Docosahexaenoic acid

About: Docosahexaenoic acid is a research topic. Over the lifetime, 14412 publications have been published within this topic receiving 620852 citations. The topic is also known as: all-cis-DHA & all-cis-docosa-4,7,10,13,16,19-hexaenoic acid.

Extremely limited synthesis of long chain polyunsaturates in adults: implications for their dietary essentiality and use as supplements.

Abstract: There is considerable interest in the potential impact of several polyunsaturated fatty acids (PUFAs) in mitigating the significant morbidity and mortality caused by degenerative diseases of the cardiovascular system and brain. Despite this interest, confusion surrounds the extent of conversion in humans of the parent PUFA, linoleic acid or alpha-linolenic acid (ALA), to their respective long-chain PUFA products. As a result, there is uncertainty about the potential benefits of ALA versus eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA). Some of the confusion arises because although mammals have the necessary enzymes to make the long-chain PUFA from the parent PUFA, in vivo studies in humans show that asymptotically equal to 5% of ALA is converted to EPA and <0.5% of ALA is converted to DHA. Because the capacity of this pathway is very low in healthy, nonvegetarian humans, even large amounts of dietary ALA have a negligible effect on plasma DHA, an effect paralleled in the omega6 PUFA by a negligible effect of dietary linoleic acid on plasma arachidonic acid. Despite this inefficient conversion, there are potential roles in human health for ALA and EPA that could be independent of their metabolism to DHA through the desaturation - chain elongation pathway.

The effect of dietary omega-3 fatty acids on coronary atherosclerosis. A randomized, double-blind, placebo-controlled trial.

Abstract: Background Epidemiologic studies, studies of mechanisms of action, and many animal studies indicate that dietary intake of omega-3 fatty acids has antiatherosclerotic potential. Few trials in humans have examined this potential. Objective To determine the effect of dietary intake of omega-3 fatty acids on the course of coronary artery atherosclerosis in humans. Design Randomized, double-blind, placebo-controlled, clinically controlled trial. Setting University preventive cardiology unit. Patients 223 patients with angiographically proven coronary artery disease. Intervention Fish oil concentrate (55% eicosapentaenoic and docosahexaenoic acids) or a placebo with a fatty acid composition resembling that of the average European diet, 6 g/d for 3 months and then 3 g/d for 21 months. Measurements The results of standardized coronary angiography, done before and after 2 years of treatment, were evaluated by an expert panel (primary end point) and by quantitative coronary angiography. Patients were followed for clinical and laboratory status. Results Pairs of angiograms (one taken at baseline and one taken at 2 years) were evaluated for 80 of 112 placebo recipients and 82 of 111 fish oil recipients. At the end of treatment, 48 coronary segments in the placebo group showed changes (36 showed mild progression, 5 showed moderate progression, and 7 showed mild regression) and 55 coronary segments in the fish oil group showed changes (35 showed mild progression, 4 showed moderate progression, 14 showed mild regression, and 2 showed moderate regression) (P = 0.041). Loss in minimal luminal diameter, as assessed by quantitative coronary angiography, was somewhat less in the fish oil group (P > 0.1). Fish oil recipients had fewer cardiovascular events (P = 0.10); other clinical variables did not differ between the study groups. Low-density lipoprotein cholesterol levels tended to be greater in the fish oil group. Conclusion Dietary intake of omega-3 fatty acids modestly mitigates the course of coronary atherosclerosis in humans.

Dietary modification of inflammation with lipids

Abstract: The n-3 polyunsaturated fatty acids (PUFA) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are found in high proportions in oily fish and fish oils. The n-3 PUFA are structurally and functionally distinct from the n-6 PUFA. Typically, human inflammatory cells contain high proportions of the n-6 PUFA arachidonic acid and low proportions of n-3 PUFA. The significance of this difference is that arachidonic acid is the precursor of 2-series prostaglandins and 4-series leukotrienes, which are highly-active mediators of inflammation. Feeding fish oil results in partial replacement of arachidonic acid in inflammatory cell membranes by EPA. This change leads to decreased production of arachidonic acid-derived mediators. This response alone is a potentially beneficial anti-inflammatory effect of n-3 PUFA. However, n-3 PUFA have a number of other effects which might occur downstream of altered eicosanoid production or might be independent of this activity. For example, animal and human studies have shown that dietary fish oil results in suppressed production of pro-inflammatory cytokines and can decrease adhesion molecule expression. These effects occur at the level of altered gene expression. This action might come about through antagonism of the effects of arachidonic acid-derived mediators or through more direct actions on the intracellular signalling pathways which lead to activation of transcription factors such as nuclear factor kappa B (NFB). Recent studies have shown that n-3 PUFA can down regulate the activity of the nuclear transcription factor NFB. Fish oil feeding has been shown to ameliorate the symptoms in some animal models of chronic inflammatory disease and to protect against the effects of endotoxin and similar inflammatory challenges. Clinical studies have reported that oral fish oil supplementation has beneficial effects in rheumatoid arthritis and among some patients with asthma, supporting the idea that the n-3 PUFA in fish oil are anti-inflammatory. There are indications that inclusion of n-3 PUFA in enteral and parenteral formulas might be beneficial to patients in intensive care or post-surgery.

Arachidonic and docosahexaenoic acids are biosynthesized from their 18-carbon precursors in human infants

Abstract: It is becoming clear that an adequate level of long-chain highly unsaturated fatty acids in the nervous system is required for optimal function and development; however, the ability of infants to biosynthesize long-chain fatty acids is unknown. This study explores the capacity of human infants to convert 18-carbon essential fatty acids to their elongated and desaturated forms, in vivo. A newly developed gas chromatography/negative chemical ionization/mass spectrometry method employing 2H-labeled essential fatty acids allowed assessment of this in vivo conversion with very high sensitivity and selectivity. Our results demonstrate that human infants have the capacity to convert dietary essential fatty acids administered enterally as 2H-labeled ethyl esters to their longer-chain derivatives, transport them to plasma, and incorporate them into membrane lipids. The in vivo conversion of linoleic acid (18:2n6) to arachidonic acid (20:4n6) is demonstrated in human beings. All elongases/desaturases necessary for the conversion of linolenic acid (18:3n3) to docosahexaenoic acid (22:6n3) are also active in the first week after birth. Although the absolute amounts of n-3 fatty acid metabolites accumulated in plasma are greater than those of the n-6 family, estimates of the endogenous pools of 18:2n6 and 18:3n3 indicate that n-6 fatty acid conversion rates are greater than those of the n-3 family. While these data clearly demonstrate the capability of infants to biosynthesize 22:6n3, a lipid that is required for optimal neural development, the amounts produced in vivo from 18:3n3 may be inadequate to support the 22:6n3 level observed in breast-fed infants.