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Soy protein linked to reduced CHD risk

Consumption of soy protein mayprovide health benefits includ-ing reduced risk of coronary

heart disease (CHD). according to ameta analysis published in the NewEngland Journal of Medicine.

The meta analysis by James Ander-son. professor of medicine at the Uni-versity of Kentucky. included evalua-tion of data from nearly 30 clinicalstudies involving more than 700 per-sons. "This is the bottom line-increased intake of soy equalsdecreased risk of coronary heart dis-ease." Anderson said.

His paper. "Meta-Analysis ofEffects of Soy Protein Intake onSerum Lipids in Humans:' alsoaddresses practical ways in whichpeople can incorporate soy productsinto their diet. "Too often the scientif-ic community tells Americans whatthey need to cal. but doesn't worryabout how they' 11eat it. Soy can easi-ly be a part of everyone's diet. andthis paper helps show people how:' hesaid.

To accompany the article. JohnErdman. director of the University ofIllinois's Division of Nutritional Sci-ences, wrote an editorial for the sameAug. 3. 1995. issue. addressing thesafety and practicality of eating soyprotein.

The report noted that replacing ani-mal protein with an average of 47 g ofsoy protein a day C,!t1 significantlylower levels of low-density lipopro-tein (LDL) cholesterol without affect-ing high-density lipoprotein (HDL)cholesterol. One study at the Universi-ty of Illinois has shown that 25 g ofsoy protein a day lowered LDL inmen with elevated cholesterol levels.Erdman said it is not yet knownwhether an even lower amount of soyprotein, if combined with a high-fiber.low-fat diet. might have the sameeffect.

University of Illinois nutrition pro-fessor Sue Pouer is conducting a studyexamining the effect of soy proteinand isoflavones on heart disease andosteoporosis in 75 women who havegone through menopause.

Peter Gann. a professor of preven-

tivc medicine at Northwestern Univer-sity Medical School, has announcedthere will be a clinical study undertak-en this fall at Northwestern to trackthe hormonal effeets of soy consump-tion in women and to examine a possi-ble link between lowered estrogenlevels and reduced risk of breast can-cer. according to a report in the July24, 1995, Food Chemical News.

In Ganns research project, 200women will be given randomizedamounts of lsotlavones in the fonn ofpowdered soybean isolate for use inmuffins and other recipes. The womenwill be tracked for 15 months. Gannnoted that much research is neededbefore determining whether increasedsoy consumption is a useful strategyfor breast cancer prevention.

Obese mice lose weightwhen given hormoneScientists treating obese mice with agenetically engineered hormone havefound the mice lost 22--40% of theirweight in just a month, according 10research findings published inScience.

The hormone. named leptin. is nat-urally produced by the ob gene clonedlast year by Jeffrey M. Friedman andcolleagues at the Howard HughesMedical Institute at Rockefeller Uni-versity.

Friedman and colleagues reportedin December that they had found theob gene in mice as well as a counter-part in humans. They hypothesizedthat the gene produces a hormone thathelps regulate the body's storage offat. Subsequently, mice studies atFriedman's laboratory as well as attwo other laboratories have verifiedthat lept!n helped reduce excess fat inmice.

In this latest research, scientiststwice a day injected leptin into ob-defective mice. as well as into normalmice and mice with a gene defect thatmakes them diabetic. The ob-defec-rive mice quickly began losing fatcells. ate less food and spent more

time exercising. Most of the exrrcrnelyfat mice experienced body weightreduction by about 30%. Normal miceinjected with leptin lost almost all oftheir body fat, representing about 12%of their body weight. The diabeticmice were not affected.

Leptin is found in the blood of nor-mal mice but not in a mouse bred tohave the flawed ob gene.

Scientists said more research isneeded to see if it is safe to give thehuman version of the hormone tohumans. If no safety questions arise,experimental human trials may beginin another year. Amgen Inc., a drugcompany in Thousand Oaks, Califor-nia, holds a license from RockefellerUniversity for use of the ob gene andtepun hormone. The research wasdescribed in Science's July 28, 1995.issue.

Dietary choices affectedby complex factorsAlthough many persons believe thatdietary behaviors are based purely onpersonal choices and therefore aremodifiable, research suggests thatsome dietary choices are influencedby brain chemistry and body composi-tion, according 10 Adam Drewnowski,director of the Human Nutrition Pro-gram at the University of MichiganSchool of Public Health.

Writing on the impact of taste pref-erences on dietary choices and foodconsumption patterns in the May-June1995 issue of Food & Nutrition News,Drewnowski pointed out that the plea-sure response to fats. controlled bybrain neurotransmitters or peptides,may playa prominent role in dictatingfood choices.

"If so. then human biochemistry.rather than behavior, may be responsi-ble for the failure to achieve recom-mended fat intake goals:' he wrote.

Fat consumption may satisfy sever-al physiological and psychologicalneeds. "The sensory pleasure responseappears to be mediated by the releaseof endogenous opiate peptides-plea-

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sure-enhancing molecules manufac-tured by the human brain:' he wrote."Since opiate peptides are alsoinvolved in mediating the pleasureresponse to foods, it may be that fatconsumption affects the mental healthand well-being of the individual:'

Taste preferences for sugar, as wellas fat, appear to be under opiate con-uol, according to Drewnowski.

Increased personal income, accom-panied by increased availability of Iatsand sugars in the food supply, is onefactor favoring increased fat and sugarconsumption. he wrote. Interhealth, adisease prevention program of theWorld Health Organization. has exam-ined changing dietary patterns anddisease risks in 14 countries."Between 1954 and 1986, the avail-ability of dietary fats increased in eachone of the 14 Interheahh countries. Inevery case, fat displaced complex car-bohydrate as an energy source, whiledietary protein remained constant,"Drewnowski wrote.

Dietary interventionssubject of conferenceThefollowing report was prepared byKenneth K. Carroll, director of theCentre for Human Nutrition at TheUniversity of Western Ontario. Lon-don, Ontario, Canada. and an associ-ate editor of INFORM.Concern about the efficacy of theAmerican Heart Association (AHA)Step J and Step II diets led to a May3-5, 1995. scientific conference onthe Efficacy of HypocholesterolemicDietary Interventions, held in SanAntonio, Texas.

The Step I and Step II diets aredesigned to lower serum cholesterollevels through reductions in saturatedfat and cholesterol intakes. However.a recent AHA fact sheet shows that40% of Americans in the 45-55 yearage group have blood cholesterol lev-els of 240 }.1g/dLor more.

The conference, attended byapproximately 100 persons. featuredoral and poster presentations on vari-ous factors influencing blood choles-terol levels. including different dietarycomponents. genetics. diseases such

as diabetes. and obesity.The conference opened with an

overview of epidemiological studieson the role of diet and hypercholes-terolemia in cardiovascular disease.presented by Lewis H. Kuller of theUniversity of Pittsburgh. This was fol-lowed by a discussion of the rationalefor current dietary guidelines, present-ed by Scott M. Grundy of the Univer-sity of Texas Southwestern MedicalCenter at Dallas.

Results of Step I diet trials weredescribed by Henry N. Ginsberg ofColumbia University College ofPhysicians and Surgeons, New YorkCity. New York; Penny Kris-Ether-ton of Pennsylvania State University.University Park, Pennsylvania: AliceLichtenstein of Tufts University.Boston, Massachusetts: and PatriciaJ. Elmer, University of Minnesota,Minnesota. for the DELTA ResearchGroup. Also, D. Mark Hegsted ofHarvard University in Boston andHenry C. McGill Jr. of the SouthwestFoundation for Biomedical Researchin San Antonio described interven-tion studies related to dietary fattyacid composition and dietary choles-terol.

In sessions on other dietary factors.discussions and speakers included thefollowing: effects of dietary proteinand amino acids. Kenneth K. Carrollof the Centre for Human Nutrition.University of Western Ontario: dietaryfiber, Barbara Schneeman. Universityof California at Davis; plant sterolsand structured triglycerides, DavidKritchevsky, The Wi star Institute,Philadelphia. Pennsylvania: anddietary calcium. Margo A. Denke,University of Texas SouthwesternMedical Center at Dallas. Also, R.James Barnard of the University ofCalifornia at Los Angeles describedthe effects of very low-fat diets. whileMichael Davidson of the ChicagoCenter for Clinical Research spoke onfat substitutes.

In a session on genetic-environ-mental interactions on lipoprotein lev-els, Barbara V. Howard of the Med-lantic Research Institute of washing-ton, D.C .• spoke on obesity. Othertalks centered on gender. by PhyllisBowen of the University of Illinois atChicago: genetic factors. by Ronald

M. Krauss of the Lawrence BerkeleyLaboratory, University of California atBerkeley: and diabetes. discussed byJohn D. Brunzell of the University ofWashington in Seattle.

The concluding session consistedof a summary of major conclusionspresented by Grundy. followed by apanel discussion.

"This symposium reaffirmed theimportance of diet in the prevention ofcoronary heart disease (CHD) in theUnited States. Although great strideshave been taken in the treatment ofhigh blood cholesterol with drugs, theuse of drugs will be largely limited tohigh-risk patients." Grundy noted.adding. "The latter will includepatients with established CHD orthose with subclinical atheroscleroticdisease or multiple risk factors.Dietary modification. combined withavoidance of cigarette smoking andregular physical activity, affords thebest opportunity for the lifetime pre-vention of CHD. Three dietary factorsneed attention for modification. Theseare excess dietary cholesterol, choles-terol-raising fatty acids. and excessenergy intake leading to obesity. Thecholesterol-raising fatty acids includepalmitic acid. lauric acid. myristicacid and trails fatty acids,"

Participants generally agreed thatreduced intakes of dietary choles-terol. cholesterol-raising fatty acidsand total energy (in overweight peo-ple) are the bases for dietary preven-tion of CHD. For the general public,total fat intake should be 30% or lessof total energy. However, there wasnot complete agreement on what rep-resents a useful "therapeutic diet" fortreatment of hypercholesterolemia.Most investigators favored an intakeof less than 20 mg/day of cholesteroland intake of cholesterol-raisingfauy acids of less than 7% of totalenergy intake. Whether a "therapeu-tic diet" should have a total fatintake below 20-25% of total calo-ries was a continuing point of dis-pute. Otherwise, there was generalagreement on the overall dietaryapproach to prevent CHD.

AHA plans to publish a summaryof the conference later this year in its

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[continued from page J 161)

journal, Arteriosclerosis, Thrombosis,and Vascular Biology.

Conference advocatesmore olive oil in dietThe following report from the Firstinternational Conference on Fats andOils Consumption in Health and Dis-ease held April 24-25, 1995, in NewYork, was written by Mark A. Bieber.chairperson of the AOeS Health andNutrition Division,The First International Conference onFats and Oils Consumption in Healthand Disease presented very little newdata but did solidly place olive oil andthe Mediterranean diet in a truer sci-entific context.

As a result. the conference, whichdrew about 250 attendees, supportedthe drive for further use of olive oil,particularly in developed countriessuch as the United States. Primarysponsor for the conference was theInternational Olive Oil Council; co-hosts were The New York Hospital,Cornell University Medical College,The Rockefeller University, HarvardMedical School, The Regional Nutri-tion Center at the New York Academyof Medicine, and the Strang CancerPrevention Center.

The following are some of thehighlights from the conference.

Antonia Trichopoulou of the WorldHealth Organization pointed out that63% of the world's population hasaccess to less than 60 g of fat per day,while II% has access to over 120 gper day. In developed societies, themore educated eat less total fat andmore margarine than butter. The nutri-tional focus has been on the polyun-saturated/saturated ratio, with only amention of rncnounsaturates. TheMediterranean Pyramid, however,helps "solve" this void by includingolive oil as an integral part of the diet.This pyramid is based on the historicaluse of olive oil in the region and theperceived good health of the peopleliving there.

Nancy Ernst of the National Insti-tutes of Health discussed National

Health and Nutrition ExaminationSurvey IIJ data showing that Ameri-cans eat about 34% of calories as fat,with about 12% derived from satu-rates, about 13% from monounsatu-rates and about 7% from polyunsatu-rates. Males consume an average of350 mg of cholesterol per day whilefemales consume 230 mg. Over the1972-1990 time period, the change indietary fat, when "plugged into" theKeys and Hegsted equations, wouldresult in a net change of about -IImg/dL in blood cholesterol levels;actual measurement of populationblood cholesterol levels showed adrop of 12 mg/dL This change wasonly in low-density lipoprotein (LDL)cholesterol, not high-density lipopro-tein (HDL) cholesterol.

Martijn Karan of the AgriculturalUniversity in Wageningen, TheNetherlands, asked, "What should wereplace saturated fats with: alcohol,protein, carbohydrate, or other typesof fat?" His conclusion from metaanalysis is that a high-oil diet rich inmonounsaturates, with fat represent-ing about 35% of calories, is prefer-able to a high-carbohydrate diet sincethe latter results in elevated triglyc-erides and lower HDL cholesterol.

Acknowledging that a high-oil dietcould lead to obesity faster and proba-bly would be lower in dietary fiberthan a high-carbohydrate diet, Katansaid evidence concerning glucose tol-erance favors the high-oil diet. Dis-playing fat replacement graphs show-ing that trans fatty acids modestlyraise LDL and that poly unsaturatesare slightly better than monounsatu-rates, Katan still recommendedmonounsaturates as the "nutrient fat"of choice.

Michael Oliver, professor emeritusat the National Heart and Lung Insti-tute in London, England, revieweddiet trials to lower coronary heart dis-ease (CHD), concluding that there wasa decrease in CHD only in those whoachieved a significant lowering ofblood cholesterol levels. Most diet tri-als were unable to achieve the highdegree of cholesterol lowering neededto see a change in clinical events. Ofthe 14 diet trials that have been con-ducted, six were primary trials andonly two have shown true CHD low-

ering. Oliver stressed that a rigorousdiet regimen is needed to achieve adifference in cholesterol levels. Hepointed out that significant loweringof cholesterol levels, whether by dietor drugs, is needed to reduce CHD.Fish oil feeding results in a strikingdecrease in CHD incidence. However,this is not due to cholesterol mecha-nisms but rather to changes in throm-bosis and protection against arrhyth-mias, he said.

Scott M. Grundy of the Universityof Texas Southwestern Medical Cen-ter at Dallas recommended that the"ideal" diet would contain less than30% of calories as fat, with a saturate-to- monou nsaturate-to- pol yunsatu rateratioof7:14:7.

Elliott Berry of the Hadassah Med-ical School at Hebrew University inJerusalem, Israel, said results from theJerusalem study with diabeticsshowed increased CHD risk in maleswith a higher intake of polyunsatu-rates. It is not clear why this occurred.He hypothesized that n-3 fatty acidsare less likely to lead to obesity butthat a high monounsaturate diet is pre-ferred since they oxidize more slowlythan other fatty acids. Low oxidationis important, especially for diabetics.

David Rose of the AmericanHealth Foundation presented the samestory for cancer and relied on animalmodel data showing that olive oil con-sumption resulted in less tumors thanwith com oil. Prostaglandin synthesisdecreased with olive oil or fish oilintake. In nude mice, olive oil and fishoil protected against tumor progres-sion. However, it should be pointedout that human data are inconsistentwith animal data in that no relation-ship between polyunsaturates and can-cer has been found.

Walter Willett of the HarvardSchool of Public Health and SamShapiro of Boston University debatedthe effects of trailS fatty acids in thediet. Willen likened the presence oftrans fatty acids in food to conductinguncontrolled research withoutinformed consent. Shapiro concentrat-ed on methodology issues, pointingout inadequate epidemiology in con-ducting trans studies thus far, particu-larly the lack of a dose/response andextremely poor statistics.

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Michael Crawford of the Zoologi-cal Society of London pointed out thatthe human brain is mostly lipid andthat 70% of fetal energy is used to Jaydown brain lipid. With very low birth-weight infants. brain developmentmay pose a major problem. Low birth-weight infants also are unprepared 10fight off the oxygen attack of birthbecause of insufficient antioxidants intheir tissues. Arachidonic and docosa-hexaenoic acids arc nceded in thenewborn. with breast milk a superiorsource than formula. Crawford said.

Daniel Steinberg of the Universityof California at San Diego. the "origi-nator" of the antioxidant hypothesis ofatherosclerosis. said consumers shouldobtain antioxidants from food ratherthan supplements. Oxidized LDLleads to fatty streaks. not plaque,Steinberg said. adding that the hypoth-esis is still attractive although human

intervention data are not totally sup-portive. Thus. more research is need-ed. In addition. he questioned if moreeffective antioxidants are needed.

Enzo Fedeli of Stazione Sperimen-tale pointed out that there are threetypes of olive oil-virgin. refined andpomace-and low molecular-weightphenols are present to act as autioxi-darns. For flavor, floral terpenes andaliphatics are present. including somesalicylic acid derivatives. Tirosolo.with strong antioxidant properties, isfound in 12 different forms in variousolive oils.

JoAnn Manson of Harvard MedicalSchool discussed how obesity is a riskfactor in CHD. She pointed out abody-weight paradox. where thethinnest and fattest people have higherrisk of dying from coronary-relatedincidents than those with a middle-range weight. Cigarette smoking can

account for some of the thin person'shigher risk. but not all of it. In Sev-enth Day Adventists, a positive rela-tionship was observed between bodymass index (BMI) and increased riskof death. In the Nurses Health study. a8MI up to 29 was associated with noincreased risk.

The optimum 8MI lies between 20and 28. a much wider range than pre-viously recommended, according toReubin Andres of the National Insti-tutes of Health. He attributed the high-er risk in the low 8MI group to smok-ing and illness.

Dimitrious Trichopoulos of theHarvard School of Public Healthconcluded that the Mediterraneandiet is healthful and should be adapt-ed in all Western societies. Not onlythe diet but also the more relaxedlifestyle associated with it is needed.he said. •

Brain Development: Relationship to DietaryLipid and Lipid MetabolismJ. Jumpsen and M.T. Clandinin

The development of the brain is an important consideration for studentsof nutrition, lipid scientists, and other health-care professionals concerned with thegrowth of premature infants and for researchers involved in developing new infant formu-las and infant foods. With an increase in the number of surviving premature infants and agrowing interest in developing the "gold standard" for infant formulas, bringing togetherinformation regarding brain development and lipids may be beneficial and useful formany, The requirement and timely availability of the correct nutrients are critical becausebrain development is such a precise, complex, and one-time-only event. Limiting thisbook to only a concise discussion of lipids was not easy. It was accomplished by examin-ing the different lipids and their roles in the brain, an organ highly concentrated in lipids,This book's objectives are to both provide a focused overview (morphological, biochemi-cal, and functional) of brain development and to exemplify the role of lipids in the impor-tant developmental events and the concepts that are potentially altered by physiologicalchanges in brain lipid composition.

To order. contact:AOCS PressPublication Orders Oept.P.O. Box 3469Champaign.IL 61826·3489Phone: 1·217·3S9·5401. e.l. 128: Fa.' 1·217·351·8091TolI·lree: 1·800·336·AOCS in me Un,led Slates and Canada

Hardbound. 1995ISBN 0-935315·65--9lIem: 1092list: $70.00AOeS Member; $56.00

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tNFORM.VOl.6. no. 10 (October 1995)