Docosahexaenoic Acid Is the Preferred Dietary n-3 Fatty Acid for the Development of the Brain and Retina

Abstract

ABSTRACT. The metabolism of individual dietary n-3 fatty acids was studied in n-3 fatty acid-deficient newly hatched chicks. Laying hens were fed the n-6 fatty acid, ethyl linoleate, as the only source of polyunsaturated fat. Chicks were then fed the n-3-deficient hens' diet, or one of three other diets supplemented with the ethyl ester of 18:3n-3, 20:5n-3 [eicosapentaenoic acid (EPA)], or 22:6n-3 [docosahexaenoic acid (DHA)] at 0.44% of calories. At the end of 0, 1, 2, and 3 wk, the fatty acid composition of the brain, retina, liver, and serum was determined. Dietary EPA and DHA were equally effective at raising levels of DHA in the brain and retina. Dietary 18:3 was relatively ineffective in restoring brain and retina DHA. In the n-3-deficient chicks fed EPA or DHA, levels of DHA recovered to control values in both the brain and retina by 3 wk. Very little EPA accumulated in the brain or retina of chicks fed EPA. Hepatic synthesis of DHA from EPA appeared low, suggesting that the brain and retina synthesized the DHA that accumulated rapidly in these tissues after the feeding of EPA. The 6-4-desaturase enzyme was apparently very active, then, in the brain and retina. Retroconversion of dietary 22:6 to 22:5 and 20:5 was evident in the serum, liver, and retina but not in the brain. Thus, it was possible to study the relative metabolism and especially the interconversion of n-3 fatty acids in a environment uncomplicated by existing stores of these essential fatty acids. This study would suggest that 18:3 as the sole source of n-3 fatty acids in the diets of animals, including the human infant, may not be adequate for the biochemical development of the brain and retina and that dietary DHA is the preferred fatty acid of the n-3 series. (Pediatr Res 27: 89-97, 1990) Abbreviations DHA, docosahexaenoic acid EPA, eicosapentaenoic acid The n-3 family of polyunsaturated fatty acids has become the focus of much interest because of evidence that these compounds

Dietary low linolenic acid compared with docosahexaenoic acid alter synaptic plasma membrane phospholipid fatty acid composition and sodium–potassium ATPase kinetics in developing rats

“…The higher 20:4n-6 and 22:6n-3 content in SPM phospholipids of rats fed the AA + DHA diet compared with control or low LNA diet is similar to data by Anderson et al (1990) and Jumpsen et al (1997) demonstrating that pre-formed 20:4n-6 and 22:6n-3 are readily incorporated into brain phospholipids. Both delta-6-and delta-5-desaturases are present in liver and brain of the newborn rodents (Ravel et al 1985;Bourre et al 1990) and some 18:2n-6 and 18:3n-3 can be converted to 20:4n-6 and 22:6n-3 in the suckling rat (Nouvelot et al 1983).…”

Can Prenatal N-3 Fatty Acid Deficiency Be Completely Reversed after Birth? Effects on Retinal and Brain Biochemistry and Visual Function in Rhesus Monkeys

“…Similarly, in the present study, erythrocytes still had not responded to the repletion diet at 4 wk, whereas fish oil produced substantial increases in erythrocyte DHA after 2 wk (14). We previously also observed the superiority of dietary DHA over its 18-carbon dietary precursor, alpha-linolenic acid, in repletion studies in chicks (30).…”

Dietary intake of n-3, n-6 fatty acids and fish: Relationship with hostility in young adults—the CARDIA study

“…The n-3 family includes alinolenic acid (18:3), eicosapentaenoic acid (EPA,20:5) and docosahexaenoic acid (DHA,22:6). DHA is the major polyunsaturated fatty acid in the adult mammalian brain (Anderson et al, 1990;Green & Yavin, 1998;Innis, 2000) and is selectively concentrated at synaptic neuronal membranes (Innis, 2000). DHA and EPA are present in fatty fish (salmon, tuna, mackerel), although it can be obtained from n-3-enriched eggs (Lewis et al, 2000).…”