Omega-3 fatty acids , also called ? - 3 fatty acids or n -3 fatty acids , is a polyunsaturated fatty acid (PUFA). The fatty acids have two ends, the carboxylic acid (-COOH) end, which is considered the beginning of the chain, so that "alpha", and methyl end (-CH 3 ), are considered "tail" chains, omega ". One of the so-called fatty acids is determined by the location of the first double bond, calculated from the tail, ie, omega (? -) or n-end. Thus, in the omega-3 fatty acid the first double bond is between the third and fourth carbon atoms from the tail end. However, the standard chemical nomenclature (IUPAC) system starts from the carboxyl end.
The three types of omega-3 fatty acids involved in human physiology are -linolenic acid (ALA), found in plant oils, and eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), both commonly found in marine oils. Seaweed and phytoplankton are the main sources of omega-3 fatty acids. Common sources of vegetable oil containing ALA include walnuts, edible seeds, sage seed oil, algae oil, linseed oil, Sacha Inchi oil, Echium oil, and hemp oil, while the source of omega fats -3 EPA and DHA acids include fish, fish oil, eggs from chickens fed EPA and DHA, squid oil, and krill oil. Dietary supplementation with omega-3 fatty acids does not appear to affect the risk of death, cancer or heart disease. Furthermore, fish oil supplement research failed to support claims to prevent heart attacks or strokes.
Omega-3 fatty acids are important for normal metabolism. Mammals can not synthesize omega-3 fatty acids, but can obtain ALA (18 carbon and 3 double bond) omega-3 fatty acids through diet and use them to form more important long-chain omega-3 fatty acids. , EPA (20 carbon and 5 double bonds) and then from EPA, most importantly, DHA (22 carbon and 6 double bonds). The ability to make long-chain omega-3 fatty acids from ALA can be impaired in aging. In foods exposed to air, unsaturated fatty acids are susceptible to oxidation and rancidity.
Video Omega-3 fatty acid
Health effects
Supplementation does not seem to be associated with a lower risk of all-cause mortality.
Cancer
The evidence linking the consumption of omega-3 marine fats with lower cancer risk is poor. With the possible exclusion of breast cancer, there is not enough evidence that supplementation with omega-3 fatty acids has an effect on different cancers. The effects of consumption on prostate cancer are not conclusive. There is a reduced risk with higher blood DPA levels, but an increased risk of more aggressive prostate cancer is indicated by higher blood EPA and DHA levels. In people with advanced cancer and cachexia, supplements of omega-3 fatty acids may be beneficial, increasing appetite, weight, and quality of life.
Cardiovascular Disease
Evidence in the general population does not support a beneficial role for supplementation of omega-3 fatty acids in preventing cardiovascular disease (including myocardial infarction and sudden cardiac death) or stroke. However, supplementing omega-3 fatty acids over one gram daily for at least a year may protect against cardiac death, sudden death, and myocardial infarction in people with a history of cardiovascular disease. There is no protective effect on the development of stroke or all causes of death seen in this population. Eating high fish foods containing long chain omega-3 fatty acids does appear to reduce the risk of stroke. Fish oil supplementation has not been shown to benefit abnormal revascularization or heart rhythm and has no effect on admission rates of heart failure hospitals. Furthermore, fish oil supplement research failed to support claims to prevent heart attacks or strokes.
Evidence suggests that omega-3 fatty acids slightly lower blood pressure (systolic and diastolic) in people with hypertension and in people with normal blood pressure. Some evidence suggests that people with certain circulatory problems, such as varicose veins, may benefit from the consumption of EPA and DHA, which can stimulate blood circulation and improve the breakdown of fibrin, a protein involved in blood clotting and scar formation. Omega-3 fatty acids reduce blood triglyceride levels but do not significantly alter the levels of LDL cholesterol or HDL cholesterol in the blood. The American Heart Association position (2011) is a rising triglyceride in the limit, defined as 150-199 mg/dL, can be decreased by 0.5-1.0 grams of EPA and DHA per day; High triglycerides 200-499 mg/dL beneficial from 1-2 g/day; and & gt; 500 mg/dL treated under a physician's supervision with 2-4 g/day using the prescribed product.
ALA does not provide cardiovascular health benefits of EPA and DHA.
The effects of omega-3 polyunsaturated fatty acids on stroke are unclear, with possible benefits in women.
Inflammation
A systematic review of 2013 finds provisional evidence of benefits for reducing levels of inflammation in healthy adults and in people with one or more biomarkers of the metabolic syndrome. Consumption of omega-3 fatty acids from marine sources decreases inflammatory blood markers such as C-reactive protein, interleukin 6, and TNF alpha.
For rheumatoid arthritis, a systematic review found consistent, but simple, evidence for n-3 PUFA marine effects on symptoms such as "swelling and joint pain, duration of morning stiffness, global assessment of pain and disease activity" and use of non-inflammatory anti- steroids. The American College of Rheumatology has stated that there may be modest benefits from the use of fish oil, but it may take months for the effects to be seen, and warn for possible gastrointestinal side effects and possible supplements containing mercury or vitamin A at toxic levels. The National Center for Complementary and Integrative Health has concluded that "[n] dietary supplements have shown clear benefits for rheumatoid arthritis", but that there is preliminary evidence that fish oil may be beneficial, but it needs further study.
Developmental flaw
Although not supported by current scientific evidence as a primary treatment for attention deficit hyperactivity disorder (ADHD), autism, and other developmental defects, omega-3 fatty acid supplements are given to children with this condition.
One meta-analysis concluded that supplementation of omega-3 fatty acids showed a simple effect to correct the symptoms of ADHD. A Cochrane review of PUFA supplementation (not necessarily omega-3) found "there is little evidence that PUFA supplementation provides any benefit to ADHD symptoms in children and adolescents", while different reviews find "insufficient evidence to draw conclusions about use of PUFA for children with certain learning disorders ". Another review concluded that evidence can not be inferred for the use of omega-3 fatty acids in neurodicenerative neuropsychiatric behaviors and disorders such as ADHD and depression.
Fish oil has little benefit on the risk of premature birth. The 2015 meta-analysis of the effects of omega-3 supplementation during pregnancy did not show a decline in preterm birth rates or improved outcomes in women with single pregnancies without previous preterm births. A systematic review and meta-analysis published in the same year reached the opposite conclusion, in particular, omega-3 fatty acids were effective in "preventing premature birth and premature labor".
Mental health
There is some evidence that omega-3 fatty acids are associated with mental health, including that they can be temporarily useful in addition to the treatment of depression associated with bipolar disorder. Significant benefits due to EPA supplementation are only seen, however, when treating depressive symptoms and not manic symptoms suggest a link between omega-3 and the depression mood. There is also preliminary evidence that EPA supplementation is helpful in cases of depression. The relationship between omega-3 and depression has been linked to the fact that many products of the omega-3 synthesis pathway play a key role in regulating inflammation such as prostaglandin E3 that has been associated with depression. This association with inflammatory regulation has been well supported in in vitro and in vivo studies as well as in meta-analysis studies. The exact mechanisms in which omega-3s work on inflammatory systems are still controversial because it is generally believed to have anti-inflammatory effects.
Nevertheless, there are significant difficulties in interpreting the literature due to participants' recollections and systematic differences in diet. There is also controversy about the efficacy of omega-3s, with many meta-analysis papers finding heterogeneity among the results that can be explained largely by publication bias. Significant correlations between shorter treatment trials are associated with increased efficacy of omega-3s to treat further depressive symptoms that imply a bias in publications.
A study in 2013, (Stafford, Jackson, Mayo-Wilson, Morrison, Kendall), states the following in his conclusion: "Although the evidence of benefits for any particular intervention is not conclusive, these findings suggest that it is possible to delay or prevent a transition to psychosis Further research should be undertaken to establish the exact potential benefits of psychological intervention in the treatment of people at high risk of psychosis. "
Cognitive aging
Epidemiological studies are inconclusive about the effects of omega-3 fatty acids on the mechanism of Alzheimer's disease. There is early evidence of an effect on mild cognitive problems, but it does not support the effects on healthy people or those with dementia.
Brain and visual functions
Brain function and vision depend on DHA intake to support various properties of cell membranes, especially in gray matter, which is rich in membranes. The main structural component of the mammalian brain, DHA is the most abundant omega-3 fatty acids in the brain. It is being studied as an essential nutritional candidate with a role in neural development, cognition, and neurodegenerative disorders.
Atopic diseases
Results of research investigating the role of LCPUFA supplementation and LCPUFA status in the prevention and treatment of atopic diseases (allergic rhinoconjunctivitis, atopic dermatitis and allergic asthma) are controversial; therefore, in our present stage of knowledge (in 2013) we can not argue that the n-3 fatty acid intake has a clear preventive or therapeutic role, or that the n-6 fatty acid intake has a promoting role. in the context of atopic diseases.
Deficiency risks
People with PKU often have low intake of omega-3 fatty acids, because nutrients rich in omega-3 fatty acids are removed from their diet due to their high protein content.
Asthma
In 2015 there is no evidence that taking omega 3 supplements can prevent asthma attacks in children.
Maps Omega-3 fatty acid
Chemistry
Omega-3 fatty acids are double-bonded fatty acids, in which the first double bond is between the third and fourth carbon atoms from the ends of the carbon atom chain. The "short chain" omega-3 fatty acids have 18 or fewer carbon atoms, while the "long chains" of omega-3 fatty acids have 20 or more chains.
Three omega-3 fatty acids are important in human physiology ,? -linolenic acid (18: 3, n -3; ALA), eicosapentaenoic acid (20: 5, n-EPA), and docosahexaenoic acid (22: 6 , n -3; DHA). These three polyunsaturations have 3, 5, or 6 double bonds in each carbon chain of 18, 20, or 22 carbon atoms. Like most naturally produced fatty acids, all the double bonds are in the cis configuration, in other words, the two hydrogen atoms are on the same side of the double bond; and the double bond is disturbed by the methylene bridge (- CH
2 -), so there are two single bonds between each pair of adjacent double bonds. List of omega-3 fatty acids
This table lists several different names for the most common omega-3 fatty acids found in nature.
Form
Omega-3 fatty acids appear naturally in two forms, triglycerides and phospholipids. In triglycerides, they, along with other fatty acids, are bound to glycerol. Omega-3 phospholipids consist of two fatty acids attached to phosphate and choline, compared with three fatty acids attached to glycerol in triglycerides.
Triglycerides may be converted to free fatty acids or methyl or ethyl esters, and individual esters of omega-3 fatty acids are available.
Biochemistry
Carrier
DHA in the form of lysophosphatidylcholine is transported to the brain by membrane transport proteins, MFSD2A, exclusively expressed in the blood-brain barrier endothelium.
Action mechanism
Essential fatty acids were named after researchers found that they were essential for normal growth in children and animals. Omega-3 DHA fatty acids, also known as docosahexaenoic acid, are found in high abundance in the human brain. This is produced by the desaturation process, but humans lack the desaturase enzyme, which acts to insert double bonds in position? 6 and? 3 . Therefore, 6 and? 3 polyunsaturated fatty acids can not be synthesized and rightly called essential fatty acids.
In 1964 it was found that enzymes found in sheep tissue convert omega-6 arachidonic acid into an inflammatory agent called prostaglandin E 2 both of which cause pain sensation and accelerate healing and immune response in traumatized and infected tissues.. In 1979 more than what is now known as eikosanoid is found: thromboxanes, prostacyclins, and leukotrienes. Eicosanoids, which have important biological functions, usually have a short active period in the body, beginning with the synthesis of fatty acids and ending with metabolism by enzymes. If the rate of synthesis exceeds the metabolic rate, the excess eikosanoid may, however, have a destructive effect. The researchers found that certain omega-3 fatty acids were also converted to eikosanoids, but to a much slower rate. Eicosanoids made from omega-3 fatty acids are often referred to as anti-inflammatory, but in reality they are just less inflamed than those made from omega-6 fats. If omega-3 and omega-6 fatty acids are present, they will "compete" for alteration, so the long-chain ratio of omega-3: omega-6 fatty acids directly affects the resulting eicosanoid type.
Interconversion
The conversion efficiency of ALA to EPA and DHA
Humans can convert short chain omega-3 fatty acids into long chain (EPA, DHA) forms with efficiencies below 5%. The efficiency of omega-3 conversion is greater in women than in men, but is poorly studied. Higher ALA and DHA values ​​found in female plasma phospholipids may be due to higher desaturase activity, especially delta-6-desaturase.
This conversion occurs competitively with omega-6 fatty acids, which is a closely related chemical analogue derived from linoleic acid. They both used the same desaturase and elongase proteins to synthesize inflammatory regulatory proteins. The products of both pathways are essential for the growth of making a balanced diet of omega-3s and omega-6s essential for an individual's health. A 1: 1 balanced intake ratio is believed to be ideal for proteins to synthesize both pathways adequately, but this is controversial in recent studies.
The conversion of ALA to EPA and further into DHA in humans has been reported to be limited, but varies with individuals. Women have a higher conversion efficiency of ALA-to-DHA than men, which is thought to be caused by lower levels of ALA use for beta-oxidation. One preliminary study showed that EPA could be increased by decreasing the amount of dietary linoleic acid, and DHA could be increased by increasing dietary ALA intake.
Omega.E2.88.926_to_omega.E2.88.923_ratio"> Omega-6 to omega-3 ratio
The human diet has changed rapidly in the last few centuries resulting in increased omega-6 diet compared to omega-3s. The rapid evolution of human diet is far from the 1: 1 ratio of omega-3 and omega-6, as during the Neolithic Farm Revolution, it may be too soon for humans to adapt to biological profiles that are adept at balancing omega-3s and omega. -6 ratio 1: 1. This is generally believed to be the reason why modern diet correlates with many inflammatory disorders. While omega-3 polyunsaturated fatty acids may be beneficial in preventing heart disease in humans, the level of omega-6 polyunsaturated fatty acids (and, hence, the ratio) is not a problem.
Omega-6 and omega-3 fatty acids are essential: humans should consume them in their diet. Omega-6 and omega-3 eighteen-carbon polyunsaturated fatty acids compete for the same metabolic enzyme, so omega-6: omega-3 fatty acid ratio ingested has a significant influence on the ratio and production rate of eicosanoids, a group of closely involved hormones in the body's inflammatory and homeostatic processes, which include prostaglandins, leukotrienes, and thromboxanes, among others. Changing this ratio can alter the metabolic and inflammatory conditions of the body. In general, grass-fed animals collect more omega-3s than grain-eating animals, which collect more omega-6. The omega-6 metabolites are more inflammatory (especially arachidonic acids) than omega-3s. This requires omega-6 and omega-3 to be consumed in a balanced proportion; the healthy ratio of omega-6: omega-3, according to some authors, ranges from 1: 1 to 1: 4. Other authors believe that the 4: 1 ratio (4 times as omega-6 as omega-3) is healthy. Studies show an evolutionary human diet, rich in game, seafood, and other omega-3 sources, may have provided such a ratio.
Western food provides a ratio between 10: 1 and 30: 1 (ie, omega-6 levels are much higher than omega-3). The ratio of omega-6 to omega-3 fatty acids in some common vegetable oils are: 2: 1 canola, hemp 2-3: 1, 7: 1 soybeans, 3-13: 1 olives, sunflower (no omega-3) hemp 1: 3, cotton seeds (almost no omega-3), groundnuts (no omega-3), grape seed oil (almost no omega-3) and 46: 1 corn oil.
History
Although omega-3 fatty acids have been known to be essential for normal growth and health since the 1930s, awareness of their health benefits has increased dramatically since the 1980s.
On September 8, 2004, the US Food and Drug Administration granted EPA and DHA omega-3 fatty acid status claims, "the supportive but inconclusive study suggests that EPA and DHA [omega- 3] acid can reduce the risk of coronary heart disease ". It updated and modified their health risk advice letter 2001 (see below).
The Canadian Food Inspection Agency has recognized the importance of omega-3 DHA and allows the following claims for DHA: "DHA, an omega-3 fatty acid, supports the normal physical development of the brain, eyes and nerves especially in children under two years of age."
Historically, all diet foods contain adequate amounts of omega-3s, but because omega-3s are easily oxidized, the tendency for stable foods stored on the shelves has led to a lack of omega-3s in the food they produce.
Food source
Dietary recommendations
In the United States, the Institute of Medicine publishes a food reference intake system, which includes the Recommended Dietary Allowances (RDAs) for individual nutrients, and Acceptable Macronutrient Distribution Ranges (AMDRs) for specific nutrient groups, such as fat. When there is not sufficient evidence to determine the RDA, the agency may publish the Intensive Intake (AI) instead, which has the same meaning, but is less certain. AI for? -linolenic acid is 1.6 grams/day for men and 1.1 grams/day for women, whereas AMDR is 0.6% to 1.2% of total energy. Because the physiological potential of EPA and DHA is much greater than ALA, it is impossible to estimate an AMDR for all omega-3 fatty acids. About 10 percent of AMDR can be consumed as EPA and/or DHA. The Institute of Medicine has not established RDA or AI for EPA, DHA or a combination, so there is no Daily Value (VD is from the RDA), no food labels or supplements as a percentage of these fatty acids per serving, and no food labels or supplements as an excellent source, or "High in..." As for safety, there was sufficient evidence in 2005 to set a tolerable upper limit for omega-3 fatty acids, although the FDA has suggested that adults can safely consume up to 3 grams daily from DHA and EPA combined, with no more than 2 grams of dietary supplements.
The American Heart Association (AHA) has made recommendations for EPA and DHA for their cardiovascular benefits: individuals without a history of coronary heart disease or myocardial infarction should consume oily fish twice per week; and "Treatment is reasonable" for those diagnosed with coronary heart disease. For the latter the AHA does not recommend a certain amount of EPA DHA, although it noted that most experiments were at or near 1000 mg/day. Benefits seem to be on the order of a 9% decrease in relative risk. The European Food Safety Authority (EFSA) approved the claim "EPA and DHA contribute to the normal functioning of the heart" for products containing at least 250 mg of EPA DHA. The report does not address the issue of people with pre-existing heart disease. The World Health Organization recommends consumption of fish regularly (1-2 servings per week, equivalent to 200 to 500 mg/day EPA DHA) as a protective against coronary heart disease and ischemic stroke.
Contamination
Heavy metal poisoning by the accumulation of traces of heavy metals, especially mercury, lead, nickel, arsenic, and cadmium, is a possible risk of consuming fish oil supplements. Also, other contaminants (PCB, furan, dioxin, and PBDE) can be found, especially in the less refined fish oil supplements. However, the toxicity of heavy metals from consuming fish oil supplements is highly unlikely, as heavy metals selectively bind to proteins in fish flesh rather than accumulate in oil. An independent test in 2005 of 44 fish oils in the US market found all products passed safety standards for potential contaminants.
Throughout their history, the Responsible Nutrition Council and the World Health Organization have published acceptance standards on contaminants in fish oil. The most stringent stream standard is the International Fish Oil Standard. Fish oil that is molecularly distilled under vacuum usually makes this highest grade; contaminant levels are expressed in parts per billion per trillion.
Fish
The most widely available food sources of EPA and DHA are oily fish, such as salmon, herring, mackerel, anchovies, menhaden, and sardines. The oil of this fish has a profile of about seven times as much omega-3 as omega-6. Other oily fish, such as tuna, also contain n -3 in slightly lower amounts. Oily fish consumers should be aware of potential heavy metals and fat-soluble pollutants such as PCBs and dioxins, which are known to accumulate food chains. After extensive review, researchers from the Harvard Public Health School at the Journal of the American Medical Association (2006) report that the benefits of fish intake are generally far greater than the potential risks. Although fish are a source of food for omega-3 fatty acids, fish do not synthesize them; they get it from algae (especially microalgae) or plankton in their diet.
Fish oil
Sea and freshwater fish oils vary in arachidonic acid, EPA and DHA. They also differ in their effects on lipid organs. Not all forms of fish oil can be digested equally. Of the four studies comparing the bioavailability of the glyceryl ester form of fish oil vs the ethyl ester form, two have concluded a better form of natural glyceryl ester, and two other studies found no significant difference. No studies have shown that the form of ethyl ester is superior, although it is cheaper to produce.
Krill
Crude oil is a source of omega-3 fatty acids. The effects of krill oil, at low doses of EPA DHA (62.8%), were shown to be similar to fish oils at blood lipid levels and healthy inflammatory markers in humans. Though not an endangered species, krill is a mainstay diet of many marine-based species including whales, which cause environmental and scientific concerns about their sustainability.
Plant source
Table 1. ALA content as a percentage of seed oil.
Table 2. ALA content as a percentage of overall food.
Flaxseed (or linseed) ( Linum usitatissimum ) and its oil may be the most widely available vegetable source of the omega-3 ALA fatty acids. Linseed oil consists of about 55% ALA, which makes it six times richer than most fish oils in omega-3 fatty acids. A portion of this is altered by the body to the EPA and DHA, although the actual percentage of conversions may differ between men and women.
In 2013 Rothamsted Research in the UK reported they have developed a genetically modified form of the Camelina plant that produces EPA and DHA. Oil from seeds of this plant contains an average of 11% EPA and 8% DHA in one development and 24% EPA in other countries.
Egg
Eggs produced by green-fed chickens and insects contain higher levels of omega-3 fatty acids than those produced by corn-fed chickens or soybeans. In addition to feeding insects and green chickens, fish oil can be added to their diet to increase the concentration of omega-3 fatty acids in eggs.
The addition of linseed and canola to chicken diet, both are a good source of alfa-linolenic acid, increases the omega-3 content of eggs, especially DHA.
The addition of green algae or seaweed to the diet increases the content of DHA and EPA, which is an FDA-approved form of omega-3 for medical claims. A common consumer complaint is "Omega-3 eggs sometimes have a fishy taste when chicken is fed in marine oil".
Meat
Omega-3 fatty acids are formed in green leaf chloroplasts and algae. While seaweed and algae are a source of omega-3 fatty acids present in fish, grass is a source of omega-3 fatty acids present in grass-fed animals. When cattle are taken from grasses rich in omega-3 fatty acids and sent to fattening to be fattened on omega-3 fatty acids, they begin to lose their savings from these beneficial fats. Every day an animal spends on feeding, the amount of omega-3 fatty acids in its flesh is reduced.
Comparison of omega-6: omega-3 from grass-fed beef about 2: 1, making it a more useful source of omega-3 than grain-fed beef, which usually has a 4: 1 ratio.
In a 2009 joint study by the USDA and researchers at Clemson University in South Carolina, grass-fed cows were compared to smoothed beef. The researchers found that the higher-grained beef was higher in moisture content, 42.5% lower total fat content, 54% lower in total fatty acids, 54% higher in beta-carotene, 288% higher in vitamin E ( alpha-tocopherol), higher. in vitamin B thiamin and riboflavin, higher in calcium, magnesium and potassium minerals, 193% higher total omega-3, 117% higher in CLA (cis-9, trans-11 octadecenoic acid, kojugated linoleic acid, which is potential cancer fighters), 90% higher in vascular acid (which can be converted to CLA), lower in saturated fats associated with heart disease, and have a healthy ratio of omega-6 to omega-3 fatty acids (1.65). vs. 4.84). The protein and cholesterol content is the same.
In most countries, commercially available lamb is usually fed on grass, and thus higher in omega-3s than meat sources fed on whole grains or grains. In the United States, sheep are often finished (ie, fattened before slaughter) with wheat, producing lower omega-3s.
The omega-3 content of chicken meat can be increased by increasing the intake of foods from high-omega-3 seeds, such as hemp, chia, and canola.
Angry meat is also a source of omega-3, with fillets and steaks containing 74 º, mg per 100 g of raw meat.
Seal oil
Oil seals are a source of EPA, DPA, and DHA. According to Health Canada, it helps support brain, eye, and nervous development in children up to age 12. Like all seal products, it is not allowed to be imported into the EU.
Other sources
Recent trends have fortified the food with omega-3 fatty acid supplements. Global food companies have launched fortified omega-3 fatty acid bread, mayonnaise, pizza, yogurt, orange juice, children's pasta, milk, eggs, popcorn, candy and formula.
Microalgae Crypthecodinium cohnii and Schizochytrium are rich sources of DHA but not EPA, and can be commercially produced in bioreactors. Oil from brown algae (seaweed) is an EPA source. The alga Nannochloropsis also has a high EPA rate.
In 2006, the Journal of Dairy Science published a study that found that butter made from grass-fed cattle milk contained more linlinolenic acid than cow's milk butter that had limited access to pasture.
References
Further reading
External links
- University of Maryland Medical Center, Omega-3 Fatty Acids
Source of the article : Wikipedia
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