An exellent summary of reasons why you should strongly consider assessing your intake of omega threes and sixes.
RB
http://www.ajcn.org/cgi/content/full/70/3/560S
Artemis P Simopoulos
1 From The Center for Genetics, Nutrition and Health, Washington, DC.
http://www.ajcn.org/cgi/content/full/70/3/560S
ABSTRACT
TOP
ABSTRACT
INTRODUCTION
EVOLUTIONARY ASPECTS OF DIET
BIOLOGICAL EFFECTS OF n-6...
CONCLUSIONS AND RECOMMENDATIONS
REFERENCES
Human beings evolved consuming a diet that contained about equal amounts of n-3 and n-6 essential fatty acids. Over the past 100–150 y there has been an enormous increase in the consumption of n-6 fatty acids due to the increased intake of vegetable oils from corn, sunflower seeds, safflower seeds, cottonseed, and soybeans. Today, in Western diets, the ratio of n-6 to n-3 fatty acids ranges from {approx}20–30:1 instead of the traditional range of 1–2:1. Studies indicate that a high intake of n-6 fatty acids shifts the physiologic state to one that is prothrombotic and proaggregatory, characterized by increases in blood viscosity, vasospasm, and vasoconstriction and decreases in bleeding time. n-3 Fatty acids, however, have antiinflammatory, antithrombotic, antiarrhythmic, hypolipidemic, and vasodilatory properties. These beneficial effects of n-3 fatty acids have been shown in the secondary prevention of coronary heart disease, hypertension, type 2 diabetes, and, in some patients with renal disease, rheumatoid arthritis, ulcerative colitis, Crohn disease, and chronic obstructive pulmonary disease. Most of the studies were carried out with fish oils [eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)]. However, {alpha}-linolenic acid , found in green leafy vegetables, flaxseed, rapeseed, and walnuts, desaturates and elongates in the human body to EPA and DHA and by itself may have beneficial effects in health and in the control of chronic diseases.
Key Words: Essential fatty acids • eicosapentaenoic acid • EPA • docosahexaenoic acid • DHA • linoleic acid • LA • {alpha}-linolenic acid • ALA • coronary heart disease • diabetes • hypertension • ventricular premature complexes
INTRODUCTION
TOP
ABSTRACT
INTRODUCTION
EVOLUTIONARY ASPECTS OF DIET
BIOLOGICAL EFFECTS OF n-6...
CONCLUSIONS AND RECOMMENDATIONS
REFERENCES
Over the past 20 y many studies and clinical investigations have been carried out on the metabolism of polyunsaturated fatty acids (PUFAs) in general and on n-3 fatty acids in particular. Today we know that n-3 fatty acids are essential for normal growth and development and may play an important role in the prevention and treatment of coronary artery disease, hypertension, diabetes, arthritis, other inflammatory and autoimmune disorders, and cancer (1–7). Research has been done in animal models, tissue cultures, and human beings. The original observational studies have given way to controlled clinical trials. Great progress has taken place in our knowledge of the physiologic and molecular mechanisms of the various fatty acids in health and disease. Specifically, their beneficial effects have been shown in the prevention and management of coronary heart disease (8, 9), hypertension (10–12), type 2 diabetes (13, 14), renal disease (15, 16), rheumatoid arthritis (17), ulcerative colitis (18), Crohn disease (19), and chronic obstructive pulmonary disease (20). However, this review focuses on the evolutionary aspects of diet, the biological effects of n-6 and n-3 fatty acids, and the effects of dietary {alpha}-linolenic acid (ALA) compared with long-chain n-3 derivatives on coronary heart disease and diabetes.
EVOLUTIONARY ASPECTS OF DIET
TOP
ABSTRACT
INTRODUCTION
EVOLUTIONARY ASPECTS OF DIET
BIOLOGICAL EFFECTS OF n-6...
CONCLUSIONS AND RECOMMENDATIONS
REFERENCES
On the basis of estimates from studies in Paleolithic nutrition and modern-day hunter-gatherer populations, it appears that human beings evolved consuming a diet that was much lower in saturated fatty acids than is today's diet (21). Furthermore, the diet contained small and roughly equal amounts of n-6 and n-3 PUFAs (ratio of 1–2:1) and much lower amounts of trans fatty acids than does today's diet (Figure 1)Go (21, 22). The current Western diet is very high in n-6 fatty acids (the ratio of n-6 to n-3 fatty acids is 20–30:1) because of the indiscriminate recommendation to substitute n-6 fatty acids for saturated fats to lower serum cholesterol concentrations (23). Intake of n-3 fatty acids is much lower today because of the decrease in fish consumption and the industrial production of animal feeds rich in grains containing n-6 fatty acids, leading to production of meat rich in n-6 and poor in n-3 fatty acids (24). The same is true for cultured fish (25) and eggs (26). Even cultivated vegetables contain fewer n-3 fatty acids than do plants in the wild (27, 28). In summary, modern agriculture, with its emphasis on production, has decreased the n-3 fatty acid content in many foods: green leafy vegetables, animal meats, eggs, and even fish.
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