Fatty acids in serum phospholipids and carotid intima media thickness in Spanish subjects with primary dyslipidemia
Fatty acids in serum phospholipids and carotid intima media thickness in Spanish subjects with primary dyslipidemia
Year: 2010
Authors: SalaVila, A. Cofan, M. PerezHeras, A. Nunez, I. Gilabert, R. Junyent, M. et al
Publication Name: Am J Clin Nutr.
Publication Details: Volume 92; Number 1; Pages 186-193
Abstract:
Low rates of incident ischemic heart disease (IHD) and cardiac death occur in Spain despite a high prevalence of cardiovascular risk factors. High consumption of unsaturated fatty acid rich foods, such as olive oil, nuts, and seafood, might underlie this paradox. We investigated whether serum phosphatidylcholine enrichment in oleic, linoleic, alpha linolenic, and n3 (omega3) long chain polyunsaturated fatty acids (as biomarkers of olive oil, seed oil, walnut, and fish intake, respectively) relate to carotid atherosclerosis in Spanish subjects at risk of IHD. In a cross sectional study, we measured fatty acid concentrations in serum phosphatidylcholine and measured carotid intima media thickness (IMT) by using ultrasound in 451 asymptomatic subjects (261 men, 190 women; mean age 45 y) with primary dyslipidemia. Main and secondary outcomes were mean and maximum IMT in the common carotid artery (CCA) and other carotid segments, respectively. Phosphatidylcholine fatty acid composition was similar to that reported for other Spanish populations. Multiple regression analyses showed that proportions of oleic and docosahexaenoic acids were inversely related to mean CCA IMT (P less than 0.02, all) after adjustment for several confounders. In similar models, alpha linolenic acid related inversely to mean and maximum internal carotid artery IMT (P less than 0.05 for all). Linoleic and eicosapentaenoic acids were unrelated to IMT. Higher phospholipid proportions of oleic, alpha linolenic, and docosahexaenoic acids showed inverse associations with IMT at specific carotid segments in subjects with primary dyslipidemia. High intakes of healthy fats might explain, in part, the Spanish paradox of low IHD rates in the face of a high burden of cardiovascular risk factors. (Authors abstract)
Ischemic heart disease (IHD) is a leading cause of death in the world. Low rates of both incident IHD and cardiac death occur in some populations despite a high background prevalence of cardiovascular risk factors. Spain, a Mediterranean country, is a paradigmatic case of this paradox. Local dietary habits are thought to be responsible, in part, for IHD protection in Mediterranean countries, as suggested by the evidences of the beneficial effect of a greater adherence to the Mediterranean diet on cardiovascular mortality. Tissue or blood membrane proportions of PUFAs are good biomarkers of their intake, and blood phospholipid enrichment with these fatty acids, particularly ALA and DHA, have been shown to be consistently lower in patients with IHD than in healthy subjects. A well validated surrogate marker of future IHD events is carotid intima media thickness (IMT). The authors hypothesized that the proportions of unsaturated fatty acids in plasma phospholipids (as markers of intake) would be inversely related to carotid IMT in Spanish individuals. To address this issue, the fatty acids of serum phosphatidylcholine and carotid IMT were measured in 451 Spanish subjects with primary dyslipidemia who were well phenotyped for cardiovascular risk factors. The results confirmed the hypothesis that the main unsaturated fatty acids characteristic of Mediterranean foods that are highly consumed in Spain, namely OA from olive oil, ALA from walnuts. and DHA from fish, would show inverse associations with carotid IMT. First, the OA proportion of serum phosphatidylcholine was independently and inversely related to mean CC IMT in the population with a high intake of olive oil. Second, the results showed that the DHA proportion of serum phosphatidylcholine was also inversely related to mean CCA IMT. Third, ALA in serum phosphatidylcholine was inversely related to mean and maximum IMT in the ICA and nearly related to mean IMT of the bifurcation. In both the bifurcation and the internal carotid atherosclerosis is accelerated because of hemodynamic factors. IMT enlargement of these segments is a marker of more advanced disease than increased CCA IMT. Finally, the LA proportion in serum phosphatidylcholine was nonsignificantly related to maximum bifurcation and ICA IMT. The proportion of LA in tissues, a valid marker of intake of seed oils rich in LA, such as sunflower oil appears to be unrelated to IHD risk. These subjects barely consumed sunflower oil (the major seed oil for culinary use in Spain), but this oil is used by the food industry to produce snacks and other fatty foods of which the study subjects consumed sizeable amounts. Thus, the borderline direct relation between LA and carotid IMT might depend more on the characteristics of the foods containing it than on the proportions of LA proper. In conclusion, both DHA and OA in serum phosphatidylcholine related inversely to mean CCA IMT, whereas ALA was inversely related to mean IMT at plaque prone carotid segments in asymptomatic Spanish subjects with primary dyslipidemia. Because the major food sources of these fatty acids (fish, olive oil, and nuts) are key components of the Mediterranean diet, the results provide additional evidence of the anti atherosclerotic effect of this dietary pattern. The results might also explain, in part, the Spanish paradox of low IHD rates in the face of a high burden of cardiovascular risk factors. (Editors comments)
