Docosahexaenoic acid essentiality

DHA, C22 6 i 3 cis-,cis-,cis-, cA-,cA-,cA-4,7,10,13,16,19-Docosahexaenoic acid). Essential fatty acids support the cardiovascular, reproductive, immune, and nervous systems, including the production of prostaglandins, which regulate body functions such as heart rate, blood pressure, blood clotting, fertility, and conception, and they are essential in the inflammatory response. 

Mitchell DC, Gawrisch K, Litman BJ, Salem NJ. Why is docosahexaenoic acid essential for nervous system function Biochem Soc Trans 1998 26 365-370. 

Rhodopsin in photoreceptors is immersed in a lipid environment highly enriched in phospholipids containing docosahexaenoic acid, which is essential for rhodopsin function 587... 

Human milk is rich in essential fatty acids of both the omega-3 and omega-6 families. This suggests that the activity of the A -desaturase may be too low in the infant to provide a sufficient amount of these fatty acids for development of tissues, particularly the brain and retina. It has been shown that development of visual acuity in infants is dependent upon the presence of docosahexaenoic acid in mother s milk. Hence, it is recommended that breastfeeding should be carried out for as long as 12 months after birth. These fatty acids are now added to commercial infant feeds (Chapter 15, Table 15.8). 

There is some evidence that, in these patients, the interconversion between the polyunsaturated fatty acids is disturbed, which restricts the formation of eicosapentaenoic and docosahexaenoic acids. Such children are less likely to have been breastfed (breast milk contains these omega-3 fatty acids) they are more likely to suffer from allergies associated with essential fatty acid deficiency and also dry skin and hair and the membranes of the erythrocytes contain less omega-3 fatty acids compared with normal children. So far, the results of supplementation of the diet of these children with this disorder have not been conclusive. 

Su, H.M., Moser, A.B., Moser, H.W., and Watkins, P.A., Peroxisomal straight-chain Acyl-CoA oxidase and D-bifunctional protein are essential for the retroconversion step in docosahexaenoic acid synthesis, J. Biol. Chem., 276, 38115, 2001. 

Booyens, J., Englebrecht, P., Le Roux, S., and Louwrens, C.C. 1984. Some effects of the essential fatty acid linoleic and alpha-linolenic acid and their metabolites gamma-linolenic acid, arachidonic acid, eicosapentaenoic acid, docosahexaenoic acid, and of prostaglandins A1 and El on the proliferation etc. Prostaglandins Leukot. Med. 15, 15-33. 

Cw-polyenoic acids are present at low concentrations in milk fat, because of the biohydrogenation reactions that take place in the rumen. These acids are comprised almost exclusively of linoleic acid (9c, 12c-18 2), about 1.2 to 1.7% and a-linolenic acid (9c, 12c, 15c-18 3), about 0.9 to 1.2% (Table 1.2). These two fatty acids are essential fatty acids they cannot be synthesised within the body and must be supplied by the diet. In recent times, the usage of the term essential has been extended to include derivatives of these fatty acids, which are not synthesised in significant quantities (e.g., eicosapentaenoic acid, 20 5 and docosahexaenoic acid, 22 6). The proportion of a-linolenic acid appears to be affected by the cow s diet the concentration is higher in milk from pasture-fed cows than in milk from barn-fed cows (Hebeisen et al., 1993 Wolff et al., 1995). In the case of linoleic... 

The essential dietary fatty acids include linolenic acid (LA, C18 2 co6) and alpha-linolenic acid (LN, C18 3 oo3). Mammals are missing a fatty acid desaturase capable of introducing a double bond between C9 and the methylene end of the fatty acid. Hence, to synthesize essential HUFAs, LA and LN are both required in the diet (Fig. lb). LA is the precursor to arachi-donic acid (AA, C20 4 006) and derivative eicosanoids, whereas LN is the precursor to eicosapentaenoic acid (EPA, C20 5 oo3), docosahexaenoic acid (DHA,C22 6 oo3), and oo3-derived... 

Omega-3 fatty acids are long-chain polyunsaturated fatty acids. The parent fatty acid of this group is alpha-linolenic acid, an essential fatty acid that the body is unable to synthesize alpha-linolenic acid can be converted in the body to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). In animals and man, these acids reduce the production of several compounds that are involved in inflammation and thrombosis, such as eicosanoids (prostaglandins, thromboxanes, prostacyclin, and leukotrienes) and cytokines (interleukin II-l) (1). The extent of the conversion of alpha-linolenic acid to EPA and DHA is unclear. The conversion process appears to be inhibited by a high intake of linoleic acid, another essential fatty acid (2). In addition, alpha-linolenic acid is found in dark green vegetables and the oils of certain nuts and seeds, especially rape seeds and soya beans. 

The essential fatty acids are also converted in the body to the 22-carbon fatty acids docosapentaenoic acid (DPA)and docosahexaenoic acid (DHA). DPAis made from linoleic acid DHA is made from linolenic acid.The functions of these 22-carb-on fatty acids are not clear, but they may be important for vision and for other functions of the nervous system. DPA and DHA can be further elongated, in the body, to the "very-long-chain fatty acids." The very-long-chain fatty adds contain 24 to 34 carbons, and occur in the brain, rods of the retina, and in the testes (Sixh et al., 1996). Their functions are not clear. 

Omega-3 PUFAs are essential unsaturated fatty acids obtained from food sources or from supplements. Amongst nutritionally important polyunsaturated n-3 fatty acids, a-linolcnic acid (ALA), eicosapentae-noic acid (EPA), and docosahexaenoic acid (DHA) are highly concentrated in the brain and have antioxidative stress, anti-inflammatory and antiapoptotic effects. The exposure to n-3 fatty acids enhances adult hippocampal neurogenesis associated with cognitive and behavioral processes, promotes synaptic plasticity by increasing longterm potentiation, and modulates synaptic protein expression to stimulate the dendritic arborization and new spine formation [496]. 

DHA and Coenzyme Q10. Coenzyme Q10 (CoQlO) is an essential cofactor involved in the mitochondrial electron transport chain. Zinc toxicity also affects cellular energy production by decreasing oxygen consumption rate (OCR) and ATP turnover in human neuronal cells, which can be restored by the neuroprotective effect of docosahexaenoic acid (DHA). DHA is specifically neuroprotective against zinc-triggered mitochondrial dysfunction, and CoQlO has shown to be protective against both Ap- and zinc-induced alterations in mitochondrial function [502],... 

One important group of nutrients, rarely included in the Western diet, is the essential fatty acids. These compounds are precursors to prostaglandins, which inhibit testosterone binding in the prostate. They also act as anti-inflammatory agents and restrain protein synthesis and cell growth in the prostate. The omega-3 marine lipids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been shown to inhibit the growth of prostatic tumors. Flax seed, a rich source of essential fatty acids, has been shown to inhibit cancer metastasis in studies done with mice. 

If sufficient scientific evidence is not available to calculate an Estimated Average Requirement, a reference intake called an Adequate Intake (Al) is used instead of a Recommended Dietary Allowance. The Al is a value based on experimentally derived intake levels or approximations of observed mean nutrient intakes by a group (or groups) of healthy people. The Al for children and adults is expected to meet or exceed the amount needed to maintain a defined nutritional state or criterion of adequacy in essentially all members of a specific healthy population LA = linoleic acid LNA = n-linolenic acid DHA = docosahexaenoic acid EPA = eicosapentaenoic acid TRANS-EA = trans fatty acids SAT = saturated fatty acids MONOs = monounsaturated fatty acids. 

Dratz EA, Holte LL. The molecular spring model for the function of docosahexaenoic acid (22 6w-3) in biological membranes. In 8inclair A, Gibson R, eds. Essential Fatty Acids and Eicosanoids. American Oil Chemists 8ociety, Champaign, IL, 1992, pp. 122-127. 

Ruyle M, Connor WE, Anderson GJ, Lowensohn RL Placental-transfer of essential fatty-acids in humans— venous arterial difference for docosahexaenoic acid in fetal umbilical erythrocytes. Proc Natl Acad Sci USA 1990 87(20) 7902-7906. 

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