Bioavailability and Potential Uses of Vegetarian Sources of Omega-3 Fatty Acids: A Review of the Literature

Abstract

Presently alpha-linolenic acid (ALA) is the most widely used vegetarian LC3PUFA, but only marginal amounts are converted into eicosapentaenoic (EPA) and docosahexaenoic acid (DHA); both of which are strongly related to human health. Currently, fish oils represent the most prominent dietary sources of EPA and DHA; however, these are unsuitable for vegetarians. Alternative sources include flaxseed, echium, walnut, and algal oil but their conversion to EPA and DHA must be considered. The present systematic review sets out to collate information from intervention studies examining the bioavailability of alternative vegetarian long chain omega-3 (n-3) polyunsaturated fatty acids (LC3PUFA) sources. Ten key papers published over the last 10 years were identified with seven intervention studies reporting that ALA from nut and seed oils was not converted to DHA at all. Three studies showed that ingestion of micro-algae oil led to significant increases in blood erythrocyte and plasma DHA. Further work is now needed to identify optimal doses of alternative vegetarian LC3PUFAs and how these can be integrated within daily diets. The potential role of algal oils appears to be particularly promising and an area in which further research is warranted.

Bioavailability of long-chain n-3 fatty acids from enriched meals and from microencapsulated powder

“…Although part of α-linolenic acid is theoretically converted to EPA and DHA, recent research has shown that conversion is often low and this is in particular true for DHA. 9 Bioavailability of FAs can vary significantly depending on their various chemical forms, for example, natural triglycerides, re-esterified triglycerides or ethyl esters. 18 Not only the type of chemical bonds but also the concomitant intake of food affect the uptake of LC n-3 PUFAs.…”

“…[6][7][8] It should be mentioned here that α-linolenic acid frequently found in seeds and plant oils is another potential source of EPA and DHA; however, the conversion rate (especially to DHA) is considered to be very low. 9 Considering the low consumption of seafood products in large parts of the population, attempts have been made to fortify food accordingly or to produce dietary supplements with LC n-3 PUFAs from marine sources. It has been shown that enriched foods with LC n-3 PUFAs increase plasma phospholipid DHA and EPA.…”

Algae as nutritional and functional food sources: revisiting our understanding

“…Fortified snack bars also delivered equivalent amounts of DHA on a DHA dose basis (Arterburn et al 2007). A systematic review of plant omega-3 fatty sources by Lane et al (2014) concluded that further research on algal sources was warranted based on promising preliminary work.…”

Healthy yogurt fortified with n-3 fatty acids from vegetable sources

“…Among bioactive ingredients, n-6 and n-3 PUFA serve as the primary components of biologi-cal structures in the cell membranes of higher mammals (Hulbert et al, 2005) and are also well recognized as essential elements in the human diet (Vella et al, 2013;Ganesanet al, 2014). Among these n-3 PUFA, eicosapentaenoic acid (EPA), docohexaenoic acid (DHA), and α-linolenic acid (ALA) are the most important (Lane et al, 2014). Eicosapentaenoic acid and DHA are mainly found in marine sources such as fish, fish oils, and algae (El Abed et al, 2008;Iafelice et al, 2008;Bermúdez-Aguirre and Barbosa-Cánovas, 2011), whereas ALA is commonly found in vegetable sources such as flaxseed, walnut, and echium seed oils (DeFilippis and Sperling, 2006;Iafelice et al, 2008;Bermùdez-Aguirre and Barbosa-Cánovas, 2012).…”