Abstract
Plant-based diets are becoming increasingly popular, and scientific information concerning the nutritional status in this population is needed. This study determined the fatty acid profile of Spanish lacto-ovo vegetarians (LO-vegetarians) and vegans. Participants were 104 healthy adults, LO-vegetarians (n = 49) and vegans (n = 55). Lifestyle habits and consumption of food and omega-3 supplements were estimated by questionnaires. BMI, blood pressure, and abdominal and body fat were determined. Serum was collected to analyze fatty acids, glucose, lipids, homocysteine, insulin, and leptin. Volunteers were classified according to serum omega-6 to omega-3 (n-6/n-3) ratio into three groups: n-6/n-3 < 10, n-6/n-3 ≥ 10 to 20, and n-6/n-3 > 20. Results showed low cardiovascular risk and high insulin sensitivity with negligible differences between diet types. Linoleic acid (C18:2n-6) was the major serum fatty acid, followed by oleic (C18:1n-9) and palmitic (C16:0) acids. In contrast, serum eicosapentaenoic acid (EPA, C20:5n-3) and docosahexaenoic acid (DHA, C22:6n-3) were (median, interquartile range) 0.27, 0.18% and 1.59, and 0.93%, respectively. Users of n-3 supplements (<10% of total vegetarians) had significantly higher EPA than non-users, while frequent consumption of flax-seeds was associated with increased α-linolenic acid (C18:3n-3). However, neither n-3 supplementation nor food consumption affected DHA levels in this vegetarian population.
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Key Points
Assessment of fatty acids intake can be based on dietary questionnaires and food composition databases. However, information on the composition of new foods and vegetarian foods is lacking or incomplete, which limits the applicability of this procedure. Currently, the use of intake biomarkers is preferred. Therefore, in the present study, serum fatty acids were analyzed as short-term intake markers. Participants were healthy young adults, with similar sample sizes of LO-vegetarians and vegans, and less than 10% of the volunteers consumed n-3 supplements. Lifestyle habits, body composition, physical activity, and cardiometabolic markers indicate that this population has low cardiovascular risk and high insulin sensibility.
The major serum fatty acid was LA, followed by OA and PAL; while levels of n-3 PUFA, except for ALA, were low in comparison with the data reported for general population. These results show an inadequate n-6/n-3 ratio, indicating a metabolic imbalance. Moreover, vegans presented higher OA (and consistently higher MUFA and OA/STE) and lower ELA, the trans isomer of OA, compared to LO-vegetarians. This trans fatty acid is a marker of ultra-processed food, e.g., margarine, chocolate, potato flakes, potato fries, breakfast cereals, etc. which would suggest a more unfavorable diet in LO-vegetarians than vegans. Vegans presented lower n-3 levels than LO-vegetarians, which can be mainly attributed to their lower percentage of DHA; but the fatty acid profiles did not markedly differ between these groups.
As the group with n-6/n-3 < 10 included consumers and non-consumers of n-3 supplements, the influence of any specific food item intake on serum long-chain n-3 fatty acids was evaluated and showed similar consumption patterns of nuts and oils in the three n-6/n-3 groups while among the seeds, results suggest an improvement of the n-6/n-3 ratio associated with higher frequency of consumption of flax-seeds.
Fatty acid profile of Spanish LO-vegetarians and vegans is characterized by high levels of LA and OA, as olive oil is widely consumed in this Mediterranean population. However, levels of long-chain n-3 fatty acids are very low, and consumption of n-3 supplements is associated with an increase in EPA but not DHA. Similarly, frequent consumption of ALA-rich seeds is reflected in serum ALA levels, but further conversion to EPA and DHA is undetected.