Age-related alterations in blood fatty acid composition and ratios, omega-3 fatty acid Levels and association with PhenoAge acceleration: a cross-sectional analysis of the NHANES 2021-2023 data

Introduction

Polyunsaturated fatty acid (PUFA) status is an important marker of metabolic health across the lifespan, and omega-3 (n-3) PUFA were shown to have anti-inflammatory and cardioprotective effects. The omega-3 index, a composite of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), is widely used to assess n-3 PUFA supplementation status, and product-to-precursor fatty acid ratios are used as proxy indices of desaturation and elongation. Previous data indicate a higher proportion of n-3 PUFA with age. Whether the same pattern can be found in an NHANES cohort, and whether long-chain n-3 status relates to phenotypic age (PhenoAge), a composite measure of biological age, has not been established.

Methods

We analyzed erythrocyte fatty acid profiles measured by electron capture negative-ion mass spectrometry in erythrocytes of participants of the National Health and Nutrition Examination Survey (NHANES) 2021-2023. Adults aged 20-79 years with a complete 21-fatty-acid panel were included (n = 4,863) and stratified into five age groups (20-34, 35-44, 45-54, 55-64, 65-79 years). In the fasting subsample with a measured fasting glucose (n = 2,822) we additionally computed PhenoAge according to Levine and assessed PhenoAge acceleration (PhenoAge regressed on chronological age) in relation to EPA and DHA.

Results

Percentage of summarized PUFA and n-6 PUFA decreased with age while percentage of n-3 PUFA and EPA + DHA increased. In contrast, total saturated fatty acids did not differ across age groups. EPA and DHA rose with age, whereas linoleic acid (LA), dihomo-γ-linolenic acid (DGLA) and α-linolenic acid (ALA) declined. The delta-5-desaturase (D5D) index (AA/DGLA) and the AA/LA ratio were positively associated with age, while elongation-related proxies ELOVL2 (DTA/AA, DPA/EPA) and ELOVL5 (DGLA/GLA) were inversely associated.

Higher EPA + DHA was associated with lower PhenoAge acceleration with the most pronounced effect of - 4,7 years in the group with highest (≥8%) EPA+DHA content.

Discussion

Age-related shifts in erythrocyte PUFA composition and in desaturase and elongase proxy indices reported previously in a clinical cohort from Germany are reproduced in a large US population. In addition, long-chain n-3 status was inversely associated with PhenoAge acceleration.