Oral Presentation 49th Nutrition Society of Australia Annual Scientific Meeting 2025

Predictors of omega-3 long-chain polyunsaturated fatty acid status in a vegan population (130051)

Welma Stonehouse 1 , Hajar Mazahery 1 2 , Kelly Joy 1 , Kathryn L Beck 3 , Cath A Conlon 3 , Karen Mumme 3 , Pamela R von Hurst 3
  1. Institute for Physical Activity and Nutrition (IPAN), School of Exercise and Nutrition Sciences, Deakin University, Burwood, VIC, Australia
  2. Curtin School of Population Health, Curtin University, Perth, WA, Australia
  3. School of Sport, Exercise and Nutrition, College of Health, Massey University, Auckland, New Zealand

Vegans exclude animal-based foods, including oily fish, a key source of omega-3 long-chain polyunsaturated fatty acids (n-3 LCPUFA). Consequently, vegans are at risk of low  n-3 LCPUFA status(1), which may adversely affect brain function, mental health, eye health, and pregnancy outcomes(2). The omega-3 index (O3I; % of total fatty acids in red blood cells as eicosapentaenoic acid [EPA] + docosahexaenoic acid [DHA]) is a biomarker, with targets > 8% associated with improved health(2). Personalised (individual-level) and precision (group-level) strategies to reach this target require understanding the factors influencing O3I. While vegans are advised to consume plant-based omega-3 supplements and alpha-linolenic acid (ALA) food sources(3), ALA conversion to EPA and DHA is limited and further reduced by high linoleic acid (LA) intakes, common in plant-based diets, due to substrate competition. Conversion is more efficient in females(1). This study investigated n-3 LCPUFA status and predictors of O3I among vegans. Data (n = 199; 53 males, 146 females) were derived from the Vegan Health Study, a cross-sectional study in Auckland, NZ. Inclusion criteria were healthy adults (≥ 18 years), vegan ≥ 2 years, not pregnant/breastfeeding, and Auckland-based. Demographic, anthropometric, body composition, and supplement data were collected. O3I, blood LA and ALA (dietary intake markers) were assessed from finger-prick dried blood spots. Multiple regression analysis identified predictors of log-transformed O3I. Variables included were log LA:ALA ratio, age, sex, smoking, BMI, and algae-supplement use. Values are median (25th, 75th percentile). O3I ranged from 1.95% to 6.64%, with >92% having an O3I ≤ 4%, and none achieving > 8%. Median O3I was 3.1% (2.7, 3.5)%. Only 16% used algae supplements. Median blood LA:ALA ratio was 36.5 (28.8, 47.5). O3I was positively associated with algae-supplement use (p < 0.001) and female sex (p = 0.04), and negatively with blood LA:ALA ratio (p = 0.01) (Adjusted model R² = 0.14; p < 0.001). In conclusion, O3I levels in this vegan population is very low(3), with minimal supplement use. Female sex and algae-supplementation were positive predictors, while LA:ALA ratio was negatively associated with O3I. Dietary recommendations for vegans should emphasise increasing ALA-rich food intake (e.g., flax, chia, hemp seeds and oils), reducing LA-rich sources (e.g., soybean, sunflower oil), and increasing algae-supplement use to support optimal O3I. Dietary modelling studies may help identify practical ways to adjust LA:ALA ratios, particularly for foods rich in both LA and ALA, and common in vegan diets (e.g., tofu, walnuts), while maintaining overall nutrient adequacy.  

  1. 1. Klein L, Lenz C, Krüger K et al. (2025) Lipids Health Dis, 24, 133. 2. Schuchardt JP, Beinhorn P, Hu XF et al. (2024) Prog Lipid Res, 95, 101286. 3. Craig WJ, Mangels AR. (2009) J Am Diet Assoc, 109, 1266-82.
  2. 2. Schuchardt JP, Beinhorn P, Hu XF et al. (2024) Prog Lipid Res, 95, 101286.
  3. 3. Craig WJ, Mangels AR. (2009) J Am Diet Assoc, 109, 1266-82.