Determinants of Blood Cell Omega-3 Fatty Acid Content

Abstract

BACKGROUND: Although red blood cell eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA) content (the Omega-3 Index) predicts cardiovascular death, the factors determining the Index are unknown. METHODS: In 704 outpatients, we undertook an investigation of the clinical determinants of the Index. RESULTS: Factors associated with the Index in decreasing order were: EPA+DHA supplement use, fish consumption frequency, triglyceride level, age, high cholesterol history, and smoking. These factors explained 59% of Index variability, with capsules/fish intake together accounting for 47%. The Index increased by 13% (p< 0.0001) for each serving level increase in fish intake and EPA+DHA supplementation correlated with a 58% increase (p< 0.0001) regardless of background fish intake (p=0.25; test for interaction). A 100 mg/dL decrease in serum triglycerides was associated with a 15% higher (p<0.0001) Index. CONCLUSIONS: The intake of EPA+DHA-rich foods and supplements principally determined the Omega-3 Index, but explained only about half of the variability.

Figure 1

Multiplier effects on the Omega-3 Index for all predictors included in the final multivariable log-normal regression model. The fish consumption estimates are compared to the reference of never eating fish. Data are presented as point estimates with 95% confidence intervals.

Figure 2

Raw data of the Omega-3 Index with 95% confidence intervals for each group with a combination of fish intake frequency and fish oil supplementation status, including group samples sizes.