Acides Gras Oméga-3 et Santé Yvon A. Carpentier • Laboratoire de Chirurgie Expérimentale ULB • Clinique des Lipides Hôpital Erasme
Acides Gras Oméga-3 et Santé
Yvon A. Carpentier
• Laboratoire de Chirurgie Expérimentale ULB
• Clinique des Lipides
Hôpital Erasme
Structure etStructure et nomenclature des acides gras nomenclature des acides gras
COOH
H3C
H3C COOH
H3C
COOH
Acide stéarique 18:0
Acide oléique 18:1n-9
Acide linoléique 18:2n-6
Acide-linolénique 18:3n-3H3C COOH
9
6
3
Solide à température ambiante vs. Liquide à température ambianteSolide à température ambiante vs. Liquide à température ambiante
n-6 serie n-3 serie
Linoleic ac. Alpha-linolenic ac.
C18:2n-6 C18:3n-3
6-desaturase
Gamma-linolenic ac. Octadecatetraenoïc ac.
C18:3n-6 C18:4n-3
Elongation
Dihomo-gamma-linolenic ac. Eicosatetraenoïc ac.
C20:3n-6 C20:4n-3
5-desaturase
Arachidonic ac. Eicosapentaenoïc ac.
C20:4n-6 C20:5n-3
Elongation
Docosatetraenoïc ac. Docosapentaenoïc ac.
C22:4n-6 C24:5n-6 C24:6n-3 C22:5n-3
Docosapentaenoïc ac. Docosahexaenoïc ac.
C22:5n-6 C22:6n-3
EPA
DPA
DHA
AA
Elongation - unsaturation of essential FA
Metabolism of -linolenic acid
From Cunnane SC, J Physiol Pharmacol, 1996
Trends in the intake of fatty acids in the UKTrends in the intake of fatty acids in the UK
% Energy% Energy
5050
4040
3030
2020
1010
0019401940 1950 1950 1960 1960 1970 1970 1980 1980 1990 1990
PUFA to SFA ratio
1
0.8
0.6
0.4
0.2
0
Total fatTotal fat
SFASFAMUFAMUFA
PUFAPUFA
Last 30 Years - Large Increase in the Intake of n-6 PUFAs in Industrialized Countries
Last 30 Years - Large Increase in the Intake of n-6 PUFAs in Industrialized Countries
•Between 1972 and 1998 the n-6 fatty acids rose from 4% to 6%.
•Upsurge of Asthma in the UK, Australia, New Zealand and Germany might be a related phenomenon.
•The unexplained increase in the incidence of edema, allergic rhinitis, and regional differences of inflammatory diseases within countries may relate to increased n-6 fatty acid intake.
Roberts 1991, Dept. of Health UK 1994,Black and Sharp 1997, Lewis et al. 1996, Grimble 1998
Fü-Out-13b
Evolution des habitudes alimentaires
Paléolithique « Western » AHA
• Lipides (% cal) 21 34 <30
• Sat (% cal) <10 ~13 <10
• P:S 1.4 ~0.5 >1.0-3/ -6 1/1-1/2 1/10-1/20 1/1-1/5
• Fibres (g/j) ~46 ~20 >25
DONNEES EPIDEMIOLOGIQUES
Populations consommant bcp AG n-3
• faible incidence de pathologies cardiovasculaires• faible incidence de pathologies inflammatoires et allergiques• faible incidence de cancers (colon, sein, prostate)• faible incidence de lithiases rénales• faible incidence de diabète type I• allongement de durée de gestation• incidence accrue d’insuffisance rénale chronique
CORRELATION AVEC COMPOSITION EN ACIDES GRAS DES
MEMBRANES CELLULAIRES ET FORMATION EICOSANOIDES
Acides Gras oméga-3Rôles-clés en Santé Humaine
• Développement cognitif• Développement vision• Réponses immunes/inflammatoires• Grossesses & développement foetal• Maladies neurodégénératives • Aspects psychologiques• Maladies cardio-vasculaires
Modes and sites of action of n-3 PUFA’s
• Formation of eicosanoids
(tissue level, locally and at distance)
Membrane Pool (PL)
F2-isoprostanes
Metabolic Pool (TG, FFA)
18:2 n-6 18:3 n-6 20:3 n-6 20:4 n-6 (LA) (GLA) (DGLA) (AA)
Cyclo -oxygenase
PGI2 PGE2TXA2
PGE1
Lipoxygénases
LT4 HETES
Arachidonic acid in cell membrane phospholipidArachidonic acid in cell membrane phospholipid
Free arachidonic acidFree arachidonic acid
Phospholipase APhospholipase A22
PGGPGG22
PGHPGH22
15-HPETE15-HPETE 12-HPETE12-HPETE 5-HPETE5-HPETE
15-HETE15-HETE 12-HETE12-HETE LTALTA44 5-HETE5-HETE
PGDPGD22
PGEPGE22
PGIPGI22 TXATXA22
PGFPGF22
LXALXA44 LTCLTC44 LTBLTB44
LTDLTD44 LTELTE44
A major role of arachidonic acid is as A major role of arachidonic acid is as a precursor for eicosanoidsa precursor for eicosanoids
COX 15-LOX 12-LOX 5-LOX
Membrane Pool (PL)
F3 - and F4 - isoprostanes
Metabolic Pool (TG, FFA)
18:3 n-3 20:5 n-3 22:5 n-3 22:6 n-3 (ALA) (EPA) (DGLA) (DHA)
Cyclo-oxygénases
PGI3 PGE3
TXA3
Lipoxygenases
LT5
Eicosanoids derived from n-3 (vs. n-6) PUFAs
• Less inflammatory
• Less thrombogenic
• Less chemo-attractive
• Weaker protection of gastro-intestinal mucosa
• Retard delivery (increase pregnancy duration)
Arachidonic acid in membrane phospholipids
Free arachidonic acid
2-series PG and TX 4-series LT
COX-2
5-LOX
Phospholipase A2
Inflammatory effects Inflammatory effects
EPADHA
Classic view of the anti-inflammatory Classic view of the anti-inflammatory action of long chain action of long chain -3 PUFA-3 PUFA
Resolvins & related compoundsResolvins & related compounds
EPAEPA DHADHA
E-series resolvinsE-series resolvins D-series resolvins, D-series resolvins, neuroprotectins etc.neuroprotectins etc.
Anti-inflammatory; inflammation resolvingAnti-inflammatory; inflammation resolving
COX-2 (& presence of aspirin)COX-2 (& presence of aspirin)
From J.A. Ross et al, Curr Opin Clin Nutr Metab Care, 1999
Possible sites of action of n-3 & n-6 PUFAs
Modes and sites of action of n-3 PUFA’s
• Formation of eicosanoids
(tissue level, locally and at distance)
• Components of membrane phospholipids
(membrane physical properties & interaction with membrane proteins : cell level)
• Second messengers in signalling pathways (molecular level)
• Regulators of gene expression (transcription factors : molecular level)
Signalisation cellulaire: voie des MAP-Kinases
AdhesionAdhesion
ChemoattractantsChemoattractants
EicosanoidsEicosanoids
CytokinesCytokines
Reactive Reactive speciesspecies
PAFPAF
InflammationInflammation
ChemotaxisChemotaxis
InjuryInjury
Lipides plasmatiquesPression artérielle
Tendance aux thrombosesRésistance à insuline
OxydationHomocystéineInflammation
Fonction endothélialeIrritabilité ventriculaire
NUTRITION MCV
Nutrition et Pathologies Cardio-vasculaires
From WC Willett, 2004
Acides Gras Oméga 3 et le Coeur triglycérides (4g/j) arythmies arrêts cardiaques réactions inflammatoires coagulation• Synergie avec l’aspirine• Pas d’effets secondaires• Pas d’effet sur le cholestérol
morbidité et mortalité des maladies coronaires
The New EnglandJournal of Medicine
• Volume 312 May 9, 1985 Number 19
THE INVERSE RELATION BETWEEN FISH CONSUMPTION AND 20-
YEAR MORTALITY FROM CORONARY HEART DISEASE
Daan KROMHOUT, PH.D., M.P.H., EDWARD B., BOSSCHIETER, M.D.,
AND COR DE LEZENNE COULANER, M.SC.
1960: town of Zutphen, the Netherlands
852 middle-aged men without CHD
dietary history
20 year follow-up:
78 deaths from CHD
(> 50%) mortality from CHD in subjects eating > 30 g fish/day
2033 men having recovered from myocardial infarction (M.I.)
Dietary intervention in secondary prevention of M.I.
I. fat intake (to 30% energy intake) and P/S ratio (to 1.0)
II. fatty fish intake (200-400g/week)
III. cereal fibre intake (18g/day)
2 year follow-up :
29% REDUCTION OF MORTALITY (all causes) IN ‘‘FISH’’ GROUP II
Effects of changes in fat, fish, and fibre intakes on death and myocardial reinfarction : diet and reinfarction trial (DART)
M.L. Burr et al., The Lancet, 1989
Dietary intake and cell membrane levels of long-chain n-3 Polyunsaturated Fatty Acids and the risk of
primary cardiac arrest
D.C. Siscovick et al.
« Compared with no dietary intake of eicosapentaenoic acid (C20:5n-3) and docosahexaenoic acid (C22:6n-3), an intake of 5.5 g of n-3 fatty acids per month (... equivalent of one fatty fish meal per week) was associated with a 50% reduction in the risk of primary cardiac arrest (odds ratio [OR], 0.5; 95% confidence interval [Cl], 0.4 to 0.8), after adjustment for potential confounding factors. »
JAMA, 1995
Prevention and termination of arrhythmia by EPA
J.X. Kang & A. Leaf, Proc Natl Acad Sci USA, 1994
Dog model of cardiac sudden death
surgically, large myocardial infarct + inflatable cuff around left circumflex coronary art. (LCA)
1 month later:
Treadmill running + LCA occlusion
Ventricular fibrillation and death in all controls & soybean oil (n = 7)
Survival in 5/7 dogs infused for 1h with EPA
6/8 dogs infused for 1h with DHA
6/8 dogs infused for 1h with LNA
Prevention of Sudden Cardiac Death by Dietary Pure -3 Polyunsaturated Fatty Acids in Dogs
G.E. Billman et al, Circulation, 1999
Association of n-3 polyunsaturated fatty acids with stability of atherosclerotic plaques :
a randomised controlled trial• 188 patients en attente endartériectomie carotide (7-189j)• Suppl. HP (1.4g EPA/DHA/j) vs. Tournesol vs. Palme/Soja
Résultats - Suppl. HP vs. 2 autres groupes: EPA & DHA dans lipides de plaque ( incorporation avec temps)
• Plus de plaques avec couche fibreuse épaisse
• Moins de plaques avec couche fibreuse fine & inflammatoire
• Moins d’infiltration de macrophages dans plaques
t/o rapide des acides gras dans lipides des plaques
effet marqué de suppl. HP sur morphologie & fragilité des plaques F. Thies et al, The Lancet, 2003
Dietary Fish Oil Supplementation Reduces Myocardial Infarct Size in a Canine Model
of Ischemia and Reperfusion
0.06 g/kg.day EPA for 6 weeks
Occlusion of left circumflex coronary art. for 90 min followed by 6h
of reperfusion
Infarct size: 13.3% ( 3) vs 29.7% (control) (p<0.05);
no difference in regional blood flow or oxygen consumption
Protective mechanisms:• inhibition of TXA2• inhibition of free radical production by leucocytes?
H. J. Oskarsson et al., J Am Coll Cardiol, 1993
Acides Gras -3 et Endothélium
• Amélioration profil lipoprotéines
• Amélioration profil éicosanoïdes
• Effet sur membranes cellulaires (et Chol dans cavéoles)
• Modulation de facteurs de transcription nucléaire
• Amélioration défenses anti-oxidantes de cellule vasorelaxation coagulation, act plaquettes & molécules adhésion sensibilité aux cytokines & radicaux libres activation CML
essential for maturation of foetal CNS and retina (DHA)
reduce inflammatory response
anti-thrombotic effect
prevent impaired cellular immunity when caused
by PGE2 production
decrease plasma triglyceride concentration (also post-prandial)
decrease plasma free fatty acid concentration (also p-prandial)
BENEFICIAL EFFECTS OF n-3 PUFA ( I )
decrease cell reactivity to various stimuli (e.g. ventricular arrhythmia’s,...)
prevent / reverse cancer & inflammatory cachexia
increase tolerance to organ transplantation and improve function of the graft
help maintaining adequate tissue microperfusion
reduce cellular accumulation of fat (e.g., liver)
potential interest for supplying n-3 PUFA to « acute » patients
BENEFICIAL EFFECTS OF n-3 PUFA ( II )
Limitations to n-3 FA supply with Fish Oils
• Gastro-intestinal administration
FO TG : poor substrate for pancreatic lipase
slow & rather unefficient absorption
• Intravenous infusion
FO TG : poor substrate for lipoprotein lipase
slow plasma elimination
! a proportion of n-3 FA used for oxidative purposes !
Obésité, syndrome métabolique, et insulino-résistance
• Influence du patrimoine génétique• 85% des diabétiques T2 sont obèses• 30% des obèses sont diabétiques (T2) prévalence• Différences entre ethnies (NB: asiatiques)• Influence facteurs comportementaux
(nutrition, activité physique, …)• Relation avec stress & inflammation
Le Syndrome Métabolique
• Combinaison de 3 facteurs: - obésité abdominale : tour taille > 94 cm (H) ou > 80 cm (F) - conc. triglycérides 1.7 mmol/L (150 mg/dL) ou traitt - conc. HDL-cholestérol < 1.03 mmol/L (40 mg/dL) H ou traitt < 1.28 mmol/L (50 mg/dL) F ou traitt - tension artérielle 130/85 mm Hg ou traitt - conc. glucose à jeun 5.56 mmol/L (100 mg/dL) ou traitt prévalence: 44% pour population USA > 50 ans (2003) prévalence coronaropathies (>> facteurs isolés)
FACTEURS ASSOCIES AU SYNDROME METABOLIQUE
• Insulino-résistance & risque diabète T2
• Dépôts ectopiques de TAG (foie, muscles, … )
• Altérations lipoprotéines (sd LDL athérogènes)
• Composante inflammatoire
• Dysfonction endothéliale
activité ortho-sympathique
Etiologie multiple (nutrition, sédentarité, …)
Serum sialic acid concentration in 263 overweight women without (0) or with 1-3 other features of metabolic syndrome : insulin resistance;
dyslipidemia; hypertension
L. Browning, Proc Nut Soc, 2003
Gene variants, insulin resistance, and dyslipidaemia
M.Lakso, Curr Opin Lipidol, 2004
Hypotheses: primary effect of variants on insulin resistance or on dyslipidaemia
Interaction between dietary lipids and physical inactivity on insulin sensitivity and on intramyocellular lipids in
healthy men
• 8 healthy male volunteers• 60h complete bed rest + high fat or high CHO diet• Hyperinsulinemic –euglycemic clamp (glucose disposal)• 1H-magnetic resonance spectroscopy• Bed rest + high fat : glucose disposal (- 24%) intramyocellular lipid content (+ 32%) R. Stettler et al, Diabetes Care, 2005
Mitochondrial dysfunction and type 2 diabetes
Maintenance of normal glucose level :• insulin responsiveness of skeletal muscle & liver defect insulin resistance• insulin secretion by pancreatic beta cells defect hyperglycemia
both defects may be caused by mitochondrial dysfunction
Lowell BB & Shulman GI, Science, 2005
Insulin resistance associated to obesity and type 2 diabetes
• Molecular defects of insulin signaling in muscle
glucose disposal and transport (role of fatty acids & metabolites)
• Insulin resistance in liver
glucose output (overexpression of glucose-6-Pase)
• Visceral obesity & ectopic fat storage (e.g., muscle & liver)
poor modulation of fat oxidation
• Non-alcoholic fatty liver disease (NAFLD) and steato-hepatitis (NASH) lipolysis, oxidative stress, cytokine induction
• Altered activity of desaturases
9 & 5 6 desaturase DB Savage et al, Hypertension, 2005
N-3 long chain polyunsaturated fatty acids: a nutritional tool to prevent insulin resistance associated to
type 2 diabetes and obesity ?RAT STUDIES
• N-3 PUFAs improve molecular defects of insulin signaling in muscle
IRS-1 phosphorylation PI 3’-kinase act, GLUT-4 mRNA
muscle TAG content & LCFA CoA
• N-3 PUFAs improve insulin resistance in liver
expression & activity of G-6-Pase; normalize glucose output
• N-3 PUFAs improve visceral obesity & ectopic fat storage (muscle & liver)
fat oxid (PPAR)
lipogenesis, TG formation, & fat deposition
N-3 long chain polyunsaturated fatty acids: a nutritional tool to prevent insulin resistance associated to
type 2 diabetes and obesity ?HUMAN STUDIES (Healthy volunteers)
• 3 week supplementation w FO (1.1 g EPA + 0.7 g DHA)• Oral glucose load (after supplementation n-3 PUFA) : insulin response (- 40%) glycemic response glucose oxidation lipid oxidation glycogen storage
N.B.: no effect after short-term supplementation (need for n-3 FA incorporation in cell membranes ?)
J. Delarue et al, Reprod Nutr Dev, 2004
L. Browning, Proc Nut Soc, 2003
Changes in AUC for insulin (final-baseline) after supplementation with n-3 PUFA vs. placebo in premenopausal non-diabetic subjects
Subjects :
- age : 19-51 years
- BMI : 24-44 kg/m2
P < 0.05
Inflammatory status (IS) :
- low IS : sialic acid < 2.00 mM
- high IS : sialic acid > 2.20 mM
Fish oil prevents the adrenal activation elicited by mental stress in healthy men
• 7 healthy volunteers
• 2 tests of mental stress, before & after suppl 7.2g FO/d (3wks)
• Before: heart rate blood pressure energy expenditure
plasma cortisol plasma epinephrine plasma NEFAs
• After n-3 PUFA supplementation :
heart rate blood pressure energy expenditure
plasma cortisol plasma epinephrine plasma NEFAs
blunting of sympatho-adrenal stimulation (at CNS level ?)
potential role in prevention of insulin resistance
J. Delarue et al, Diabetes Metab, 2003
Diabetogenic impact of long-chain omega-3 fatty acids on pancreatic beta-cell function and the regulation of endogenous
glucose production
• Dietary saturated lipids in healthy subjects:
ins resist but ins secretion glucose tolerance maintained
• Substitution 7% dietary lipids with n-3 PUFA (4 weeks):
reverses peripheral insulin resistance (normal glucose disposal)
HOWEVER:
no suppression of hepatic insulin resistance
no suppression glucose output
no compensatory insulin secretion (+ direct impairment ?)
glucose level MJ Holness et al, Endocrinology, 2003
Body weight modulates cholesterol metabolism in non-insulin dependent type 2 diabetics
BMI, serum insulin and/or blood glucose levels: cholesterol synthesis bile acid synthesis cholesterol excretion in bile cholesterol t/o
cholesterol absorption serum cholestanol & plant sterols
PP Simonen et al, Obes Res, 2002
FFAFFA FAFA
CHOCHO
TGTG
Apo BApo B
VLDLVLDLapoBapoB
VLDL -TGVLDL -TG
LPLLPL
FAFA
IDLIDL
LDLLDL
Chylo-RChylo-R
ChyloChylo
Visceral Visceral adipose tissueadipose tissue
Lipoprotein metabolism in the metabolic syndrome
Designed from PHR Barett & GF Watts, Curr Opin Lipidol, 2003
LPLLPL
COCO22
FFAFFA FAFA
COCO22
TGTG
Apo BApo B
VLDLVLDLapoBapoB
VLDL -TGVLDL -TG
LPLLPL
FAFA
IDLIDL
LDLLDL
Chylo-RChylo-R
ChyloChylo
Visceral Visceral adipose tissueadipose tissue
Designed from PHR Barett & GF Watts, Curr Opin Lipidol, 2003
Lipoprotein metabolism in the metabolic syndrome : Effects of n-3 PUFA supplementation
LPLLPL
CHOCHO
N-3 Fatty Acids and Plasma Lipoproteins
plasma triglycerides
plasma VLDL-TG and VLDL-cholesterol
or HDL-cholesterol, but apo A-1
LDL-cholesterol (generally slight)
fraction of small dense LDL (phenotype B subjects)
Dietary effects on postprandial triglyceride levels
M. Weintraub et al, J Clin Invest, 1988
SFA
n-6 PUFA
n-3 PUFA
Differential effects of n-3 fatty acids
• Mildly hyperlipidemic subjects
- TAG conc. : 1.7g/d EPA+DHA > 9.5g/d ALA
LDL sensitivity to oxidation with 1.7g EPA+DHA
YE Finnegan et al, AJCN, 2003
- TAG conc. : comparable with 4g/d EPA and 4g/d DHA
LDL size : only with 4g/d DHA
forearm blood flow : only with 4g/d DHA
TA Mori et al, AJCN & Circulation, 2000
Regulatory effects of HMG CoA reductase inhibitor and Fish Oils on apolipoprotein B-100 kinetics in insulin-resistant obese male
subjects with dyslipidemia
• 48 obese insulin-resistant subjects 6 wks Atorva 40mg vs Omacor 4g vs Atorva+Omacor EPA/DHA : plasma VLDL-apo B
VLDL-apo B secretion VLDL to LDL conversion
Atorva : plasma apo B lipoproteins FCR of VLDL-, IDL-, LDL-apo B
Atorva + EPA/DHA : cumulative effects DC Chan, Diabetes, 2002
0
20
40
60
80
100
120
Apo-B (mg/dl)
00,20,40,60,8
11,21,4
Triacylglycerols (mmol/l)
0
1
2
3
4
5
6
Total cholesterol (mmol/l)
00,5
11,5
22,5
33,5
4
LDL-cholesterol (mmol/l)
00,20,40,60,8
11,21,41,6
HDL-cholesterol (mmol/l)
Swedish
Mediterranean
Healthy Swedish Subjects with mild hyperlipidaemia
(after 4 weeks of Mediterranean vs. Swedish diet)
A. Ambring et al, Clin Sci, 2004
P < 0.05P < 0.05
P < 0.05 P < 0.05
• Randomized single-blind trial ;120 premenopausal obese women (BMI ≥ 30) with no diabetes, hypertension, or hyperlipidemia
• Low energy mediterranean diet + physical activity vs. Healthy food + exercise
K Esposito et al, JAMA, 2003
Effect of weight loss and lifestyle changes on vascular inflammatory markers in obese women
Le Syndrome Métabolique: stratégie
• Unique ? AG n-3
effet préventif, non thérapeutique, sur insulino-résistance
inflammation défenses anti-oxydantes cellulaires
(modérée) pression artérielle
TAG HDL-chol sdLDL mais LDL-chol
• Globale nutrition : association avec AG saturés et AGMI
(alimentation type méditerranéen)
amélioration contrôle pondéral
activité physique
si indiquée, association à hypolipémiants
Le syndrome métabolique : effets des fibres (FOS) chez le rat
satiété prises alimentaires
absorption glucides & acides gras
glycémie & triglycéridémie post-prandiales
sécrétion insuline
phénomènes inflammatoires (NFkB)
possibilité effets complémentaires et/ou synergiques à ceux des AG w 3
Delivery of DHA and EPA via alpha linolenic acid is not efficient
Delivery of DHA and EPA via increased fish oil intake is very
efficient
Current intake of fish oil EPA and DHA in the USA is ~1/3 – 1/6 of
recommended levels
General Conclusions and recommendations Fish and Omega-3 fatty acid intake
• Clear benefits in secondary prevention
• Less strong evidence in primary prevention
• Include (fatty) fishes as part of healthy preventive diet
• Temporary limited intake in specific subgroups
(pregnant women & children)
• Increased intake in other specific subgroups
(high risk & hypertriglyceridaemia)
• Possibility to use (good quality) supplements
Fish and Omega-3 fatty acid intake :The unanswered questions
• Indications for primary prevention in high risk groups (renal failure, insulin-resistance, transplantation, …) ?
• Doses in different indications ?
• Effect of DHA vs. EPA ?
• Intake of ALA (and w3/w6 intake) ?
• Prevention of lipid peroxidation ?
• Optimising intestinal absorption & cell incorporation ?