Clinical correlates and heritability of erythrocyte eicosapentaenoic and docosahexaenoic acid content in the Framingham Heart Study.
OBJECTIVE
Red blood cell (RBC) levels of eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA, the omega-3 index, expressed as a percent of total fatty acids) are inversely related to risk for cardiovascular disease (CVD). Although several mechanisms underlying this relationship have been proposed, understanding the associations between the omega-3 index and markers of CVD in the community can shed additional light on this question. The objectives of this study were to define the relations between the omega-3 index and clinical factors and to determine the heritability of the omega-3 index.


METHODS
RBC samples (n = 3196) drawn between 2005 and 2008 from participants in the Framingham Study [Examination 8 of the Offspring cohort plus Examination 3 of the Omni (minorities) cohort] were analyzed for fatty acid composition by gas chromatography.


RESULTS
The mean (SD) omega-3 index was 5.6% (1.7%). In multivariable regression models, the factors significantly and directly associated with the omega-3 index were age, female sex, higher education, fish oil supplementation, dietary intake of EPA + DHA, aspirin use, lipid pharmacotherapy, and LDL-cholesterol. Factors inversely associated were Offspring cohort, heart rate, waist girth, triglycerides and smoking. The total explained variability in the omega-3 index for the fully adjusted model was 73%, which included major components due to heritability (24%), EPA + DHA intake (25%), and fish oil supplementation (15%).


CONCLUSIONS
The variability in the omega-3 index is determined primarily by dietary and genetic factors. An increased omega-3 index is associated with a generally cardioprotective risk factor milieu.
Sanford Research/USD, 2301 E. 60th St. N, Sioux Falls, SD 57104, USA. bill@omegaquant.com
William S
WS
Harris
James V
JV
Pottala
Sean M
SM
Lacey
Ramachandran S
RS
Vasan
Martin G
MG
Larson
Sander J
SJ
Robins
D000368:Aged; D002318:Cardiovascular Diseases / Q000097:blood* / Q000453:epidemiology / Q000235:genetics* / Q000517:prevention & control; D016009:Chi-Square Distribution; D002849:Chromatography, Gas; D019587:Dietary Supplements; D004281:Docosahexaenoic Acids / Q000097:blood* / Q000627:therapeutic use; D015118:Eicosapentaenoic Acid / Q000097:blood* / Q000627:therapeutic use; D004912:Erythrocytes / Q000378:metabolism*; D005260:Female; D020022:Genetic Predisposition to Disease; D040941:Heredity; D006801:Humans; D016018:Least-Squares Analysis; D016014:Linear Models; D050356:Lipid Metabolism / Q000235:genetics*; D008297:Male; D008404:Massachusetts / Q000453:epidemiology; D008875:Middle Aged; D015999:Multivariate Analysis; D010641:Phenotype; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors
D004281:Docosahexaenoic Acids; D015118:Eicosapentaenoic Acid