Very-long-chain omega-3 fatty acids as markers for habitual fish intake in a population consuming mainly lean fish: the EPIC cohort of Gipuzkoa. European Prospective Investigation into Cancer and Nutrition

OBJECTIVE: To assess the relationship between habitual fish intake and fatty acid levels in serum as well as in the LDL fractions of serum phospholipids and cholesteryl esters. DESIGN: Cross-sectional study. SETTING: Cohort of Gipuzkoa (Basque Country, northern Spain) included in the European Prospective Investigation into Cancer and Nutrition (EPIC) project. SUBJECTS: Random sample of 120 healthy volunteers of both sexes aged 35-65 y, divided into various consumption groups according to daily fish intake. METHODS: Data on habitual intake over the previous year was collected by trained interviewers by means of a computerized questionnaire based on the diet history method. Fasting venous blood samples were drawn and fatty acids were measured by gas-liquid chromatography. RESULTS: Lean fish accounted for 78% of all fish consumption in the highest consumption group (>115 g/day) and for 60% in the lowest (<31 g/day). The mean concentrations of omega-3 polyunsaturated fatty acids (PUFA), eicosapentaenoic acid (EPA, C20:5, omega-3), and docosahexaenoic acid (DHA, C22:6, omega-3) in serum and in the LDL fractions of serum phospholipids and cholesteryl esters increased significantly from the lowest to the highest fish consumption categories. Fish intake showed a statistically significant relationship with omega-3 PUFA, EPA and DHA in serum and in the LDL fractions of serum phospholipids and cholesteryl esters both in the simple linear regression analysis and in a multiple regression model adjusted by age, body mass index (BMI) and vegetable intake. CONCLUSIONS: Habitual fish intake is reflected in the content of EPA and DHA in serum and in the LDL phospholipid and cholesteryl esters fractions. The concentrations of very-long-chain omega-3 fatty acids are useful biomarkers for dietary fish intake, mainly lean fish. SPONSORSHIP: Europe Against Cancer Programme of the European Union (agreement SOC 97 200302 05F02); 'Fondo de Investigaciones Sanitarias', Spanish Ministry of Health (FIS grant 99/0024-05); Government of the Basque Country; and 'Fundación Científica de la Asociación Espa?ola contra el Cáncer'.