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practice applicationsBEYOND THE HEADLINES

Sifting through the Research on Supplementsfttias

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t seems that news about herbs andsupplements makes it into themainstream media every day, both

n print and online (1,2). Peer-re-iewed journals also publish studieshat support the effectiveness or inef-ectiveness of a variety of differentupplements (3,4). Such hot topics inecent years include the treatment ofardiovascular disease with the use ofertain dietary supplements as wells the treatment of depression witht John’s wort (5,6). It is the positionf the American Dietetic Associationhat “additional nutrients from forti-ed foods and/or supplements canelp some people meet their nutri-ional needs as specified by science-ased nutrition standards such as theietary Reference Intakes” (7). Butespite the almost overwhelmingmount of information about differ-nt supplements and the acceptancef their use by authoritative associa-ions such the American Dietetic As-ociation, many food and nutritionrofessionals may feel unsure aboutow to speak with confidence on theopic or even find the best informationvailable.“It is important not to become over-helmed given the rapidly expanding

nformation on dietary supplements,”ays Cynthia Thomson, PhD, RD, anssistant professor in the Universityf Arizona at Tucson’s Department ofutritional Sciences, who has over aecade of research experience on dietnd cancer prevention and whoorked as principal investigator on

wo studies on the effectiveness ofreen tea. “You have to be open-inded in order to best meet theeeds of your patients.”Both Thomson and Leila G. Sal-

anha, PhD, RD, president of NutrIQ,nutrition-oriented consulting firm

ased in Washington, DC, that pro-ides specialized services related to

This article was written byJennifer Mathieu, a freelancewriter in Houston, TX.

idoi: 10.1016/j.jada.2007.04.019

12 Journal of the AMERICAN DIETETIC ASSOCIATIO

ood and dietary supplements, offerips and suggestions to food and nu-rition professionals for better assess-ng and understanding the enormousmount of information about dietaryupplements currently available.

O NOT RELY ON MAINSTREAM MEDIADietitians are busy and rely tooeavily on the media to do the re-earch,” says Thomson. “You have tout on your scientist hat, criticalhinking hat.” When a report on theenefits of garlic or St John’s wortakes it onto CNN, food and nutri-

ion professionals need to know howo evaluate such a report. They alsoeed to be mindful of the fact that theedia will often “capitalize on prelim-

nary research findings in an effort tonhance audience and readership rat-ngs” (8). Use the media as a way tonow what is being talked about.on’t use it as a way to determine

onclusions about a particular sup-lement.

DMIT WHEN YOU DON’T KNOWOMETHINGDon’t give knee-jerk responses,” sayshomson. “You have the right to readhe literature and get the answersou need.” If a patient or client comeso you with a question and you juston’t know the answer, say so. Theno some real research and get back tohem.

AMILIARIZE YOURSELF WITH THEESEARCH TERMINOLOGY AND WHAT ITEANS

n order to feel more confident whennalyzing research on supplements,t may be a good idea to brush up onesearch terminology. Below are somemportant terms you should know (9):

Randomized, controlled, double-lind study: This is “the gold stan-ard” when it comes to substantiatingealth claims for supplements andoods, says Saldanha. In these stud-

es, a computer randomly generates o

N © 2007

ho receives the test supplement,nd neither the researcher nor theubjects knows who is receiving thectual supplement and who is receiv-ng a placebo.

Case-control study: In these stud-es, patients who have developed aisease are identified and their pastxposure to suspected etiological fac-ors is compared with that of controlsho do not have the disease.Cross-sectional study: These stud-

es are a snapshot of what’s happen-ng within a certain group of the pop-lation. They do not usually provide

nformation on the etiology of the dis-ase or condition being studied. In-tead, they look at the exposure toertain risk factors and the occur-ence of a disease or health problemn a population at one point in time.

Prospective cohort study: These ep-demiological studies follow a group ofubjects for a specified amount of timeo observe the relationship betweenertain characteristics of the popula-ion, such as dietary supplement use,nd predetermined outcomes, such asiseases.Crossover-design study: These

tudies compare two or more treat-ents with subjects typically com-

leting one course of treatment beforeoving on to another course. “These

re popular because you can use aelatively small sample size,” sayshomson. “The subjects act as theirwn control.” However, she adds,rossover studies must have longnough “washout” periods betweenreatments to ensure the first treat-ent has completely left the body.Power analysis: A quality study

hould provide its power analysis,ays Thomson. In basic terms, atudy’s power analysis refers to itsbility to test the hypothesis, givenhat the hypothesis exists. Generallystudy should enroll enough subjects

o set the power at 85% or higher.Meta-analysis: This is a sophisti-

ated statistical methodology thatroups like studies that test the same

r very similar hypotheses. Review-

by the American Dietetic Association

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BEYOND THE HEADLINES

ng a meta-analysis can give youoncise information in an efficientanner; one recent example of aeta-analysis is a study on the root

alerian and its ability to affect sleep.he analysis showed some possibleenefit from the supplement (4).What I like about meta-analysis ishat it saves time in that I am neveroing to have time to read 150 articlesn garlic and hypertension, for exam-le, but a well-designed meta-analy-is does just that,” says Thomson.Phase 1 studies: These are very pre-

iminary studies that are not used toest hypotheses and often garner me-ia attention. Be extremely waryhen reviewing results from phase 1

tudies, says Thomson. They usuallynvolve a very tiny group of subjectsnd are completed only to determinehat doses are tolerable for humansefore continuing on to the next phasef the study.

OOK AT THE DOSEWhat was the substance tested?”sks Saldanha. “If the study is look-ng at calcium, what form of calciumas it? How did they source it? Was it

ested and analyzed before it wassed in the study?” Saldanha addshat these questions are especiallymportant in studies that examine bo-anicals.

When considering the testing dose,t can sometimes be important touestion how the placebo was cre-ted. “If you are creating a placeboill for garlic,” says Thomson, “it cane challenging to develop one thatooks, smells, and tastes like the realhing.”

In addition to knowing the answerso these questions, food and nutritionrofessionals should understandhat the dose was and how long itas given to subjects. For example,

ays Thomson, certain dietary sup-lements must be used for severaleeks before they begin to have an

mpact on the body. A study that mea-ured calcium and its ability to pro-ote changes in bone mineral densityould be meaningless if the calciumas not given for a long enough pe-

iod of time.

OOK AT THE STUDY POPULATIONhen examining a study population,

ood and nutrition professionals may j

ave to consider whom the study mayenefit. “If [a registered dietitian]ants to use a product in white fe-ales and the study was done on mal-

ourished children in a developingountry, you have to ask, how trans-erable is the data?” says Saldanha.he sample size should also be largenough to create clinically meaning-ul data.

In order to feel moreconfident when

analyzing researchon supplements, it

may be a good ideato brush up on

researchterminology.

An ideal study would include inten-ion to treat analysis, says Thomson.his analysis includes everyone whoarticipated in the study, whether orot they completed it. When examin-

ng sample size, she adds, it’s impor-ant to look at where dropouts oc-urred. “If the dropout rate was equaln both groups, that may be okay. Butf they happened all in one group, that

ight be a problem.”And what about studies performed

n animals? While Thomson sayshey may “give us direction” in termsf human testing, it is unwise to relyolely on them for clinical guidance.

ON’T STUDY JUST THE ABSTRACT ORESULTShen reviewing a peer-reviewed

tudy in a journal, you may beempted to read just the abstract. Af-er all, it’s a brief summary that maye easiest to digest given a busychedule. Or, you might want to headtraight for the results. According tohomson, the very best informationay sometimes be gleaned from read-

ng the methods and discussions.hat’s where you’ll get the best sensef how the study was performed. Inddition, Thomson encourages foodnd nutrition professionals to e-mailhe corresponding author with anyuestions.Saldanha suggests that British

ournals may have more international t

June 2007 ● Journa

tudies, although Thomson remindsood and nutrition professionals thathile many countries provide valu-ble data, not all of them have theame stringent peer-review processs is found in the United States. Sal-anha suggests considering a jour-al’s impact factor, that is, how oftenhe journal was cited in other jour-als, when reviewing a study.Thomson also says it’s important to

eep in mind the fact that while manyeer-reviewed journals have a biasgainst null findings, journals areore likely to publish null findingshen it comes to supplements. “Whileistorically null studies were unlikelyo be published, in recent years jour-als have begun to publish more nullrials, sometimes in brief to betterresent the balance of knowledge,”ays Thomson. “This change in phi-osophy—to present all data null orignificant—may account somewhator the number of null trials pub-ished in reaction to dietary supple-

ent research in recent years.”

SK YOURSELF, WHERE DID THE STUDYOME FROM?hile it may be your first instinct torite off studies funded by the sup-lement industry, Thomson warnshat is not always wise. “While youave to ask who funded the study,ometimes we have to get the indus-ry involved,” she says. “The impor-ant thing is author disclosure of thisnformation.” Still, adds Saldanha,everyone has conflict of interest. If its a peer-reviewed publication, theuality of the study is more impor-ant. For example, to what extentoes the paper conform to theONSORT guidelines [a set of guide-

ines endorsed by major medical jour-als regarding randomized trials10)]?”

Also, be wary when all the studiesnd data to support the efficacy of aiven dietary supplement come from

single group of researchers, sayshomson.“In the ’90s, a group published

ight papers,” says Thomson. “It washe same group out of Cuba, and theyust changed the lead author. That’s aed flag.” The fact that no otherroups published on the same topicold Thomson that “[other research-rs] found nothing and didn’t publish

heir results.”

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9

SE THE RIGHT RESOURCES AND KEEPEARNINGt’s hard to read dozens of peer-re-iewed journals, acknowledges Thom-on. However, there are several high-uality resources available for foodnd nutrition professionals who wanto advance their knowledge of re-earch on supplements.One resource food and nutrition pro-

essionals may find handy is the Depart-ent of Health and Human Services’gency for Healthcare Research anduality (www.ahrq.gov). According tohomson, the Web site brings togethercientific experts who review printed,eer-review journals and summarize re-ent findings. It’s often very up to date.nother major resource is the Office ofietary Supplements of the National In-

titutes of Health, available at http://ietary-supplements.info.nih.gov. Othernline sources include the Natural Med-cines Comprehensive Database’s Phar-

acist’s Letter (www.pharmacistsletter.om), the National Center for Com-lementary and Alternative Medicinewww.nccam.nih.gov), and Supplement-

atch (www.supplementwatch.com).

14 June 2007 Volume 107 Number 6

If you’re looking for a print re-ource, try ADA’s The Health Profes-ional’s Guide to Popular Dietaryupplements, coauthored by Thom-on. The introduction includes termso know as well as questions to askourself when examining a study.The number one way to becomeore knowledgeable is to keep edu-

ating yourself, says Thomson. “Getourself on some listservs, join a [di-tetic practice group],” she encour-ges. “The most important thing is forregistered dietitians] to get involvedn this. We can’t wait for other profes-ionals to handle it. Our patientseed our professional guidance now.”

eferences1. Reynolds G. Give us this day, our daily

supplements. New York Times. March 4,2007 Available at: http://www.nytimes.com/2007/03/04/sports/playmagazine/04play-supplement.html?ex�1175140800&en�329fe4786e6e2e62&ei�5070. Accessed March27, 2007.

2. DeNoon D. Antioxidant supplements raisedeath: Study shows no benefit, slightlyhigher death risk for antioxidant supple-

ments. WebMD Medical News. Available at:http://www.webmd.com/news/20070227/

antioxidant-supplements-up-death-risk. Ac-cessed March 11, 2007.

3. Mangione CM. Treating symptoms of meno-pause: A study of the effectiveness of blackcohosh alone and with other herbal therapiesor soy. Ann Intern Med. 2006;145:869-879.

4. Bent S, Padula A, Moore D, Patterson M,Mehling W. Valerian for sleep: A systematicreview and meta-analysis. Am J Med. 2006;199:1005-1012.

5. Shekelle P, Morton S, Jungvig L, Udani J,Spar M, Tu W, Suttorp M, Coulter I, New-berry S, Hardy M. Effect of supplementalvitamin E for the prevention and treatmentof cardiovascular disease. J Gen Intern Med.2004;19:380-389.

6. Woelk H. Comparison of St. John’s wort andimipramine for treating depression: Random-ised controlled trial. BMJ. 2000;321:536-539.

7. American Dietetic Association. Position ofthe American Dietetic Association: Fortifica-tion and nutritional supplements. J Am DietAssoc. 2005;105:1300-1311.

8. American Dietetic Association. Position ofthe American Dietetic Association: Food andnutrition misinformation. J Am Diet Assoc.2006;106:601-607.

9. Sarubin-Fragakis A, Thomson C. The HealthProfessional’s Guide to Popular Dietary Sup-plements. 3rd ed. Chicago, IL: American Di-etetic Association; 2007:xix-xx.

0. The CONSORT Statement Web site. CON-SORT Statement. Available at: http://www.consort-statement.org/Statement/

revisedstatement.htm. Accessed March 15,2007.