Chemical Properties
Clear Colourless Liquid
Occurrence
Ordinary types of cooked salmon contain 500 – 1500 mg DHA and 300–1000 mg EPA per 100 grams.(USDA) Additional top fish sources of DHA are: tuna, bluefish, mackerel, swordfish, anchovies, herring, sardines, and caviar.
The discovery of algae - based DHA
In the early 1980s, NASA sponsored scientific research in search of a plant-based food source that could generate oxygen and nutrition on long-duration space flights. The researchers discovered that certain species of marine algae produced rich nutrients. This research led to the development of an algae-based, vegetable-like oil that contains two essential polyunsaturated fatty acids: DHA and ARA (Arachidonic acid).
Use as a food additive
DHA is widely used as a food supplement. It was first used primarily in infant formulas. In 2004, the US Food and Drug Administration endorsed qualified health claims for DHA , and by 2007 DHA - fortified dairy items (milk, yogurt, cooking oil) started to appear in grocery stores.
DHA is believed to be helpful to people with a history of heart disease, for premature infants, and to support healthy brain development especially in young children along with supporting retinal development. Some manufactured DHA is a vegetarian product extracted from algae, and it competes on the market with fish oil that contains DHA and other omega-3's such as EPA. Both fish oil and DHA are odorless and tasteless after processing as a food additive.
Studies of vegetarians and vegans
Vegetarian diets typically contain limited amounts of DHA, and vegan diets typically contain no DHA. Vegetarians and vegans have substantially lower levels of DHA in their bodies, and short-term supplemental ALA has been shown to increase EPA, but not DHA. However, supplemental preformed DHA, available in algae-derived oils or capsules, has been shown to increase DHA levels. While there is little evidence of adverse health or cognitive effects due to DHA deficiency in adult vegetarians or vegans, fetal and breast milk levels remain a concern.
DHA and EPA in fish oils
Fish oil is widely sold in gelatin capsules containing a mixture of omega-3 fatty acids including EPA and smaller quantities of DHA. One study found fish oil higher in DHA than EPA lowered inflammatory cytokines, such as IL-6 and IL-1β, associated with neurodegenerative and autoimmune diseases. They note the brain normally contains DHA, but not EPA, though both DHA and EPA plasma concentrations increased significantly for participants.
Uses
Docosahexaenoic acid is found in fish oils in nature. It is also
commercially manufactured from microalgae; Crypthecodinium
cohnii and Schizochytrium.
Uses
Nutritional supplement.
Uses
Omega-3 fatty acid found in marine fish oils and in many phospholipids. Major structural component of excitable membranes of the retina and brain; synthesized in the liver from a-linolenic acid. Nutritional supplement.
Definition
ChEBI: A docosahexaenoic acid having six cis-double bonds at positions 4, 7, 10, 13, 16 and 19.
General Description
An omega-3 fatty acid essential for normal brain growth and
function, docosahexaenoic acid (DHA) plays an important role as a signaling factor in cells for both anti- and pro-inflammatory processes. Levels of docosahexaenoic acid as well as other fatty acids are analyzed by GC/MS or LC-MS/MS methods to monitor patients undergoing diet therapy for mitochondrial or peroxisomal disorders. This Certified Spiking Solution? is suitable for use as starting material in the
preparation of linearity standards, calibrators, or controls in mass spectrometry-based DHA testing applications such as assessment of cardiovascular disease risk and fatty acid deficiency, and detection and quantification of DHA in nutraceuticals and dietary supplements.
Biological Activity
Endogenous omega-3 fatty acid. Acts as a selective retinoid X receptor (RXR) agonist that displays no activity at RAR, thyroid hormone receptor or the vitamin D receptor (VDR). Activates all three RXR isoforms. Also shown to inhibit A β 1-42 fibrillation and toxicity in vitro .
Biochem/physiol Actions
Docosahexaenoic acid, DHA, is an omega-3 polyunsaturated fatty acid with 22 carbons and six double bonds, the first double bond occuring at position three from the methyl terminus (22:6 n-3). DHA is a component of lipid membranes and the myelin sheath. DHA also serves as a precursor for signaling molecules such as prostaglandins and eicosanoids.
Purification Methods
Its solubility in CHCl3 is 5%. It has been purified from fish oil by GLC using Ar as mobile phase and EGA as stationary phase with an ionisation detector [UV: Stoffel & Ahrens J Lipid Res 1 139 1959], and via the ester by evaporative "molecular" distillation using a 'continuous molecular still' at 10-4 mm with the highest temperature being 110o and a total contact time with the hot surface being 60sec [Farmer & van den Heuvel J Chem Soc 427 1938]. The methyl ester has b 208-211o/2mm, d4 0.9398, 20 1.5035. nD With Br2 it forms a dodecabromide m ca 240o(dec). Also, the acid was converted to the methyl ester and purified through a three-stage molecular still [as described by Sutton Chem Ind (London) 11383 1953] at 96o, and the rate was adjusted so that one-third of the material was removed each cycle of three distillations. The distillate (numbered 4) (13g) was dissolved in EtOH (100mL containing 8g of KOH) at -70o and set aside for 4hours at 30o with occasional shaking under a vacuum. Water (100mL) was added and the solution was extracted with pentane, washed with HCl, dried (MgSO4), filtered and evaporated to give a clear oil (11.5g) m -44.5o to -44.1o. In the catalytic hydrogenation of the oil six mols of H2 are absorbed and docosanoic acid (behenic acid) is produced with m 79.0-79.3o undepressed with an authentic sample (see docosanoic acid below) [Whitcutt Biochem J 67 60 1957]. [Beilstein 2 IV 1812.]
