Apolipoprotein A-I, A-II, and VLDL-B-100 metabolism in men: comparison of a low-fat diet and a high-monounsaturated fatty acid diet

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1 Apolipoprotein A-I, A-II, nd VLDL-B-100 metbolism in men: comprison of low-ft diet nd high-monounsturted ftty cid diet Sophie Desroches,*, Mrie-Eve Prdis,*, Mélnie Pérusse,* W. Roodly Archer,*, Jen Bergeron, Ptrick Couture,*, Nthlie Bergeron,*, nd Benoît Lmrche 1, *,, Institute on Nutrceuticls nd Functionl Foods,* Lvl University, Ste-Foy, Québec, Cnd; Deprtment of Food Sciences nd Nutrition, Lvl University, Québec, Cnd; nd Lipid Reserch Center, Lvl University Medicl Reserch Center, Ste-Foy, Québec, Cnd Abstrct The impct of low-ft diet nd high-mufa diet on polipoprotein A-I (poa-i), poa-ii, nd VLDL-poB- 100 metbolism in conditions of unrestricted (d libitum) energy intke ws compred in 65 men rndomly ssigned to one of two predefined experimentl diets. A subsmple of 18 men prticipted in the kinetic study. Before nd fter the 6 7 week dietry intervention, kinetic subjects received primed-constnt infusion of [5,5,5-2 H 3 ]l-leucine for 12 h under feeding conditions. ApoA-I production rte (PR; 31.5%; P 0.001) nd frctionl ctbolic rte (FCR; 24.3%; P 0.05) were significntly decresed fter the low-ft diet. These chnges in poa-i PR nd FCR with the low-ft diet were lso significntly different from those observed with the high-mufa diet (P 0.01 nd P 0.05, respectively). ApoA-II FCR ws significntly incresed in the high-mufa group only. No significnt within- or between-diet difference ws found in VLDL-poB-100 PR or FCR. These results emphsize the differentil impct of the low-ft diet nd high-mufa diet on HDL metbolism. Desroches, S., M-E. Prdis, M. Pérusse, W. R. Archer, J. Bergeron, P. Couture, N. Bergeron, nd B. Lmrche. Apolipoprotein A-I, A-II, nd VLDL-B-100 metbolism in men: comprison of low-ft diet nd high-monounsturted ftty cid diet. J. Lipid Res : Supplementry key words high density lipoprotein very low density lipoprotein polipoprotein kinetics Incresed plsm LDL-cholesterol (LDL-C) concentrtions (1), incresed triglyceride (TG) concentrtions, nd low plsm HDL-cholesterol (HDL-C) concentrtions (2) re well-estblished risk fctors for coronry hert disese (CHD). Among the different strtegies to reduce the risk of CHD in the generl popultion, the Americn Hert Assocition hs recommended the doption of diet low Mnuscript received 28 July 2004 nd in revised form 26 August Published, JLR Ppers in Press, September 1, DOI /jlr.M JLR200 in sturted ft nd high in complex crbohydrte (CHO) (3), minly for its beneficil lowering properties on LDL-C concentrtions. However, controlled nutritionl interventions conducted under isocloric conditions, in which body weight ws rtificilly held constnt for experimentl purposes, hve been ssocited with undesirble reductions in plsm HDL-C concentrtions nd increses in TG concentrtions fter low-ft/high-cho diet (4). It is on tht bsis tht scientists hve rised concerns regrding the ppropriteness of low-ft/high-cho diets to reduce the risk of CHD. On the other hnd, it hs been suggested tht d libitum feeding of low-ft/high-cho diets my not induce deleterious chnges in HDL-C nd TG concentrtions by being ssocited with weight loss ttributble to spontneous reduction of energy intke (5). Mediterrnens show low prevlence of CHD, despite the consumption of diet tht cn provide more thn 35% of energy s ft depending upon the geogrphicl region (6). The lrge mount of MUFAs consumed minly in the form of olive oil in the trditionl Mediterrnen diet is thought to ccount for prt of its protective effect ginst CHD (7). Dt from the lrge Nurses Helth Study hve lso demonstrted the crdiovsculr benefits ttributble to greter intke of MUFAs (8). Therefore, the consumption of high-ft diets rich in MUFAs hs been dvocted s preferble lterntive to low-ft/high-cho diets, bsed upon the LDL-C- nd TG-lowering properties of MUFAs nd their reltively neutrl effects on plsm HDL-C concentrtions (9). Thus, the identifiction of the most pproprite diet in terms of plsm HDL-C nd TG modifiction remins Abbrevitions: poa-i, polipoprotein A-I; CHD, coronry hert disese; CHO, crbohydrte; FCR, frctionl ctbolic rte; HDL-C, HDL-cholesterol; IEF, isoelectric focusing; LDL-C, LDL-cholesterol; PR, production rte; TG, triglyceride. 1 To whom correspondence should be ddressed. e-mil: benoit.lmrche@inf.ulvl.c Copyright 2004 by the Americn Society for Biochemistry nd Moleculr Biology, Inc. This rticle is vilble online t Journl of Lipid Reserch Volume 45,

2 mtter of controversy. A better understnding of the mechnisms by which different dietry interventions ffect HDL nd VLDL composition nd metbolism my help to revel the most effective dietry regimen to prevent CHD risk. To dte, only few kinetic studies hve been conducted in humns to help understnd the effects of lowft/high-cho diets (10 12) nd high-unsturted ftty cid diets (13 15) on polipoprotein kinetics. The objective of the present study, therefore, ws to compre the effects of low-ft/high-cho diet nd high-mufa diet consumed d libitum on plsm polipoprotein A-I (poa-i), poa-ii, nd VLDL-poB-100 kinetics in men. TABLE 1. Constituent Nutritionl composition of the experimentl diets Low-Ft/High-CHO Diet High-MUFA Diet CHO (% energy) Ft (% energy) Sturted (% energy) Monounsturted (% energy) Polyunsturted (% energy) Protein (% energy) Totl fibers (g/1,000 kcl) Polyunsturted/sturted rtio Cholesterol (mg/1,000 kcl) Significntly different from the low-ft/high-crbohydrte (CHO) diet (P 0.01). METHODS Study design The study prticipnts nd design hve been described in detil previously (16). Briefly, 65 men, of which 18 prticipted in the kinetic study, were recruited in the Québec metropolitn re. Prticipnts were recruited to cover wide rnge of diposity nd hd to be nonsmokers nd free of ny endocrine, crdiovsculr, heptic, or renl disorder. Subjects using mediction likely to interfere with lipid metbolism t the time of screening were excluded. Individuls with unusul dietry hbits, such s vegetrinism, food versions, or llergies, nd those who hd experienced significnt weight chnge within the yer tht preceded the study onset were lso excluded. Ech prticipnt signed consent form pproved by the Lvl University Ethics Committee. Subjects were rndomly ssigned to either low-ft/ high-cho diet or high-ft diet rich in MUFAs, which they consumed for 6 7 weeks. Subjects were instructed to mintin their usul level of physicl ctivity throughout the study nd to refrin from intense physicl exercise for the 3 dys preceding the beginning nd the end of the study. Prticipnts nd lbortory technicins were blinded to dietry ssignments. Experimentl diets The low-ft/high-cho diet nd the high-mufa diet comprised food prepred dily in the metbolic kitchen nd weighed in individul portions. Both diets consisted of the sme mels, which differed minly in the mount of ft nd CHO provided (Tble 1). The diets were composed of nonhydrogented unsturted fts, minly olive oil, with whole grins nd vegetbles s the min forms of CHOs. Simple sugrs were used only in the preprtion of muffins nd some desserts. The nutritionl composition of the experimentl diets ws ssessed with the Cndin Nutrient File dtbse (Helth Cnd, Ottw, 1997) nd Nutrition Dt System for Reserch softwre (Nutrition Coordinting Center, Minnepolis, MN; dtbse version 4.03_30,1999). Dietry intervention On weekdys, subjects cme to the metbolic unit to consume their lunch mel nd were given their next dinner nd brekfst mels pckged to tke home. Weekend mels were given to the prticipnts on Fridys. The brekfst represented 20% of the dily energy intke in ech diet nd hd to be consumed completely, wheres lunch nd dinner mels ech provided 40% of dily energy intke. To chieve d libitum conditions, subjects were provided with food representing 150% of their usul dily energy intke s ssessed by 3-dy food record (2 weekdys nd 1 weekend dy) obtined t bseline. Uneten portions hd to be returned to the metbolic unit for mesurement of ctul energy intke. On demnd, prticipnts were provided with 200 kcl sncks prepred in the metbolic kitchen. The mcronutrient content of the sncks mtched tht of the two experimentl diets. Subjects were sked to restrict their intke of cffeine-contining beverges to less thn two per dy but hd free ccess to wter nd to diet/cffeine-free soft drinks. As indicted previously, complince with the diet ws judged to be excellent (16). Anthropometric mesurements Body weight nd wist circumference were mesured ccording to stndrdized procedures (17). Lipid nd lipoprotein nlyses The lipoprotein-lipid nd HDL profiles were determined t the beginning nd the end of the dietry interventions. Plsm nd HDL lipid concentrtions were mesured by enzymtic methods on Technicon RA-500 nlyzer (Byer Corp., Trrytown, NY) s previously described (18). Plsm VLDL (d g/ml) ws isolted by ultrcentrifugtion, nd the HDL frction ws obtined fter precipittion of LDL in the infrntnt (d g/ml) with heprin nd MnCl 2 (19). The cholesterol, TG, nd phospholipid contents of the infrntnt frction were mesured before nd fter the precipittion step. The lipid content of the HDL 2 nd HDL 3 subfrctions ws lso determined on the Technicon RA-500 nlyzer fter further precipittion of HDL 2 with dextrn sulfte (20). HDL prticle size ws determined by polycrylmide grdient gel electrophoresis s described previously (21). Plsm poa-i, poa-ii, nd VLDL-poB-100 concentrtions were mesured by nephelometry in the vrious smples (22). Plsm HDL s tht contin poa-i but not poa-ii (LpA-I) nd HDL s tht contin both poa-i nd poa-ii (LpA-I:A-II) concentrtions were ssessed by n electroimmunodiffusion technique using commercilly vilble grose gels with polyclonl nti-poa-i nd nti-poa-ii ntibodies incorported into the gels (Lbortories Sebi, Norcross, GA) s described previously (23). Kinetic study The kinetic study ws performed t the beginning nd t the end of the dietry interventions using primed constnt infusion of [5,5,5-2 H 3 ]l-leucine. After 12 h fst, kinetic subjects were fed cookies (65% CHO, 20.2% lipids, 14.5% protein) every 30 min for 15 h. Ech hlf-hourly portion represented 1/30th of their dily energy requirements. Three hours fter their first hlf-hourly mel, subjects received n intrvenous bolus dose of 10 mol/kg [5,5,5-2 H 3 ] l-leucine, which ws subsequently followed by constnt infusion t 10 mol/kg/h. Throughout the infusion, blood smples were collected by second intrvenous line into Vcutiner tubes contining EDTA t 0, 0.25, 0.5, 1, 2, 3, 4, 6, 8, 10, nd 12 h. We hve recently shown tht this fed-stte kinetic protocol 2332 Journl of Lipid Reserch Volume 45, 2004

3 llowed study prticipnts to chieve stedy stte rpidly, with plsm TG concentrtions being mintined throughout the infusion period (24). Isotopic enrichment mesurement ApoA-I nd poa-ii were isolted from the d 1.25 g/ml frction obtined fter centrifugtion of whole plsm for 48 h t 50,000 rpm t 4 C in Beckmn 50.4 Ti rotor. Infrntnt ws then dilyzed overnight in NCl-Tris-Bse-EDTA buffer, incubted with cystemin for 4 h t 37 C, nd delipidted using ceton-ethnol nd diethylic ether s described previously (25). ApoA-I nd poa-ii were then seprted using preprtive isoelectric focusing (IEF) on polycrylmide-ure gels. VLDL-poB- 100 (d g/ml) ws seprted by SDS-PAGE ccording to stndrdized procedures (26) s described previously (27). Apolipoproteins on IEF nd SDS polycrylmide gels reveled with Coomssie blue were excised nd hydrolyzed with 6 N HCl nd incubted t 110 C for 24 h. Free mino cids in the hydrolyste were purified by ction-exchnge chromtogrphy nd derivtized by dding propnol/cetyl chloride nd heptfluorobutyric nhydride regents. Smples were then nlyzed using gs chromtogrph-mss spectrometer (GC 6890N, MS 5973N; Agilent Technologies, Plo Alto, CA). Identifiction of lbeled nd unlbeled leucine ws obtined by methne-negtive chemicl ioniztion. Selective ion monitoring t m/z 352/349 ws used to determine the trcer/trcee rtio, which ws clculted using the formul described previously (28). Kinetic nlyses ApoA-I, poa-ii, nd VLDL-poB-100 frctionl ctbolic rte (FCR) ws determined by fitting the trcer/trcee rtios to monoexponentil function. Using SAAM II softwre (University of Wshington, Deprtment of Bioengineering, Settle, WA), dt were fitted to the mthemticl function Z(t) Z p (1 e k(t d) ), where Z(t) is the trcer/trcee rtio t time t, Z p is the trcer/ trcee rtio corresponding to the plteu of the curve representing the precursor mino cid pool, d is the dely time in hours, nd k is the FCR in pools per hour. The VLDL-poB-100 enrichment plteu ws used s the forcing function, reflecting precursor pool enrichment for ll polipoproteins. The bsolute production rte (PR) ws clculted (in mg/kg/d) using the following formul: FCR (pools/dy) plsm polipoproteins pool size (mg) PR = body weight (kg) (Eq. 1) Pool size ws clculted s the plsm poa-i, poa-ii, or VLDLpoB-100 concentrtion (mg/l) multiplied by plsm volume (vlue fixed t l/kg body weight) (29). Sttisticl nlyses Dt were nlyzed using SAS (version 8.2; SAS Institute, Inc., Cry, NC). The significnce of the differences within nd between dietry groups ws ssessed with the PROC MIXED procedures for repeted mesures using the lest-squres men test. Vlues with skewed distribution were log-normlized. Adjustment for multiple comprisons using the Tukey procedure hd no impct on the results unless otherwise specified. Correltion nlyses were conducted using Spermn rnk correltions. RESULTS Sixty-five men (men ge, yers; dt not shown) were rndomized to either the low-ft/high-cho diet or the high-mufa diet. Bseline chrcteristics of prticipnts ssigned to ech dietry protocol were comprble except for the ge of prticipnts in the kinetic subsmple, who were older in the high-mufa group thn in the low-ft/high-cho group ( yers vs yers; P 0.05). Subjects hd reltively norml lipid profile t bseline nd were modertely obese s group, with pproximtely two-thirds of the group with body mss index 27 kg/m 2 nd the remining one-third with body mss index 27 kg/m 2. The mcronutrient intke t bseline in subjects llocted to ech dietry group ws comprble (dt not shown). As reported previously, the low-ft/high-cho diet induced cliniclly meningful 20.6% reduction in LDL-C concentrtions (Tble 2) (16). The high-mufa diet induced significnt reductions in plsm LDL-C, totl TG, nd VLDL-poB-100 concentrtions. Chnges in plsm TG nd VLDL-poB-100 concentrtions were sttisticlly different between dietry tretments (P 0.01 nd P 0.05, respectively). Both d libitum diets led to comprble reductions in obesity indices (16). Ad libitum consumption of the low-ft/high-cho diet led to significnt reduction in plsm HDL-C concentrtions ( 10%; P 0.001; Tble 3), which ws exclusively TABLE 2. Effects of the low-ft/high-cho nd high-mufa diets on lipid profiles nd nthropometric chrcteristics Low-Ft/High-CHO Diet (n 33) High-MUFA Diet (n 32) Vrible Pre Post Chnge P (Post vs. Pre) Pre Post Chnge P (Post vs. Pre) P (Between Diets) b Body weight (kg) Body mss index (kg/m 2 ) Wist circumference (cm) Totl cholesterol (mmol/l) LDL-C (mmol/l) Triglycerides c (mmol/l) Totl cholesterol/hdl-c rtio Plsm pob-100 (g/l) VLDL-poB-100 c (g/l) Vlues shown re mens SD. pob-100, polipoprotein B-100; HDL-C, HDL-cholesterol; LDL-C, LDL-cholesterol. P vlue for the within-diet effects. b P vlue for the between-diet effects (low-ft/high-cho vs. high-mufa). c Vlues were log-trnsformed before sttisticl nlyses. Desroches et l. Low-ft vs. high-mufa diets nd polipoprotein kinetics 2333

4 TABLE 3. Effects of the low-ft/high-cho nd high-mufa diets on HDL composition Low-Ft/High-CHO Diet (n 33) High-MUFA Diet (n 32) Vrible Pre Post Chnge P (Post vs. Pre) Pre Post Chnge P (Post vs. Pre) P (Between Diets) b HDL-C (mmol/l) HDL 2 -C (mmol/l) HDL 3 -C (mmol/l) HDL 2 -C/HDL 3 -C HDL-TG c (mmol/l) HDL-PL (mmol/l) ApoA-I (g/l) ApoA-II (g/l) LpA-I (g/l) LpA-I:A-II (g/l) LpA-I/LpA-I:A-II HDL prticle size (Å) HDL-PL, HDL-phospholipids; HDL-TG, HDL-triglycerides; LpA-I, HDL s tht contin poa-i but not poa-ii; LpA-I:A-II, HDL s tht contin both poa-i nd poa-ii. Vlues shown re mens SD. P vlue for the within-diet effects. b P vlue for the between-diet effects (low-ft/high-cho vs. high-mufa). c Vlues were log-trnsformed before sttisticl nlyses. ttributble to prllel 16.7% reduction in plsm HDL 3 -C concentrtions (P ) with no chnge in HDL 2 -C concentrtions. As result, the HDL 2 -C/HDL 3 -C rtio incresed by 21.6% (P 0.01). Significnt reductions in HDL-phospholipid, plsm poa-i, poa-ii, nd LpA-I:A-II concentrtions were lso observed fter the low-ft/high-cho diet. HDL prticle size, on the other hnd, incresed significntly with the low-ft/high-cho diet (P 0.05). The high-mufa diet-induced reductions in plsm HDL-C ( 3%) nd HDL 3 -C ( 11.8%) concentrtions were significntly less importnt thn in the lowft/high-cho group (P 0.05). Among the subjects who prticipted in the kinetic studies, the mgnitude of the chnge in wist circumference nd in plsm lipid levels fter the low-ft/high- CHO diet ws similr to the chnge in the entire low-ft/ high-cho group (Tble 4). Although the reduction in obesity indices tended to be more importnt in the subgroup involved in the kinetic studies within the high-mufa dietry group, chnges in lipid levels were similr in mgnitude to those seen in the entire high-mufa group. Consumption of the low-ft/high-cho diet resulted in significnt reduction in poa-i PR (P 0.001) long with prllel reductions in plsm poa-i concentrtions nd pool sizes (P 0.05 nd P 0.01, respectively; Tble 5). A significnt reduction in poa-i FCR in the low-ft/high- CHO group ws lso observed (P 0.05). The only significnt difference in poa-i kinetics found within the high- MUFA dietry group ws reduction in poa-i pool size (P 0.05). The diet-induced chnges in poa-i PR nd FCR (P 0.01 nd P 0.05, respectively) were significntly different between the two dietry groups (Tble 5). ApoA-II plsm concentrtions nd pool size were significntly nd similrly reduced by both dietry interventions (Tble 5). In both dietry groups, these reductions ppered to be ttributble to n increse in poa-ii FCR, s TABLE 4. Effects of the low-ft/high-cho nd high-mufa diets on lipid profiles nd nthropometric chrcteristics in the kinetic subgroup Low-Ft/High-CHO Diet (n 10) High-MUFA Diet (n 8) Vrible Pre Post Chnge P (Post vs. Pre) Pre Post Chnge P (Post vs. Pre) P (Between Diets) b Body weight (kg) Body mss index (kg/m 2 ) Wist circumference (cm) Totl cholesterol (mmol/l) LDL-C (mmol/l) Triglycerides c (mmol/l) Totl cholesterol/hdl-c rtio Plsm pob-100 (g/l) HDL-C (mmol/l) HDL 2 -C (mmol/l) HDL 3 -C (mmol/l) Vlues shown re mens SD. P vlue for the within-diet effects. b P vlue for the between-diet effects (low-ft/high-cho vs. high-mufa). c Vlues were log-trnsformed before sttisticl nlyses Journl of Lipid Reserch Volume 45, 2004

5 TABLE 5. Effects of the low-ft/high-cho nd high-mufa diets on poa-i, poa-ii, nd VLDL-poB-100 kinetic prmeters Low-Ft/High-CHO Diet (n 10) High-MUFA Diet (n 8) Vrible Pre Post Chnge P (Post vs. Pre) Pre Post P (Between Chnge P (Post vs. Pre) Diets) b ApoA-I kinetics poa-i (g/l) Pool size (mg) 4, , , , PR (mg/kg/dy) FCR (pools/dy) ApoA-II kinetics poa-ii (g/l) Pool size (mg) 1, , c 1, , PR (mg/kg/dy) FCR (pools/dy) d 0.24 VLDL-poB-100 kinetics VLDL-poB-100 (g/l) Pool size (mg) PR (mg/kg/dy) FCR (pools/dy) Vlues shown re mens SD. FCR, frctionl ctbolic rte; PR, production rte. P for the within-diet effects. b P for the between-diet effects (low-ft/high-cho vs. high-mufa). c After Tukey djustment for multicomprison in the PROC MIXED procedure (P 0.10). d After Tukey djustment for multicomprison in the PROC MIXED procedure (P 0.16). reflected by the inverse correltions found between the diet-induced chnges in plsm HDL 3 -C nd chnges in poa-ii FCR observed within the high-mufa group (r 0.90, P 0.01) nd the low-ft/high-cho group (r 0.71, P 0.05). However, the increse in poa-ii FCR ws significnt only in the high-mufa group (P 0.05). Although the chnges did not rech sttisticl significnce, in the low-ft/high-cho group, VLDL-poB-100 PR nd FCR tended to be reduced eqully ( 15.8% vs. 17.4%, respectively), resulting in no chnge in plsm concentrtions of TG nd VLDL-poB-100. The reduction in VLDL-poB-100 nd TG levels in the high-mufa group ppered to be lmost entirely ttributble to reduction in VLDL-poB-100 PR ( 29.5%), lthough this reduction lso did not rech sttisticl significnce. However, vritions in plsm VLDL-poB-100 concentrtions in the high-mufa group were positively correlted with dietinduced vritions in VLDL-poB-100 PR (r 0.69, P 0.06) nd showed no ssocition with VLDL-poB-100 FCR (r 0.28, P 0.51). Diet-induced chnges in body weight did not correlte with vritions in VLDL-poB-100 kinetics in either dietry group. DISCUSSION The present study investigted the effects of low-ft/ high-cho diet nd high-mufa diet consumed under d libitum conditions on poa-i, poa-ii, nd VLDL-poB- 100 kinetics in men. First, the reduction in plsm HDL-C concentrtions induced by the low-ft/high-cho diet ws minly ttributble to concurrent reductions in plsm HDL 3 -C concentrtions. Second, the reduction in plsm HDL-C nd HDL 3 -C concentrtions with the low-ft/high- CHO diet ws ttributble lrgely to reduction in poa-i PR. Third, the significnt reduction in HDL 3 -C concentrtions induced by the consumption of the high-mufa diet ws medited by n increse in poa-ii FCR. Finlly, no sttisticlly significnt diet effect on VLDL-poB-100 kinetics ws observed in the kinetic subgroup. The evidence supporting the fct tht low-ft/high- CHO diets re ssocited with decrese of HDL-C concentrtions nd n increse of plsm TG concentrtions under isocloric conditions hs been consistent. In met-nlysis of 27 well-controlled trils conducted under isocloric conditions published by Mensink nd Ktn (30), it ws clculted tht for ech 10% of energy from CHO replced by ft, HDL-C concentrtions incresed by 0.07 mmol/l (5 10%). However, becuse it is recognized tht body weight nd more specificlly bdominl obesity re importnt determinnts of HDL-C concentrtions nd metbolism (31), the extent to which conclusions drwn from studies performed under isocloric conditions cn be pplied to the dy-to-dy mngement of obese ptients weight nd risk profile hs been questioned. In lndmrk study, Schefer et l. (5) mesured plsm HDL-C concentrtions in 27 slightly overweight men nd women during their usul, high-ft diet (35% ft, 49% CHO), during n isocloric low-ft/high-cho diet (15% nd 68% of energy from ft nd CHO, respectively) when weight remined stble for 5 6 weeks, nd during n d libitum low-ft/high-cho diet lsting 12 weeks, during which prticipnts spontneously lost n verge of 3.63 kg. Consumption of the low-ft diet under weight mintennce conditions ws ssocited with significnt increse in plsm TG concentrtions nd reciprocl 22% decrese in HDL-C concentrtions compred with the usul high-ft diet. The low-ft d libitum phse induced significnt reduction in plsm TG concentrtions, wheres HDL-C concentrtions did not decrese further reltive to the low-ft, weight-mintennce diet period. Lichtenstein et l. (32) obtined similr re- Desroches et l. Low-ft vs. high-mufa diets nd polipoprotein kinetics 2335

6 sults. In the present study, the low-ft/high-cho diet ws ssocited with significnt 10% reduction in plsm HDL-C concentrtions. The mgnitude of the chnge in plsm HDL-C concentrtions ws not relted to the dietinduced reduction in body weight or body ft distribution (16). We hve further exmined the impct of both diets on vrious subclsses of HDL chrcterized on the bsis of their composition nd size. In generl, HDLs tht contin poa-i but not poa-ii (LpA-I) re found within prticles of lrger size nd lower density (HDL 2 ), wheres LpA-I:A-II (HDLs tht contin both poa-i nd poa-ii) re generlly ssocited with smller HDL 3 prticles (33). Although erlier dt tended to suggest tht most of the crdioprotective properties ttributed to HDL would reside within LpA-I prticles nd HDL 2 rther thn within LpA-I:A-II or HDL 3 (33, 34), recent dt from the lrge Prospective Epidemiologicl Study of Myocrdil Infrction reveled tht both LpA-I nd LpA-I:A-II were inversely relted to the incidence of CHD (35). Our knowledge of the low-ft diet-induced chnges in the concentrtions of specific HDL subfrctions is rther limited. It ws reported tht compred with diet high in sturted ft nd cholesterol, consumption of Ntionl Cholesterol Eduction Progrm (NCEP) Step 2 diet for 6 months under isocloric conditions resulted in significnt reductions in HDL prticles tht do nd do not contin poa-ii (LpA-I:A-II nd LpA-I, respectively) (36). Isoenergetic replcement of dietry ft with CHO hs lso been ssocited with reductions in HDL 3, HDL 2, HDL 2b, nd HDL prticle size (37). In the present study, the low-ft/high-cho diet ws ssocited with significnt reduction in plsm HDL 3 -C nd LpA-I:A-II concentrtions but with no chnge in HDL 2 -C nd LpA-I concentrtions. As result, the HDL 2 -C/HDL 3 -C rtio nd HDL prticle size incresed fter the low-ft/ high-cho diet. The incresed HDL 2 -C/HDL 3 -C rtio nd HDL size nd the lck of chnge in HDL 2 -C concentrtions fter the low-ft/high-cho diet would suggest beneficil modifiction in terms of crdiovsculr risk (33, 34). Consumption of the high-mufa diet yielded similr results, with the exception of smller reduction in plsm HDL-C nd HDL 3 -C concentrtions compred with the low-ft/high-cho diet. Few studies hve reported the effects of dietry chnges on plsm poa-i nd poa-ii kinetics, nd to our knowledge the present study is the first to compre the impct of n unrestricted low-ft/high-cho diet vs. high-mufa diet on HDL kinetics. Among those, Blum et l. (11) studied three women in whom 39.1% increse in poa-i FCR ws observed when n isocloric CHO-rich diet (80% CHO, 5 g of ft) ws compred with norml diet (40% ft, 40% CHO). Brinton, Eisenberg, nd Breslow (10) showed significnt reduction in poa-i PR nd n increse in poa-i FCR fter n isocloric very-low-ft/high- CHO diet (9% ft, 76% CHO, 16% protein) compred with bseline diet (42% ft, 43% CHO, 15% protein). More recently, Vélez-Crrsco et l. (12) lso reported in n isocloric study tht low-sturted-ft diet (25% ft, 60% CHO, 15% protein) induced significnt decrese in poa-i PR nd no chnge in poa-i FCR, poa-ii PR, nd poa-ii FCR compred with bseline diet (36% ft, 49% CHO, 15% protein). Interprettions of the study by Blum et l. (11) re limited by the smll number of subjects investigted. However, consistent with dt from the present study, two previous studies hve found tht lowft/high-cho diets reduced poa-i PR, which in turn explined the decresed plsm HDL-C concentrtions. The effects of low-ft/high-cho diets on the poa-i FCR pper to be less consistent. The increse in poa-i FCR fter low-ft diet observed by Brinton, Eisenberg, nd Breslow (10) nd Blum et l. (11) ws prlleled by n increse in plsm TG concentrtions in both studies. On the other hnd, Vélez-Crrsco et l. (12) did not observe differences in plsm TG concentrtions when low-ft/high-cho Step 2 diet ws substituted for bseline diet, nd no chnge in poa-i FCR ws reported. In the present study, the low-ft/high-cho diet ws ssocited with significnt reduction in poa-i FCR in the bsence of chnge in plsm TG concentrtions. We hypothesize tht the lck of deleterious chnge in plsm TG concentrtions combined with moderte weight loss nd incresed HDL prticle size in the low-ft/high-cho group my hve fvorbly reduced the HDL ctbolic rte. Interestingly, the reduction in HDL 3 -C concentrtions in the high-mufa diet ppers to be ttributble to n enhnced ctbolism of poa-ii. Becuse of the significntly greter reduction in HDL 3 -C concentrtions observed with the low-ft/high-cho diet compred with the high-mufa diet, it my hve been interesting to perform kinetic nlyses on the HDL 3 subclss to ddress this issue further. However, previous study by Frenis et l. (38) indicted tht HDL 2 nd HDL 3 hd similr kinetics when mesured using the primed-infusion methodology. It must be stressed tht in our study, poa-i nd poa-ii were isolted from the plsm d 1.25 g/ml frction by ultrcentrifugtion, process tht my provoke the dissocition of the loosely bound polipoproteins from lipoproteins. Horowitz et l. (39) hve shown tht low-hdl condition ws ssocited with greter proportion of poa-i being dissocited from HDL upon ultrcentrifugtion. Becuse on-diet HDL-C concentrtions were the sme in the high- CHO nd the high-mufa groups (Tble 3), we hypothesize tht diet per se my not hve ffected the pool of dissocible poa-i. Severl studies hve suggested tht low-ft diets provoke n increse in the PR rte of VLDL from the liver, lthough this is not consistent observtion (40). In the present study, d libitum consumption of low-ft/high- CHO diet consisting of solid foods, when ccompnied by smll but significnt weight loss, ws not ssocited with incresed plsm TG nd VLDL-poB-100 levels. Consistently, the low-ft/high-cho diet hd no effect on VLDLpoB-100 PR or FCR. The extent to which chnges in body weight my hve modulted the impct of the lowft/high-cho diet on VLDL-poB-100 kinetics is uncler, but there ws no correltion between diet-induced chnges in body weight or wist circumference nd vritions in VLDL-poB-100 kinetics. In the high-mufa group, the re Journl of Lipid Reserch Volume 45, 2004

7 duction in VLDL-poB-100 PR ( 29.5%), lthough not significnt, ppered to be proportiontely greter thn chnges in VLDL-poB-100 FCR ( 3.8%). There ws lso positive correltion between diet-induced chnges in plsm VLDL-poB-100 concentrtions nd VLDL-poB- 100 PR. These dt suggest tht the chnges in the PR of VLDL-poB-100 my be lrgely responsible for the observed reductions in plsm VLDL-poB-100 concentrtions ssocited with the high-mufa diet. Very few studies hve investigted the impct of diets rich in MUFA on VLDL kinetics. Replcing dietry sturted ftty cids with MUFA under isocloric conditions hd no impct on plsm TG levels nd did not ffect VLDL 1 nd VLDL 2 plsm concentrtions or kinetics (15). Despite greter reduction in plsm TG nd VLDLpoB-100 concentrtions with the high-mufa diet compred with the low-ft/high-cho diet in the entire group of subjects, our study ws not ble to revel significnt between-diet differences in VLDL-poB-100 kinetic prmeters, lthough VLDL-poB-100 PR ws reduced by 2-fold in the high-mufa group compred with the low-ft/high- CHO group. One of the study subjects in the high-mufa group hd mrkedly incresed VLDL-poB-100 PR, prticulrly t bseline, thus explining the high SD in tht group. Excluding tht subject from sttisticl nlyses performed on VLDL-poB-100 kinetic prmeters did not ffect our results. Limittions of the present study must be ddressed. First, it must be cknowledged tht crossover study design my hve llowed us to better pprecite the between-diet differences in the kinetics of the vrious polipoproteins, minly becuse of the incresed sttisticl power it provides. However, the d libitum nture of the study, which led to significnt vritions in body weight, would hve mde such design rther complex. Second, the ge difference mong subjects llocted to the lowft/high-cho diet nd the high-mufa diet in the kinetic subgroup is n issue tht deserved to be investigted further. Adjustment for ge hd very little impct on the between-diet comprison of kinetic dt, with the exception of the difference in poa-i FCR, which ws ttenuted (P 0.13; dt not shown). Finlly, lthough our study smple ws heterogeneous in terms of obesity levels, it cnnot be excluded tht our results my hve been influenced by the body composition sttus of the subjects who were overweight s group. Becuse of the smll number of subjects in the kinetic substudies, it ws impossible to ssess the impct of the experimentl diets on kinetic prmeters within subgroups of len nd obese individuls. In conclusion, our results suggest tht reduction in poa-i PR ppers to explin the consistent decrese of HDL-C concentrtions ttributble to low-ft diets. However, the decrese in poa-i FCR possibly ttributble to body weight reduction nd incresed HDL prticle size with the low-ft diet consumed under d libitum conditions my hve prevented further undesirble decreses of plsm HDL-C levels. Our dt lso indicted tht the reduction in HDL 3 -C concentrtions in the high-mufa group ws medited by n increse in poa-ii FCR, suggesting tht low-ft/high-cho nd high-mufa diets my exert their effects on HDL through different mechnisms. Using prllel study design, we were not ble to revel ny difference in VLDL-poB-100 kinetics between lowft/high-cho diet nd high-mufa diet consumed d libitum nd ssocited with moderte weight loss. The uthors express their grtitude to the prticipnts for their invluble contribution nd to Louise Corneu for her dedicted work. S.D. is the recipient of Cnd Grdute Scholrship Doctorl Awrd from the Cndin Institute of Helth Reserch nd of studentship from the Fonds de l Recherche en Snté du Québec (FRSQ). M-E.P. is the recipient of studentship from the FRSQ. P.C. is the recipient of fellowship from the FRSQ. J.B. is clinicl reserch scholr from the FRSQ. B.L. is the recipient of Cnd Reserch Chir in Nutrition, Functionl Foods, nd Crdiovsculr Helth. REFERENCES 1. S. S. S. S. Group Rndomized tril of cholesterol lowering in 4444 ptients with coronry hert disese: the Scndinvin Simvsttin Survivl Study (4S). Lncet. 344: Lmrche, B., J. P. Després, S. Moorjni, B. Cntin, G. Dgenis, nd P. J. Lupien Triglycerides nd HDL-cholesterol s risk fctors for ischemic hert disese. Results from the Québec Crdiovsculr Study. Atheroslerosis. 119: Kruss, R. M., R. H. Eckel, B. Howrd, L. J. Appel, S. R. Dniels, R. J. Deckelbum, J. W. Erdmn, P. Kris-Etherton, I. J. Goldberg, T. A. Kotchen, A. H. Lichtenstein, W. E. Mitch, R. Mullis, K. 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Lmrche A new method for HDL prticle sizing by polycrylmide grdient gel electrophoresis using whole plsm. J. Lipid Res. 42: An, P., T. Rice, J. Ggnon, I. B. Borecki, J. Bergeron, J. P. Despres, A. S. Leon, J. S. Skinner, J. H. Wilmore, C. Bouchrd, nd D. C. Ro Segregtion nlysis of polipoproteins A-1 nd B-100 mesured before nd fter n exercise trining progrm: the HER- ITAGE Fmily Study. Arterioscler. Thromb. Vsc. Biol. 20: Couillrd, C., J. Bergeron, J. P. Despres, J. Ggnon, T. Rnkinen, A. S. Leon, D. C. Ro, J. S. Skinner, J. H. Wilmore, nd C. Bouchrd Apolipoprotein AI- nd AI:AII-contining lipoproteins in white men nd women of the HERITAGE Fmily study: ssocitions with metbolic risk profile vribles. Metbolism. 52: Trembly, A. J., B. Lmrche, I. L. Ruel, J. C. Hogue, J. Bergeron, C. Ggné, nd P. Couture Lck of evidence for reduced plsm po B48 ctbolism in ptients with heterozygous hypercholesterolemi crrying the sme null LDL receptor gene muttion. Atherosclerosis. 172: Btl, R., M. Trembly, L. Krimbou, O. Mmer, J. Dvignon, J. Genest, Jr., nd J. S. Cohn Fmilil HDL deficiency chrcterized by hyperctbolism of mture poa-i but not propoa-i. Arterioscler. Thromb. Vsc. Biol. 18: Kotite, L., N. Bergeron, nd R. J. Hvel Quntifiction of polipoproteins B-100, B-48, nd E in humn triglyceride-rich lipoproteins. J. Lipid Res. 36: Trembly, A. J., B. Lmrche, I. L. Ruel, J. C. Hogue, J. Bergeron, C. Ggne, nd P. Couture Incresed production of VLDL pob-100 in subjects with fmilil hypercholesterolemi crrying the sme null LDL receptor gene muttion. J. Lipid Res. 45: Cobelli, C., G. Toffolo, nd D. M. Foster Trcer-to-trcee rtio for nlysis of stble isotope trcer dt: link with rdioctive kinetic formlism. Am. J. Physiol. 262: E968 E Gregersen, M. I., nd R. A. Rwson Blood volume. Physiol. Rev. 39: Mensink, R. P., nd M. B. Ktn Effect of dietry ftty cids on serum lipids nd lipoproteins. A met-nlysis of 27 trils. Arterioscler. Thromb. 12: Després, J. P Dyslipidemi nd obesity. Billères Clin. Endocrinol. Metb. 8: Lichtenstein, A. H., L. M. Ausmn, W. Crrsco, J. L. Jenner, J. M. Ordovs, nd E. J. Schefer Short-term consumption of lowft diet beneficilly ffects plsm lipid concentrtions only when ccompnied by weight loss. Arterioscler. Thromb. 14: Fruchrt, J. C., G. Ailhud, nd J. M. Brd Heterogeneity of high density lipoprotein prticles. Circultion. 87: III22 III Lmrche, B., S. Moorjni, B. Cntin, G. R. Dgenis, P. J. Lupien, nd J. P. Despres Associtions of HDL2 nd HDL3 subfrctions with ischemic hert disese in men. Prospective results from the Quebec Crdiovsculr Study. Arterioscler. Thromb. Vsc. Biol. 17: Luc, G., J. M. Brd, J. Ferrieres, A. Evns, P. Amouyel, D. Arveiler, J. C. Fruchrt, nd P. Ducimetiere Vlue of HDL cholesterol, polipoprotein A-I, lipoprotein A-I, nd lipoprotein A-I/A-II in prediction of coronry hert disese: the PRIME Study. Prospective Epidemiologicl Study of Myocrdil Infrction. Arterioscler. Thromb. Vsc. Biol. 22: Cheung, M. C., A. H. Lichtenstein, nd E. J. Schefer Effects of diet restricted in sturted ftty cids nd cholesterol on the composition of polipoprotein A-I-contining lipoprotein prticles in the fsting nd fed sttes. Am. J. Clin. Nutr. 60: Willims, P. T., D. M. Dreon, nd R. M. Kruss Effects of dietry ft on high-density-lipoprotein subclsses re influenced by both polipoprotein E isoforms nd low-density-lipoprotein subclss ptterns. Am. J. Clin. Nutr. 61: Frenis, R., K. Ouguerrm, C. Mugeis, P. Mhot, P. Mugere, M. Krempf, nd T. Mgot High density lipoprotein polipoprotein AI kinetics in NIDDM: stble isotope study. Dibetologi. 40: Horowitz, B. S., I. J. Goldberg, J. Merb, T. M. Vnni, R. Rmkrishnn, nd H. N. Ginsberg Incresed plsm nd renl clernce of n exchngeble pool of polipoprotein A-I in subjects with low levels of high density lipoprotein cholesterol. J. Clin. Invest. 91: Prks, E. J., nd M. K. Hellerstein Crbohydrte-induced hypertricylglycerolemi: historicl perspective nd review of biologicl mechnisms. Am. J. Clin. 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