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

Authors: RICHARDSON, CHRISTINE - University Of California, Davis; KRISHNAN, SRIDEVI - University Of California, Davis; Gray, Ira; Keim, Nancy; Newman, John

Submitted to: Frontiers in Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/12/2022
Publication Date: 2/4/2022
Citation: Richardson, C.E., Krishnan, S., Gray, I.J., Keim, N.L., Newman, J.W. 2022. 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. Frontiers in Nutrition. 9. Article 810003. https://doi.org/10.3389/fnut.2022.810003.
DOI: https://doi.org/10.3389/fnut.2022.810003

Interpretive Summary: 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 individuals level of omega-3 fatty acids in their body at the time they start consuming these nutrients will influence how quickly such a dietary intake will influence their status. In this study, we sought to determine if consuming a DGA-conforming diet (DGAD) can increase a persons omega-3 status into a health promoting range and reduce fasting triglycerides in 8wks, while exploring factors including diet and body fat distribution, that influence a persons omega-3 status and their response to dietary omega-3 fatty acids. To accomplish this, overweight to obese women were randomly assigned to an 8d rotating DGAD (n =22) or typical American diet (TAD; n =20) menu. Neither the study participants nor the researchers new which group individuals were assigned to. The DGAD and TAD provided individuals with 16 ± 2 g/wk and 1.2 ± 0.12 g/wk of the long chain omege-3 fatty acids eisocapentaenoic acid (EPA) + docosahexaenoic acid (DHA), respectively. Habitual diet and body composition were determined at baseline, while omega-3 status, fasting triglycerides, glucose and insulin were measured at 0, 2 and 8wk. We found that the study group baseline omega-3 status, which was in the neutral range with regards to cardiovascular risk, was positively correlated to the estimated dietary long chain fatty acids as a percentage of total fatty intake, but not the reported estimates of the omega-3 fatty acids themselves. In addition, women with higher levels of fat in there upper body and buttocks (i.e. an apple shaped body) had lower omega-3 status at the beginning of the study. After 8wk of feeding the TAD-group omega-3 status remained unchanged, while the DGAD-group increased significantly, with 9 of 22 (i.e. 41%) participants reaching a health promoting level. However, roughly half of the women in the DGAD group had a strong response to the diet, while the other half had a weak response, with the baseline-dependent response to treatment being influenced by body fat content and its distribution. Fasting triglyceride were not changed. Therefore, consuming a TAD for 8wks can stabilize the omega-3 status in a healthy range, while consuming a DGAD for the same period of time can increase the omega-3 status into a health-promoting range, but did not reduce fasting triglycerides. The distribution of fat on a womens body and their omega-3 status at the time they start on the diet are primary factors influencing the ability of these dietary omega-3 fatty acids to shift the omega-3 status in overweight women.

Technical 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 basal omega-3 status is inversely correlated to treatment efficacy. Objective: We sought to determine if a DGA-conforming diet (DGAD) can increase the omega-3 index (OM3I) into a health promoting range (i.e. >8%) and reduce fasting triglycerides in 8wks, while exploring dietary and body composition determinants of basal OM3I and the OM3I response to treatment. Design: This is a secondary analysis of a randomized, double-blind 8-wk dietary intervention in overweight and 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 and fasting triglycerides, glucose and insulin were measured at 0, 2 and 8wk. Results: The cohort baseline OM3I (5.8 ± 1.3; n =42) was positively correlated to the dietary (EPA+DHA):saturated fat ratio (p =0.006), negatively correlated to the android fat mass (p =0.0007) and was equivalent between diet groups. At 8wk, the TAD-group OM3I remained unchanged (5.8 ± 0.76), while the DGAD-group OM3I increased (7.33 ± 1.36; p <0.001) with 9 of 22 (i.e. 41%) participants achieving an OM3I >8%. DGAD subgroups indicated that baseline-dependent response to treatment was influenced by body fat content and distribution . 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 women.