Plasma lipid and lipoprotein response of humans to beef fat, coconut oil and safflower oil13

Transcription

1 Plsm lipid nd lipoprotein response of humns to beef ft, coconut oil nd sfflower oil13 Rymond Reiser, PhD, JL Probsifield, MD, Abrhm Silvers, PhD, LW Scott, MA, RD, ML Shorney, RD. RD Wood, PhD, Brbr C O Brien, PhD, AM Gotto, Jr. MD, D Phil, nd Willim Insull, Jr, MD Introduction ABSTRACT This study s purpose ws to evlute the fsting humn plsm lipid nd lipoprotein responses to dietry beef ft (BF) by comprison with coconut oil (CO) nd sfflower oil (SO), fts customrily clssified s sturted nd polyunsturted. Nineteen freeliving normo lipidemic men ged 25.6 ± 3.5 yr consumed centrllyprepred lunches nd dinners of common foods hving 35% ft clories, 60% of which ws the test ft. The test fts were isocloriclly substituted, nd ech fed for five weeks in rndom sequences with intervening five weeks of hbitul diets. Plsm totl cholesterol (TC), highdensity lipoprotein cholesterol (HDLC), nd lowdensity lipoprotein cholesterol (LDLC) concentrtions mong individuls follows the sme reltive rnk regrdless of diet. Triglycerides (TG) concentrtions mong individuls lso mintin their reltive rnk regrdless of diet but in different order from tht of the cholesterols. Plsm TC, HDLC, nd LDLC responses to BF were significntly lower nd TG higher thn to CO. As compred to SO, BF produced equivlent levels of TG, HDLC, nd LDLC nd mrginlly higher TC. Thus, the customry considertion of BF s sturted nd grouping it with CO ppers unwrrnted. Am J Clin Nuir l985;42:l90l97. KEY WORDS Diet fts, beef ft, sfflower oil, coconut oil, sturted ft, polyunsturted ft, plsm cholesterol, triglyceride, highdensity lipoprotein cholesterol, lowdensity lipoprotein cholesterol, plsm lipids, lipoproteins The effects of dietry beef ft (BF) upon plsm lipid nd lipoprotein concentrtions re incompletely described lthough this is prominent ft in the Americn diet, nd mny diet investigtions hve described the effects on plsm lipids of most other diet fts (14). BF is commonly considered to be sturted ft, including it in group with coconut oil (CO), coco butter, hydrogented vegetble oils, butterft, nd swine ft, nd ttributing hypercholesterolemic effects to it. Of these fts, only CO ppers to consistently elevte plsm cholesterol when compred with other fts (5). Nonetheless, dietry dvisories recommend restricting consumption of BF (67). The effects of BF on plsm From the Deprtment of Medicine (JLP, AS, LWS, MLS, AMG, WI), Bylor College of Medicine, Houston, TX; nd Deprtment of Biochemistry nd Biophysics (RR, RDW, BCO), Texs A&M University, College Sttion, TX. 2Add reprint requests to: Rymond Reiser, PhD, Deprtment of Biochemistry nd Biophysics, Texs A&M University, College Sttion, TX Supported in prt by the Diet Modifiction Section of the Ntionl Hert nd Blood Vessel Reserch nd Demonstrtion Center, Bylor College of Medicine nd the Methodist Hospitl, grntsupported project of the Ntionl Hert, Lung nd Blood Institute, Ntionl Institutes of Helth, Grnt No HL 17269, the Clinicl Reserch USDHS Grnt No the Lipid Reserch clinics (LRC) Contrct No HVI2l56L, the Ntionl Live Stock nd Met Bord, the Texs Cttle Feeders Assocition, nd the Stndrd Met Co of Fort Worth, Texs. Received July 16, Accepted for publiction Jnury 1, The Americn Journl of Clinici Nutrition 42: AUGUST 1985, pp Printed in USA 1985 Americn Society for Clinicl Nutrition

2 HUMAN LIPIDEMIC RESPONSES TO BEEF FAT lipids nd lipoproteins need to be defined to serve s bsis for rtionl recommendtions. The present study ims to define the effects of BF more specificlly by compring the responses of fsting plsm lipids nd lipoproteins to BF, CO. nd sfflower oil (SO) when fed to freeliving normolipidemic men. Methods Experimentl design This study ws divided into seven feeding periods of five weeks ech, durtion sufficient to estblish the effect of ech diet on lipids nd lipoproteins (8). The bseline diet fed during the initil period nd subsequent three oddnumbered periods, consisted of the prticipnts hbitul foods tken d lib t cloric level to mintin constnt weight. The study diets fed during the three evennumbered periods consisted of the foods contining one of the three study fts for lunch nd supper, nd low ft, high crbohydrte foods for brekfst. Upon enrollment, the men were rndomly ssigned mong six tretment groups which would hve the three test diets in different sequences in order to rndomly distribute ny bis in results due to the order of the test diets. The initil period ws to estblish the control bseline vlues for plsm lipids nd body weight, to determine the chrcteristics of hbitul diets, nd to instruct nd cclimte the prticipnts to the opertion of the study. The subsequent oddnumbered peiods were lso with the hbitul diet to llow the effects of the preceding test diets to dissipte nd the plsm lipids to return to bseline vlues, nd to provide the subjects relief from the rigors of dherence to the test diet procedures. Fsting bloods were drwn t the end of ech of the lst two weeks of ech diet period with mesurements of plsm totl cholesterol (TC) nd triglycerides (TG). The lst plsm obtined in ech time period ws lso nlyzed for the concentrtions of highdensity lipoprotein cholesterol (HDLC). The two successive mesurements of TC nd TG were to determine tht the lipid chnges were estblished. The men vlues of the fourth nd fifth weeks of ech of these periods were used to evlute the finl lipid chnges. The intrsubject vrince ws less thn 3%. The intrssy vrince is 3% for cholesterol nd triglycerides. Subjects Nineteen helthy volunteer mle medicl students were rndomized mong six tretment groups with different test diet sequences nd subsequently completed 2 or 3 diets. All subjects hd verge norml vlues for their fsting plsm lipids during the study s evluted by the ge nd sexspecific vlues observed in the Americn popultion groups of the prevlence study of the Lipid Reserch Clinics. The subjects were recruited from the Texs Medicl Center community in Houston, Texs. Potentil subjects were excluded if they were tking plsm lipidlowering mediction or hd significnt orgnic, psychitric or metbolic disese, hyperlipidemi, lcoholism or hypertension. The study ws pproved by the Bylor College of Medicine Humn Reserch Committee. All prticipnts were volunteers, were completely informed bout the tril, nd signed informed consent forms t entry. In order to guide food intke during the study, weight ws mesured in the clinic nd t home under stndrd conditions, without shoes nd suitcots. Food preprtion nd distribution Foods for two mels ech dy, lunch nd supper, were prepred nd provided by the centrl food service to ech prticipnt t no cost. These mels were composed of nturl foods, with clories distributed s follows: protein 15%, crbohydrtes 50% nd fts 35%. Sixty percent of the ft clories were from the test fts. These study fts (60% of totl ft) were pproximtely 25% in the met dishes, 25% in bred spreds, 25% in filled ice crem, nd 25% bked in cookies. The nonstudy ft (40% of totl ft) ws distributed in the following proportions: 45% from fish, chicken or turkey, nd skimmed milk, 49% from lrdbsed mrgrine, 3% from bked goods, nd 3% from vegetbles nd grins. The proportions of ftty cids of this mrgrine were: 14:01.2%, 16:029.1%, 17:0 less thn 0.25%, 18:012.3%, 16:1 2.0%, 17:1 less thn 0.25%, 18:146.7%, nd 18:27.7%. The food consisted of the min entrees of met, poultry or fish, mjor strch food, nd green vegetbles. Stndrd menus for ten different mels over five dys were prepred, nd these mels were served in consecutive cycles every five dys to provide vriety nd to void cycling the sme mels on the sme dys of the week. The prepred foods were dispensed twice weekly from the centrl source. The prticipnts provided nd consumed stndrd brekfst ccording to their hbits, lrgely crbohydrte nd low ft. According to instructions, they supplied nd prepred their own beverges, fresh lefy vegetbles, nd fruit for sncks nd desserts. Provisions were mde for cold lunches when necessry. The test mels were modified by the use of vrious spices during the study to meet the tste preferences of the subjects. Adherence to the test diets ws judged to be good on the bsis of self report nd regulr interviews with the study nutritionists. Test fts The BF, CO, nd SO were donted or purchsed. (See Acknowledgements.) Their ftty cid compositions were determined by gsliquid chromtogrphy (Tble 1). Filled ice crem Ice crem mixes were prepred t the Diry Science Section, Deprtment of Animl Science, Texs A&M University nd were to contin 40.76% totl solids, 16 of which ws of the test fts. Ft consisted of BF, SO, or CO. Other diet constituents The reminder of the ft in the test diets consisted of ft from poultry, fish, nd diry foods. TC intke ws pproximtely 450 mg/dy, one hlf of n egg yolk being dded/dy to the CO nd SO diets. With this ddition, the TC in the diets equls the mount in the BF diet.

3 192 REISER ET AL TABLE 1 Ftty cid composition of diet test fts Ftty ids Diet ft 14:0 14:1 16:0 16:1 17:0 17: :1 18:2 % Beef ft Sfflower Coconut oil oil 2.1 T T = Denotes detectble quntities less thn 0.25%. * = Other ftty cids present re 8:0, 3.2%; 10:0, 4.8%; nd 12:0, 55.4%. The diet ws blnced in composition nd nutritionlly dequte. Stndrd menu plns were estblished for ll feeding periods. The mount of food for ech individul ws quntittively djusted to mintin constnt body weight ccording to cloric requirements s determined by prestudy dietry histories They vried from 1700 to 5000 clories/dy, with men of Alcoholic beverges were permitted provided tht the intke ws moderte nd kept constnt throughout the study t the prticipnt s customry level. Clinicl lbortory tests Plsm lipid nd lipoprotein determintion Plsm lipid nd lipoprotein concentrtions were mesured fter twelvehour fst using stndrdized bloodletting techniques. Determintions of TC, TG, nd HDLC were done in the Lipid Reserch Clinicl Lbortory ccording to previously reported methodology (9) using the regulrly monitored qulity control by the Center of Disese Control (CDC). Plsm lowdensity lipoprotein cholesterol (LDLC) ws clculted by the method of Fnedewld nd collegues (10). Dt mngement nd nlysis Sttisticl nlysis on the 19 subjects used the 4 nd 5 wk TC nd TG vlues nd their mens, nd 5 wk HDLC vlues. The 5 wk LDLC vlues were clculted. The dt were ssembled by ft regrdless of diet sequence. The nlysis ssumed tht ) the 5 wk diet period is long enough to eliminte crryover effects, nd b) there is no longterm trend in the response vrible br ny of the subjects. In order to utilize the hbitul diet lipid vlues to obtin the withinsubject vrince, rndomized block nlysis of vrince ws performed upon the totl cholesterol nd triglyceride vlues for the three test ft diets nd their respective preceding hbitul diets, 2.1 T with individuls s blocks nd 6 diet periods s tretments. These nlyses were not possible on the HDLC nd LDLC becuse too mny vlues were missing. Anlyses of ll plsm lipids were performed upon vlues for the three test ft diets. The model for these nlyses of vrince ws lso tht of rndomized block, with individuls s blocks nd test diets s tretments. Due to the lck of blnce of tretments (12 men completing ll the test diets, 16 men completing the SO diet nd 17 ech completing the CO nd BF diets), generl liner model nlysis ws performed. In ddition to significnt tests for diets in generl, soclled djusted men tretment mens were produced (lest squre mens in SAS). Also produced by the nlysis re tests on differences between djusted tretment mens of individul diets. Since these were not preplnned comprisons, the sttisticl significnce of the individul comprisons re somewht overstted. Results All subjects hd norml lipid vlues during the periods of hbitul diets nd the diets of test fts (Tble 2). Twelve men completed the study with ll three diets Additionlly, three men completed the BF nd CO, two men the BF nd SO, nd two men the CO nd SO diets, 19 in ll. Seventeen men completed the BF nd CO diets, nd 16 the SO diet. Comprisons between 4 nd 5 wk vlues for TC nd TG for ech test ft diet period nd ech hbitul diet period showed no significnt differences. This indicted tht the test periods were of sufficient durtion to chieve stble tretment effects, nd tht the

4 HUMAN LIPIDEMIC RESPONSES TO BEEF FAT 193 TABLE 2 Plsm lipids nd lipoprotein cholesterol concentrtions of men, twentysix yers old, consuming hbitul diets nd test diets with 21% of clories s coconut oil, beef ft,or sfflower oil for 5 weeks* Totelt cholesterol HDLq obeerved mens LDL.q Triglyceridest mg/di ± SEM Hbitul: preb9 (17)1 157 ± ± ± ± 8.9 preco(l6) 158± ±3.0 96± ± 7.5 preso(l7) 152±6.7 42±2.7 96± ±9.6 Test: BF(l7) 155±3.0 40±1.2 98± ±3.5 CO(16) 168±3.0 46± ± ±3.6 SO(l7) 141±3.1 40± ± ±3.7 p vlue& BF vs CO BF vs SO CO vs SO * 12 completed ll 3 diets, 2 the BFnd SO diets, 2 the CO nd SO diets, nd 3 the BFnd CO diets; 17 completed the BF, 17 the CO, nd 16 the SO diets. t Averge of fourth nd fifth weeks on the diets. There ws no significnt difference between the two. f Fifth week vlues. BF = beef ft, Co = coconut oil, SO = sfflower oil. tsee section on Dt Mngement. p vlues> 0.05 re not significntly different. I Vlues in prentheses represent number of prticipnts. plsm lipid effects of the hbitul diets were not chnging significntlyduring ech observtion period. Comprisons of plsm lipid vlues mong the hbitul diet periods prior to ech test ft diet showed no significnt differences (Tble 2). These observtions substntited the design ssumptions tht the pretretment hbitul diets were not different in their lipid effects, nd tht there were no significnt crryover effects from previous diets of test fts. The ingestion of CO compred to SO resulted in significnt differences in ll plsm lipids except TO, respectively: TC 168 nd 141 mg/dl; HDLC 44 nd 40 mg/dl; LDL C 110 nd 90 mg/dl; TO 75 nd 80 mg/dl (Tble 2). Anlyses of test diet responses using the hbitul diet vlues similrly showed significnt difference for TC, p <0.05, but no significnt TO difference. The lower cholesterol levels with SO were due to lower vlues of both LDLC nd HDLC. The ingestion of BF compred to CO showed significnt differences for ll lipids except LDLC. TC nd HDLC were lower with BF, 155 versus 168 mg/dl nd 36 versus 44 mg/dl respectively, nd TO higher, 89 versus 75 mg/dl. The LDLC concentrtion ws insignificntly lower, 98 versus 110 mg/dl. The ingestion of BF compred to SO showed only TC to be significntly different, 155 versus 141 mg/dl respectively. This ws ccompnied by insignificntly higher LDL C, HDLC, nd TO. Tbles 3 nd 4 show tht the concentrtions of the plsm lipids nd lipoproteins continue in the sme reltive rnk regrdless of chnges in bsolute vlues ffected by dietry mnipultion. The rnkings re not ll perfect in direction of chnges in mgnitude, probbly due to vritions in metbolic response nd some crossovers mong the qurtiles. The tbles lso show tht TC, HDLC nd LDLC concentrtions follow one order, Tble 3, nd TG different order, Tble 4. The vlues in the tbles cnnot be verged nd compred to Tble 2. There re only 17 prticipnts represented in Tble 3, insted of ll 19 who consumed 2 or 3 diets, becuse the BF vlues were used to estblish rnk nd subjects 4 nd 10 did not et the BF diet. Furthermore, since subjects 14 nd 35 did not prticipte in the CO diet, those

5 194 REISER ET AL.,, columns lso represent only 17 subjects. Also, prticipnts 16, 18, nd 33 did not prticipte in the SO diet. uj ii #{149} Li ,(.. 00 N 1#{149}) O\ O O N N O 0 r #{149}! I, F#{149} F 8 U. I 8 U. I I N O r N re,...,( r 00 O 1 r r,.. r i m O N.., m i ) I1 N O N. o.,, r, N N. 1..o. m r i 0. 1 i#{149}s, m N r ( i z,r, i m 4 00.Nr1.0 e 4 m 1#{149}....t : Oor ri. u I). 0.,. U i *.I..$+co,= Discussion The present study ws designed to describe the response of humns to diet BF becuse of the importnce plced on ruminnt ft nd met in diet recommendtions by vrious governmentl gencies nd public helth groups, its prominent role in the Americn diet, nd the pucity of humn studies of BF. The Americn Hert Assocition (AHA) (11), the Sente Select Committee on Nutrition nd Humn Needs (7), the US Deprtment of Agriculture (USDA) nd Deprtment of Helth, Eduction nd Welfre (12), nd the Office of the Surgeon Oenerl (13), hve recommended the prtil substitution of poultry nd fish for ruminnt nd swine mets. This recommendtion hs been mde becuse BF is sid to be sturted, to give rise to hypercholesterolemi, nd therefore, is expected to increse the risk of coronry hert disese. Our dt suggest tht BF my not rise plsm cholesterol. The hypothesis tht sturted fts re hypercholesterolemic is bsed minly on studies with CO nd polyunsturted vegetble oil, nd on regression equtions which pper to relte plsm cholesterol levels to diet levels of sturted luric, myristic, nd plmitic cids on one hnd, nd polyunsturted ftty cids on the other, with fctor for cholesterol (14). Sturted cids of 18 crbons or more, of 10 crbons or less, nd of monoenoic cids re sid to be neutrl. Both the results of the studies with sturted fts other thn CO. such s hydrogented vegetble oils (5), nd the use of regression equtions (4, 14), hve been chllenged (15). There pper to be no welldefined humn studies testing BF, but there re some using beef tissue, the results of which cn be scribed to its constituent ft. Thus, Hodges, et l (2), found tht university students with serum cholesterol of bout 150 mg/dl mintined tht vlue when consuming norml or polyunsturted beef. Students with serum cholesterol of bout mg/dl responded to norml beef with cholesterol levels

6 HUMAN LIPIDEMIC RESPONSES TO BEEF FAT 195 TABLE 4 Plsm triglyceride responses to beef ft, coconut oil nd sfflower oil rrnged by qurtiles of triglyceride response to hbitul diet D Subjects Hbitul BP C0 S0 mg/d! 3, 5, 28, 32, 34 (5)1 61 (5) 68 (5) 58 (5) 53 1, l8,* 20, 33, 35 (5) 81 (5) 86 (4) 83 (4) 59 11, 144 l6, 19, 30 (5) 91 (5) 101 (4) 93 (4) 81 4,t l0,t 27, 31 (4) 125 (2) 112 (4) 85 (4) 101 weighted mens * BF = beef ft; CO = coconut oil; SO = sfflower oil. t Did not prticipte in BF diet. f Did not prticipte in CO diet. Did not prticipte in SO diet. Includes ll bseline nd betweendiet vlues. #{182} Vlues in prentheses represent numbers of prticipnts. of 210 mg/dl nd to polyunsturted beef nd diry products with vlues round 165 mg/dl. In study compring the effect of beef with fish nd poultry, no difference ws found in plsm cholesterol (16). Six subjects were involved in study compring norml nd polyunsturted ruminnt fts, including milk products (1). The norml fts produced 0, 5.5, 6.0, 8.0, 12 nd 14% higher serum cholesterol levels respectively in the six subjects. In 1957 study BF t 40% of clories produced n verge serum cholesterol of 20 mg/dl higher thn corn oil, 180 mg/dl vs 161 mg/dl (8). Prolonged consumption of CO ws reported for two groups of ntive Polynesins who consumed 63% nd 34% respectively of their food energy from CO (17). The respective verge serum cholesterol vlues (mles plus femles ges 1564 yers) were 209 mg/dl nd 172 mg/dl. The uthors observed, however, tht Vsculr disese is uncommon in both popultions nd there is no evidence of the high sturted ft intke hving hrmful effect in these popultions. The three fts tested did hve some significntly different effects on the plsm concentrtions, especilly BF vs CO, nd SO vs CO. Increses or decreses from the concentrtions were observed with the hbitul diets before nd between the CO nd SO diets. However, there ws no significnt difference between the BF nd hbitul diet vlues. In the present study BF, compred with CO, ws ssocited with significnt differences in the concentrtions of lmost ll the lipids tested: TC ws lower by 13 mg/dl (8%), HDLC lower by 8 mg/dl (18%), nd TO higher by 14 mg/dl (19%). Only the difference in LDLC, lower by 12 mg/dl (11%), ws not significnt. Clerly BF ws different from CO. BF when compred with SO ws ssocited with significntly higher TC levels by 14 mg/dl (10%), but not significntly different with respect to HDLC, LDLC, or TO. The study subjects showed the nticipted responses to the reference fts, CO nd SO. BF, though intermedite between the CO nd SO reference fts in its effects on TC, ffected insignificnt differences in its effect on LDLC, HDLC, nd TG s compred to SO. An explntion for the lower plsm TO ccompnying CO ingestion my be found in differences in the trnsport nd reltive rtes of deposition nd ctbolism of the constituent ftty cids (1820). CO contins bout 8% of prtilly wtersoluble 8 nd 10 crbon cids, 55% nd 20% of intermedite 12 nd 14 crbon cids respectively, 8% of 16 crbon plmitic cid, nd only 5.5% oleic nd 1.4% linoleic cids. It hs been shown tht the wtersoluble cids re bsorbed vi the portl system (2 122) nd re quickly ctbolized or elongted (18). The 12 nd 14 crbon cids re deposited to only slight degree in dipose tissue; nd the 16 crbon plmitic, even if fed t high level, does not gretly increse levels of plmitic in dipose tissue, possibly being elongted nd destu

7 196 REISER ET AL rted to oleic cid. Oleic nd linoleic cids cn ccumulte to very high levels. The dt in Tbles 3 nd 4 demonstrte tht the levels of plsm lipids nd lipoproteins mong individuls resonbly mintin their reltive rnk regrdless of diet, homeosttic phenomenon relted to the previously identified intrinsic chrcteristic (23). However, it is new observtion tht TC nd the cholesterolcontining lipoproteins follow one rnk order, but tht TO follows different order. Of the 19 subjects, only 2 my be sid to hve experienced lipidemic chnges from benign to mrginlly high risk levels by consumption of BF or CO. Thus, subject 32 hd TC concentrtions of 155, 198, nd 222 mg/ dl during the consumption of SO, BF, nd CO respectively. The corresponding vlues for subject 33 were 191 (estimted), 215, nd 226 mg/dl. The highest other vlues during SO, BF nd CO consumption were 156, 197, nd 196 mg/dl in subject 34, nd 175, 184, nd 188 mg/dl respectively in subject 19. The common clssifiction of BF together with CO, coco butter, hydrogented vegetble oils, nd butter ft s hypercholesterolemic sturted fts ppers inpproprite. BF in this study clerly hd significntly different effects on vrious plsm lipids compred to the common reference sturted ft,co, but hd very similr effects compred to SO. Oiven the present stte of knowledge of diet nd plsm lipoprotein metbolism, with different effects on coronry risk ttributed to LDLC nd HDLC, ech dietry ft should be evluted on the bsis of its effects on individul lipoproteins. The clssifiction of dietry fts solely s sturted, unsturted, or hypercholesterolemic is misleding, nd my obscure complex of significnt metbolic effects (18, 24). Further studies of BF nd its effects on lipids nd lipoprotein metbolism re needed to more clerly define the effects nd estblish rtionl perspective on BF in the Americn diet. Studies of BF should include the following: 1) comprison of BF with the vriety of common dietry fts to estblish the reltive mgnitudes of its vrious lipoprotein effects, 2) comprison of the effects of vrious proportions of BF in the diet to estblish mountresponse reltionships, 3) controlled feeding investigtions compring BF with other dietry fts in popultions of other ges nd sexes to estblish the generl pplicbility of the results of the present study, 4) studies to define the effects of BF compred to other dietry fts upon the proportions nd composition of the subclsses of the HDLC, nd 5) studies of BF to differentite between the effects of its ftty cid composition nd its sterol content. An overlooked re of ft metbolism bsic to the diethert theory is the possible metbolic pthwys nd mechnisms by which individul ftty cids or glycerides my control the levels of plsm cholesterol nd lipoproteins. The uthors re indebted to the following collegues: Mr Muro Nv nd Dr Gost Dhien for their performnce of the lipid nd lipoprotein cholesterol ssys, Dr Chrles W Dill for his preprtion of the filled ice crem, Ms Grce Lin nd Dr Ri Freund for the sttisticl nlysis, nd Ms D McLin for preprtion of sndwiches nd dinner entrees. The uthors grtefully cknowledge the gifts of sfflower seed oil by the Pcific Vegetble Oil Co of Richmond, Cliforni, nd of coconut oil by the AndersonClyton Foods of Richrdson, Texs References 1. Nestle Pi, Hvenstein N, Whyte HW, Phil D, Scott Ti, Cook U: Lowering of plsm cholesterol nd enhnced sterol excretion with the consumption of polyunsturted ruminnt fts. N Engl S Med l973288: Hodges RE, Sbel AF, Dunkley WL, et l. Plsm lipid chnges in young dult couples consuming polyunsturted mets nd diry product& Am S Clin Nutr l97528:l Brown HB, de Wolfe VG, Nito HK, Hrper Wi, Plmquist DL Polyunsturted met nd diry products in ft modified food ptterns for hyperlipidemi. S Am Diet Assoc 1976;69: Hegsted DM, McGndy RB, Myers ML., Stre FJ. Quntittive effects of dietry ft on serum cholesterol in mn. Am S Clin Nutr 1965;l7: Reiser R. Sturted ft in the diet nd serum cholesterol concentrtion. A criticl exmintion of the literture. Am J Clin Nutr l973;26: Americn Hert Assocition Committee Report. Diet nd coronry hert disese. Press relese, Circ 58:76276, Sente Select Committee on Nutrition nd Humn Needs Dietry guidelines for the United Sttes. US Sente, 2nd ed. Wshington, DC: US Government Printing Office, Supt Documents Ahrens EH, Insull W, Blomstrnd R, Hirsch 5, Tslts TT, Peterson ML. The influence of dietry ft on serum lipid levels in mn. Lncet 1957; 1:94353.

8 HUMAN LIPIDEMIC RESPONSES TO BEEF FAT The Lipid Reserch Clinics Progrm. Mnul of lbortory opertions. I. Lipid nd lipoprotein nlysis. DHEW Publiction no (NIH) 75628, Friedewld WT, Levy RI, Fredrickson DS. Estimtion of the concentrtion of lowdensity lipoprotein cholesterol in plsm without use of the preprtive ultrcentrifuge. Clin Chem 1972;18: Diet Modifiction to Control Hyperlipidemi. Steering Committee for Medicl nd Community Progrms. Americn Hert Assocition. Dietry Gols for the United Sttes. Circ 1978;58: Nutrition nd your helth: Dietry guidelines for Americns. USDA/HHS. Wshington, DC: US Government Printing Office, Helthy people: The surgeon generl s report on helth promotion nd disese prevention, HHS, Public Helth Services, Superintendent of Documents, Wshington, DC, Keys AS, Anderson T, Grnde F. Serum cholesterol response to chnges in the diet IV. Prticulr sturted ftty cids in the diet. Metbolism l965;l4: Ahrens EH Jr. Dietry fts nd humn serum lipid levels. In: Chemistry of lipids s relted to therosclerosis. Springfield, IL Thoms, O Brien BC nd Reiser R. Humn plsm lipid response to red met, poultry, fish nd ens. Am S Cm Nutr l98033: Prior IA, Dvidson F, Slmond CE, Czochnsk Z. Cholesterol, coconuts nd diet on polynesin dults: nturl experiment: The Pukpuk nd Tokelu Islnd studies.am S Clin Nutr l981;34:l5526l. 18. Reiser R, Willims MC, Sorrels MF, Murty ML Biosynthesis of ftty cids nd cholesterol s relted to diet ft. Arch Biochem nd Biophys l963;l02: Bottino N, Anderson RE, Reiser R. Dietry ftty cids their metbolic fte nd influence on ftty cid biosynthesis. S Am Oil Chem Soc l965;42: Bollinger SN, Reiser R. The metbolic fte of ftty cids derived from dietry triglycerides. S Am Oil Chem Soc l965;42:l Bloom R, Chikofi, Reinhrdt WO. Intestinl lymph s pthwy for trnsport of bsorbed ftty cids of different chin length. Am S Physiol l951;l66: Bloomstrnd R. Trnsport form of decnoic cidl 4C in the lymph during intestinl bsorption in the rt. Act Physiol Scnd l955;34: Keys A, Anderson it, Grnde 1. Serum cholesterol response to chnges in the diet III differences mong individuls. Metbolism l965;l4: Kritchevsky D, Tepper SA. Influence of mediumchin triglyceride (MTC) on cholesterol metbolism in rts. J Nutr 1965;86:6772.