Abstract P106: Omega-3 Fatty Acids in Erythrocyte Membranes Are Differentially Associated With Cardiometabolic Risk Factors in Brazilian and Puerto Rican Adults
Authors: Duarte Batista Lais , Fisberg Regina , Tucker Katherine L , Bigornia Sherman , E. Noel Sabrina , Harris William S , Marques Braga Ribanna Aparecida , Damasceno Nagila T , Mattei Josiemer 
Published: May 2024

Introduction:
Intake of omega-3 fatty acids (ω–3) may protect against CVD, but this evidence was generated from studies with limited ethnic diversity, and thus, findings may not be generalizable to wider populations, especially those with low habitual intake of ω–3. This study aimed to investigate the association between ω–3 in erythrocyte membranes (a biomarker of ω–3 intake) and cardiometabolic risk factors in Brazilian and Puerto Rican adults.

Hypothesis:
We hypothesized that Brazilians and Puerto Ricans have different ω–3 erythrocyte membrane composition, but that the ω–3 index is inversely associated with cardiometabolic risk factors in both populations.

Methods:
This cross-sectional analysis included 367 Brazilians living in São Paulo, Brazil, and 1,293 Puerto Ricans living in Boston, USA, aged 45-75 years, from two population-based studies: The 2015 Health Survey of São Paulo and the Boston Puerto Rican Health Study. In both studies, fatty acids composition (as % of total fatty acids) was quantified in erythrocyte membranes from fasting blood samples using a gas chromatograph with a flame ionization detector (Shimadzu, CG-2010, Kyoto, Japan). The ω–3 index was calculated as the sum of EPA and DHA. Blood lipids, waist circumference, and insulin resistance (fasting plasma glucose and HOMA-IR) were measured from standardized protocols. Generalized linear models with gamma distribution and log link or ordinary least squares regression assessed the associations of the ω–3 index and cardiometabolic risk factors.

Results:
Puerto Ricans had worse indicators for cardiometabolic risk factors than Brazilians, except for total cholesterol, LDL-c, and non-HDL-c. The mean ω–3 index did not differ between the studies (4.43% for Puerto Ricans and 4.45% for Brazilians,
P
= 0.87). However, there were less total saturated (41.2% vs. 51.5%,
P
< 0.001) and more total polyunsaturated fatty acids (41.8% vs. 31.3%,
P
< 0.001) in Puerto Ricans than Brazilians. After adjusting for age, sex, BMI, physical activity, and diet quality (AHEI-2010 without the EPA+DHA component), the ω–3 index was inversely associated with fasting plasma glucose (β ± SE = -2.78 ± 1.37,
P
= 0.044), triglycerides (β = -0.05 ± 0.02,
P
= 0.004), VLDL-c (β = -1.22 ± 0.42,
P
= 0.003), and TG-HDL-ratio (β = -0.05 ± 0.02,
P
= 0.025) in Puerto Ricans, but positively associated with total cholesterol (β = 2.74 ± 1.30,
P
= 0.035), LDL-c (β = 2.48 ± 1.15,
P
= 0.031), and non-HDL-c (β = 2.81 ± 1.27,
P
= 0.028) in Brazilians.

Conclusion:
Despite similar ω–3 indices in Brazilian and Puerto Rican adults, there were differences in the magnitude, direction, and specific cardiometabolic risk factors with which it was associated. Variations in the dietary intake and cardiometabolic profile between the populations may explain the contrasting results. Assessing specific ω–3 in diverse populations is essential when studying their role in cardiometabolic health.