An 8 week randomized Dietary Guidelines for Americans -based diet intervention improves the omega-3 index of healthy women

Abstract

Background: The Dietary Guidelines for Americans (DGA) recommends consuming >1.75g/wk of long-chain omega-3 fatty acids to reduce the risk of cardiovascular disease (CVD) through triglyceride reduction, however individual responses to treatment vary. Objective: We sought to determine if a DGA-conforming diet (DGAD) can increase the omega-3 index (OM3I), a diet-sensitive biomarker of omega-3 fatty acid status, into a health promoting range and reduce fasting triglycerides in 8 weeks. We further explored determinants of the basal OM3I and its response to treatment. Design: This is a secondary analysis of a randomized, double-blind 8wk dietary intervention of overweight/obese women fed an 8d rotating DGAD (n =22) or typical American diet (TAD; n =20) registered at www.clinicaltrials.gov as NCT02298725. The DGAD and TAD provided individuals with 16 ± 2 g/wk and 1.2 ± 0.12 g/wk of eisocapentaenoic acid (EPA) + docosahexaenoic acid (DHA), respectively. Habitual diet and body composition were determined at baseline. OM3I, fasting triglycerides, glucose and insulin were measured at 0, 2 and 8wk. Results: Baseline OM3I (5.8 ± 1.3; n =42) was positively correlated to the dietary (EPA+DHA):dietary fat ratio (p =0.006), negatively correlated to the android fat mass (p =0.0007) and was not different between diet groups. At 8wk, while the TAD-group average OM3I was unchanged (5.8 ± 0.76), the DGAD-group OM3I increased (7.33 ± 1.36; p <0.001). In the DGAD-group 9 of 22 (i.e. 41%) participants achieving an OM3I >8%. Subgroup analyses of the DGAD-group revealed that body fat content and distribution influenced the baseline-dependent response to treatment. Fasting triglyceride and OM3I changes did not correlate. Conclusions: An 8wk TAD stabilized the OM3I in a healthy range, while a DGAD increased the OM3I into a health-promoting range, but did not reduce fasting triglycerides. Fat distribution and basal omega-3 status are primary factors influencing omega-3 efficacy in overweight/obese women.

The Omega-3 Index Response to an 8 Week Randomized Intervention Containing Three Fatty Fish Meals Per Week Is Influenced by Adiposity in Overweight to Obese Women

“…An earlier versions of this manuscript has been posted as a preprint online (38). We would like to thank the following colleagues: Sean H. Adams, Lindsay H. Allen, Kevin D. Laugero, and Charles B. Stephenson for their efforts in the study design and execution of the larger study in which the current experiments were nested; Dustin Burnett for menu design and production management; Leslie Woodhouse for managing the generation of clinical data; Janet Peerson for guidance and review of statistical analyses.…”