[The essential fatty acids omega-6 and omega-3: from their discovery to their use in therapy]. / Gli acidi grassi essenziali omega-3 ed omega-6: dalla loro scoperta alle prospettive terapeutiche.

In 1929 Burr and Burr discovered the essential fatty acids omega-6 and omega-3. Since then, researchers have shown a growing interest in unsaturated essential fatty acids as they form the framework for the organism's cell membranes, particularly the neurones in the brain, are involved in the energy-transformation process, regulate the information flows between cells. Polyunsaturated fatty acids are also precursors of ''hormonal'' molecules, often with opposing effects, prostaglandins, prostacyclins, thromboxanes, leukotrienes, lipossines, resolvines, protectines that regulate immunity, platelet aggregation, inflammation, etc. They showed that raised levels of polyunsaturated fatty acids omega-3 in tissue correlate with a reduced incidence of degenerative cardiovascular disease, some mental illnesses such as depression, and neuro-degenerative diseases such as Alzheimer's. The balance between omega-3 and omega-6 acids allows the cell membranes to develop with exactly the right flexibility and fluidity, to carry messages between neurones, that is a determining factor in physical and mental well-being and has a profound influence on all the body's inflammatory responses. The results of a number of scientific studies suggest that omega-3 acids contribute to measuring and restricting inflammatory symptoms, whereas omega-6 acids (and saturated fats) give free range to inflammatory responses and amplify allergic reactions. Today in the Western countries, the ratio of omega-3 acids to omega-6 in the diet is weighted 1:10 in favour of omega-6 to up to 1:25 in some areas, while for proper functioning a 4:1 ratio of omega-6 acids to omega-3 acids is generally considered the optimum. In addition, the type of diet followed in the Western countries is very rich in saturated fats like butter and animal fats, but because of an excessive supply of these less noble fats, the cell membranes lose flexibility and this can affect the way they work. An appropriate supplement can be an efficient, effective and often necessary way to meet the body's needs, enhance its daily functions and promote health and longevity.

Dietary composition and contaminants in north Greenland, in the 1970s and 2004.

OBJECTIVES: The fatty acid composition and other nutrients in traditional Inuit food appear to provide some protection against diseases of affluent industrialized societies, such as cardiovascular diseases and type 2 diabetes. A transition towards increased amounts of imported food might increase the occurrence of these diseases among Inuit. However, since the 1970s it has become evident that the marine-based Inuit diet also contains high levels of potentially toxic lipophilic organic pollutants and heavy metals. Since these two opposing effects on health appear to be inseparable, the phenomenon has become known as "The Arctic Dilemma". However, both the fatty acid composition and the contaminant levels vary in Greenlandic food items. Thus, in theory, it is possible to compose a diet where the benefits outweigh the risks. Our objective was to compare traditional and modern meals in Greenland regarding dietary composition, content of n-3 fatty acids and contaminants. STUDY DESIGN: The present study was part of the Arctic Monitoring and Assessment Programme, AMAP, comparing the results of dietary composition and nutrients in 177 traditional meals collected in Uummannaq municipality, north Greenland in 1976 with 90 meals sampled in Uummannaq town in 2004 under similar conditions. Eleven pesticides, 14 PCB congeners, heavy metals, selenium, and fatty acids were analysed in meals and blood samples from the participants. Contaminant levels were compared between 1976 and 2004 after adjustment for n-3 fatty acids, indicating local food content. RESULTS: Between the traditional meals collected 30 years ago and the meals from 2004, dramatic and significant changes have occurred in the dietary composition. The percentage of local food has decreased, and with it the intake of n-3 fatty acids. Calculated as daily intake, all but three contaminants had decreased significantly. However, this could be explained by the lower intake of local food. After adjustment for n-3 fatty acid content in the food, significant declines of concentration in the local food were evident only for PCBs and lead, whereas for mercury, DDTs, and chlordanes the levels were unchanged, and for hexachlorobenzene, mirex, and toxaphenes, the levels had increased significantly. CONCLUSION: The consumption of locally produced food has decreased in Greenland during the last 30 years and this has led to a reduction in the daily intake of contaminants. However, the concentrations of contaminants in local food items have not decreased, except for PCB and Lead. Therefore, we recommend that the consumption of local products is not increased beyond the present level, until the level of contaminants is reduced to a safer level.