Omega-3’s are fatty acids; and like all fatty acids, consist of chains of carbon atoms linked together by chemical bonds. On one end (terminal) of the carbon chain is a methyl group and on the other terminal is a carboxyl group.
Being classified as polyunsaturated fatty acids (PUFA), Omega-3’s have a double bond in the third carbon position from the methyl terminal (hence the use of "3" in their description). They are also known as essential acids because our body does not produce them but depend on them for general health and well-being.
Foods high in omega-3 fatty acids include salmon, halibut, cod, tuna, catfish, spinach, sardines, albacore, trout, herring, walnut, flaxseed oil, black seed oil and canola oil. The three known Omega-3’s are the long chain (with 14 or more carbons) fatty acids: ALA (alpha linolenic acid), EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). ALA is mainly found in flax and chia seeds, and is a precursor to EPA and DHA, however, the conversion rate in our bodies is extremely low (less than 1 percent of ALA is converted to EPA and DHA), therefore most of the time we are deficient in EPA and DHA.
EPA vs DHA needs throughout life
EPA and DHA have different functions in the human body and our requirements for these two fatty acids changes throughout life.
DHA is important for normal growth and development, brain (CNS) function and the retina of the eyes, therefore it is mostly required by pregnant and breastfeeding women as well as children. Children continue to need DHA up until the age they start school due to its benefits on brain development and growth.
After the age of five, the need for EPA naturally increases due to its importance for academic performance, focus and attention. Dry skin conditions, asthma and allergies are also common in children and good levels of EPA at this time can help reduce the inflammation associated with these issues.
Between the ages of five and 65, the body continues to require sufficient levels of EPA. Low EPA levels in adolescents and adults have been associated with mental health issues, including depression, dyslexia and dyspraxia, heart problems, joint and bone conditions, as well as neurodegenerative diseases such as MS and Parkinson’s. EPA also protects our genes and cell cycle, as well as helping to keep our stress response regulated, so an adequate supply of EPA throughout adult life can help prevent a range of chronic illness. In later life, the risk of cognitive decline and brain deterioration may become a concern; therefore the need for both, EPA and DHA is highly required. EPA has been shown to lower the risk of developing and worsening cognitive decline and dementia (Lin et al., 2012).
Benefits of Omega-3 Fatty Acids
Omega-3 Fatty Acids and Foetal Development
The need for fatty acids during pregnancy is hugely important. EPA and DHA supplementation during pregnancy has been associated with multiple benefits for the infant (Judge et al., 2007; Dunstan et al., 2008; Olsen et al., 2007). It is important that the mother has adequate nutrition with sufficient amount of omega-3 because the amount of omega-3 fatty acid in the mother is going to correlate with the amount found in the foetus.
This is because during pregnancy, the placenta transfers nutrients, including EPA & DHA, from the mother to the foetus. Several studies confirmed the benefit of omega-3 supplementation during pregnancy in terms of proper development of the brain and retina. During the third trimester, vast amounts of DHA accumulate in foetal tissue including the retina and brain, which may correlate with normal eyesight and brain function (Swanson et al., 2012).
A study by Judge et al.(2007) found that children whose mothers had taken DHA supplementation during pregnancy demonstrated significantly better problem-solving skills at 9 months old than those whose mothers had not taken DHA supplementation during pregnancy.
Another study that performed a cognitive assessment of children 2.5 years after maternal EPA+DHA supplementation and children in a placebo group, demonstrated that the children in the EPA + DHA supplemented group attained significantly higher scores for eye and hand coordination than those in the placebo group (Dunstan et al., 2008).
Omega-3 Fatty Acids and Cardiovascular Disease
One of the most well-known benefits of omega-3s are the way they positively affect risk factors associated with heart disease. Chronic inflammation is thought to be the cause of many chronic diseases, including cardiovascular disease (Swanson et al., 2012).
EPA and DHA are known to have anti-inflammatory properties and significant role in oxidative stress, ability to improve cellular function through changes in gene expression and ability to influence the levels of cholesterol by reducing bad (LDL), and increasing good (HDL) cholesterol (Bouwens et al., 2009). Inflammatory markers such as C-reactive protein (CRP), TNF a, IL-1 and IL-6 are sign for an increased probability of experiencing a cardiovascular disease.
A study of 89 patients showed that those treated with EPA and DHA had a significant reduction in high-sensitivity CRP (Ebrahimi et al., 2009). The same study confirmed the cardio protective effect of omega -3’s further by demonstrating a significant reduction in heat shock proteins which have been shown to be overexpressed in heart muscle cells after myocardial ischemia (Ebrahimi et al., 2009).
Omega-3’s have also been shown to decrease arterial cholesterol deposition by anchoring LDL at the intimal layer, thus decreasing its penetration into deeper layers, and consequently preventing the development of atherosclerosis (Sudheendran et al., 2010).
Omega-3 Fatty Acids in Mental Disorders and Cognitive Decline
Depression and anxiety are common mental health concerns which can be improved with sufficient levels of omega-3. Several studies have already demonstrated an improvement in depression and anxiety symptoms after omega-3 supplementation, in double-blinded, randomized, controlled trials (Lin & Su, 2007; Kiecolt-Grasser et al., 2011; Ginty & Conklin, 2015).
Some studies have also demonstrated correlation between omega-3s and a decrease in violence, antisocial behaviour, ADHD and bipolar disorder (Balanzá-Martínez et al., 2011; Peet & Stokes, 2005). Omega-3s have also been shown to reverse some cognitive decline. DHA is present in large amounts in neuron membrane phospholipids, where it is involved in proper function of the nervous system, which is why it is thought to play a role in Alzheimer Disease.
A recent study found that a diet characterized by higher intakes of foods high in omega-3 fatty acids (nuts, fish, tomatoes, poultry, cruciferous vegetables, fruits, dark and green leafy vegetables) was strongly associated with a lower AD risk (Gu et al., 2010). Low omega 3 levels have also been linked with low levels of melatonin, which is the hormone responsible for helping us fall asleep. A study by Lavialle et al. (2008) demonstrated that deficient omega 3’s diet reduces night time melatonin secretion, which returns to normal with supplemented DHA.
Omega-3 Fatty Acids for Healthy Bones & Joints
Omega-3s have been shown to increase calcium absorption from the gut, in part by enhancing the effects of vitamin D; to reduce urinary excretion of calcium, to increase calcium deposition in bone and improve bone strength, as well as to enhance the synthesis of bone collagen.
These actions of omega 3s have been pointed beneficial in reducing ectopic calcification which is a pathologic deposition of calcium salts in tissues (Kruger & Horrobin, 1997). Omega 3s can also impact the development of arthritis.
A study published in the British Journal of Nutrition (2012) , found that when a high-dose fish oil supplement is added to so-called triple therapy for rheumatoid arthritis (methotrexate, sulfasalazine and hydroxychloroquine), patients achieved better outcomes: they were far less likely to reach remission than those who did not take a supplement (Orchard et al., 2012).
Balanzá-Martínez, V., Fries, G.R. et al. (2011). Therapeutic use of omega-3 fatty acids in bipolar disorder. Expert Rev Neurother. 11 (7), 1029-1047.
Bouwens, M., Dellschaft, N. et al. (2009). Fish-oil supplementation induces anti-inflammatory gene expression profiles in human blood mononuclear cells. American Journal of Clinical Nutrition. 9 (90), 415–424.
Gu, Y., Nieves, J.W. et al (2010). Food combination and Alzheimer disease risk: a protective diet. Arch Neurol. 10 (67), 699–706.
Dunstan, J.A., Mitoulas, L.R., Dixon, G. et al. (2008). The effects of fish oil supplementation in pregnancy on breast milk fatty acid composition over the course of lactation: a randomized controlled trial. Pediatr. Res. 7 (62), 689–794.
Ebrahimi, M., Ghayour-Mobarhan, M. et al. (2009).Omega-3 fatty acid supplements improve the cardiovascular risk profile of subjects with metabolic syndrome, including markers of inflammation and auto-immunity. Acta Cardiol. 9 (64), 321–327.
Judge, M.P., Harel, O., Lammi-Keefe, C.J. (2007). Maternal consumption of a docosahexaenoic acid containing functional food during pregnancy: benefit for infant performance on problem-solving but not on recognition memory tasks at age 9 months. American Journal of Clinical Nutrition. 7 (85), 1572–1773.
Kiecolt-Grasser, J.K., Belury, M.A. et al. (2011). Omega-3 supplementation lowers inflammation and anxiety in medical students: a randomized controlled trial. Brain Behaviour Immunity . 25 (8), 1725-1734.
Lavialle, M., Champeil-Potokar, G. et al. (2008). An (n-3) polyunsaturated fatty acid-deficient diet disturbs daily locomotor activity, melatonin rhythm, and striatal dopamine in Syrian hamsters. Journal of Nutrition. 8 (38), 1719–1724.
Lin, P.Y., Chiu, C.C. et al. (2012). A meta-analytic review of polyunsaturated fatty acid compositions in dementia. The Journal of Clinical Psychiatry. 73 (9), 1245-1355.
Lin, P.Y., Su, K.P. (2007). A meta-analytic review of double-blind, placebo-controlled trials of antidepressant efficacy of omega-3 fatty acids. Journal of Clinical Psychiatry. 68 (7), 1056-1061.
Olsen, S.F., Osterdal, M.L. et al. (2007). Duration of pregnancy in relation to fish oil supplementation and habitual fish intake: a randomised clinical trial with fish oil. European Journal of Clinical Nutrition. 7 (61), 976–985.
Orchard, T.S., Cheek, F., Pan, X. (2012). A systematic review of omega-3 fatty acids and osteoporosis. British Journal of Nutrition. 6 (12), 253-260.
Peet, M., Stokes, C. (2005). Omega-3 fatty acids in the treatment of psychiatric disorders. Drugs. 65 (8), 1051-1059.
Sudheendran, S., Chang, C.C. et al. (2010). N-3 vs. saturated fatty acids: effects on the arterial wall. Prostaglandins Leukot Essent Fatty Acids. 10 (82), 205–209.
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