Fish Oils Control Obesity and Prevent Degenerative Diseases
Omega-3 Fatty Acids Revisited
By
Karen Kaufman, MS, CCN
New studies indicate that there is a common predisposing factor for a number of chronic diseases including obesity, Type II diabetes, hypertension, coronary artery disease (CAD) and stroke, breast, prostate and colon cancer, depression, bipolar disorder, attention deficit disorder, cognitive dysfunction and Alzheimer’s disease. This common causative factor may be the amount of essential fatty acids (EFAs) in our diet. Research suggests that we may be able to dramatically reduce the incidence and severity of many diseases by simply changing the type of essential fats we consume.
The Alpha and Omega of Fatty Acids
Fat performs a number of critically important functions in human health. The most important forms of fats are essential fatty acids, or EFAs. Essential refers to the fact that they are not synthesized by the body, but are required for health and must be obtained through dietary sources. EFAs serve as a highly efficient source of energy and as the primary component of cell membranes and hormones. Deficiencies in EFAs are associated with abnormal development and health problems involving the nervous, cardiovascular, and immune systems.
While there are several types of fatty acids, the two most important types in human health are omega-3 and omega-6 fatty acids. Each is made up of a long chain of carbon atoms, with oxygen atoms attached to one end (the COOH, or carboxyl group) and three hydrogen atoms attached to the other end (the CH3, or methyl group). The end attached to the oxygen atoms is called the alpha end, and the end attached to the hydrogen atoms is called the omega end.
The number of each fatty acid refers to the position of chemical bonds in the fatty acid chain. Fatty acids are held together by both single and double bonds between the carbon atoms. If the first double bond is located three carbons from the omega end, the fatty acid is considered an omega-3. If the first double bond is six carbons from the omega end, it’s considered an omega-6 fatty acid.
Omega-6 Fatty Acids
The predominant essential fatty acid in the western diet is an omega-6 fatty acid known as Linoleic Acid (LA). Sources of LA include corn, safflower, sunflower and soybean oil, as well as a number of trans-fatty acids. Trans-fatty acids are made by hydrogenating liquid oils to form a solid fat (at room temperature), such as margarine. Together these omega-6 fatty acids are referred to as polyunsaturated fatty acids, or PUFAs, for short.
In the body omega-6 fatty acids are metabolized into another compound called arachidonic acid (AA) (Fig. 1). In turn, arachidonic acid serves as the raw material for a whole family of chemicals called eicosanoids. Eicosanoids, such as prostaglandins (PGs), thromboxanes (TXs), and leukotrienes (LTs), are implicated in promoting tumor growth, immune responses, and inflammation. Sources of arachidonic acid include meat, poultry, and full-fat dairy products.
Omega-3 Fatty Acids
The other primary dietary EFA is an omega-3 fatty acid called alpha-linolenic acid (ALA). Sources of ALA include nuts and flaxseed. In the body ALA is converted into eicosapentaenoic acid (EPA). In turn, EPA can then be converted to docosahexaenoic acid (DHA). Converting ALA into EPA and DHA requires a number of enzymes that may become deficient in the body, due to advancing age or disease.
Recent Changes in the Human Diet
To understand the role of dietary fats in human health—and how certain fats contribute to or help control health problems—we need to look at relatively recent changes in human dietary habits. Until recently, humans consumed a diet that contained nearly equal amounts of omega-6 and omega-3 EFAs. However, in the last 100 to 150 years this ratio has changed dramatically. Instead of a ratio of 1 to 1, modern diets commonly provide ratios as high as 30 parts omega-6 to 1 part omega-3 (Fig. 2). Many researchers now believe that this dramatic increase in consumption of omega-6 EFAs may be at the root of many of the health issues we face today.
Fish-Sourced Omega-3 EFAs
Omega-3 fatty acids offer considerable potential for preventing diseases and aiding in their therapy. Numerous studies indicate that increasing the ratio of omega-3 fatty acids could prevent or help alleviate CAD, hypertension, diabetes, arthritis, other inflammatory disorders, autoimmune disorders, and certain cancers. Most of the research on the potential dietary benefits of omega-3 fatty acids has been conducted with EFAs from marine sources in the form of fish oil capsules.
Heart Disease
A landmark study of Greenland Eskimos revealed a surprisingly low rate of mortality from cardiovascular disease. The scientists attributed the low incidence of heart disease among the Eskimos to their high-fat diet. The scientists knew that omega-3 fatty acids found in fish oils—particularly eicosapentaenoic acid (EPA) —convert into a form of thromboxane (TXA3) that acts as a weak vasodilator. Conversely, omega-6 fatty acids lead to formation of a type of thromboxane that acts as a potent vasoconstrictor. EPA has also been shown to increase levels of another strong vasodilator, Prostacyclin I3, which also acts to inhibit formation of potentially deadly clots.
While fish oil seems to have no effect on total cholesterol levels, it does lower serum triglycerides. Elevated triglycerides are an independent risk factor for heart disease. Italian researchers reported that fish oil supplementation could increase the survival of individuals who had suffered a heart attack (myocardial infarction), concluding that the number of lives saved would equal the number saved by treatment with statin drugs.
Additionally, researchers working in Denmark have suggested that frequent consumption of fish or fish oils can reduce levels of C-reactive protein (CRP). CRP is an inflammatory protein that is also a risk factor for atherosclerosis and CAD.
Hypertension
Hypertension is a leading cause of cardiovascular disease and stroke. A number of recent studies have shown that daily supplementation with EPA/DHA may reduce death rates in hypertensive patients.
Cancer
A number of epidemiological and experimental studies have implicated the omega-6 fatty acids as stimulators of the development and progression of a range of human cancers including breast, colon and perhaps prostate cancer. The researchers proposed that a high intake of omega-6 fatty acids contribute to oxidative damage and have effects on cell proliferation. Conversely, fish oil has been found to suppress both breast and colon cancer tumor growth and metastasis. Other studies have found the cancer protective effect of DHA is due to its ability to induce apoptosis (programmed cell death).
Diabetes
While there is little evidence that fish oils can actually prevent diabetes, a number of studies suggest that the omega-3 fatty acids from fish oil can improve insulin resistance in type II diabetics. In addition, all the different aspects of heart disease that improve with fish oil supplementation would also apply to diabetics, as they are at increased risk of developing heart disease. Unfortunately, the diet recommended by the American Diabetes Association is high in carbohydrates and low in fat. Also, diabetic patients are often instructed to replace saturated fats with omega-6 vegetable oils that actually worsen atherosclerosis. The net effect of these recommendations is often to worsen insulin resistance and increase triglyceride levels.
Obesity
A study published recently in the journal Circulation may shed some light on the connection between a lack of omega-3 fatty acids in the diet and the growing epidemic of obesity. Researchers reported on two closely related African tribes living in Tanzania. One group lived close to a lake, the other lived inland. The tribe residing by the lake subsisted on a diet high in freshwater fish, whereas the group living inland consumed a primarily vegetarian diet of fruits and vegetables. The researchers monitored both tribes to compare levels of a hormone called leptin. Leptin is secreted by fat tissue to signal a sense of fullness that helps normal weight people stop eating. Higher levels of leptin have been associated with obesity. The researchers learned that the tribe eating fish had lower levels of leptin than the tribe eating the vegetarian diet.
Extending Lifespan
Animal studies have demonstrated that the amount and type of dietary fatty acids can profoundly affect lifespan. Researchers placed two groups of mice on a calorie-restricted diet. One group was supplemented with omega-3 EFAs (fish oil), while the other was supplemented with omega-6 EFAs (corn oil). The group on the restricted, fish oil diet had a significantly longer lifespan which led the authors of the study to conclude, These observations may have additional implications in the management of obesity, diabetes, cancer and/or the aging process.
Omega 3 Fatty Acids and the Brain
DHA is highly concentrated in the prenatal brain during the third trimester and early in the postnatal period when the rate of brain growth is maximal. Consequently, it seems logical that omega-3 fatty acids play a critical role in many aspects of neurological development. Postnatal deficiencies of DHA, an ingredient in breast milk, have been found to adversely effect visual acuity, behavior and neurodevelopment. In fact, a study of infant formulas recently recommended that DHA be added to infant formulas—something that has never been allowed in this country. A deficiency of DHA seems to play a role in ADD. Some children with attention deficit disorder are not able to convert the precursor omega-3 fatty acids to the longer chain DHA. Andrew Stoll, MD, working at McLean’s Hospital (part of Harvard University Medical School) has done a number of studies using omega-3 fatty acids in depression and bi-polar disorder. He found that omega-3 fatty acids may inhibit neuronal signal transduction pathways in a manner similar to that of lithium … It has also been demonstrated that EPA, DHA, and total omega-3 fatty acid levels are significantly lower in red blood cell membranes of depressed subjects compared to the control group. Decreases in DHA in the brain are associated with cognitive decline during aging and with the onset of sporadic Alzheimer’s disease.
Inflammatory and Autoimmune Diseases
Many studies have demonstrated the benefits of fish oil supplementation in inflammatory diseases, such as rheumatoid arthritis and systemic lupus erythematosus (SLE). When the lipid profile changes from arachidonic to eicosapentanoic and docosahexanoic acids, the body produces a series of eicosanoids that are far less inflammatory. New research shows that omega-3 fatty acids can help keep Crohn’s Disease in remission through the same mechanism. It is clear that omega-3 fatty acids in fish oil have powerful anti-inflammatory and immuno-modulatory effects.
Gamma Linoleic Acid
Gamma Linolenic Acid (GLA) is an omega-6 EFA that has been shown to have beneficial effects similar to those of the omega-3 EFAs from fish oil. GLA is found in Evening Primrose Oil, Black Currant Oil and Borage Oil. Research on GLA suggests that this EFA is useful in treating rheumatoid arthritis, PMS, breast pain from PMS, and diabetic peripheral neuralgia. GLA, as with fish oils, seems to work by altering eicosanoids from arachidonic acid to a less inflammatory series of eicosanoids. As with omega-3 fatty acids, some of the effects of these EFAs seem independent of eicosanoid production. Both EFAs appear to act directly on T lymphocyte proliferation and interleukin 2 (IL-2) production. IL2 is a marker for inflammation. Furthermore, both EFAs seem to have the ability to suppress protein kinase C (PKC) activity. PKC is an important enzyme involved in cell signaling, along with cyclic AMP. PKC plays a significant role as an initiator of the inflammatory cascade. PKC may well play a role in diabetes and neurological conditions, such as depression and bi-polar disorder.
Conclusion
It is clear that a high ratio of omega-6 to omega-3 fatty acids can have profound adverse health effects. Although omega-6 fatty acids are essential, it is also essential that the ratio of omega-6 to omega-3 fatty acids be balanced. In order to optimize the balance of these essential substances, we recommend increased consumption of flax seeds and fatty fish, as well as fish oil supplements. For optimum health, fish oil capsules should contain both EPA and DHA.
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