Omega fatty acids also known as polyunsaturated fatty acids [PUFAs] are a group of naturally occurring lipids. They are also known as essential fatty acids (EFA) because they not synthesized in the human body and hence have to be obtained through diet. Decreased risk of cardiovascular disease and incidence of cancer was observed in Greenland Eskimos and Alaskans who consumed fish enriched with long chain polyunsaturated fatty acids [LCPUFAs]. Since Burr and Burr’s discovery of EFA in 1954, the subject on EFAs has opened to a better understanding of their importance in human health and disease.
Importance Of Omega-Fatty Acids In Human Health
Omega fatty acid And Brain
Docosahexaenoic acid is the most abundant omega-3 fatty acid present in the brain. It is essential for prenatal brain development and normal maintenance of brain function and visual learning ability in adults. It has neuro-protective function. A preponderance of the research studies around the globe has focused on DHA, that is preferentially deposited in brain phospholipids and has been beneficial in reducing anxiety, suicide, mood disorders, depression, schizophrenia, aggression, attention deficient hypersensitivity disorder and the risk of neurodegenerative diseases such as Dementia, Huntington’s Disease, Alzheimer’s and Parkinson’s disease. Docosahexaenoic acid in baby formulas for new borns (both premature & full term) influences their visual and cerebral capacities including both cognitive and intellectual functions. Therefore, most of the baby formulas that has been marketed in recent years have been supplemented with polyunsaturated fatty acids in general and DHA in particular.
Omega fatty acid And Cardiovascular Diseases
Globally, cardiovascular disease is one of the leading causes of mortality and morbidity. Trans fatty acids, cholesterol and saturated fats are chiefly responsible for various kinds of cardiac associated problems. Cardiovascular protective nature of LCPUFAs is attributed to its property of reducing cholesterol, blood triglyceride levels and thus the risk of heart attack, atherosclerosis, serum triglyceride in blood serum level of hyperglycemia patients, blood pressure, platelet aggregation, thrombosis and inflammation. Intake of omega fatty acids in the form of fish oil capsules has shown beneficial effects on asthmatic patients.
Prevention of cardiovascular diseases appears to be achieved by replacing saturated fats with healthy omega-3-fatty acids. Cardiac societies from across the globe recommend intake of 1g/day of the two LCPUFAs namely EPA and DHA for cardiovascular disease prevention, treatment after myocardial infarction and secondary prevention of cardiovascular disease.
Recent Development: The Omega-3 Index
Research studies reports that, higher levels of omega-3 fatty acids in blood have been shown to be associated with lower risk of cardiovascular events. Omega-3 index is defined as the percentage of EPA and DHA in the red blood cell membrane. It helps in determining biomarkers of omega-3 fatty acids (determining EPA + docosapentaenoic acid + DHA in whole blood, fatty acid composition of cardiac samples, serum EPA and DHA).
When considering biomarkers of omega-3 fatty acids, concentration-risk dependence is observed: Persons with 6.5% omega-3 fatty acids in red blood cell membranes have 90% less risk for sudden cardiac death as compared to persons with 3.3%. These data are from a case control study in Seattle, performed on victims of sudden cardiac death and matched controls. In the Physicians health study, similar results have been observed: Physicians with 6.87% omega-3 fatty acids in their whole blood had 90% less risk for sudden cardiac death, as compared to physicians with 3.58%.
Omega fatty acid And Pregnancy
Intake of various kinds of diet by pregnant women influences her pregnancy, foetal, overall infant development and lactation. Docosahexaenoic acid has been of particular interest in pregnancy nutrition because of beneficial effects on maternal health and the development of foetus. Metabolic demand for DHA increases as pregnancy advances. In the third trimester, increase in accumulation of LCPUFAs in the foetal blood circulation, in particular DHA is observed, in order to support brain growth and visual development.
Growing lines of evidence suggest that, last trimester of pregnancy is the time when DHA accretion into the foetal brain and nervous system is maximum. Growing foetus accumulates on an average of 67mg of omega fatty acids, predominantly in the form of DHA per day during the last trimester of pregnancy. This increased metabolic need for DHA during pregnancy may be supplied by maternal diet rich in docosahexaenoic acid. Imbalance in the fatty acid composition is considered as one of the leading causes of attention deficit hyperactivity disorder (ADHD), a neurobehavioral disorder that is defined by persistent symptoms of hyperactivity and inattentiveness most commonly seen in childhood and adolescence, which often extend to the adult years.
Omega fatty acid and Cancer
Despite progress in cancer therapy, conventional cytotoxic therapies lead to unsatisfactory long-term survival, mainly related to development of drug resistance by tumour cells and toxicity towards normal cells. Long chain polyunsaturated fatty acids can exert anticancer property in human cancer cells either alone or in combination with conventional therapies. Indeed, LCPUFAs potentially increase the sensitivity of tumour cells to conventional therapies, possibly by improving their efficacy especially against cancer cells which are resistant to treatment. Moreover, in contrast to traditional therapies, LCPUFAs appear to cause selective cytotoxicity towards cancer cells with little or no toxicity on normal cells.
Research studies conducted by various researchers reported potential applications of LCPUFAs in the treatment of breast, prostate and colon cancer.
Omega fatty acid and Inflammation
Anti-inflammatory properties of LCPUFAs are used in the treatment of inflammatory diseases such as inflammatory bowel disease (IBD), eczema, psoriasis and rheumatoid arthritis etc
Types of Polyunsaturated Fatty Acids
Long chain polyunsaturated fatty acids belong to the family of omega-fatty acids. There are two classes of PUFAs namely- omega-3 fatty acids and omega-6 fatty acids. Examples of omega-3 fatty acids are Eicosapentaenoic acid (EPA) and Docosahexaenoic acid (DHA) and examples of omega-6 fatty acids are Gamma-linolenic acid (GLA), Arachidonic acid (AA) and Di-homo- gamma-linolenic acid (DGLA).
Sources of omega fatty acids
Fishes such as cod, fresh tuna, sardines, salmon, mackerel, oyster, halibut, haddock, herring etc are enriched with omega fatty acids. Plant seed oils such as flax seed oil, canola oil, rapeseed oil, chia seed oil, olive oil etc predominantly contains omega fatty acids. Nuts such as walnuts, hazel nuts, almond etc also contain omega fatty acids in various proportions. Lipids obtained from micro-organisms such as bacteria, fungi and algae also serve as an alternative source of omega-fatty acids. Breast milk comprises of all types of omega fatty acids essential for infant growth.
People of all the age groups have to be advised to consume fish on a regular basis. Those who do not consume fish may be advised to take fish oil capsules as a supplement. It is important, particularly during pregnancy to avoid fish that may contain relatively high levels of methyl mercury and other contaminants. Consuming foods such as fruits, vegetables, whole-grain products and consuming low amounts of saturated fat and trans-fatty acids have to be encouraged. In addition, maintaining a healthy weight, regular exercise, avoiding smoking and alcohol are other important strategies for preventing of various health complications.