Essential fatty acid interactions

Last updated
Fatty acid breakdown Fatty Acid Breakdown.jpg
Fatty acid breakdown

There are many fatty acids found in nature. Two types of fatty acids considered essential for human health are the omega-3 and omega-6 types. These two essential fatty acids are necessary for some cellular signalling pathways and are involved in mediating inflammation, protein synthesis, and metabolic pathways in the human body.

Contents

Arachidonic acid (AA) is a 20-carbon omega-6 essential fatty acid. [1] It sits at the head of the "arachidonic acid cascade," which initiates 20 different signalling pathways that control a wide array of biological functions, including inflammation, cell growth, and the central nervous system. [2] [3] Most AA in the human body is derived from dietary linoleic acid (18:2 ω-6), which is found in nuts, seeds, vegetable oils, and animal fats. [4] [5] [6]

Other dietary essential fatty acids are involved in inflammatory signalling and can oppose the impact of the arachidonic acid cascade. For example, EPA (20:5 ω-3) competes with AA and is ingested from oily fish, algae oil, or alpha-linolenic acid (derived from walnuts, hemp oil, and flax oil). Another example is DGLA (20:3 ω-6), derived from dietary GLA (18:3 ω-6), is found in borage oil and can also. These two parallel cascades soften the inflammatory-promoting effects of specific eicosanoids made from AA.

The diet from a century ago had much less ω-3 than the diet of early hunter-gatherers but also much less pollution than today, [7] which evokes the inflammatory response. We can also look at the ratio of ω-3 to ω-6 in comparison with their diets. These changes have been accompanied by increased rates of many diseases—the so-called diseases of civilization—that involve inflammatory processes. There is now very strong evidence [8] that several of these diseases are ameliorated by increasing dietary ω-3. There is also more preliminary evidence showing that dietary ω-3 can ease symptoms in several psychiatric disorders. [9]

Eicosanoid series nomenclature

Eicosanoids are signaling molecules derived from the essential fatty acids (EFAs). They are a major pathway by which the EFAs act in the body. There are four classes of eicosanoid and two or three series within each class.

The plasma membranes of cells contain phospholipids, composed of a hydrophilic phosphate head and two hydrophobic fatty acid tails. Some of these fatty acids are 20-carbon polyunsaturated essential fatty acids (AA, EPA, or DGLA).[ citation needed ] In response to various inflammatory signals, these EFAs are cleaved out of the phospholipid and released as free fatty acids. Next, the EFA is oxygenated (by either of two pathways) and further modified, yielding the eicosanoids.[ citation needed ] Cyclooxygenase (COX) oxidation removes two C=C double bonds, leading to the TX, PG, and PGI series. Lipoxygenase oxidation removes no C=C double bonds and leads to the LK. [10]

After oxidation, the eicosanoids are further modified, making a series. Members of a series are differentiated by a letter and are numbered by the number of double bonds, which does not change within a series. For example, cyclooxygenase action upon AA (with 4 double bonds) leads to the series-2 thromboxanes [3] (TXA2, TXB2... ), each with two double bonds. Cyclooxygenase action on EPA (with 5 double bonds) leads to the series-3 thromboxanes (TXA3, TXB3, etc.), each with three double bonds. There are exceptions to this pattern, some of which indicate stereochemistry (PGF2α).

Table (1) shows these sequences for AA (20:4 ω-6). The sequences for EPA (20:5 ω-3) and DGLA (20:3 ω-6) are analogous.

Table 1 Three 20-carbon EFAs and the eicosanoid series derived from them
Dietary
Essential Fatty Acid		AbbreviationFormula
carbons: double bonds ω		Eicosanoid product series
TX
PG
PGI		LKEffects
Gamma-linolenic acid
  via Dihomo gamma linolenic acid 		GLA
DGLA		18:3ω6
20:3ω6		series-1series-3less inflammatory
Arachidonic acid AA20:4ω6series-2series-4more inflammatory
Eicosapentaenoic acid EPA20:5ω3series-3series-5less inflammatory

All prostanoids are substituted prostanoic acids. Cyberlipid Center's Prostenoid page [11] illustrates the parent compound and the rings associated with each series letter.

The IUPAC and the IUBMB use the equivalent term icosanoid. [11]

Arachidonic acid cascade in inflammation

Figure (1) The Arachidonic acid cascade, showing biosynthesis of AA's eicosanoid products. EPA and DGLA compete for the same pathways, moderating the actions of AA and its products. Eicosanoid synthesis.svg
Figure (1) The Arachidonic acid cascade, showing biosynthesis of AA's eicosanoid products. EPA and DGLA compete for the same pathways, moderating the actions of AA and its products.

In the arachidonic acid cascade, dietary linoleic acid (18:2 ω-6) is desaturated and elongated to form arachidonic acid (and other omega-6 acids), which is then esterified into a phospholipid in the cell membrane. [12] Next, in response to many inflammatory stimuli, such as air pollution, smoking, second-hand smoke, hydrogenated vegetable oils, and other exogenous toxins, phospholipase is generated and cleaves this phospholipid, releasing AA as a free fatty acid.[ citation needed ] AA can then be oxygenated and then further modified to form eicosanoids—autocrine and paracrine agents that bind receptors on the cell or its neighbors to alert the immune system of cell damage. Alternatively, AA can diffuse into the cell nucleus and interact with transcription factors to control DNA transcription for cytokines or other hormones.

Mechanisms of ω-3 eicosanoid action

Figure 2. Essential fatty acid production and metabolism to form eicosanoids EFA to Eicosanoids.svg
Figure 2. Essential fatty acid production and metabolism to form eicosanoids

Eicosanoids from AA have been found to promote inflammation. Those from GLA (via DGLA) and from EPA are generally less inflammatory, inactive, or anti-inflammatory. (This generalization is qualified: an eicosanoid may be pro-inflammatory in one tissue and anti-inflammatory in another. (See discussion of PGE2 at Calder [13] or Tilley. [14] )

Figure 2 shows the ω-3 and -6 synthesis chains, along with the major eicosanoids from AA, EPA, and DGLA.

Dietary ω-3 and GLA counter the inflammatory effects of AA's eicosanoids in three ways: displacement, competitive inhibition, and direct counteraction.

Displacement

Dietary ω-3 decreases tissue concentrations of AA. Animal studies show that increased dietary ω-3 decreases AA in the brain and other tissues. [15] alpha-Linolenic acid (18:3 ω-3) contributes by displacing linoleic acid (18:2 ω-6) from the elongase and desaturase enzymes that produce AA. EPA inhibits phospholipase A2's release of AA from the cell membrane. [16]  Other mechanisms involving the transport of EFAs may also play a role.

The reverse is true: high dietary linoleic acid decreases the body's conversion of α-linolenic acid to EPA. However, the effect is not as strong; the desaturase has a higher affinity for α-linolenic acid than it has for linoleic acid. [17]

Competitive Inhibition

DGLA and EPA compete with AA for access to the cyclooxygenase and lipoxygenase enzymes. So the presence of DGLA and EPA in tissues lowers the output of AA's eicosanoids. For example, dietary GLA increases tissue DGLA and lowers TXB2. [18] [19] Likewise, EPA inhibits the production of series-2 PG and TX. [13] Although DGLA does not form LTs, a DGLA derivative blocks the transformation of AA to LTs. [20]

Counteraction

Some DGLA and EPA-derived eicosanoids counteract their AA-derived counterparts. For example, DGLA yields PGE1, which powerfully counteracts PGE2. [21]  EPA yields the antiaggregatory prostacyclin PGI3 [22] . It also yields the leukotriene LTB5, which vitiates the action of the AA-derived LTB4. [23]

The paradox of dietary GLA

Studies have shown that dietary oxidized linoleic acid (LA, 18:2 ω-6) has inflammatory properties. In the body, LA is desaturated to form GLA (18:3 ω-6), yet dietary GLA is anti-inflammatory. Some observations partially explain this paradox: LA competes with α-linolenic acid (ALA, 18:3 ω-3) for Δ6-desaturase and thereby eventually inhibits the formation of anti-inflammatory EPA (20:5 ω-3). In contrast, GLA does not compete for Δ6-desaturase. GLA's elongation product, DGLA (20:3 ω-6), competes with 20:4 ω-3 for the Δ5-desaturase, and it might be expected that this would make GLA inflammatory, but it is not, perhaps because this step isn't rate-determining. Δ6-desaturase does appear to be the rate-limiting step; 20:4 ω-3 does not significantly accumulate in bodily lipids.

DGLA inhibits inflammation through both competitive inhibition and direct counteraction (see above). Dietary GLA leads to sharply increased DGLA in the white blood cells' membranes, whereas LA does not. This may reflect white blood cells' lack of desaturase. Supplementing dietary GLA increases serum DGLA without increasing serum AA. [21] [24]

It is likely that some dietary GLA eventually forms AA and contributes to inflammation. Animal studies indicate the effect is small. [19] The empirical observation of GLA's actual effects argues that DGLA's anti-inflammatory effects dominate. [25]

Complexity of pathways

Eicosanoid signaling paths are complex. It is therefore difficult to characterize the action of any particular eicosanoid. For example, PGE2 binds four receptors, dubbed EP1–4. Each is coded by a separate gene, and some exist in multiple isoforms. Each EP receptor, in turn, couples to a G protein. The EP2, EP4, and one isoform of the EP3 receptors couple to Gs. This increases intracellular cAMP and is anti-inflammatory. EP1 and other EP3 isoforms couple to Gq. This leads to increased intracellular calcium and is pro-inflammatory. Finally, yet another EP3 isoform couples to Gi, which both decreases cAMP and increases calcium. Many immune system cells express multiple receptors that couple these apparently opposing pathways. [14] Presumably, EPA-derived PGE3 has a somewhat different effect on this system, but it is not well characterized.

The arachidonic acid cascade in the Central Nervous System

The arachidonic acid cascade is arguably the most elaborate signaling system neurobiologists have to deal with.

Daniele Piomelli Arachidonic Acid [3]

The arachidonic acid cascade proceeds somewhat differently in the central nervous system (CNS). Neurohormones, neuromodulators, or neurotransmitters act as first messengers. They activate phospholipids to release AA from neuron cell membranes as a free fatty acid.[ citation needed ] During its short lifespan, free AA may affect the activity of the neuron's ion channels and protein kinases. Or it may be metabolized to form eicosanoids, epoxyeicosatrienoic acids (EETs), neuroprotectin D, or various endocannabinoids (anandamide and its analogs).

The actions of eicosanoids within the brain are not as well characterized as they are in inflammation. Studies suggest that they act as second messengers within the neuron, possibly controlling presynaptic inhibition and the activation of protein kinase C. They also act as paracrine mediators, acting across synapses to nearby cells. The effects of these signals are not well understood. (Piomelli, 2000) states that there is little information available.

Neurons in the CNS are organized as interconnected groups of functionally related cells (e.g. in sensory systems). A diffusible factor released from a neuron into the interstitial fluid, and able to interact with membrane receptors on adjacent cells would be ideally used to "synchronize" the activity of an ensemble of interconnected neural cells. Furthermore, during development and in certain forms of learning, postsynaptic cells may secrete regulatory factors that diffuse back to the presynaptic component, determining its survival as an active terminal, the amplitude of its sprouting, and its efficacy in secreting neurotransmitters—a phenomenon known as retrograde regulation. Studies have proposed that arachidonic acid metabolites participate in retrograde signaling and other forms of local modulation of neuronal activity.

Table 2.The arachidonic acid cascades act differently between the inflammatory response and the brain.
Arachidonic Acid Cascade
 In inflammationIn the brain
Major effect onInflammation in tissueNeuronal excitability
AA released fromWhite blood cellsNeurons
Triggers for AA releaseInflammatory stimuliNeurotransmitters, neurohormones
and neuromodulators
Intracellular effects onDNA transcription of cytokines and other
mediators of inflammation		Activity of ion channels and protein
kinases
Metabolized to formEicosanoids, resolvins, isofurans, isoprostanes,
lipoxins, epoxyeicosatrienoic acids (EETs)		Eicosanoids, neuroprotectin D, EETs
and some endocannabinoids

The EPA and DGLA cascades are also present in the brain, and their eicosanoid metabolites have been detected. The effects of EPA and DGLA cascades on mental and neural processes are not as well characterized as their effects on inflammation.

Further discussion

Figure 2 shows two pathways from EPA to DHA, including the exceptional Sprecher's shunt.

5-LO acts at the fifth carbon from the carboxyl group. Other lipoxygenases—8-LO, 12-LO, and 15-LO—make other eicosanoid-like products. To act, 5-LO uses the nuclear-membrane enzyme 5-lipoxygenase-activating protein (FLAP), first to a hydroperoxyeicosatetraenoic acid (HPETE), then to the first leukotriene, LTA.

See also

Related Research Articles

<span class="mw-page-title-main">Lipid</span> Substance of biological origin that is soluble in nonpolar solvents

Lipids are a broad group of organic compounds which include fats, waxes, sterols, fat-soluble vitamins, monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include storing energy, signaling, and acting as structural components of cell membranes. Lipids have applications in the cosmetic and food industries, and in nanotechnology.

Omega−3 fatty acids, also called Omega−3 oils, ω−3 fatty acids or n−3 fatty acids, are polyunsaturated fatty acids (PUFAs) characterized by the presence of a double bond, three atoms away from the terminal methyl group in their chemical structure. They are widely distributed in nature, being important constituents of animal lipid metabolism, and they play an important role in the human diet and in human physiology. The three types of omega−3 fatty acids involved in human physiology are α-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). ALA can be found in plants, while DHA and EPA are found in algae and fish. Marine algae and phytoplankton are primary sources of omega−3 fatty acids. DHA and EPA accumulate in fish that eat these algae. Common sources of plant oils containing ALA include walnuts, edible seeds, and flaxseeds as well as hempseed oil, while sources of EPA and DHA include fish and fish oils, and algae oil.

Essential fatty acids, or EFAs, are fatty acids that humans and other animals must ingest because the body requires them for good health, but cannot synthesize them.

<span class="mw-page-title-main">Arachidonic acid</span> Fatty acid used metabolically in many organisms

Arachidonic acid is a polyunsaturated omega-6 fatty acid 20:4(ω-6), or 20:4(5,8,11,14). It is structurally related to the saturated arachidic acid found in cupuaçu butter. Its name derives from the ancient Greek neologism arachis (peanut), but peanut oil does not contain any arachidonic acid.

<span class="mw-page-title-main">Eicosanoid</span> Class of compounds

Eicosanoids are signaling molecules made by the enzymatic or non-enzymatic oxidation of arachidonic acid or other polyunsaturated fatty acids (PUFAs) that are, similar to arachidonic acid, around 20 carbon units in length. Eicosanoids are a sub-category of oxylipins, i.e. oxidized fatty acids of diverse carbon units in length, and are distinguished from other oxylipins by their overwhelming importance as cell signaling molecules. Eicosanoids function in diverse physiological systems and pathological processes such as: mounting or inhibiting inflammation, allergy, fever and other immune responses; regulating the abortion of pregnancy and normal childbirth; contributing to the perception of pain; regulating cell growth; controlling blood pressure; and modulating the regional flow of blood to tissues. In performing these roles, eicosanoids most often act as autocrine signaling agents to impact their cells of origin or as paracrine signaling agents to impact cells in the proximity of their cells of origin. Some eicosanoids, such as prostaglandins, may also have endocrine roles as hormones to influence the function of distant cells.

gamma-Linolenic acid or GLA is an n−6, or omega-6, fatty acid found primarily in seed oils. When acting on GLA, arachidonate 5-lipoxygenase produces no leukotrienes and the conversion by the enzyme of arachidonic acid to leukotrienes is inhibited.

Linoleic acid (LA) is an organic compound with the formula HOOC(CH2)7CH=CHCH2CH=CH(CH2)4CH3. Both alkene groups are cis. It is a fatty acid sometimes denoted 18:2 (n-6) or 18:2 cis-9,12. A linoleate is a salt or ester of this acid.

<span class="mw-page-title-main">Docosahexaenoic acid</span> Chemical compound

Docosahexaenoic acid (DHA) is an omega-3 fatty acid that is a primary structural component of the human brain, cerebral cortex, skin, and retina. It is given the fatty acid notation 22:6(n-3). It can be synthesized from alpha-linolenic acid or obtained directly from maternal milk, fatty fish, fish oil, or algae oil. The consumption of DHA contributes to numerous physiological benefits, including cognition. As the primary structural component of nerve cells in the brain, the function of DHA is to support neuronal conduction and to allow optimal function of neuronal membrane proteins.

In molecular biology, prostanoids are active lipid mediators that regulate inflammatory response. Prostanoids are a subclass of eicosanoids consisting of the prostaglandins, the thromboxanes, and the prostacyclins. Prostanoids are seen to target NSAIDS which allow for therapeutic potential. Prostanoids are present within areas of the body such as the gastrointestinal tract, urinary tract, respiratory and cardiovascular systems, reproductive tract and vascular system. Prostanoids can even be seen with aid to the water and ion transportation within cells.

Dihomo-γ-linolenic acid (DGLA) is a 20-carbon ω−6 fatty acid. In physiological literature, it is given the name 20:3 (ω−6). DGLA is a carboxylic acid with a 20-carbon chain and three cis double bonds; the first double bond is located at the sixth carbon from the omega end. DGLA is the elongation product of γ-linolenic acid. GLA, in turn, is a desaturation product of linoleic acid. DGLA is made in the body by the elongation of GLA, by an efficient enzyme which does not appear to suffer any form of (dietary) inhibition. DGLA is an extremely uncommon fatty acid, found only in trace amounts in animal products.

Fatty acid desaturases are a family of enzymes that convert saturated fatty acids into unsaturated fatty acids and polyunsaturated fatty acids. For the common fatty acids of the C18 variety, desaturases convert stearic acid into oleic acid. Other desaturases convert oleic acid into linolenic acid, which is the precursor to alpha-linolenic acid, gamma-linolenic acid, and eicosatrienoic acid.

Eicosatetraenoic acid (ETA) designates any straight chain 20:4 fatty acid. Eicosatetraenoic acid belongs to the family of eicosanoids, molecules synthesized from oxidized polyunsaturated fatty acids (PUFAs) to mediate cell-cell communication. The eicosanoids, working in tandem, contribute to a lipid signaling complex widely responsible for inducing an inflammatory immune response. Common signs of inflammation are both internal and external, with effects like visible redness, pain in the surrounding area, swelling, and the sensation of heat—many of these an effect of varying eicosanoid species. These effects are associated with and have been observed in patients with cancers and various neurological/metabolic disorders.

William E.M. Lands is an American nutritional biochemist who is among the world's foremost authorities on essential fatty acids.

<span class="mw-page-title-main">Mead acid</span> Chemical compound

Mead acid is an omega-9 fatty acid, first characterized by James F. Mead. As with some other omega-9 polyunsaturated fatty acids, animals can make Mead acid de novo. Its elevated presence in the blood is an indication of essential fatty acid deficiency. Mead acid is found in large quantities in cartilage.

Nonclassic eicosanoids are biologically active signaling molecules made by oxygenation of twenty-carbon fatty acids other than the classic eicosanoids.

<span class="mw-page-title-main">Linoleoyl-CoA desaturase</span> Class of enzymes

Linoleoyl-CoA desaturase (also Delta 6 desaturase, EC 1.14.19.3) is an enzyme that converts between types of fatty acids, which are essential nutrients in the human body. The enzyme mainly catalyzes the chemical reaction

<span class="mw-page-title-main">ALOX15</span> Lipoxygenase found in humans

ALOX15 is, like other lipoxygenases, a seminal enzyme in the metabolism of polyunsaturated fatty acids to a wide range of physiologically and pathologically important products. ▼ Gene Function

Epoxygenases are a set of membrane-bound, heme-containing cytochrome P450 enzymes that metabolize polyunsaturated fatty acids to epoxide products that have a range of biological activities. The most thoroughly studied substrate of the CYP epoxylgenases is arachidonic acid. This polyunsaturated fatty acid is metabolized by cyclooxygenases to various prostaglandin, thromboxane, and prostacyclin metabolites in what has been termed the first pathway of eicosanoid production; it is also metabolized by various lipoxygenases to hydroxyeicosatetraenoic acids and leukotrienes in what has been termed the second pathway of eicosanoid production. The metabolism of arachidonic acid to epoxyeicosatrienoic acids by the CYP epoxygenases has been termed the third pathway of eicosanoid metabolism. Like the first two pathways of eicosanoid production, this third pathway acts as a signaling pathway wherein a set of enzymes metabolize arachidonic acid to a set of products that act as secondary signals to work in activating their parent or nearby cells and thereby orchestrate functional responses. However, none of these three pathways is limited to metabolizing arachidonic acid to eicosanoids. Rather, they also metabolize other polyunsaturated fatty acids to products that are structurally analogous to the eicosanoids but often have different bioactivity profiles. This is particularly true for the CYP epoxygenases which in general act on a broader range of polyunsaturated fatty acids to form a broader range of metabolites than the first and second pathways of eicosanoid production. Furthermore, the latter pathways form metabolites many of which act on cells by binding with and thereby activating specific and well-characterized receptor proteins; no such receptors have been fully characterized for the epoxide metabolites. Finally, there are relatively few metabolite-forming lipoxygenases and cyclooxygenases in the first and second pathways and these oxygenase enzymes share similarity between humans and other mammalian animal models. The third pathway consists of a large number of metabolite-forming CYP epoxygenases and the human epoxygenases have important differences from those of animal models. Partly because of these differences, it has been difficult to define clear roles for the epoxygenase-epoxide pathways in human physiology and pathology.

<span class="mw-page-title-main">Oxylipin</span> Class of lipids

Oxylipins constitute a family of oxygenated natural products which are formed from fatty acids by pathways involving at least one step of dioxygen-dependent oxidation. These small polar lipid compounds are metabolites of polyunsaturated fatty acids (PUFAs) including omega-3 fatty acids and omega-6 fatty acids. Oxylipins are formed by enyzmatic or non-enzymatic oxidation of PUFAs.

Cytochrome P450 omega hydroxylases, also termed cytochrome P450 ω-hydroxylases, CYP450 omega hydroxylases, CYP450 ω-hydroxylases, CYP omega hydroxylase, CYP ω-hydroxylases, fatty acid omega hydroxylases, cytochrome P450 monooxygenases, and fatty acid monooxygenases, are a set of cytochrome P450-containing enzymes that catalyze the addition of a hydroxyl residue to a fatty acid substrate. The CYP omega hydroxylases are often referred to as monoxygenases; however, the monooxygenases are CYP450 enzymes that add a hydroxyl group to a wide range of xenobiotic and naturally occurring endobiotic substrates, most of which are not fatty acids. The CYP450 omega hydroxylases are accordingly better viewed as a subset of monooxygenases that have the ability to hydroxylate fatty acids. While once regarded as functioning mainly in the catabolism of dietary fatty acids, the omega oxygenases are now considered critical in the production or break-down of fatty acid-derived mediators which are made by cells and act within their cells of origin as autocrine signaling agents or on nearby cells as paracrine signaling agents to regulate various functions such as blood pressure control and inflammation.

References

  1. ↑ Cunnane SC (November 2003). "Problems with essential fatty acids: time for a new paradigm?". Progress in Lipid Research. 42 (6): 544–568. doi:10.1016/S0163-7827(03)00038-9. PMID   14559071.
  2. ↑ de Melo Reis RA, Isaac AR, Freitas HR, de Almeida MM, Schuck PF, Ferreira GC, et al. (2021). "Quality of Life and a Surveillant Endocannabinoid System". Frontiers in Neuroscience. 15: 747229. doi: 10.3389/fnins.2021.747229 . PMC   8581450 . PMID   34776851.
  3. 1 2 3 Piomelli, Daniele (2000). "Arachidonic Acid". Neuropsychopharmacology: The Fifth Generation of Progress. Archived from the original on 2006-07-15. Retrieved 2006-03-03.
  4. ↑ Freitas HR (2017-08-25). "Chlorella vulgaris as a Source of Essential Fatty Acids and Micronutrients: A Brief Commentary". The Open Plant Science Journal. 10 (1): 92–99. doi: 10.2174/1874294701710010092 (inactive 2024-04-24). ISSN   1874-2947.{{cite journal}}: CS1 maint: DOI inactive as of April 2024 (link)
  5. ↑ Freitas HR, Isaac AR, Malcher-Lopes R, Diaz BL, Trevenzoli IH, De Melo Reis RA (December 2018). "Polyunsaturated fatty acids and endocannabinoids in health and disease". Nutritional Neuroscience. 21 (10): 695–714. doi:10.1080/1028415X.2017.1347373. PMID   28686542. S2CID   40659630.
  6. ↑ Freitas HR, Ferreira GD, Trevenzoli IH, Oliveira KJ, de Melo Reis RA (November 2017). "Fatty Acids, Antioxidants and Physical Activity in Brain Aging". Nutrients. 9 (11): 1263. doi: 10.3390/nu9111263 . PMC   5707735 . PMID   29156608.
  7. ↑ Simopoulos A (2001). "Evolutionary aspects of diet and essential fatty acids". Fatty Acids and Lipids – New Findings (PDF). World Review of Nutrition and Dietetics. Vol. 88. pp. 18–27. doi:10.1159/000059742. ISBN   978-3-8055-7182-1. PMID   11935953. Archived from the original (PDF) on 2006-09-26.{{cite book}}: |journal= ignored (help)
  8. ↑ National Institute of Health (2005-08-01). "Omega-3 fatty acids, fish oil, alpha-linolenic acid". Archived from the original on February 8, 2006. Retrieved August 21, 2010.
  9. ↑ De Caterina R, Basta G (2001). "n-3 Fatty acids and the inflammatory response — biological background". European Heart Journal Supplements. 3 (suppl D): D42–D49. doi: 10.1016/S1520-765X(01)90118-X .
  10. ↑ Cyberlipid Center. "Polyenoic fatty acids". Archived from the original on September 30, 2018. Retrieved February 11, 2006.
  11. 1 2 Cyberlipid Center. "Prostanoids". Archived from the original on February 8, 2007. Retrieved February 11, 2006.
  12. ↑ Whelan J, Fritsche K (May 2013). "Linoleic acid". Advances in Nutrition. 4 (3): 311–312. doi: 10.3945/an.113.003772 . PMC   3650500 . PMID   23674797.
  13. 1 2 Calder, Philip C. (September 2004). "n-3 Fatty Acids and Inflammation – New Twists in an Old Tale". Archived from the original on March 16, 2006. Retrieved February 8, 2006.
    • Invited review article, PUFA Newsletter.
  14. 1 2 Tilley SL, Coffman TM, Koller BH (July 2001). "Mixed messages: modulation of inflammation and immune responses by prostaglandins and thromboxanes". The Journal of Clinical Investigation. 108 (1): 15–23. doi:10.1172/JCI13416. PMC   209346 . PMID   11435451.
  15. ↑ Medical Study News (25 May 2005). "Brain fatty acid levels linked to depression" . Retrieved February 10, 2006.
  16. ↑ KP Su; SY Huang; CC Chiu; WW Shen (2003). "Omega-3 fatty acids in major depressive disorder. A preliminary double-blind, placebo-controlled?" (PDF). Archived from the original (PDF) on February 8, 2005. Retrieved February 22, 2006.
  17. ↑ Phinney SD, Odin RS, Johnson SB, Holman RT (March 1990). "Reduced arachidonate in serum phospholipids and cholesteryl esters associated with vegetarian diets in humans". The American Journal of Clinical Nutrition. 51 (3): 385–392. doi:10.1093/ajcn/51.3.385. PMID   2106775. Archived from the original on February 12, 2007. Retrieved February 11, 2006.
    • "[D]ietary arachidonic acid enriches its circulating pool in humans; however, 20:5n-3 is not similarly responsive to dietary restriction."
  18. ↑ Guivernau M, Meza N, Barja P, Roman O (November 1994). "Clinical and experimental study on the long-term effect of dietary gamma-linolenic acid on plasma lipids, platelet aggregation, thromboxane formation, and prostacyclin production". Prostaglandins, Leukotrienes, and Essential Fatty Acids. 51 (5): 311–316. doi:10.1016/0952-3278(94)90002-7. PMID   7846101.
    • GLA decreases triglycerides, LDL, increases HDL, decreases TXB2 and other inflammatory markers. Review article; human and rat studies.
  19. 1 2 Karlstad MD, DeMichele SJ, Leathem WD, Peterson MB (November 1993). "Effect of intravenous lipid emulsions enriched with gamma-linolenic acid on plasma n-6 fatty acids and prostaglandin biosynthesis after burn and endotoxin injury in rats". Critical Care Medicine. 21 (11): 1740–1749. doi:10.1097/00003246-199311000-00025. PMID   8222692. S2CID   36538810.
    • IV Supplementation with gamma-linolenic acid increased serum GLA but did not increase the plasma percentage of arachidonic acid (rat study), decreased TXB2.
  20. ↑ Belch JJ, Hill A (January 2000). "Evening primrose oil and borage oil in rheumatologic conditions". The American Journal of Clinical Nutrition. 71 (1 Suppl): 352S–356S. doi: 10.1093/ajcn/71.1.352s . PMID   10617996.
    • "DGLA itself cannot be converted to LTs but can form a 15-hydroxyl derivative that blocks the transformation of arachidonic acid to LTs. Increasing DGLA intake may allow DGLA to act as a competitive inhibitor of 2-series PGs and 4-series LTs and thus suppress inflammation."
  21. 1 2 Fan YY, Chapkin RS (September 1998). "Importance of dietary gamma-linolenic acid in human health and nutrition". The Journal of Nutrition. 128 (9): 1411–1414. doi: 10.1093/jn/128.9.1411 . PMID   9732298.
    • "[D]ietary GLA increases the content of its elongase product, dihomo-gamma linolenic acid (DGLA), within cell membranes without concomitant changes in arachidonic acid (AA). Subsequently, upon stimulation, DGLA can be converted by inflammatory cells to 15-(S)-hydroxy-8,11,13-eicosatrienoic acid and prostaglandin E1. This is noteworthy because these compounds possess both anti-inflammatory and antiproliferative properties."
  22. ↑ Fischer S, Weber PC (September 1985). "Thromboxane (TX)A3 and prostaglandin (PG)I3 are formed in man after dietary eicosapentaenoic acid: identification and quantification by capillary gas chromatography-electron impact mass spectrometry". Biomedical Mass Spectrometry. 12 (9): 470–476. doi:10.1002/bms.1200120905. PMID   2996649.
  23. ↑ Prescott SM (June 1984). "The effect of eicosapentaenoic acid on leukotriene B production by human neutrophils". The Journal of Biological Chemistry. 259 (12): 7615–7621. doi: 10.1016/S0021-9258(17)42835-3 . PMID   6330066.
  24. ↑ Johnson MM, Swan DD, Surette ME, Stegner J, Chilton T, Fonteh AN, Chilton FH (August 1997). "Dietary supplementation with gamma-linolenic acid alters fatty acid content and eicosanoid production in healthy humans". The Journal of Nutrition. 127 (8): 1435–1444. doi: 10.1093/jn/127.8.1435 . PMID   9237935.
  25. ↑ Stone KJ, Willis AL, Hart WM, Kirtland SJ, Kernoff PB, McNicol GP (February 1979). "The metabolism of dihomo-gamma-linolenic acid in man". Lipids. 14 (2): 174–180. doi:10.1007/BF02533869. PMID   423720. S2CID   41372225.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.