Introduction
As aquaculture intensifies, optimizing fish nutrition remains a critical aspect of improving growth performance, health status and product quality, all of which are closely related to diet composition and nutrient availability (Glencross et al., 2020). Fundamental to the success of this sector is the formulation of nutritionally balanced feeds, in which fatty acids play a key role in supporting fish growth, health and overall product quality. Carnivorous fish species such as gilthead seabream have dietary requirements for the essential fatty acids (EFA), especially the LC-PUFA (n‒3 and n‒6 series with 20 or more carbons), eicosapentaenoic acid (EPA; 20:5n‒3), docosahexaenoic acid (DHA, 22:6n‒3) and arachidonic acid (ARA, 20:4n‒6). These fatty acids not only contribute to fish health and growth but also improve the nutritional profile of aquaculture products for human consumption, supporting cardiovascular and cognitive benefits (Calder, 2020). EPA and DHA fatty acids are essential for proper brain development, including foetus, infants and toddlers (Innis, 2007; Lauritzen et al., 2016). The European Commission authorized 9 of the 54 health claims requested for the health benefits of DHA, including visual development in children, proper brain development and proper functioning of the circulatory system (R (UE) 1924/2006). In the case of EPA, there were 82 claims requested, but only 3 were authorized, related to the proper functioning of the circulatory system. Unauthorized claims denial was based on the fact that the available scientific evidence on the claimed effects was not sufficiently substantiated (R (UE) 1924/2006).
Traditionally, fishmeal (FM) and fish oil (FO) have been the main sources of essential fatty acids in aquafeeds, considering both the biological quality of the protein, and its digestibility. However, their continued use poses significant challenges, including sustainability concerns linked to overfishing, fluctuating costs and environmental impact (Moutinho et al., 2022; Naylor et al., 2021). These problems have prompted extensive research into alternative ingredients capable of replacing FM and FO without compromising feed efficiency or the quality of the fish produced.
This study investigates the potential of alternative feed (PAP and ALT)—as substitutes for traditional fishmeal (CTRL) in the diet of Sparus aurata (gilthead seabream), with a focus on the nutritional and health claims authorized in the European Union. The trial assessed the fatty acid profile across two key growth stages (300 g and 800 g). Results were interpreted in the context of EU Regulation (EC) No 1924/2006 on nutrition and health claims made on foods. The findings contribute to the development of sustainable feed capable of delivering fish products with added value for human health.
Materials and methods
Three types of feed formulations (n=3, CTRL: fish meal-based diet, PAP: processed animal protein-based diet, and ALT: alternative protein-based diet). Fish sampling took place at two growing stages: when fish reached 300 g and 800 g. The nomenclature for fish was as follows: i) individuals reached 300 g: CTRL300, PAP300 and ALT300; and, ii) individuals reached 800 g: CTRL800, PAP800 and ALT800. A Gas chromatograph coupled to a Flame Ionization Detector (GC-FID) was used for detection and semi quantification of fatty acids. Sample (50 mg) was methylated following a direct extraction-methylation method with a first basic step with sodium methoxide followed by an acid step with boron trifluoride 14% in methanol as described by Trigueros & Sendra (2015).
Results and discussion
European Union rules on nutrition and health claims were established by Regulation (EC) No 1924/2006 . This regulation is the legal framework used by food business operators to inform consumers through labelling or advertising on the beneficial effects of their products, concerning health and nutrition.
The specification of the three authorized Health Claims (HC) other than risk reduction and children’s claims are detailed as follows: i) HC 1: DHA helps maintain normal triglyceride levels in the blood. This claim can only be used for foods that provide a daily intake of 2 g of DHA and contain DHA in combination with eicosapentaenoic acid (EPA). For a product to carry this claim, consumers must be informed that the beneficial effect is obtained with a daily intake of 2 g of DHA; ii) HC 2: DHA and EPA contribute to maintaining normal blood pressure. This claim can only be used for foods that provide a daily intake of 3 g of EPA and DHA. For a product to carry this claim, consumers must be informed that the beneficial effect is obtained with a daily intake of 3 g of EPA and DHA; and, iii) HC 3: DHA and EPA contribute to maintaining normal triglyceride levels in the blood. This claim can only be used for foods that provide a daily intake of 2 g of EPA and DHA. For a product to carry this claim, consumers must be informed that the beneficial effect is obtained with a daily intake of 2 g of EPA and DHA. It is essential to mention that following the recommended serving size for an average consumer, a portion of fish ranges between 125-150 g. Considering the percentage of DHA and EPA in the total analysed fat for each diet in 300 g and 800 g fish, we can only apply Claim 1 to ALT800 (2.07). However, claims 2 and 3 can be used for all diets (EPA: 1.79-2.08 g per serving; DHA: 1.75-2.32 g per serving; EPA+DHA: 3.45-4.39 g per serving). If we consider a 150 g serving, all three claims can be applied to all diets for both 300 g and 800 g fish (EPA: 2.15-2.5 g per serving; DHA: 2.22-2.79 g per serving; EPA+DHA: 4.37-5.27 g per serving).
On the other hand, as to authorizing nutritional claims (NC) under European Union regulation, the established criteria are included in the following lines: i) NC1: Source of omega-3 fatty acids: if the product contains at least 0.3 g of alpha-linolenic acid per 100 g and per 100 kcal, or at least 40 mg of the sum of eicosapentaenoic acid and docosahexaenoic acid per 100 g and per 100 kcal; ii) NC2: High content of omega-3 fatty acids: if the product contains at least 0.6 g of alpha-linolenic acid per 100 g and per 100 kcal, or at least 80 mg of the sum of eicosapentaenoic acid and docosahexaenoic acid per 100 g and per 100 kcal; iii) NC3: High content of monounsaturated fats: if at least 45% of the fatty acids present in the product come from monounsaturated fats and these monounsaturated fats provide more than 20% of the product’s total energy value; iv) NC4: High content of polyunsaturated fats: if at least 45% of the fatty acids present in the product come from polyunsaturated fats and these polyunsaturated fats provide more than 20% of the product’s total energy value; and v) NC5: High content of unsaturated fats : if at least 70% of the fatty acids present in the product come from unsaturated fats and these unsaturated fats provide more than 20% of the product’s total energy value. Taking the requirements into account, it can be said that both growth stage fishes of the three diets can be considered both a source and high in Omega-3 fatty acids. The CTRL300, CTRL300, and CTRL800 showed a high level of MUFA, while none of the treatments exhibit a high content of PUFA and/or SFA.
Conclusions
According to European Union regulations, fish raised with traditional feed is considered a healthy and nutritious option due to its beneficial levels of EPA, DHA, MUFA and omega 3 fatty acids. Furthermore, the use of the proposed alternative feeds does not compromise these properties, as the levels of these essential fatty acids remain within the recommended ranges for health benefits. This ensures that fish-fed with proposed alternative diets continue to provide the same nutritional advantages, making them a suitable and sustainable option without any detriment to their health and nutritious-promoting qualities.