Case Conference: Omega-3 Polyunsaturated Fatty Acids Group II – Section AALFONSO, ALJAMA, ALUZAN, AMURAO, ARELLANO, ARROYO
Case: Omega-3 Fatty Acid Supplementation• A 42-year old male with a strong familial history of coronary heart disease was presently asymptomatic. He read several articles in national magazines and in the newspapers that fish oil capsules may help prevent coronary thrombosis.
Case: Omega-3 Fatty Acid Supplementation• Such dietary supplements are available over the counter without a prescription. In an attempt to protect himself against coronary heart disease, he purchased 500 mg fish oil capsules containing 50% omega-3 polyunsaturated fatty acids and ingested six capsules daily.
Overview and Introduction• POLYUNSATURATED FATTY ACIDS• Straight chain derivatives of fatty acids containing• Two or more double bonds.• ESSENTIAL FATTY ACIDS• Molecules that cannot be synthesized by the human body but are vital for normal metabolism•• One of these essential fatty acids is the• Omega-3 Polyunsaturated Fatty Acids
Omega-3 Polyunsaturated Fatty Acids• -essential dietary fatty acids, belonging to the lenolenic family of PUFAs -contain a double bond on the third carbon from the methyl end•• CHIEF DIETARY SOURCES: ocean fishes and fish oils• *Fish oil is obtained in the human diet by eating oily ﬁshes such as herring, mackerel, salmon, albacore tuna, and sardines, or by consuming ﬁsh oil supplements or cod liver oil
Omega-3 Polyunsaturated Fatty Acids• Nutritionally important n−3 fatty acids include α-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), all of which are polyunsaturated.
α-linolenic acid (ALA)• -type of omega-3 fatty acid found in plants.• -alpha-linolenic acid can be converted into EPA and DHA in the body• -highly concentrated in flaxseed oil and, to a lesser extent, in canola, soy, perilla, and walnut oils.•
Eicosapentaenoic acid (EPA)• -EPA acts as a precursor for prostaglandin- 3 (which inhibits platelet aggregation), thromboxane- 3, and leukotriene-5 groups
Docosahexanoic acid (DHA)• Obtained directly from fish oil• Present in high concentration in retina, cerebral cortex, testis and sperm• Needed for brain and retinal development
Omega-3 will alter a host of biophysical properties of membranes• like: 1. formation of metarhodopsin II, is modulated by the degree of unsaturation of retinal phospholipid. Fatty acids such that DHA- rich bilayers support the highest levels of metarhodopsin II formation. 2. DHA-rich membranes reduce the inhibitory effect of cholesterol on rhodopsin activation 3. enhances the sodium-potassium-ATPase pump 4. enable specialized cellular functions, such as the rapid firing of neurons. 5. they are chemically unstable that they oxidize very quickly. This instability can cause gradual oxidation reaction especially in the brain thereby participating further in the brain aging process.
Eicosanoid Synthesis• Marine plants, especially the unicellular algae in phytoplankton, carry out chain elongation and further desaturation of α-linolenic acid to yield the long-chain n-3 PUFAs eicosapentaenoic and docosahexaenoic acids• It is the formation of these long chain n-3 PUFAs by marine algae and their transfer through the food chain to fish that accounts for their abundance in some marine fish oils.
ω-3 Fatty Acids• Marine plants, especially the unicellular algae in phytoplankton, carry out chain elongation and further desaturation of α-linolenic acid to yield the long-chain n-3 PUFAs eicosapentaenoic and docosahexaenoic acids• It is the formation of these long chain n-3 PUFAs by marine algae and their transfer through the food chain to fish that accounts for their abundance in some marine fish oils.
Eicosanoids• Eicosanoids are family of oxygenated derivatives of arachidonic (n-6 FA) and eicosapentaenoic acids (n-3 FA)• The precursor PUFA is released from membrane phosphatidylcholine by the action of phospholipase A2• Eicosapentaenoic acids, competitively inhibit the oxygenation of arachidonic acid by cyclooxygenase and lipoxygenase
Eicosanoid Synthesis• Figure 1. Synthesis of eicosanoids from arachidonic and eicosapentaenoic acids.
How are the ω-3 fatty acids related to eicosanoid synthesis?• Consumption of fish oil, which contains ω-3 fatty acids (long chain n-3 PUFA of eicosapentaenoic acid) results in partial replacement of arachidonic acid in cell membranes by eicosapentaenoic acid• This leads to decreased arachidonic acid available for eicosanoid synthesis
Eicosanoid Synthesis• Figure 2. Basis of the anti-inflammatory effects of eicosapentaenoic acid . • EPA, eicosapentaenoic acid; COX, cyclooxygenase; LOX, lipoxygenase; • LT, leukotrien; PG, prostaglandin; TX, thromboxane
Eicosanoid Synthesis• Table 1.2: Physiological and biochemical effects of the most physiologically important eicosanoids. (LT, leukotrien; PG, prostaglandin; TX, thromboxane)
Arachidonic acid vs. Eicosapentaenoic acid • Inhibiting metabolism of arachidonic acid, eicosapentaenoic acid give rise to derivatives which have a different structure to those produced from arachidonic acid (i.e., 3-series PG and TX and 5-series LT). • Thus, the eicosapentaenoic acid-induced suppression in the production of arachidonic acid-derived eicosanoids is accompanied by an elevation in the production of eicosapentaenoic acid-derived eicosanoids
Arachidonic acid vs. Eicosapentaenoic acid • The eicosanoids produced from eicosapentaenoic acid are considered to be less biologically potent than the analogues synthesised from arachidonic acid • Thus, TXA3 has much lower potency to activate platelets or to induce vasoconstriction than TXA2 and LTB5 is much weaker in stimulation neutrophil activation than LTB4.
ω-3 fatty acids• The reduction in generation of arachidonic acid- derived mediators which accompanies fish oil consumption has led to the idea that fish oil is anti- inflammatory.• Clinical studies have reported that oral fish oil supplementation has beneficial effects in multiple sclerosis, asthmatics diseases and other immunity depending diseases.• Supporting the idea that the n-3 PUFAs in fish oil are anti-inflammatory.