Summary
Background
The outcome of coronary diseases is influenced by lifestyle and diet. Among dietary factors, n-3 polyunsaturated fatty acids reduce mortality from cardiovascular diseases.
Aims
To evaluate the impact of dietary and lifestyle advice by calculation of scores and analysis of plasmatic lipids and the fatty acid composition of erythrocyte membrane phospholipids after 1 year of patient education in 66 patients with acute coronary syndromes.
Methods
The answers given by patients during questioning were transformed into scores (atherosclerosis risk, dietary habits and global scores) at inclusion and after 1 year of follow-up. Classical metabolic risk factors and fatty acid composition of erythrocyte phospholipids were determined at the same time.
Results
After 1 year of education, patients improved their different scores, particularly by changing dietary habits. The positive impact was seen in the blood lipid and erythrocyte fatty acid levels: plasma low-density lipoprotein cholesterol and triglyceride concentrations were lowered and n-3 polyunsaturated fatty acid percentages were improved in phospholipids.
Conclusion
Global score, lipid variables and the nature of the polyunsaturated fatty acids in erythrocyte phospholipids help us to evaluate patients with high coronary artery disease risk and the benefits of long-term dietary and lifestyle advice.
Résumé
Contexte
Le pronostic des patients après un syndrome coronaire aigu dépend du mode de vie et de l’alimentation. Parmi les facteurs alimentaires, les acides gras poly-insaturés n-3 réduisent la mortalité associée aux maladies cardiovasculaires.
Objectif
Évaluer l’impact de l’éducation nutritionnelle pendant un an de 66 patients, ayant présenté un syndrome coronaire aigu, par la mise en place de scores de risque cardiovasculaire et de l’hygiène de vie et l’analyse concomitante des lipides plasmatiques du profil des acides gras des phospholipides érythrocytaires.
Méthodes
Les réponses à des items d’un entretien des patients ont été transformées en scores numériques (scores de risque d’athérosclérose, des habitudes alimentaires et score global d’hygiène de vie) à l’inclusion des patients et après un an de suivi. Les facteurs de risques métaboliques classiques ainsi que la composition des acides gras des phospholipides érythrocytaires ont été déterminés au moment des entretiens.
Résultats
Après un an d’éducation thérapeutique, les patients ont amélioré leurs différents scores, notamment par des changements de leurs habitudes alimentaires. Cette amélioration a été également retrouvée au niveau des paramètres lipidiques sanguins et de la nature des acides gras érythrocytaires : les concentrations plasmatiques de LDL-cholestérol et de triglycérides ont été diminuées et les pourcentages d’acides gras poly-insaturés améliorés dans les phospholipides des globules rouges.
Conclusion
L’établissement d’un score d’hygiène de vie ainsi qu’un dosage des lipides plasmatiques et un profil des acides gras des phospholipides érythrocytaires réalisés de façon concomitante nous permettent (1) d’évaluer les patients qui ont un risque important de maladie coronarienne et (2) d’établir de manière objective les bénéfices à long terme d’une éducation nutritionnelle.
Abbreviations
AA
arachidonic acid
ACS
acute coronary syndrome
ALA
α-linolenic acid
DHA
docosahexaenoic acid
EPA
eicosapentaenoic acid
LA
linoleic acid
MUFA
monounsaturated fatty acid
PUFA
polyunsaturated fatty acid
SFA
saturated fatty acid
Background
Multiple lines of evidence support the view that lifestyle and diet influence the outcome of patients with coronary diseases . Among nutritional factors, fatty acids – especially SFAs – are associated with a high risk of cardiovascular mortality and morbidity; their replacement with PUFAs reduces the risk of coronary events . The n-3 PUFAs, specifically of animal (fish) origin (i.e. EPA and DHA), tend to be linked with a lower risk of death associated with coronary heart diseases . The n-6/n-3 fatty acid ratio is considered to be an important determinant in the prevention and management of coronary heart disease, but the usefulness of this ratio is controversial .The fatty acid composition of membrane phospholipids plays a major role in membrane properties, such as fluidity and susceptibility to free radical attack. PUFAs are important components of cell membranes and influence cellular functions by regulating several metabolic pathways, such as the synthesis of inflammatory mediators . While dihomo-gamma linolenic acid (C20:3 n-6) is the precursor of 1-series prostaglandins, AA (C20:4 n-6) is the precursor of eicosanoid 2-series prostaglandins and thromboxanes and 4-series leukotrienes, with potent prothrombotic, proinflammatory and possibly proatherogenic effects . Because it is a competitive substrate for the AA-cascade enzyme, EPA (the precursor of 3-series prostaglandins and thromboxanes and 5-series leukotrienes) has anti-inflammatory, vasodilator and platelet antiaggregant effects, and leads to the synthesis of resolvin . The fatty acid composition of cell membranes is dependent on both dietary fat intake and metabolic pathways . However, the conversion of LA (18:2 n-6) into AA and of ALA (18:3 n-3) into EPA and DHA is poor in humans , and these PUFAs are mainly dietary in origin.
The reduction of cardiovascular risk in patients with ACS requires modification of their lifestyle. An unrestricted, low-fat, high-fibre diet combined with daily exercise can significantly improve risk factors for coronary artery diseases and diabetes . In the secondary prevention of coronary heart disease, dietary trials with low saturated fats, increased intake of n-3 fatty acids of marine or plant origin and high consumption of fruits and vegetables were associated with reduced cardiovascular morbidity and mortality, similar to that induced by the cholesterol-lowering statin .
Adherence to dietary and lifestyle recommendations is generally evaluated by questionnaires, but biological markers are not used systematically. Because red blood cells lack the capacity for de novo fatty acid synthesis or modification by desaturation or elongation, erythrocyte phospholipids are a good marker of PUFA intake . This led us to compare the fatty acid composition of red blood cell membrane phospholipids and a global score in patients with an ACS, at hospital admission and after 1 year of nutritional and lifestyle education.
Materials and methods
Subjects and scores
This was an observational, non-randomized study. Sixty-six patients hospitalized for a first episode of ACS (44% single-vessel disease; 30% two-vessel disease; 21% three-vessel disease; 5% subnormal coronary angiography) were included and gave their informed consent to participate in this study. Blood samples were collected in the 6 consecutive hours from pain onset. None of the patients had received dietary advice previously; they had a personal consultation at baseline and every 6 months with a nurse specializing in patient education. This education aims to decrease their cardiovascular risk factors and modify their food habits. The recommendations followed the European dietary guidelines for secondary prevention, with limited intake of SFAs, increased consumption of fruits and vegetables, whole grain cereals and bread, low-fat dairy products, and fish and lean meat .
The initial questioning (time of inclusion [T0]) allowed the collection of items concerning atherosclerosis risk ( Table 1 ) and dietary habits ( Table 2 ), which were converted into scores. The sum of these two scores gave a global score . The more positive the score, the higher the cardiovascular risk. Patients had blood drawn again, 1 year later (T1). At this time of evaluation, all patients were being treated with statins. Twenty healthy controls were matched by age (58 ± 10 years for patients vs 58 ± 6.7 years for controls) and sex (81% men for patients vs 75% men for controls) and benefited from one consultation to establish their scores but did not receive any patient education. The study protocol was approved by a Human Investigation Ethical Committee (Number 2004/60; Comité consultatif pour la protection des personnes dans des recherches biomédicales de Bordeaux A ) on 6 October 2004.
| Risk factor | Points |
|---|---|
| Body mass index, kg/m 2 | |
| 25–30 | +2 |
| > 30 | +3 |
| Tobacco consumption | |
| Stopped for < 5 years | +0.5 |
| 1–10 cigarettes/day | +1 |
| 11–20 cigarettes/day | +2 |
| ≥ 21 cigarettes/day | +3 |
| Diabetes a | +2 |
| Hypercholesterolaemia a | +3 |
| Arterial hypertension a | +3 |
| Physical exercise | |
| > 2 hours of physical exercise/week | −3 |
| Sedentary lifestyle | +3 |
| Average mobility | 0 |
| Dietary habit | Points |
|---|---|
| Number of glasses of wine/day | |
| 0 | 0 |
| 1–2 | −3 |
| 3–4 | +1 |
| > 4 | +3 |
| Meals containing pork delicatessen | |
| 1–2 | +1 |
| > 2 | +3 |
| Poultry consumption | |
| 1–2/day | −1 |
| 1/day to 1/week | 0 |
| 1/week or never | +1 |
| Never but consumes beef | +2 |
| Red or fatty meat (sheep or pig) | |
| 2/day | +3 |
| 1/day | +2 |
| 1/day to 1/week | +1 |
| 1/week or never | 0 |
| Fish | |
| 1/day or several times/week | −3 |
| 1/week or never | 0 |
| Never but consumes beef | +1 |
| Eggs | |
| ≥ 3/week | +1 |
| Green vegetables | |
| Every meal | −3 |
| Every other meal | −1 |
| Less frequently than every other meal | +1 |
| Usual fat consumption | |
| Olive, rapeseed oil | −1 |
| Unsaturated oil, if not olive or rapeseed | −0.5 |
| Sunflower oil | 0 |
| Peanut oil | +1 |
| Butter | +2 |
| Margarine containing trans fatty acids | +1 |
| Margarine containing n-3 fatty acids | −1 |
| Cheese | |
| Every meal | +3 |
| Every other meal | +2 |
| Less frequently than every other meal | 0 |
| Fruits/day | |
| 0 | +3 |
| 1 | +1 |
| 2 | 0 |
| 3 | −1 |
| ≥ 4 | −2 |
| Cakes/week | |
| 0–1 | 0 |
| 2 | +1 |
| ≥ 3 | +2 |
Determination of blood and erythrocyte variables
All the described variables were measured in the same blood sample. Serum lipids (total cholesterol, high-density lipoprotein cholesterol and triglycerides) were measured in the hospital clinical laboratory by routine enzymatic methods (Cobas Integra 800, Roche Diagnostics, Meylan, France). Low-density lipoprotein cholesterol was calculated by the Friedewald equation. Erythrocyte fatty acid composition was determined by capillary gas chromatography. Red blood cells were separated from plasma by centrifugation at 1730 g for 10 minutes at 4 °C and washed three times with an equal volume of cold physiological (9 g/L NaCl) solution. Lipids were extracted and phospholipids were isolated by thin layer chromatography on silica gel 60 plates (E Merck, Darmsmat, Germany). Fatty acid methyl esters were obtained by transmethylation of the phospholipid fraction in acetyl chloride (Interchim, Montluçon, France) 20% in methanol and separated by gas chromatography. The fatty acid analysis was carried out with a Dani GC 1000 gas chromatograph equipped with a CP-Wax 58 capillary column, 50 m in length, 0.25 mm external diameter, 0.2 μm thickness of the stationary phase (Varian Inc., Les Ulis, France), with helium 1 mL/min as carrier gas and a programmed temperature (60–230 °C). A programmed temperature vaporization injector and a flame ionization detector were used. 1-2 dinonadecanoyl-sn glycerol-3 phosphatidyl choline (Interchim, Montluçon, France) was used as internal standard.
Fifteen membrane phospholipid fatty acids were determined:
- •
two SFAs (palmitic acid C16:0 and stearic acid C18:0);
- •
two MUFAs (oleic acid C18:1 n-9 and palmitoleic acid C16:1 n-7);
- •
six n-6 PUFAs (LA C18:2, gamma linolenic acid C18:3, dihomo-gamma linolenic C20:3, AA C20:4, docosatetraenoic acid C22:4 and docosapentaenoic acid C22:5);
- •
four n-3 PUFAs (ALA C18:3, EPA C20:5, docosapentaenoic acid C22:5, DHA C22:6);
- •
one n-9 PUFA (eicosatrienoic acid C20:3).
Statistical analyses
Statistical analyses were performed with Systat version 8.0 software. The relationship between the variables studied was assessed using a principal component analysis based on correlation matrix. The mean differences in the variables between the two time points were tested by the Wilcoxon signed rank test. The mean differences between the patient population and the control population were tested by the non-parametric Mann-Whitney test. Differences were considered to be significant at p < 0.05.
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