Association of dietary intake of total fat and fatty acids with the Omega-3 Index: a cross-sectional analysis of NHANES 2011–2012

Abstract

BACKGROUND/OBJECTIVES The Omega-3 Index (O3I), which is the total eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in erythrocytes as a percentage of total fatty acids (FAs), is associated with fish intake. O3I also varies with body mass index, age, sex, and dietary factors other than the intake of n-3 polyunsaturated fatty acids (PUFAs). This study examined the relationship between the dietary intake of total fat and FA classes, and O3I, specifically regarding EPA+DHA intake.

SUBJECTS/METHODS Data on dietary intake and serum FAs from 2,370 participants (1,192 males and 1,178 females) aged 18–79 yrs, collected during the 2011–2012 National Health and Nutrition Examination Survey, were used in this study. The O3I was estimated from the serum EPA+DHA content.

RESULTS In the total population, O3I showed an inverse correlation with the intake of total fat (r = -0.417), saturated FAs (SFAs; r = -0.423), and monounsaturated fatty acids (MUFAs; r = -0.412) (P < 0.01). Similar relationships were observed among males. However, in females, only SFA intake was correlated with O3I (r = -0.386, P < 0.05). In contrast, no correlation was observed between n-6 PUFA intake and O3I. Multivariable regression analysis also showed that a 1% increment in energy provided by total fat, SFA, and MUFA corresponded to reductions of 0.019, 0.055, and 0.035 units in O3I, respectively (P < 0.01). Both SFA and MUFA intakes mediated the negative relationship between total fat intake and O3I in the total population and males. However, MUFA were not significant mediators in women.

CONCLUSION The intakes of total fat, SFA, and MUFA negatively influenced O3I, independent of n-3 PUFA intake.