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INTRODUCTION

The committee was asked to select a limited number of dietary supplements from those identified as commonly used and, on the basis of published reports, to identify those that may be of benefit or might pose serious hazards. The committee used the information provided at the February 12-13, 2007, workshop to select dietary supplements to review based on their frequency of use, potential for adverse events, and interest for the military. This chapter includes a review of the following dietary supplements: caffeine, chromium, creatine, dehydroepiandrosterone (DHEA), Ephedra, garlic, Ginkgo biloba, ginseng, β-hydroxy-β-methylbutyrate (HMB), melatonin, quercetin, sports bars, sports drinks, tyrosine, and valerian. HMB, creatine, sports drinks and bars, garlic, Ginkgo biloba, and ginseng were reviewed owing to their high frequency of use (see Appendix C). A review of DHEA was conducted because the use of anabolic supplements was shown as high, it is legally considered a dietary supplement, and because DHEA is popular among athletes.

The committee also considered other factors in their selection, such as severity and number of adverse events reported for a supplement or interest of the military in a particular dietary supplement. Ephedra was selected for review by the committee owing to its high frequency of use by military personnel in the past, mainly to achieve weight loss and enhancement of performance, and its adverse event profile. Ginkgo biloba extracts were selected based on their potential to enhance mental performance. Although quercetin is not frequently used by military personnel, research evaluating its effects on performance and immune response was partially supported by the Department of Defense (DoD), indicating the level of military interest in this dietary supplement. Likewise, although the frequency of use of tyrosine was not apparent, this amino acid has been of interest to the military and the object of research investigations to counteract the decrements in cognition that are associated with stress. Because of the reported use of weight-loss products, chromium was chosen as an example of a dietary supplement ingredient that is often found in such products. The known chronobiotic effects of melatonin may justify its use to ease the effects of jet lag as well as of long or night shifts, and therefore it was included for review. Similarly, valerian could be used for its alleged sedative properties and potential to alleviate sleep disorders, common in military life especially during demanding military operations that require long periods of wakefulness or unusual working shifts.

Details about the strategies used in conducting literature searches are described in Chapter 5. In general, the committee evaluated reviews that concentrated on safety and efficacy. For some dietary supplements (e.g., Gingko biloba), research on use is so broad and encompasses so many areas that the committee decided to focus the review on effects that would be of interest to the military (e.g., effects on cognition). This is especially recommended for those supplements that have already been extensively studied. Reviews of safety emphasized two areas: bioactivity and interactions with other dietary supplements or medications. For the latter, a list of the medications most frequently dispensed to active duty U.S. Army personnel was obtained from the DoD Pharmacy Operations Center, as a representation of typical medications used by military personnel. Although the committee was also asked to provide information on potential withdrawal effects, and the committee recognizes their importance, caffeine is the only supplement for which such information was found. The committee did not perform an evidence-based classification of original research on each supplement. As requested in the statement of task for this study and in accordance with the primary intent to identify supplements that pose serious concerns, the committee relied, as much as possible, on existing reviews by other authors to produce the summaries for each dietary supplement. If a review was not available for the last 10 years, original research was included. In those cases, limitations were noted where appropriate (see tables in Chapter 4).

Although the committee emphasized review of safety, the management of dietary supplements for the military needs to follow an evaluation of both risks and benefits, as the recommended framework notes. The reviews therefore also include information about benefits. When reviewing safety, effects judged to be especially pertinent to specific military subpopulations because of performance demands (e.g., cognitive or physical fitness), mission environments (e.g., high altitude, extreme temperatures), or the impact of adverse events associated with the supplement (e.g., bleeding, gastrointestinal disturbances, infectious diseases) received particular attention. The committee recognizes that when trying to identify safety concerns, the fact that dietary supplements are taken in combination and also with medications is a challenge. The committee emphasizes that it is very important that interactions between dietary supplements, medications, nutrients, and other dietary supplements be considered in all elements of this framework: when conducting surveys, when applying the framework and conducting reviews, and when examining and associating adverse events with dietary supplement use. However, when conducting the reviews, it would not be feasible for this committee to address all the potential combination scenarios for dietary supplements, and only a few known and potential interactions with medications have been noted. Because new dietary supplements are being rapidly introduced into the market, information about their quantity and purity would quickly become obsolete and, therefore, it was not included in this chapter.

Although many other dietary supplements could have been reviewed, this chapter provides a selected subset as examples of monographs developed for each dietary supplement. For example, although there are risks from the misuse of growth hormones and anabolic steroids, a review of those substances is beyond the scope of this report because they are illegal, and/or there is also no evidence of use among the military. The monographs in this chapter were developed in order to evaluate the review process outlined in Chapter 5. They present scientific reviews of safety and efficacy, but do not attempt to provide a final assessment of safety or efficacy. Monographs are intended to serve as one key tool for making decisions about how to manage each dietary supplement. Other factors affecting the decision-making process on managing use of a specific dietary supplement relate to the characteristics of the targeted population (see Box 1-3 in Chapter 1); that is, decisions about weighing benefits and risks as well as the level of concern will have to consider the tasks (i.e., mission risks and environments) of the subpopulation. The committee recognizes that the military leadership (e.g., local commanders, or leadership at the service or DoD level) is best informed to make such assessments. Examples of how conclusions from the panel of experts could be synthesized are shown in Chapter 5, Table 5-3. This table includes summary conclusions about the level of concern and the putative benefits that will be useful in making management decisions and for developing outreach materials. Also, Appendix D shows examples of how these monographs could serve as a scientific basis for decision making and includes suggestions for management actions for DHEA, melatonin, and Ephedra.

A barrier to the application of the committee’s framework was the lack of data from studies designed with subpopulations or circumstances similar to those of the military. Also, data from interactions with medications were infrequently found. It should be noted that the monographs are not exhaustive and present mainly data from reviews. The committee did not provide a list of research recommendations for each dietary supplement because research priorities need to be outlined within the scope of an overall research agenda for dietary supplements; such priorities are delineated in Chapter 7.