The Soft Science of Dietary Author(s): Gary Taubes Source: Science, New Series, Vol. 291, No. 5513 (Mar. 30, 2001), pp. 2536-2541+2543-2545 Published by: American Association for the Advancement of Science Stable URL: http://www.jstor.org/stable/3082809 Accessed: 15/03/2009 22:09

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Mainstream nutritional science has demonized dietary fat, yet 50 years and hundreds of millions of dollars of research have failed to prove that eating a low-fat diet will help you live longer The Soft Science of Dietary Fat

Whenthe U.S. SurgeonGeneral's Office set "Clearlythe thoughtsof yesterdaiy werenot Department of Agriculture's (USDA's) off in 1988 to writethe definitivereport on going to serveus very well." bookleton dietaryguidelines, published ev- the dangersof dietaryfat, the scientifictask Duringthe past 30 years,the conceptof ery 5 years,and its ubiquitousFood Guide appearedstraightforward. Four years earlier, eatinghealthy in Americahas be:come syn- Pyramid,which recommendsthat and the NationalInstitutes of Health(NIH) had onymous with avoiding dietary fat. The oils be eaten"sparingly." The low-fatgospel begunadvising every American old enough creationand marketing of reduceed-fat food spreadsfarther by a kind of societalosmo- to walk to restrictfat intake,and the presi- products has become big business; over sis, continuouslyreinforced by physicians, dent of the American Heart Association 15,000 have appeared on suIpermarket nutritionists,journalists, health organiza- (AHA) had told Timemagazine that if ev- shelves. Indeed,an entirereseare ch industry tions, and consumeradvocacy groups such eryone went along, "we will have has arisen to create palatable nonfat fat as the Centerfor Sciencein the PublicInter- []conquered" by the year substitutes, and the food indiustry now est, which refers to fat as this "greasy 2000. The SurgeonGeneral's Office itself spendsbillions of dollarsyearly selling the killer.""In America, we no longerfear God had just publishedits 700-page landmark less-fat-is-good-healthmessage The gov- or the communists,but we fear fat," says "Reporton Nutritionand Health," declaring ernmentweighs in as well, with the U.S. DavidKritchevsky of the WistarInstitute in fat the single most unwholesomecompo- Philadelphia,who in 1958 wrote the first nentof theAmerican diet. textbookon cholesterol. All of this was apparentlybased on "They say,'You re:ally As the Surgeon General'sOffice dis- sound science. So the task beforethe pro- covered,however, the science of dietaryfat ject officer was merelyto gatherthat sci- need a high level I of is not nearlyas simpleas it once appeared. ence together in one volume, have it re- The proposition,now 50 yearsold, thatdi- viewed by a committeeof experts,which proof to change the etary fat is a bane to health is based had been promptlyestablished, and publish , chiefly on the fact thatfat, specificallythe it. The projectdid not go smoothly,howev- recommendatior lS, hard,saturated fat foundprimarily in meat er.Four project officers came and went over which is ironic and dairyproducts, elevates blood choles- the next decade."It consumed project offi- :' terol levels. This in turn raises the likeli- cers," says Marion Nestle, who helped because ne, fver hood that cholesterolwill clog arteries,a launchthe projectand now runsthe nutri- they conditionknown as atherosclerosis,which tion and food studies departmentat New had a level of then increasesrisk of coronaryartery dis- YorkUniversity (NYU). Membersof the high ease, heartattack, and untimelydeath. By oversightcommittee saw draftsof an early to set thern." the 1970s, each individual step of this chapteror two, criticizedthem vigorously, proof chain from fat to cholesterolto heartdis- andthen saw little else. -Walter Willett ease had been demonstratedbeyond rea- Finally,in June 1999, 11 yearsafter the sonable doubt, but the veracity of the projectbegan, the SurgeonGeneral's Of- chainas a whole has neverbeen proven.In fice circulateda letter,authored by the last otherwords, despite decades of research,it of the projectofficers, explaining that the is still a debatableproposition whether the report would be killed. There was no consumptionof saturatedfats above rec- other public announcement and no ommendedlevels (step one in the chain) pressrelease. The letterexplained that by anyonewho's not alreadyat high riskof the relevant administrators"did not heartdisease will increasethe likelihood anticipatefully the magnitudeof the of untimelydeath (outcomethree). Nor additionalexternal expertise and staff have hundredsof millions of dollars in resources that would be needed." In trials managedto generatecompelling other words, says Nestle, the subject evidence that healthy individuals matter"was too complicated."Bill Har- MH_i ^-.w can extend their lives by V a member of the more than a few if 8 lan, oversight lIk^jw; / : weeks, committeeand associatedirector that, by eating less fat of the Office of Disease Preven- (see sidebar on tion at "the was To it NIH, says report p. 2538). put z initiatedwith a preconceivedopinion simply, the data of the but the science be- remain conclusions," _ , ~ ou as towhethambigu- hind those opinions was not holding up. ?:;A:&A:,...... : ous as to whetherS

2536 30 MARCH2001 VOL291 SCIENCE www.sciencemag.org . lzv,, i ! . low-fat diets will benefit healthyAmeri- the pasta and other carbohydratesthat the nary heart disease epidemic seemed to cans. Worse, the ubiquitous admonish- Food GuidePyramid suggests be eatenco- sweepthe country(see sidebaron p. 2540). ments to reduce total fat intake have piously.(The studiesalso suggestthat trans "Middle-agedmen, seeminglyhealthy, were encouraged a shift to high- fatty acids are unhealthful.These are the droppingdead," wrote biochemist Ancel diets, which may be no better-and may fats in margarine,for instance,and are what Keys of the Universityof Minnesota,Twin even be worse-than high-fatdiets. manyAmericans started eating when they Cities,who was amongthe first to suggest Since the early 1970s, for instance, were told that the saturatedfats in butter that dietary fats might be the cause. By Americans'average fat intakehas dropped might kill them.) Harvardepidemiologist 1952, Keys was arguing that Americans fromover 40% of totalcalories to 34%;av- WalterWillett, spokesperson for the Nurses' should reducetheir fat intaketo less than erageserum cholesterol levels have dropped HealthStudy, points out thatNIH has spent 30% of total calories,although he simulta- as well. But no compellingevidence sug- over $100 million on the threestudies and neouslyrecognized that "direct evidence on gests that these decreaseshave improved the effectof the dieton humanarteriosclero- health.Although heart disease death rates sis is verylittle and likely to remainso for have dropped-and public health offi- sometime." In the famousand very con- cials insist low-fat diets are partly | troversialSeven Countries Study, for in- responsible-the incidenceof heartdis- stance,Keys and his colleaguesreported ease does not seem to be declining,as thatthe amountof fat consumedseemed wouldbe expectedif lowerfat dietsmade to be the salientdifference between pop- a difference.This was the conclusion,for ulationssuch as thosein Japanand Crete instance,of a 10-yearstudy of heartdis- H thathad littleheart disease and those, as ease mortalitypublished in TheNew En- in Finland,that were plaguedby it. In gland Journal of Medicine in 1998, which 1961, the Framingham Heart Study suggestedthat death rates are declining linkedcholesterol levels to heartdisease, largely because doctors are treatingthe Keys madethe coverof Timemagazine, diseasemore successfully.AHA statistics andthe AHA, under his influence,began agree:Between 1979 and 1996,the number advocatinglow-fat diets as a palliativefor of medicalprocedures for heartdisease in- men with high cholesterollevels. Keys creasedfrom 1.2 million to 5.4 million a had also becomeone of the firstAmeri- year."I don'tconsider that this diseasecate- cans to consciouslyadopt a heart-healthy goryhas disappearedor anythingclose to it," diet:He andhis wife, Timereported, "do not saysone AHA statistician. eat 'carvingmeat'-steaks, chops,roasts- Meanwhile,obesity in America,which morethan three times a week." remained constant from the early 1960s "InAmerica, we no Nonetheless,by 1969the stateof the sci- through 1980, has surged upward since ence could still be summarizedby a single then-from 14%of the populationto over longer fear God or the sentencefrom a reportof the Diet-HeartRe- 22%. Diabetes has increasedapace. Both view Panel of the NationalHeart Institute obesity and diabetesincrease heart disease communists, but (now the NationalHeart, Lung, and Blood risk,which could explain why heartdisease we fear fat." Institute, or NHLBI): "It is not known incidenceis not decreasing.That this obesi- whetherdietary manipulation has any effect ty epidemicoccurred just as the government whatsoeveron coronaryheart disease." The -David Kritchevsky beganbombarding Americans with the low- chairof the panelwas E. H. "Pete"Ahrens, fat messagesuggests the possibility,howev- whose laboratoryat RockefellerUniversity er distant,that low-fat diets mighthave un- yet not one governmentagency has changed in New YorkCity did much of the seminal intended consequences-among them, its primaryguidelines to fit theseparticular researchon fat andcholesterol metabolism. weight gain. "Mostof us would have pre- data."Scandalous," says Willett."They say, Whereas proponents of low-fat diets dictedthat if we can get the populationto 'You really need a high level of proof to were concernedprimarily about the effects changeits fat intake,with its densecalories, change the recommendations,'which is of dietaryfat on cholesterollevels andheart we wouldsee a reductionin weight,"admits ironic,because they neverhad a high level disease,Ahrens and his panel-10 experts Harlan."Instead, we see the exactopposite." of proofto set them." in clinical medicine, epidemiology, bio- In the face of this uncertainty,skeptics Indeed,the historyof the nationalcon- statistics,human nutrition, and metabolism and apostateshave come along repeatedly, victionthat dietary fat is deadly,and its evo- -were equallyconcerned that eating less only to see theirwork almost religiously ig- lutionfrom hypothesisto dogma,is one in fat could have profoundeffects throughout noredas the mainstreammedical communi- which politicians,bureaucrats, the media, the body,many of whichcould be harmful. ty soughtconsensus on the evils of dietary andthe publichave played as largea role as The brain,for instance,is 70% fat, which fat. For 20 years,for instance,the Harvard the scientistsand the science.It's a storyof chieflyserves to insulateneurons. Fat is also Schoolof PublicHealth has runthe Nurses' whatcan happenwhen the demandsof pub- the primarycomponent of cell membranes. Health Study and its two sequelae-the lic healthpolicy-and the demandsof the Changingthe proportionof saturatedto un- HealthProfessionals Follow-Up Study and publicfor simpleadvice-run up againstthe saturatedfats in the diet changes the fat a the Nurses'Health Study II-accumulating confusingambiguity of realscience. composition in these membranes. This | overa decadeof dataon the diet andhealth could conceivablychange the membrane | of almost 300,000 Americans.The results Fearof fat permeability,which controlsthe transport - suggestthat total fat consumedhas no rela- Duringthe firsthalf of the 20thcentury, nu- of everythingfrom glucose, signalingpro- | tion to heartdisease risk; that monounsatu- tritionistswere more concernedabout mal- teins,and hormones to bacteria,viruses, and ratedfats like olive oil- lowerrisk; and that nutritionthan aboutthe sins of dietaryex- tumor-causingagents into and out of the u saturatedfats are little worse,if at all, than cess. AfterWorld War II, however,a coro- cell. Therelative saturation of fatsin the diet

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What IfAmericans Ate Less Saturated Fat? not,"wrote Taylorand his colleagues. The following year, the U.S. Surgeon General'sOffice funded a Eat less saturated fat, live longer. For 30 years, this has stood as study at the Universityof California,San Francisco,with the expec- one cornerstone of nutritionaladvice given to Americans(see main tation that its results would counterbalancethose of the Harvard text). But how much longer? Between 1987 and 1992, three inde- analysis.Led by epidemiologistWarren Browner, this study conclud- pendent research groups used computer models to work out the ed that cutting fat consumption in America would delay 42,000 answer.All three analyses agreed, but their conclusions have been deaths each year, but the net increase in life expectancy would av- buriedin the literature,rarely if ever cited. erage out to only 3 to 4 months. The key word was "delay,"for All three models estimated how much longer people might ex- death, like diet, is a trade-off: Everyone has to die of something. pect to live, on average, if only 10% of their calories came from "Deaths are not prevented, they are merely delayed," Browner saturated fat as recommended.In the process their total fat intake later wrote. "The'saved' people mainly die of the same things ev- would drop to the recommended 30% of calories.All three models eryone else dies of; they do so a little later in life."To be precise, a assumed that LDLcholesterol-the "bad cholesterol"-levels woman who might otherwise die at 65 could expect to live two would drop accordinglyand that this diet would have no adverse extra weeks after a lifetime of avoidingsaturated fat. If she lived to effects, although that was optimistic at the time and has become be 90, she could expect 10 additional weeks. The third study, from considerablymore so since then. All three combined national vital researchers at McGill University in Montreal, came to virtually statistics data with cholesterol risk factor data from the Framing- identical conclusions. ham Heart Study. Brownerreported his results to the Surgeon General's Office, The first study came out of HarvardMedical School and was then submitted a paper to The Journal of the American Medical published in the Annals of InternalMedicine in April 1987. Led by Association U(AMA).Meanwhile, the Surgeon General'sOffice-his William Taylor,it concluded that individuals with a high risk of source of funding-contacted JAMAand tried to prevent publica- heart disease-smokers, for instance, with high blood pressure- tion, claiming that the analysis was deeply flawed.JAMA reviewers could expect to gain, on average,one extra year by shunning satu- disagreedand publishedhis article, entitled "WhatIf Americans Ate rated fat. Healthy nonsmokers, however, might add 3 days to Less Fat?"in June 1991. As for Browner,he was left protecting his 3 months. "Althoughthere are undoubtedly persons who would work from his own funding agents. "Shootingthe messenger,"he choose to participate in a lifelong regimen of dietary change to wrote to the Surgeon General's Office, "or creating a smoke achieve results of this magnitude, we suspect that some might screen-does not change those estimates." -G.T.

could also influence cellular aging as well tically significant results.Ahrens and his col- cal establishment and the food industry- as the clotting ability of blood cells. leagues were pessimistic about whether such and by counterculture attacks on excessive Whether the potential benefits of low-fat a massive and expensive trial could ever be consumption, whether manifested in gas- diets would exceed the potential risks could done. In 1971, an NIH task force estimated guzzling cars or the classic American cui- be settled by testing whether low-fat diets such a trial would cost $1 billion, consider- sine of bacon and eggs and marbled steaks. actually prolong life, but such a test would ably more than NIH was willing to spend. And while the data on fat and health re- have to be enormous. The effect of diet Instead, NIH administrators opted for a mained ambiguous and the scientific com- on cholesterol levels is subtle for most handful of smaller studies, two of which munity polarized, the deadlock was broken individuals-especially those living in the alone would cost $255 million. Perhaps not by any new science, but by politicians. real world ratherthan the metabolic wards of more important,these studies would take a It was Senator George McGovern's biparti- nutrition researchers-and the effect of decade. Neither the public, the press, nor the san, nonlegislative Select Committee on cholesterol levels on heart disease is also U.S. Congress was willing to wait that long. Nutrition and Human Needs-and, to be subtle. As a result, tens of thousandsof indi- precise, a handful of McGovern's staff viduals would have to switch to low-fat diets Science by committee members-that almost single-handedly and their subsequenthealth comparedto that Like the flourishing American affinity for changed nutritional policy in this country of equal numbers who continued eating fat alternative medicine, an antifat movement and initiated the process of turning the di- to alleged excess. And all these people evolved independently of science in etary fat hypothesis into dogma. would have to be followed for years until the 1960s. It was fed by distrust of the McGovern's committee was founded in enough deaths accumulatedto provide statis- establishment-in this case, both the medi- 1968 with a mandate to eradicate malnutri- tion in America, and it instituted a series : ?' "There comes a point when, if you of landmark federal food assistance pro- don't make a decision, the conse- grams. As the malnu- trition work began to quences can be great as well. If you peter out in the mid- 1970s, however, the committee didn't dis- just allow Americans to keep on u band. Rather,its gen- I 0 consuming 40% of calories from fat, eral counsel, Mar- shall Matz, and staff 0 U there's an outcome to that as well." director, Alan Stone, u both young lawyers, -Basil Rifkind decided that the com- lu mittee would address

2538 30 MARCH2001 VOL291 SCIENCE www.sciencemag.org NEWS FOCUS "overnutrition,"the dietary excesses of next 7 years of controversy.Among those The guidelinesmight have then died a Americans.It was a "casualendeavor," says testifying,for instance,was NHLBIdirector quiet death when McGovern'scommittee Matz."We really were totally naive, a bunch Robert Levy, who explained that no one came to an end in late 1977 if two federal of kids, who just thought,'Hell, we should knew if eating less fat or loweringblood agencies had not felt it imperativeto re- say somethingon this subjectbefore we go cholesterollevels would preventheart at- spond. Although they took contradictory out of business.'"McGovern and his fellow tacks,which was whyNHLBI was spending points of view, one message-with media senators-all middle-aged men worried $300 million to studythe question.Levy's assistance-won out. about their girth and their health-signed position was awkward,he recalls,because The first was the USDA, where on; McGovernand his wife had both gone "thegood senatorscame out withthe guide- consumer-activistCarol TuckerForeman throughdiet-guru Nathan Pritikin's very low lines andthen called us in to get advice."He had recently been appointedan assistant fat diet and exercise program.McGovern was joined by prominentscientists, includ- secretary.Foreman believed it was incum- quitthe programearly, but Pritikin remained ing Ahrens, who testified that advising bent on USDA to turnMcGovern's recom- a majorinfluence on his thinking. Americansto eat less fat on the strengthof mendationsinto official policy, and, like McGovern's committee listened to such marginalevidence was equivalentto Mottern,she was not deterredby the exis- 2 days of testimonyon diet and disease in conductinga nutritionalexperiment with the tenceof scientificcontroversy. "Tell us what July 1976. Then residentwordsmith Nick you know and tell us it's not the final an- Mottern,a former labor reporterfor The swer,"she would tell scientists."I have to Providence Journal, was assigned the task eat and feed my childrenthree times a day, of researchingand writing the first "Di- and I want you to tell me what your best etary Goals for the United States."Mot- senseof the datais rightnow." tern,who hadno scientificbackground and Of course, given the controversy,the no experiencewriting about science, nutri- "best sense of the data"would dependon tion, or health,believed his DietaryGoals which scientistswere asked.The Food and would launch a "revolution in diet and NutritionBoard of the NationalAcademy of agriculturein this country."He avoidedthe Sciences(NAS), whichdecides the Recom- scientificand medicalcontroversy by rely- mended Dietary Allowances, would have ing almost exclusivelyon HarvardSchool been a naturalchoice, but NAS president of PublicHealth nutritionist Mark Hegsted Philip Handler,an expert on metabolism, for inputon dietaryfat. Hegstedhad stud- had told Foremanthat Mottern'sDietary ied fat and cholesterolmetabolism in the Goals were "nonsense." Foreman then early 1960s, and he believeduncondition- turnedto McGovern'sstaffers for advice ally in the benefitsof restrictingfat intake, and they recommendedshe hire Hegsted, althoughhe says he was awarethat his was which she did. Hegsted,in turn,relied on a an extreme opinion. With Hegsted as his state-of-the-sciencereport published by an muse, Motternsaw dietaryfat as the nutri- expertbut very divergentcommittee of the tionalequivalent of cigarettes,and the food American Society for Clinical Nutrition. industryas akin to the tobaccoindustry in "They were nowherenear unanimouson its willingness to suppressscientific truth anything,"says Hegsted,"but the majority in the interestsof profits.To Mottern,those supportedsomething like the McGovern scientists who spoke out against fat were committeereport." those willing to take on the industry."It American public as subjects. Even the The resultingdocument became the first took a certainamount of guts,"he says, "to AmericanMedical Association protested, editionof "Usingthe DietaryGuidelines for speak about this because of the financial suggesting that the diet proposed by the Americans."Although it acknowledgedthe interestsinvolved." guidelinesraised the "potentialfor harmful existenceof controversyand suggested that a Mottern'sreport suggested that Ameri- effects."But as these scientiststestified, so singledietary recommendation might not suit cans cut theirtotal fat intaketo 30%of the did representativesfrom the dairy,egg, and an entirediverse population, the advice to caloriesthey consumeand saturatedfat in- cattle industries,who also vigorouslyop- avoidfat andsaturated fat was, indeed,virtu- take to 10%,in accordwith AHA recom- posed the guidelines for obvious reasons. allyidentical to McGover'sDietary Goals. mendationsfor men at high risk of heart Thisjuxtaposition served to taintthe scien- Threemonths later, the NAS Food and disease.The reportacknowledged the exis- tific criticisms: Any scientists arguing NutritionBoard released its own guidelines: tence of controversybut insisted Ameri- againstthe committee'sguidelines appeared "TowardHealthful Diets." The board,con- cans had nothingto lose by following its to be eitherhopelessly behind the paradigm, sistingof a dozennutrition experts, conclud- advice. "The question to be asked is not whichwas Hegsted'sview, or industryapol- ed thatthe only reliableadvice for healthy why should we change our diet but why ogists,which was Mottern's,if not both. Americanswas to watch their weight;ev- not?" wrote Hegsted in the introduction. Althoughthe committeepublished a re- erythingelse, dietaryfat included,would "Thereare [no risks]that can be identified vised editionof the DietaryGoals laterin takecare of itself.The advicewas not taken and importantbenefits can be expected." the year,the thrustof the recommendations kindly,however, at least not by the media. This was an optimisticbut still debatable remainedunchanged. It did give in to indus- The first reports-"ratherincredulously," m position,and when DietaryGoals was re- trypressure by softeningthe suggestionthat said Handler at the time-criticized the | leased in January 1977, "all hell broke Americanseat less meat. Motternsays he NAS advicefor conflictingwith the USDA's loose," recalls Hegsted. "Practicallyno- consideredeven that a "disserviceto the and McGovern'sand thus somehowbeing body was in favorof the McGover recom- public,"refused to do the revisions,and quit irresponsible.Follow-up reports suggested mendations.Damn few people." the committee.(Mottern became a vegetari- that the board members,in the words of McGovernresponded with threefollow- an while writingthe DietaryGoals and now JaneBrody, who coveredthe story for The u up hearings,which aptlyforeshadowed the runsa food co-opin Peekskill,New York.) New YorkTimes, were "all in the pocketof

www.sciencemag.org SCIENCE VOL291 30 MARCH2001 2539 NEWS FOCUS

The ThatWasn't? of dyingfrom a heartattack at any particularage remainedunchanged: Epidemic Rather,the risingnumber of 50-year-oldsdropping dead of heart at- Forhalf a century,nutritionists have pointed to soaring death rates tackswas primarilydue to the risingnumber of 50-year-olds. as the genesis of their research into dietary fat and heart disease The secondary factor was an increase from 1948 to 1968 in the and as reason to advise Americansto eat less fat (see main text). probabilitythat a death would be classified on a death certificate "We had an epidemic of heart disease after WorldWar II,"obesity as arterioscleroticdisease or coronary heart disease. This increase, expert Jules Hirschof RockefellerUniversity in New YorkCity said however,was a figment of new diagnostic technologies-the wider just 3 months ago in The New YorkTimes. "The rates were growing use of electrocardiograms,for instance-and the changing termi- higher and higher,and people became suddenly aware of that, and nology of death certificates. In 1949, the InternationalClassifica- that diet was a factor." tion of Diseases (ICD)added a new category,"arteriosclerotic heart To proponents of the antifat message, this heart disease epi- disease,"under the more general rubric"diseases of the heart."The demic has always been an indisputablereality. Yet, to the statisti- result, as a 1958 report to the American Heart Association noted, cians at the mortality branch of the National Center for Health was dramatic:"In one year, 1948 to 1949, the effect of this revision Statistics (NCHS),the source of all the relevant statistics, the epi- was to raise coronary disease death rates by about 20% for white demic was illusory. In their view, heart disease deaths have been males and about 35% for white females."In 1965, the ICDadded a steadily decliningsince the late 1940s. category for coronary heart disease, which added yet more deaths Accordingto HarryRosenberg, director of the NCHS mortality and capped off the apparentepidemic. branchsince 1977, the key factor in the apparentepidemic, paradoxi- To Rosenbergand others at NCHS,the most likely explanation cally,was a healthierAmerican population. By the 1950s, premature for the postwar upsurge in coronary heart disease deaths is that deaths from infectiousdiseases and nutritionaldeficiencies had been physicians slowly caught on to the new terminology and changed all but eliminated,which left moreAmericans living long enoughto die the wording on death certificates."There is absolutely no evidence of chronicdiseases such as heartdisease. In other words,the actualrisk that there was an epidemic,"says Rosenberg. -G.T.

the industriesbeing hurt." To be precise,the ie WashingtonPost), demonstratedthat the methodologicalflaws had led to the nega- boardchair and one of its membersconsult- ard's "objectivity and aptitude are in tive results.They did not, at least publicly, ed for food industries,and fundingfor the ubt"(The New YorkTimes), or represented considertheir results reason to lessen their boarditself came from industrydonations. theboard's guidelines a "blowagainst the belief in the evils of fat. These industryconnections were leakedto Adfaddists who hold the publicin thrall" The sixth study was the $140 million the pressfrom the USDA. ;ience).In any case, the NAS boardhad Lipid Research Clinics (LRC) Coronary Hegstednow defendsthe NAS board,al- :n publiclydiscredited. Hegsted's Dietary PrimaryPrevention Trial, led by NHLBIad- thoughhe didn'tat the time, and calls this idelinesfor Americansbecame the offi- ministratorBasil Rifkind and biochemist kind of conflictof interest"a hell of an is- 1 U.S. policy on dietaryfat: Eat less fat. Daniel Steinbergof the Universityof Cali- sue.""Everybody used to complainthat in- velonger. fornia,San Diego. The LRCtrial was a drug dustrydidn't do anythingon nutrition,"he trial,not a diet trial,but the NHLBIherald- toldScience, "yet anybody who got involved eating"consensus" ed its outcomeas the end of the dietaryfat was blackballedbecause their positions were ice politicians,the press, and the public debate.In January1984, LRC investigators presumablyinfluenced by the industry."(In I decideddietary fat policy, the science reportedthat a medicationcalled cholestyra- 1981, Hegstedreturned to Harvard,where s left to catch up. In the early 1970s, minereduced cholesterol levels in men with his researchwas fundedby Frito-Lay.)The en NIH optedto forgo a $1 billion trial abnormally high cholesterol levels and presshad mixed feelings,claiming that the itmight be definitiveand insteadfund a modestlyreduced heart disease rates in the connections"soiled" the academy'sreputa- f-dozenstudies at one-thirdthe cost, ev- process. (The probability of suffering a tion "fortendering careful scientific advice" tonehoped these smallertrials would be heartattack during the seven-plusyears of to conclude the study was reduced from 8.6% in the - sufficientlypersuasive 2.1 thatlow-fat diets prolonglives. The placebo group to 7.0%;the probabilityof Total 1.9- Mortality results were published between dying from a heart attack dropped from to The then con- 1.7- 1980 and 1984. Fourof these trials 2.0% 1.6%.) investigators -comparing heartdisease rates and cluded,without benefit of dietarydata, that o 1.5- diet within Honolulu,Puerto Rico, cholestyramine'sbenefits could be extended 1.3- Chicago, and Framingham- to diet as well. And althoughthe trialtested e 1.1 - showedno evidencethat men who only middle-agedmen with cholesterollev- the F ate less fat livedlonger or hadfewer els higherthan those of 95%of popula- 0.9 - heartattacks. A fifth trial,the Mul- tion, they concluded that those benefits 0.7- tiple Risk FactorIntervention Trial "couldand shouldbe extendedto otherage cost $115 million and groups and women and ... other more mod- _ (MRFIT), 0.5 , I I I 0 I <160 160-199 200-239 >240 tried to amplify the subtle influ- est elevationsof cholesterollevels." ences of diet on healthby persuad- Why go so far?Rifkind says theirlogic Blood total cholesterol (mg/dl) ing subjects to avoid fat while si- was simple: For 20 years, he and his col- and had that cholesterol The big picture. Pooled risk ratios of death from

2540 30 MARCH2001 VOL291 SCIENCE www.sciencemag.org NEWS FOCUS had failed-but now they had establisheda The test of time tions: Fat has nine caloriesper gramcom- fundamentallink in the causalchain, from To the outside observer,the challenge in paredto fourcalories for carbohydratesand lower cholesterollevels to cardiovascular makingsense of any such long-runningsci- protein,and so cuttingfat from the diet surely health.With that, they could take the leapof entific controversyis to establishwhether wouldcut pounds. "This is heldalmost to be faith from cholesterol-loweringdrugs and the skepticsare simply on the wrongside of a religious truth,"says Harvard'sWillett. health to cholesterol-lowering diet and the new paradigm,or whethertheir skepti- Considerabledata, however, now suggest oth- health.And afterall theireffort, they were cism is well founded.In otherwords, is the erwise.The resultsof well-controlledclinical eager-not to mentionurged by Congress- science at issue based on sound scientific trialsare consistent:People on low-fatdiets to renderhelpful advice. "Therecomes a thinkingand unambiguous data, or is it what initiallylose a coupleof kilograms,as they point when, if you don't make a decision, Sir FrancisBacon, for instance,would have wouldon anydiet, and then the weighttends the consequencescan be greatas well,"says called "wishfulscience," based on fancies, to return.After 1 to 2 years,little has been Rifkind. "If you just allow Americansto opinions,and the exclusionof contraryevi- achieved.Consider, for instance,the 50,000 keep on consuming40% of calories from dence?Bacon offered one viablesuggestion womenenrolled in the ongoing$100 million fat,there's an outcometo thatas well." for differentiatingthe two: the test of time. Women'sHealth Initiative (WHI). Half of Withthe LRC results in press,the NHLBI Goodscience is rootedin reality,so it grows these women have been extensivelycoun- launchedwhat Levy called "a massive public anddevelops and the evidencegets increas- seled to consumeonly 20%of theircalories healthcampaign." The media obligingly went fromfat. After 3 yearson thisnear-draconian along. Time,for instance,reported the LRC regime, say WHI sources,the women had findingsunder the headline"Sorry, It's True. lost,on average,a kilogrameach. Cholesterolreally is a killer."The article The link betweendietary fat and heart abouta drugtrial began: "No whole milk. No disease is more complicated,because the butter.No fatty meats ..." Time followed up hypothesishas divergedinto two distinct 3 months later with a cover story: "And propositions:first, thatlowering cholesterol Cholesteroland Now the BadNews. .." The preventsheart disease; second,that eating coverphoto was a frowningface: a breakfast less fat not only lowerscholesterol and pre- platewith two friedeggs as the eyes and a vents heartdisease but prolongs life. Since baconstrip for the mouth.Riflind was quot- 1984,the evidencethat cholesterol-lowering ed sayingthat their results "strongly indicate drugs are beneficial-proposition number thatthe more you lowercholesterol and fat in one-has indeed blossomed, at least for yourdiet, the moreyou reduceyour risk of those at high risk of heart attack. These heartdisease," a statementthat still lacked di- drugsreduce serum cholesterol levels dra- rectscientific support. matically,and they preventheart attacks, The followingDecember, NIH effective- perhapsby othermeans as well. Theirmar- ly endedthe debatewith a "ConsensusCon- ket has now reached$4 billiona yearin the ference."The idea of such a conferenceis United States alone, and every new trial thatan expertpanel, ideally unbiased, listens seemsto confirmtheir benefits. to 2 daysof testimonyand arrivesat a con- The evidence supporting the second clusionwith whicheveryone agrees. In this proposition,that eating less fat makes for case, Rifkindchaired the planningcommit- a healthierand longer life, however,has tee, which chose his LRC co-investigator remained stubbornlyambiguous. If any- Steinbergto lead the expertpanel. The 20 inglymore compelling, whereas wishful sci- thing, it has only become less compelling speakersdid includea handfulof skeptics ence flourishesmost underits first authors over time. Indeed,since Ancel Keys start- -including Ahrens,for instance,and cardi- before"going downhill." ed advocating low-fat diets almost ologist MichaelOliver of ImperialCollege Such is the case, for instance,with the 50 yearsago, the science of fat andcholes- in London-who arguedthat it was unsci- propositionthat dietaryfat causes cancer, terol has evolved from a simple story into entific to equatethe effects of a drugwith which was an integralpart of dietary fat a very complicated one. The catch has the effectsof a diet. Steinberg'spanel mem- anxietyin the late 1970s.By 1982,the evi- been that few involved in this business bers,however, as Oliverlater complained in dence supportingthis idea was thoughtto were preparedto deal with a complicated TheLancet, "were selected to includeonly be so undeniablethat a landmarkNAS re- story.Researchers initially preferred to be- expertswho would,predictably, say thatall port on nutritionand cancerequated those lieve it was simple-that a single un- levels of blood cholesterol in the United researcherswho remainedskeptical with wholesome nutrient, in effect, could be Statesare too high and shouldbe lowered. "certaininterested parties [who] formerly isolated from the diverse richness of hu- And, of course, this is exactly what was arguedthat the association between lung man diets;public health administrators re- said."Indeed, the conferencereport, written cancerand smokingwas not causational." quireda simple story to give to Congress by Steinbergand his panel,revealed no evi- Fifteen years and hundredsof millions of and the public; and the press needed a dence of discord.There was "no doubt,"it researchdollars later,a similarlymassive simple story-at least on any particular concluded,that low-fat diets "will afford expertreport by the WorldCancer Research day-to give to editorsand readersin 30 significant protection against coronary Fundand the AmericanInstitute for Cancer columninches. But as contrariandata con- heart disease" to every American over 2 Researchcould find neither"convincing" tinued to accumulate,the complications yearsold. The ConsensusConference offi- nor even "probable"reason to believe that became increasinglymore difficult to ig- N cially gave the appearanceof unanimity dietaryfat causedcancer. nore or exclude, and the press began waf- where none existed.After all, if therehad The hypothesisthat low-fat diets are the fling or addingcaveats. The scientiststhen 0 been a trueconsensus, as Steinberghimself requisiteroute to weightloss hastaken a sim- got the blamefor not stickingto the origi- told Science, "you wouldn't have had to ilar downwardpath. This was the ultimate nal simple story, which had, regrettably, s havea consensusconference." fallbackposition in all low-fatrecommenda- neverexisted.

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Morefats, fewer answers National CholesterolEducation Program, The originalsimple story in the 1950s was also advisinglow-fat diets for everyoneover that high cholesterollevels increaseheart 2 yearsold, epidemiologistDavid Jacobs of disease risk. The seminal Framingham the Universityof Minnesota,Twin Cities, Heart Study,for instance,which revealed visitedJapan. There he learnedthat Japanese the association between cholesterol and physicianswere advisingpatients to raise heartdisease, originallymeasured only to- theircholesterol levels, because low choles- tal serumcholesterol. But cholesterolshut- terol levels were linked to hemorrhagic tles throughthe blood in an arrayof pack- stroke.At the time, Japanesemen were dy- ages. Low-density lipoprotein particles ing from stroke almost as frequently as (LDL, the "bad"cholesterol) deliver fat Americanmen were succumbingto heart and cholesterol from the liver to tissues disease.Back in Minnesota,Jacobs looked that need it, including the arterial cells, for this low-cholesterol-strokerelationship where it can lead to atherosclerotic in the MRFITdata and foundit there,too. plaques.High-density lipoproteins (HDLs, And the relationshiptranscended stroke: the "good"cholesterol) return cholesterol Menwith very low cholesterollevels seemed to the liver.The higherthe HDL, the lower proneto prematuredeath; below 160 mil- the heart disease risk. Then there are ligramsper deciliter(mg/dl), the lowerthe triglycerides, which contain fatty acids, cholesterollevel, the shorterthe life. and very low density lipoproteins The antifat movement Jacobs reportedhis results to NHLBI, (VLDLs),which transport triglycerides. which in 1990 hosted a conferenceto dis- All of these particleshave some effect was founded on the cuss the issue, bringing together re- on heartdisease risk, while the fats, carbo- searchers from 19 studies around the hydrates,and protein in the diet havevary- Puritan notion that world.The datawere consistent:When in- ing effects on all these particles. The vestigators trackedall deaths, instead of 1950s story was that saturated fats in- "something bad had to just heart disease deaths, the cholesterol crease total cholesterol, polyunsaturated curveswere U-shapedfor men and flat for fats decreaseit, and monounsaturatedfats have an evil cause, and women. In otherwords, men with choles- are neutral.By the late 1970s-when re- terol levels above 240 mg/dl tendedto die searchersaccepted the benefits of HDL- you got a heart attack prematurelyfrom heart disease. But below they realizedthat monounsaturated fats are because did some- 160 mg/dl, the men tended to die prema- not neutral. Rather, they raise HDL, at you turely from cancer,respiratory and diges- least comparedto ,and low- which tive diseases,and trauma. As for women,if er LDL.This makesthem an ideal nutrient thing wrong, anything,the higher their cholesterol,the as far as cholesterol goes. Furthermore, was too much longerthey lived (see graphon p. 2540). saturatedfats cannot be quite so evil be- eating These mortalitydata can be interpreted cause, while they elevate LDL, which is of a bad thing, rather in two ways. One, preferredby low-fatad- bad,they also elevateHDL, which is good. vocates,is thatthey cannotbe meaningful. And some saturatedfats-stearic acid, in than not having enough Rifkind,for instance,told Science that the particular, the fat in chocolate-are at excess deathsat low cholesterollevels must worstneutral. Stearic acid raisesHDL lev- of a good thing." be due to preexistingconditions. In other els but does little or nothingto LDL. And words,chronic illness leads to low choles- thenthere are trans fatty acids, which raise -John Powles terollevels, not vice versa.He pointedto the LDL,just like saturatedfat, but also lower 1990 conference report as the definitive HDL. Today,none of this is controversial, documenton the issueand as supportfor his althoughit has yet to be reflected in any much as 70%-of the fat content of a argument,although the report states un- FoodGuide Pyramid. porterhousewill improvecholesterol levels equivocallythat this interpretationis not To understandwhere this complexity comparedto what they would be if bread, supportedby the data. can lead in a simple example, consider a potatoes,or pasta were consumedinstead. The other interpretationis that what a steak-to be precise,a porterhouse,select The remaining 30% will raise LDL but low-fat diet does to serumcholesterol lev- cut, with a half-centimeterlayer of fat, the will also raise HDL. All of this suggests els, and what that in turndoes to arteries, nutritionalconstituents of which can be that eating a porterhousesteak ratherthan may be only one componentof the diet's found in the NutrientDatabase for Stan- carbohydratesmight actually improve heart effect on health. In other words, while dardReference at the USDA Web site. Af- disease risk, although no nutritionalau- low-fat diets might help preventheart dis- ter broiling,this porterhousereduces to a thoritywho hasn't writtena high-fat diet ease, they mightalso raise susceptibilityto servingof almost equal partsfat and pro- book will say this publicly. otherconditions. This is what alwayswor- tein. Fifty-onepercent of the fat is mono- As for the scientificstudies, in the years ried Ahrens. It's also one reason why the - unsaturated,of whichvirtually all (90%)is since the 1984 consensus conference,the American College of Physicians, for in- g oleic acid, the same healthy fat that's in one thingthey havenot done is pile up evi- stance, now suggests that cholesterol re- 2 olive oil. Saturatedfat constitutes45% of dence in supportof the low-fat-for-allap- ductionis certainlyworthwhile for those at S the total fat, but a third of that is stearic proachto the publicgood. If anything,they high, short-termrisk of dying of coronary acid,, which is, at the very least, harmless. have added weight to Ahrens'sfears that heart disease but of "much smaller or ... The remaining4% of the fat is polyunsatu- theremay be a downsideto populationwide uncertain"benefit for everyoneelse. | rated,which also improvescholesterol lev- low-fat recommendations.In 1986, for in- This interpretation-thatthe connection o els. In sum,well overhalf-and perhapsas stance,just 1 year afterNIH launchedthe between diet and health far transcends

www.sciencemag.org SCIENCE VOL291 30 MARCH2001 2543 NEWS Focus cholesterol-is also supportedby the single could be cut from the diet and the calories mixed carbohydrates?Do they add green most dramaticdiet-heart trial ever conduct- with it, but that'snot the case. Despite all leafy vegetables, or do they add pasta? ed: the Lyon Diet Heart Study, led by expectationsto the contrary,people tendto And so it goes. "Thesky's the limit,"says Michel de Lorgerilof the FrenchNational consumethe same numberof calories de- nutritionist Alice Lichtenstein of Tufts Instituteof Health and Medical Research spite whateverdiet they try.If they eat less Universityin Boston. "Thereare a million (INSERM)and publishedin Circulationin total fat, for instance,they will eat more perturbations." February1999. The investigatorsrandom- carbohydratesand probablyless protein, These trade-offsalso confoundthe kind ized 605 heart attack survivors, all on because most proteincomes in foods like of epidemiologicalstudies that demonized cholesterol-lowering drugs, into two saturatedfat from the 1950s onward.In groups.They counseledone to eat an AHA particular,individuals who eat copious "prudentdiet," very similarto that recom- "Most of us would amountsof meat and dairy products,and mendedfor all Americans.They counseled plentyof saturatedfats in the process,tend the otherto eat a Mediterranean-typediet, have predicted that if not to eat copious amountsof vegetables with more bread,cereals, legumes, beans, we can the and fruits.The sameholds for entirepopu- vegetables,fruits, and fish and less meat. get popula- lations. The eastern Finns, for instance, Totalfat andtypes of fat differedmarkedly tion to its fat whose lofty heartdisease rates convinced in the two diets,but the HDL,LDL, and to- change Ancel Keys anda generationof researchers tal cholesterollevels in the two groupsre- intake, with its dense of the evils of fat, live within500 kilome- mained virtually identical. Nonetheless, tersof theArctic Circle and rarely see fresh over 4 years of follow-up, the Mediter- calories, we would see produceor a green vegetable.The Scots, ranean-diet group had only 14 cardiac infamous for eating perhaps the least deathsand nonfatalheart attacks compared a reduction in weight. wholesomediet in the developedworld, are to 44 for the "Western-type"diet group. in a similarfix. Basil Rifkindrecalls being The likely explanation,wrote de Lorgeril Instead, we see the laughedat once on this pointwhen he lec- and his colleagues, is that the "protective tured to Scottish physicians on healthy effects [of the Mediterraneandiet] werenot exact opposite." diets:"One said, 'You talk about increasing related to serum concentrationsof total, fruitsand vegetable consumption, but in the LDLor HDLcholesterol." -William Harlan areaI work in there'snot a single grocery Manyresearchers find the Lyon data store.'" In bothcases, researchersjoke that so perplexingthat they'releft question- c the only greenleafy vegetable these popula- ing the methodology of the trial. tions consumeregularly is tobacco.As for Nonetheless, says NIH's Harlan,the the purportedbenefits of the widely hailed data "arevery provocative.They do Mediterraneandiet, is it the fish, the olive bringup the issue of whetherif we oil, or the freshvegetables? After all, says look only at cholesterollevels we j Harvard epidemiologist Dimitrios aren't going to miss something Trichopoulos,a native of Greece, the very important."De Lorgerilbe- olive oil is used eitherto cook vegeta- lieves the diet's protectiveeffect f bles or as dressing over salads. "The comes primarily from omega-3 quantityof vegetablesconsumed is al- fatty acids, found in seed oils, most a pound [half a kilogram]a day," meat, cereals, green leafy vegeta- he says, "and you cannot eat it without bles, and fish, and from antioxidant olive oil. And we eat a lot of legumes,and compounds,including vitamins, trace el- we cannoteat legumeswithout olive oil." ements,and flavonoids. He toldScience that Indeed, recent data on heart disease most researchersand journalists in the field trendsin Europesuggest that a likely ex- are prisonersof the "cholesterolparadigm." planationfor the differencesbetween coun- Althoughdietary fat and serumcholesterol tries and over time is the availability of "are obviously connected,"he says, "the freshproduce year-round rather than differ- connection is not a robust one" when it L n rpretathatalso ences in fat intake.While the press often comesto heartdisease. have con- plays up the Frenchparadox-the French siderable have little heartdisease despite seemingly Dietary trade-offs amountsof fat. high saturatedfat consumption-the real One inescapablereality is that death is a This plus- paradox is throughoutSouthern Europe, trade-off,and so is diet. "Youhave to eat minus problem whereheart disease death rates have steadi- something,"says epidemiologist Hugh suggests a different ly droppedwhile animal fat consumption Tunstall Pedoe of the University of interpretationfor virtuallyev- has steadilyrisen, says Universityof Cam- Dundee, U.K., spokespersonfor the 21- ery diet studyever done, including,for in- bridge epidemiologist John Powles, who nationMonitoring Cardiovascular Disease stance,the kind of metabolic-wardstudies studies nationaldisease trends.The same Projectrun by the WorldHealth Organiza- that originallydemonstrated the ability of trendappears in Japan."We have this idea , tion. "If you eat moreof one thing,you eat saturatedfats to raise cholesterol. If re- that it's the Arcadianpast, the life in the 2 a lot less of somethingelse. So for every searchersreduce the amountof saturated village, the utopiathat we've lost,"Powles | theorysaying this disease is causedby an fat in the test diet, they have to make up says; "thatthe really protectiveMediter- V excess in x, you can producean alternative the calories elsewhere. Do they add ranean diet is what people ate in the | theory saying it's a deficiency in y." It polyunsaturatedfats, for instance,or add 1950s."But that notion isn't supportedby 3 would be simple if, say, saturated fats carbohydrates?A single carbohydrateor the data:As these Mediterraneannations u

2544 30 MARCH2001 VOL291 SCIENCE www.sciencemag.org NEWS FOCUS became more affluent, says Powles, they Reaven. How this balancesout is the un- David Ludwig, director of the obesity beganto eat proportionallymore meat and known. "It's a bitch of a question,"says clinic at Children'sHospital Boston. "The with it moreanimal fat. Theirheart disease Marc Hellerstein,a nutritionalbiochemist body appearsto run out of fuel." A few rates,however, continued to improvecom- at the Universityof California,Berkeley, hoursafter eating, hunger returns. pared to populations that consumed as "maybethe great public health nutrition If the theory is correct, calories from much animal fat but had less access to questionof our era." the kind of processed carbohydratesthat fresh vegetables throughoutthe year. To The otherworrisome aspect of the car- have become the staple of the American Powles,the antifatmovement was founded bohydratetrade-off is the possibilitythat, diet are not the same as caloriesfrom fat, on the Puritannotion that "somethingbad for some individuals, at least, it might protein,or complexcarbohydrates when it had to have an evil cause, and you got a actually be easier to gain comes to controllingweight. "They may heart attack because you did something weighton low-fat/high- cause a hormonalchange that stimulates wrong, which was eating too much of a carbohydrateregi- hungerand leads to overeating,"says Lud- badthing, rather than not havingenough of mens than on wig, "especially in environmentswhere a good thing." food is abundant...." The other salient trade-off in In 1979, 2 yearsafter McGovern's com- Ahrens the plus-minusproblem of human AI: mittee releasedits DietaryGoals, diets is carbohydrates.When the , wroteto TheLancet describing what he federal governmentbegan pushing \? had learnedover 30 yearsof studying low-fat diets, the scientists and fat and cholesterolmetabolism: "It |: : administrators,and virtuallyeveryone |^ is absolutelycertain that no one else involved, hoped that Americans can reliablypredict whether a would fat calories with fruits change in dietary regimens replace ' and vegetables and legumes, but it will have any effect what- / incidence of didn'thappen. If nothingelse, economics -,p ~ soever on the workedagainst it. The food industryhas :o"y ~new events of [coronary little incentiveto advertisenonproprietary heartdisease], nor in whom."To- items: broccoli, for instance.Instead, says day, many nutritionresearchers, acknowl- NYU's Nestle, the great bulk of the $30- edgingthe complexityof the situation,find billion-plusspent yearlyon food advertis- themselvessiding with Ahrens.Krauss, for ing goes to selling carbohydratesin the instance, who chairs the AHA Dietary guise of fast food, sodas,snacks, and candy GuidelinesCommittee, now calls it "scien- bars. And carbohydratesare all too often "When you don't have tifically naive"to expect that a single di- whatAmericans eat. etary regime can be beneficial for every- Carbohydratesare what Harvard'sWil- any real good answers body:"The 'goodness' or 'badness'of any- fat and its sub- lett calls the flip side of the calorietrade- in this thingas complexas dietary off problem.Because it is exceedinglydif- business, you types will ultimatelydepend on the context ficult to add pure proteinto a diet in any have to a few of the individual." quantity,a low-fat diet is, by definition,a accept Giventhe proven success and low cost of high-carbohydratediet-just as a low-fat not so ones as the cholesterol-loweringdrugs, most physicians cookie or low-fatyogurt are, by definition, good now prescribedrug treatment for patientsat reduce high in carbohydrates.Numerous studies next best thing." high riskof heartdisease. The drugs now suggest that high-carbohydratediets LDL cholesterollevels by as muchas 30%. can raise triglyceridelevels, create small, -Ron Krauss Diet rarelydrops LDL by more than 10%, dense LDL particles,and reduceHDL-a which is effectivelytrivial for healthyindi- combination, along with a condition viduals,although it may be worththe effort known as "insulinresistance," that Stan- higher fat diets. One of the many factors for thoseat highrisk of heartdisease whose fordendocrinologist Gerald Reaven has la- that influence hunger is the glycemic in- cholesterollevels respond well to it. beled "syndrome X." Thirty percent of dex, which measures how fast carbohy- The logic underlyingpopulationwide adult males and 10% to 15% of post- dratesare brokendown into simple recommendationssuch as the latestUSDA menopausal women have this particular and moved into the bloodstream. Foods DietaryGuidelines is that limitingsaturat- syndromeX profile, which is associated with the highest glycemic index are sim- ed fat intake-even if it does little or noth- with a several-foldincrease in heart dis- ple sugars and processed grain products ing to extendthe lives of healthyindividu- ease risk, says Reaven,even among those like pasta and white rice, which cause a als and even if not all saturatedfats are patientswhose LDL levels appearother- rapid rise in blood after a meal. equallybad-might still delaytens of thou- wise normal. Reaven and Ron Krauss, Fruits,vegetables, legumes, and even un- sands of deaths each year throughoutthe who studies fats and lipids at Lawrence processed starches-pasta al dente, for entirecountry. Limiting total fat consump- BerkeleyNational Laboratoryin Califor- instance-cause a much slower rise in tion is considered reasonableadvice be- nia, have shown that when men eat high- blood sugar. Researchershave hypothe- cause it's simple and easy to understand, 1 carbohydratediets their cholesterol pro- sized that eating high-glycemic index andit may limit calorieintake. Whether it's not be | files may shift from normalto syndrome foods increases hunger later because in- scientificallyjustifiable may simply I X. In otherwords, the more carbohydrates sulin overreactsto the spike in blood sug- relevant."When you don't have any real y replacesaturated fats, the more likely the ar. "The high levels cause the nu- good answers in this business," says I end resultwill be syndromeX and an in- trientsfrom the meal to get absorbedand Krauss,"you have to accept a few not so - creasedheart disease risk. "The problem is very avidly stored away, and once they good ones as the nextbest thing." u so clear rightnow it's almosta joke,"says are, the body can't access them," says -GARYTAUBES

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