Which fatty acid is essential to the human body

This happened because AA is the main substrate for the synthesis of the pro-inflammatory mediators, such as cytokines and eicosanoids.

Other lipid mediators, such as oxylipins, were also detected in plasma. Another biomarker in inflammation can be considered the omega-3 index. The inflammatory mediators, C-reactive protein, monocytes and neutrophils, are inversely correlated to DHA, omega-3 index and total omega-3 PUFA [ 14 ]. Discovering new biomarkers in the field of psychiatry has a huge importance, because they could clarify the etiology of psychiatric problems, confirm the diagnosis of disorders with similar symptoms and predict the course of the disorder and determine how to treat it [ 15 ].

Neurodegenerative diseases are caused by several factors, including genetic mutation, membrane damage, mitochondrial dysfunction and a protein or lipid metabolism alteration. PUFAs are selectively concentrated in synaptic neuronal membranes and regulate vascular and immune functions that affect the central nervous system. Moreover, they have important functions in neurotransmitter signaling. The brain is the most lipid-enriched organ, containing several major lipid classes, including fatty acids.

During brain development, especially in the embryonic stage, polyunsaturated fatty acids are critical for cell proliferation and neuronal differentiation, and their deprivation results in apoptosis. Deregulation of fatty acids is also involved in the pathogenesis of numerous brain disorders, such as neurodegenerative diseases, mental retardation, stroke and trauma [ 2 ]. The Alzheimer disease AD is a chronic neurodegenerative disease, which usually affects the elderly people and causes dementia.

The most common early symptom is difficulty in remembering recent events, but difficulty in speech, disorganized thinking and memory loss is also common. Currently accepted biomarkers of AD include levels of brain chemicals related to amyloid or tau protein and imaging-derived estimates of the size and metabolic activity of specific brain regions. Besides these modifications of the protein metabolism, the lipid metabolism is altered as well, characterized by a decreased level of the omega-3 fatty acids.

Molecular alterations of the fatty acids that persist from preclinical stages through the dementia phase may serve as biomarkers that could aid the early diagnosis of AD. Different stages of AD may have a different gene expression for fatty acid synthesis [ 2 ]. In this disease, scientists have revealed alterations in lipid metabolism pathways and in lipid carrier proteins, such as ApoE. Alterations of the lipid metabolism were observed not only in case of patients diagnosed with Alzheimer but also in case of those with other cognitive alterations.

In each case, the biggest difference reported between the healthy volunteers and the patients was represented by the level of docosahexaenoic acid. However, other fatty acids presented an altered profile as well. Fatty acids contribute to the modulation of the structure and function of biological membranes, including elasticity, membrane organization and ion permeability, and may therefore facilitate brain glucose uptake, neurotransmission and neuronal function.

The docosahexaenoic acid C is indispensable for the neuronal myelination, and it is an important precursor for the very long chain fatty acid synthesis C, C, C, C, C, C , found in the brain.

It is also involved in neurogenesis, neurotransmission and protects the brain from the oxidative stress. It has an important role in maintaining the integrity of the basal membrane and as a phospholipid ester maintains the flexibility of the cellular membrane, helping the synaptic transmission, and it can also adjust the speed of the signal transmission.

DHA can influence the brain development because it can regulate the gene expression, monoaminergic neurotransmission or protection against apoptotic cell death [ 24 ]. During pregnancy, DHA accumulates in human neonatal brain tissue at an accelerated rate during the third trimester in association with rapid changes in cortical structural maturation.

A deficit of this fatty acid in the stage of the brain development can lead to the cognitive performance alterations [ 24 ]. The polyunsaturated fatty acids, besides their role of maintaining the integrity of the neuronal cell membrane, are involved in the synthesis of eicosapentaenoic acid from which the synthesis of the 3-series prostaglandin and 5-leukotriene begins.

EPA has neuroprotective, anti-oxidant and anti-inflammatory properties [ 24 ]. In case of deficiency of DHA and EPA, the cell permeability modifies and mitochondrial dysfunctions and inflammation appear, and along with the oxidative stress, it plays an important role in the progression of the disease.

DHA and EPA can play a role in alleviating oxidative stress and reducing the risk of neurodegenerative diseases [ 25 ]. The novel series of lipid mediators resolvins, protectins and maresins have revealed their protective and beneficial effect in neurological diseases, due to their anti-inflammatory and pro-resolving properties.

A simultaneous deficiency of LA and ALA creates serious problems in fatty acid composition of the brain. ALA deficiency alters the course of brain development and perturbed the composition of brain cell membranes, neurons, oligodendrocytes and astrocytes as well as subcellular components such as myelin, nerve endings and mitochondria.

Several other neurological disorders present altered neuronal and plasma fatty acid composition, such as depression, bipolar disorder, schizophrenia and attention deficit hyperactivity disorder.

Depression is accompanied by activation of the inflammatory response system indicated by an increased production of inflammatory cytokines and oxidative biomarker. Cytokine production is accompanied by increased oxidative stress leading to elevated production of reactive oxygen species ROS and nitric oxide NO or decreased anti-oxidant defense, such as superoxide dismutase SOD and glutathione peroxidase. Epidemiological studies also showed that low intake and blood levels of omega-3 PUFAs are associated with an increased risk for being diagnosed with major depressive disorder.

Erythrocyte levels of C, C, EPA and the omega-3 index were significantly lower in the case of patients diagnosed with major depression than in the controls, whereas erythrocyte levels of C, Cn6, Cn3, Ct and Ct were significantly higher [ 26 ].

Different studies suggest that omega-3 fatty acid status influences the development of central serotonin systems. A deficit of the omega-3 fatty acids leads to impaired serotonin release and behavioral signs of depression and aggression.

Patients with major depressive disorder present a DHA deficiency compared to healthy controls [ 27 ]. The patients diagnosed with bipolar disorder presented higher plasma concentrations of all saturated fatty acids than the controls. In this disorder too, the most important differences between the two groups were represented by the significant decreases in DHA levels and strong increases in levels of EPA and ALA [ 28 ].

The presently available data of the literature suggest that the metabolism of PUFAs is altered in patients with schizophrenia, both in the acute and chronic stages of the disease. Altered neuronal membrane structure and metabolism might contribute to some of the symptoms of schizophrenia. A change in membrane lipid composition in neuronal cells can affect neurotransmission and this way can affect the behavior in schizophrenia.

Studies showed no difference between the schizophrenia patients and control subjects in the contribution of omega-3 fatty acids to the lipid composition of the phospholipid fraction. However, the values of total omega-6 PUFAs and docosapentaenoic acid are shown to be significantly lower in case of patients with schizophrenia than in case of the control subjects.

Membrane lipids seem to fluctuate in different disease phases. This may be related to changes in neuroinflammatory and oxidative processes, which are reported to contribute to disease progression and underlie symptom severity. The healthy group presents stable PUFA levels compared to the patients group.

PUFAs are not only important components of neuronal cell membranes but also play an important role in regulation of inflammation through the formation of eicosanoids. Inflammation and oxidative stress may play a role in disease progression through lipid peroxidation and cholesterol oxidation, leading to neuronal cell death [ 29 ].

PUFA deficiency will also impair dopaminergic and glutamatergic neurotransmission, which are linked to negative symptoms. Inflammation plays a role in the etiology of many types of cancer. It was reported that high concentration of serum long-chain omega-3 fatty acid phospholipids, EPA and DHA, in particular, was associated with the increased risk of high-grade prostate cancer.

However, high concentrations of trans -fatty acids, which are known to produce inflammation, are associated with a reduced risk of prostate cancer [ 30 ].

Other studies have been realized on colorectal cancer tissues from which different fatty acids have been separated. Ekahi Ornish. Apply Online. Deli Menus. Super Saver Flyer. The Benefits of Essential Fatty Acids. Facebook Twitter Pinterest Print. These EFAs are necessary for the following processes: Formation of healthy cell membranes Proper development and functioning of the brain and nervous system Proper thyroid and adrenal activity Hormone production Regulation of blood pressure, liver function, immune and inflammatory responses Regulation of blood clotting: Omega-6 FAs encourage blood clot formation, whereas Omega-3 oil reduces clotting.

Sources of Omega-6 fatty acids include nuts, seeds, grains, legumes, and dairy. Health Topics Alternative Medicine. They are an integral part of cell membranes throughout the body and affect the function of the cell receptors in these membranes.

They provide the starting point for making hormones that regulate blood clotting, contraction and relaxation of artery walls, and inflammation. They also bind to receptors in cells that regulate genetic function. Likely due to these effects, omega-3 fats have been shown to help prevent heart disease and stroke, may help control lupus, eczema, and rheumatoid arthritis, and may play protective roles in cancer and other conditions.

The strongest evidence for a beneficial effect of omega-3 fats has to do with heart disease. These fats appear to help the heart beat at a steady clip and not veer into a dangerous or potentially fatal erratic rhythm. Omega-3 fats also lower blood pressure and heart rate, improve blood vessel function, and, at higher doses, lower triglycerides and may ease inflammation, which plays a role in the development of atherosclerosis.

Several large trials have evaluated the effect of fish or fish oils on heart disease. In the more recent Japan EPA Lipid Intervention Study JELIS , participants who took EPA plus a cholesterol-lowering statin were less likely to have a major coronary event sudden cardiac death, fatal or nonfatal heart attack, unstable angina, or a procedure to open or bypass a narrowed or blocked coronary artery than those who took a statin alone.

Most Americans take in far more of another essential fat—omega-6 fats—than they do omega-3 fats. Some experts have raised the hypothesis that this higher intake of omega-6 fats could pose problems, cardiovascular and otherwise, but this has not been supported by evidence in humans.

Although there is no question that many Americans could benefit from increasing their intake of omega-3 fats, there is evidence that omega-6 fats also positively influence cardiovascular risk factors and reduce heart disease. Researchers are taking a hard look at a different sort of balance, this one between possible effects of marine and plant omega-3 fats on prostate cancer. The pooled analysis of these trials showed no beneficial effect of omega-3 supplementation on measures of global and specific cognitive functions, measures of functional outcomes, and measures of dementia severity There was no difference between intervention and placebo arms regarding the occurrence of adverse effects Linoleic acid LA : Food sources of LA include vegetable oils, such as soybean, safflower, and corn oil; nuts ; seeds; and some vegetables.

Some foods that are rich in LA are listed in Table 2. Therefore, AA is absent in vegetable oils and fats and present in small amounts in meat, poultry, and eggs. Canola oil is also an excellent source of ALA. Some foods that are rich in ALA are listed in Table 3. Flaxseed oil also known as flax oil or linseed oil is available as an ALA supplement. A number of fish oils are marketed as omega-3 fatty acid supplements.

Cod liver oil is also a rich source of EPA and DHA, but some cod liver oil preparations may contain excessive amounts of preformed vitamin A retinol and vitamin D DHA supplements derived from algal and fungal sources are also available. All omega-3 fatty acid supplements are absorbed more efficiently with meals.

Dividing one's daily dose into two or three smaller doses throughout the day will decrease the risk of gastrointestinal side effects see Safety. Presently, manufacturers are not required to list the amounts of DHA and AA added to infant formula on the label.

However, most infant formula manufacturers provide this information. High doses of borage seed oil, evening primrose oil, or black currant seed oil may cause gastrointestinal upset, loose stools, or diarrhea Although flaxseed oil is generally well tolerated, high doses may cause loose stools or diarrhea Allergic and anaphylactic reactions have been reported with flaxseed and flaxseed oil ingestion Belching and heartburn have also been reported.

Additionally, high doses may cause nausea and loose stools. Potential for excessive bleeding: The potential for high omega-3 fatty acid intakes, especially EPA and DHA, to prolong bleeding times has been well studied and may play a role in the cardioprotective effects of omega-3 fatty acids. Although the US Institute of Medicine did not establish a tolerable upper intake level UL for omega-3 fatty acids, caution was advised with the use of supplemental EPA and DHA, especially in those who are at increased risk of excessive bleeding see Drug interactions and Nutrient interactions 1 , Potential for immune system suppression: Although the suppression of inflammatory responses resulting from increased omega-3 fatty acid intakes may benefit individuals with inflammatory or autoimmune diseases , anti-inflammatory doses of omega-3 fatty acids could decrease the potential of the immune system to destroy pathogens Studies comparing measures of immune cell function outside the body ex vivo at baseline and after supplementing people with omega-3 fatty acids, mainly EPA and DHA, have demonstrated immunosuppressive effects at doses as low as 0.

Although it is not clear if these findings translate to impaired immune responses in vivo , caution should be observed when considering omega-3 fatty acid supplementation in individuals with compromised immune systems. Potential other effects: Although fish oil supplements are unlikely to affect glucose homeostasis , people with diabetes mellitus who are considering fish oil supplements should inform their physician and be monitored if they choose to take them However, some preterm infants receiving fish oil-enriched formula had decreased plasma AA concentrations, which were associated with decreased weight but not length and head circumference , This effect was attributed to the potential for high concentrations of EPA to interfere with the synthesis of AA, which is essential for normal growth.

Randomized controlled trials have not found any adverse effects on growth in infants fed formulas enriched with AA and DHA for up to one year The safety of supplemental omega-3 and omega-6 fatty acids , including borage seed oil, evening primrose oil, black currant seed oil, and flaxseed oil, has not been established in pregnant or lactating breast-feeding women Some species of fish may contain significant levels of methylmercury, polychlorinated biphenyls PCBs , or other environmental contaminants In general, larger predatory fish, such as swordfish, tend to contain the highest levels of these contaminants.

Removing the skin, fat, and internal organs of the fish prior to cooking and allowing the fat to drain from the fish while it cooks will decrease exposure to a number of fat-soluble pollutants, such as PCBs However, methylmercury is found throughout the muscle of fish, so these cooking precautions will not reduce exposure to methylmercury.

Organic mercury compounds are toxic and excessive exposure can cause brain and kidney damage. The developing fetus, infants, and young children are especially vulnerable to the toxic effects of mercury on the brain. In order to limit their exposure to methylmercury, the US Food and Drug Administration FDA and Environmental Protection Agency have formulated joint recommendations for women who may become pregnant, pregnant women, breast-feeding women, and parents.

These recommendations are presented in Table 5. More information about mercury levels in commercial fish and shellfish is available from the FDA. Of note, the Dietary Guidelines for Americans recommend the consumption of salmon, anchovies, herring, shad, sardines, Pacific oysters, trout, and Atlantic and Pacific mackerel not king mackerel , which are higher in EPA and DHA and lower in methylmercury Although concerns have been raised regarding the potential for omega-3 fatty acid supplements derived from fish oil to contain methylmercury, PCBs, and dioxins, several independent laboratory analyses in the US have found commercially available omega-3 fatty acid supplements to be free of methylmercury, PCBs, and dioxins The absence of methylmercury in omega-3 fatty acid supplements can be explained by the fact that mercury accumulates in the muscle, rather than the fat of fish In general, fish body oils contain lower concentrations of PCBs and other fat-soluble contaminants than fish liver oils.

Additionally, fish oils that have been more highly refined and deodorized contain lower concentrations of PCBs Pyrrolizidine alkaloids, potentially hepatotoxic and carcinogenic compounds, are found in various parts of the borage plant. People who take borage oil supplements should use products that are certified free of unsaturated pyrrolizidine alkaloids High doses of black currant seed oil, borage seed oil, evening primrose oil, flaxseed oil, and fish oil may inhibit platelet aggregation; therefore, these supplements should be used with caution in people on anticoagulant medications In particular, people taking fish oil or long-chain omega-3 fatty acid EPA and DHA supplements in combination with anticoagulant drugs, including aspirin, clopidogrel Plavix , dalteparin Fragmin , dipyridamole Persantine , enoxaparin Lovenox , heparin, ticlopidine Ticlid , and warfarin Coumadin , should have their coagulation status monitored using a standardized prothrombin time assay international normalized ratio [INR].

Outside the body, PUFA become rancid oxidized more easily than saturated fatty acids. Inside the body, results of animal studies and limited data in humans suggest that the amount of vitamin E required to prevent lipid peroxidation increases with the amount of PUFA consumed One widely used recommendation for vitamin E intake is 0. Although EPA and DHA are easily oxidized outside the body, it is presently unclear whether they are more susceptible to oxidative damage within the body High vitamin E intakes have not been found to decrease biomarkers of oxidative damage when EPA and DHA intakes are increased , , but some experts believe that an increase in PUFA intake, particularly omega-3 PUFA intake, should be accompanied by an increase in vitamin E intake 1.

The potential benefits associated with obtaining long-chain omega-3 fatty acids through moderate consumption of fish e. For information about contaminants in fish and guidelines for fish consumption by women of childbearing age, see Contaminants in fish.

Seafood, nuts , seeds, and oils, which are all part of healthy dietary patterns, provide essential fatty acids. The Dietary Guidelines provide dietary recommendations regarding the amounts of these foods for those who choose to follow a healthy US-style eating pattern, a healthy Mediterranean-style eating pattern, or a healthy vegetarian eating pattern Table 8.

The American Heart Association recommends that people without documented coronary heart disease CHD eat a variety of fish preferably oily at least twice weekly Pregnant women and children should avoid fish that typically have higher levels of methylmercury see Contaminants in fish. For adults, the World Health Organization recommends an acceptable macronutrient distribution range AMDR for omega-6 fatty acid intake of 2.

The American Heart Association recommends that people without documented CHD eat a variety of fish preferably oily at least twice weekly The Linus Pauling Institute recommends that generally healthy adults increase their intake of long-chain omega-3 fatty acids by eating fish twice weekly and consuming foods rich in ALA, such as walnuts, flaxseeds, and flaxseed or canola oil.

If you don't regularly consume fish, consider taking a two-gram fish oil supplement several times a week. If you are prone to bleeding or take anticoagulant drugs, consult your physician. Originally written in by: Jane Higdon, Ph. Updated in December by: Jane Higdon, Ph. Updated in April by: Victoria J.

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