Fatty acid profile, vitamin D, and iodine status in Taiwanese vegans, vegetarians, and omnivores

A BSTRACT Objectives: Vegan diet – the exclusion of all animal products, even eggs and dairy – ranked the most climate-friendly diet, but concerns persist regarding its nutritional adequacy, particularly for omega-3 fatty acids, vitamin D, and iodine. This study compares the nutritional status of fatty acids, vitamin D, and iodine, among Taiwanese vegans, vegetarians, and omnivores. Materials and Methods: This cross-sectional study included 45 omnivores, 46 lacto-ovo vegetarians, and 24 vegans. Blood and urine samples were collected to analyze nutritional biomarkers, including erythrocyte fatty acid profiles, plasma vitamin D, and urinary iodine. Results: Vegans had the lowest median percentage of saturated fatty acids, trans-fatty acids, and omega-3 fatty acids, including EPA and DHA, but the highest levels of omega-6 fatty acids. The medians (P25–P75) of omega-3 index values were 2.6 (2.4–2.8), 3.7 (3.2–4.5), and 5.8 (5.0–6.5) for vegans, vegetarians, and omnivores, respectively. Vitamin D deficiency was most prevalent among vegans (75%), followed by omnivores (36%) and vegetarians (24%). Iodine insufficiency was also more common in vegans (76%) than in vegetarians (57%) and omnivores (56%). Conclusion: Taiwanese vegan diets may be advantageous in lowering saturated fatty acids and trans-fatty acid status but may be associated with a higher risk of deficiency for omega-3 fatty acids, vitamin D, and iodine. Strategies to enhance the adequacy of these nutrients may be needed to improve the quality of vegan diets.