Health Benefits and Applications of DHA and EPA

Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are two n-3 long-chain polyunsaturated fatty acids that are widely found in marine animals and plant plankton. Several studies have shown that DHA and EPA can reduce or prevent a variety of disease burdens, including hyperlipidemia, diabetes, cancer, inflammation, and neurodegenerative diseases. Consuming seafood 1 to 2 times a week can reduce the risk of death. ——Health benefits of dietary marine DHA/EPA-enriched glycerophospholipids

01EPA-enriched phosphoethanolamine plasmalogens regulate bile acids in LDLR–/– mice by remodeling intestinal flora to alleviate atherosclerosis

EPA-PlsEtns may remain in the microbiota-rich intestine for a long time after treatment, which reminds us that EPA-PlsEtns may affect the composition of the intestinal microbiota and its metabolites, which have been identified as factors affecting the development of cardiovascular disease. In this study, several students from Ocean University of China found that EPA-PlsEtns administration for 8 weeks significantly reduced the area of atherosclerotic lesions in low-density lipoprotein receptor-deficient (LDLR-/-) mice. Compared with the model group, mice treated with EPA-PlsEtns instead of EPA in the form of ethyl ester (EPA-EE) had significantly reduced serum total cholesterol and low-density lipoprotein cholesterol levels by 33.6% and 38.2%, respectively. Compared with EPA-EE treatment, EPA-PlsEtn administration also increased the total neutral sterol and bile acid content in feces by 92% and 39%, respectively. From a mechanistic analysis, EPA-PlsEtns may affect the abundance of intestinal microbiota, thereby changing the bile acid profile, and may inhibit the activation induction of farnesoid X receptors by increasing the expression of cholesterol 7α-hydroxylase, further accelerating the synthesis of bile acids.

EPA-PlsEtns Reduces the Incidence of Atherosclerosis Lesion area in aorta tissue fed with 1% EPA-PlsEtns was reduced by 85% compared with the model or EPA-EE groups (Figure 1A). Examination of H&E-stained aortic sinus cross sections revealed that plaques in mice in the EPA-PlsEtns group were less infiltrated by foam cells (Figure 1B).

Figure 1. EPA-PlsEtns Improves Atherosclerosis in LDLR–/– Mice.

EPA-PlsEtns Reduces Serum and Hepatic Lipid Levels EPA-PlsEtns supplementation significantly attenuated hypercholesterolemia in LDLR–/– mice, according to the reduction in aortic plaques, whereas the equivalent ethyl ester form of EPA was less effective (Figures 2A-2F). No significant differences in serum triglyceride (TG) levels were observed among the three experimental groups (Figure 2A). Compared with the model group, after EPA-PlsEtns administration, serum total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-c) levels were significantly reduced by about 33.6% (P < 0.05) and 38.2% (P < 0.05), respectively (Figure 2B, 2C), high-density lipoprotein cholesterol (HDL-c) levels did not change (Figure 2D), cholesterol and TG levels in very low-density lipoprotein (VLDL) particles were lower (Figure 2E, 2F), and liver TC (31.1%, P < 0.05, Figure 2G) and TG (25%, P < 0.05, Figure 2H) levels were lower.

Figure 2. EPA-PLs reduce serum and liver cholesterol levels.

02 Fish oil microcapsules in meat model systems: enrichment and bioavailability of EPA and DHA

Juan Carlos Solomando, Teresa Antequera and Trinidad Pérez-Palacios from the Institute of Meat and Meat Products (IProCar) of the University of Extremadura, Spain, evaluated the bioavailability of EPA and DHA in different types of fish oil microcapsules in different meat model systems. Lecithin-maltodextrin (MO) and lecithin + chitosan-maltodextrin (MU) fish oil microcapsules were prepared and added to two meat model systems: cooked (CK) and dry-cured (DC). The experiment found that the content of EPA and DHA in MO and MU was similar, but in the meat model system, the highest content of these fatty acids was DC-MU, followed by DC-MO, CK-MU and CK-MO. The highest ratio of EPA and DHA released during in vitro digestion was CK-MO, followed by CK-MU, MU and MO, DC-MU and DC-MO. Therefore, the characteristics of microcapsules and meat model systems have an impact on the enrichment and bioavailability of EPA and DHA, but the trends are different. It follows that it is necessary to analyze not only the content of EPA and DHA in enriched foods, but also the bioavailability of these bioactive compounds in most products as much as possible. The enrichment of EPA and DHA depends on the type of microcapsules and also on the type of meat model system. In the enriched meat model system, the release of fat and EPA + DHA is greatly affected by the meat model system and less by the type of microcapsules.

03 Effects of oleic acid and EPA + DHA on retinal antioxidant defense, leukocyte adhesion and vascular permeability: a study based on a hyperlipidemic rat model

The role of chronic hyperlipidemia in affecting retinal function, such as retinal defense against oxidative stress, blood-retinal barrier integrity, and leukocyte adhesion to retinal vessels, has not been resolved. In this study, Sadashivaiah Bettadahalli, Ramaprasad Ravichandra Talahalli, et al., from the Department of Biochemistry, Council of Scientific and Industrial Research (CSIR), India, evaluated the risk factors for retinal dysfunction in a hyperlipidemia rat model and the regulatory potential of oxidatively stable oleic acid and highly unsaturated oxidatively sensitive EPA+DHA on retinal dysfunction. The results showed that hyperlipidemia significantly (P < 0.05) increased markers of oxidative stress (lipid peroxides, nitric oxide, and protein carbonyl compounds) and reduced the activities of antioxidant defense enzymes (catalase, superoxide dismutase, glutathione peroxidase, and glutathione transferase) in the blood and retina. In addition, hyperlipidemia also significantly enhanced superoxide production, leukocytic stasis, and vascular permeability in the retina (P < 0.05). In contrast, dietary oleic acid and EPA+DHA significantly inhibited the retinal effects induced by hyperlipidemia (P < 0.05), confirming the potential of these fatty acids to protect the retina in metabolic abnormalities such as hyperlipidemia.

Figure 3. (A) Mechanism of action of hyperlipidemia-induced retinal microvascular dysfunction; (B) Regulation of hyperlipidemia-induced retinal microvascular dysfunction by n-3 fatty acids and oleic acid in the diet.

04 Health benefits of glycerophospholipids rich in dietary marine DHA/EPA

A typical feature of marine food is that it is rich in DHA and EPA, and a large-scale global industry related to this has been formed. DHA/EPA phospholipids (PLs) are ubiquitous in marine food and are the main DHA/EPA molecular form in fish roe, shrimp and shellfish. The type and esterification form of dietary fatty acids affect bioavailability and health benefits. Recently, many research results have shown that dietary DHA/EPA-PLs can exert their functional properties better than triacylglycerol (TAG) or ethyl ester forms of fatty acids through specific mechanisms of action. However, there is currently no comprehensive review on the health benefits of dietary DHA/EPA-PLs. In this article, several students from Ocean University of China reviewed the existing literature on the nutritional functions of DHA/EPA-rich glycerophospholipids, including the effects on brain function, anti-tumor activity, lipid metabolism and glucose metabolism, and introduced the current research status on active ingredients, sources, models, treatment methods, courses of treatment, efficacy and mechanisms. In addition, the authors also reviewed the effects of the ester bond structure at the sn-1 position, the fatty acid at the sn-2 position and the polar head group at the sn-3 position on the structure-activity relationship of DHA/EPA-PLs. DHA/EPA-PLs are one of the main dietary forms of n-3 long-chain polyunsaturated fatty acids in our diet, and the nutritional properties of DHA/EPA should be maximized.

Figure 4. Biological activity of DHA/EPA-rich glycerophospholipids in marine foods.