstream fitness magazines are owned by supplement companies.

Therefore, it is common to read articles that are very slanted towards promoting a particular product(s). Magazines are a good way to be introduced to a product, but then the consumer must continue the investigative work to determine if there is any truth behind the supplement’s claims.

6. Is the product banned by any governing agencies?

This is of particular concern for collegiate and professional athletes. There are a number of products that are banned by the NCAA, IOC, NFL, and other organizations. Whether or not a product may work is not worth risking a career over.

The banned supplement list should be posted so athletes know and understand what products are included on the list. If you work with any athletes, this is very important because they will often turn to you as the expert.

This is a basic list of questions and concerns that should be answered prior to consuming any dietary ergogenic aids. And remember to emphasize the importance of real food whenever talking to athletes about supplements.

Dietary supplements are called supplements for a reason—they are intended to supplement whole foods in the diet. No dietary supplement can or will ever be able to replace what can be obtained through the diet.

Consuming adequate energy and fluids should be the first concern. Dietary supplements should then fill in the very tip of the “iceberg,” but only if they are proven to be safe, legal, and beneficial.

About the Author:

Dr. Chris Mohr RD, PhD is a health nutrition consultant to a number of media outlets and corporations including Discovery Health Channel, Clif Bar, Waterfront Media, and Fit Fuel. He has authored and co-authored several textbooks and textbook chapters, including consulting with LL Cool J on "LL Cool J's Platinum Workout" (Rodale Press, 2006).  He is also co-creator of Meal Plans 101 nutrition software.