Over the last decades, the polyunsaturated fatty acids (PUFAs) have been largely explored not only for their nutritional value but also for the numerous biological functions and therapeutic effects. The serum and erythrocyte levels of PUFAs depend on the genetic control of metabolism as well as the dietary intake and are considered to reflect the health and disease status of an individual. Two families of PUFAs, omega-3 (n-3) and omega-6 (n-6), have gained much attention because of their involvement in the production of bioactive lipid mediators and therefore, a balanced omega-6/omega-3 ratio is crucial in maintaining the overall health of an individual. Omega-3 PUFAs, notably eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) have been shown to exert beneficial effects, possibly due to their lipid-lowering, anti-inflammatory, anti-hypertensive and cardioprotective effects, whereas omega-6 fatty acids such as arachidonic acid (ARA, 20:4n-6) exhibit the opposite properties. Even though, numerous epidemiological studies and clinical interventions have clearly established the effectiveness of omega-3 PUFAs in various pathological conditions including dyslipidemia, obesity, diabetes, cancer, cardiovascular and neurodegenerative diseases, some controversies do exist about the beneficial effects of omega-3 PUFAs and need to be clarified. Larger clinical trials with extended follow-up periods are required along with a careful dose selection, in order to confirm the clinical significance and efficacy of omega-3 PUFAs as therapeutic agents.
Omega-6 polyunsaturated fatty acids: Is a broad cholesterol-lowering health claim appropriate?