Fish Oil: What You Need to Know

By: Andrew Aguecheek

Fish oil capsules can be a good source of omega-3 fats. ­
Fish oil capsules can be a good source of omega-3 fats. ­
iStockphoto/Hanquan Chen

­There's something fishy about the American diet. Or rather, something not fishy enough. According to many health experts, a key factor linking such common health conditions as heart disease, high blood pressure, obesity and diabetes is a dietary imbalance related to fat. It's not just that we consume too much fat but the wrong kinds. Specifically, we need to increase our intake of the beneficial essential fatty acids, especially omega-3 fats. The most important of these nutrients are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). These fatty acids are "essential" because the body needs them and cannot make them on its own. Without a doubt, the best ways to get these nutrients are to eat fatty fish such as salmon and sardines or to take fish oil as a supplement.

The essential fatty acids include the categories of omega-3 and omega-6, which are distinguished from each other by the structure of their molecular bonds. Both are needed, but their proportion is very important. The omega-6 fats are found in a much wider range of nutritional sources, including most vegetable oils, eggs and cereal grains. For optimal health, the ratio of omega-6 to omega-3 in one's diet should be somewhere between even and 4:1. In the typical American diet, however, the proportion is as high as 20:1 [source: Larsen].


­The deficiency in omega-3 consumption may be responsible for a host of negative health repercussions, ranging from clogged coronary arteries to depression and attention deficit hyperactivity disorder (ADHD). Many of these symptoms relate in one way or another to inflammation, which some researchers believe is at the root of many diseases. Reducing inflammation may be the most potent effect of the omega-3 essential fatty acids.

This article will reveal why fish oil is one of the best-selling nutritional supplements on the market and explore some of the health benefits fish oil has been demonstrated to provide. Let's begin by looking at how the fatty acids function in the body.


Fish Oil at Work in Your Body


­Fatty fish and fish oil are reliable sources of EPA and DHA, the most health promoting of the essential fatty acids. While several vegetable sources, such as flaxseeds, soybean oil and walnuts, contain omega-3, that fat comes in the form of alpha-linolenic acid (ALA), which is chemically a precursor to EPA and DHA. The body must convert the ALA into the more usable EPA and DHA, a process that brings only a limited health benefit and is compromised by the consumption of more harmful fatty substances such as saturated fats and trans fats [source: Weil]. The longer one lives, the less efficient one's body gets at converting ALA into EPA and DHA.


Researchers discovered the essential fatty acids and their beneficial properties while studying the Inuit people of Greenland. It is well known that Inuit people eat an extremely high-fat diet, yet they rarely suffer from maladies associated with the American diet such as heart disease and rheumatoid arthritis. The solutions to this riddle are EPA and DHA [source: Larsen]. According to the American Heart Association, fish oil helps maintain cardiovascular health by these mechanisms:

  • Reducing and reversing inflammation
  • Reducing the coagulation of blood platelets (clotting)
  • Lowering triglyceride levels
  • Slowing down artherosclerosis (thickening of artery walls)
  • Lowering blood pressure
  • Steadying the heart rhythm [source: Oil of Pisces]

The anti-inflammatory effect is central to why fish oil is so highly touted. In their book, "Fish Oil: The Natural Anti-Inflammatory," Joseph C. Maroon and Jeffrey Bost allege that chronic inflammation is the unsung cause of health conditions ranging from heart attack and stroke to autoimmune diseases such as lupus. Non-steroidal anti-inflammatory drugs (NSAID) are among the most popular pharmaceuticals on the market, but they can have severe side effects. The omega-3 fats can match these drugs in effectiveness but are much safer and cheaper [source: Maroon and Bost].

How can fish oil help in specific health situations? Continue reading to find out.


Fish Oil Benefits

­Clinical trials have demonstrated the value of fish oil in prevention of cardiovascular disorders. Regular consumption of fish or fish oil clearly reduces the risk of heart attacks, strokes, clogged arteries and high blood pressure. There is solid evidence that omega-3 fats reduce the levels of triglycerides, the main form in which fats are stored in the blood [source: Medline Plus]. It is also widely accepted that fish oil helps prevent cardiovascular incidents by reducing the frequency of abnormal heart rhythms, although recent studies on patients with advanced heart disease have cast doubt on this conclusion [source: Weil]. To ensure these cardiovascular benefits, one should consume at least one gram of EPA and DHA daily.

Fish oil's benefits are widely distributed in the body. Its anti-inflammatory effect makes it potentially beneficial to those suffering from joint pain, rheumatoid arthritis and inflammatory bowel disorder. It is also alleged to assist in preventing breast cancer and the complications of diabetes. Fish oil supplementation has been found to reduce the symptoms of lupus, an inflammatory disease [source: Oil of Pisces].


DHA is a crucial ingredient in brain tissue, and, thus, a sufficient intake of fish oil is said to help preserve brain function, prevent memory loss and prevent Alzheimer's disease. Some research has shown that high fish consumption in a population correlates with low rates of depression. Fish oil has also been used in the treatment of psychiatric disorders such as schizophrenia [source: Larsen].

Pregnant and breastfeeding women must keep up their intake of EPA and DHA, since they supply these vital nutrients to the developing fetus and child. Some researchers link DHA deficiency to postpartum depression, premature birth, low birth weight and ADHD [source: Oil of Pisces]. Australian researchers concluded that children with satisfactory fish oil intake are at significantly less risk of asthma, probably because the fatty acids prevent inflammation of the respiratory airways [source: Larsen].


Fish Oil Side Effects


­As a nutritional supplement, fish oil has earned the characterization GRAS (generally regarded as safe) from the Food and Drug Administration (FDA). However, because of pollution in their watery habitats, many species of fish contain levels of toxicity that necessitate attention. Environmental and public health groups have raised awareness of poisons such as mercury, dioxins and PCBs found in common fish. Methylmercury is found in highest concentrations in predatory fish such as swordfish, shark and tuna [source: Environmental Defense Fund]. However, mercury accumulates only in the tissues of fish, not in fish oil, so fish oil supplements are considered non-toxic [source: Medline Plus].


High dosages or prolonged use of fish oil may lead to some side effects. Some activity in the gastrointestinal system is relatively common -- stomach upset, diarrhea and acid reflux/indigestion are regularly recorded. Fish oil takers commonly report a fishy taste in the mouth. Obviously, people allergic to fish should avoid taking fish oil [source: Medline Plus].

Some effects of fish oil may run contrary to certain health goals. There is no doubt that fish oil can lower triglyceride levels, while numerous reports also conclude that it has little to no effect on levels of low-density lipoprotein cholesterol (LDL, known as "bad" cholesterol). However, the Medline Plus database reports that LDL levels do increase by five to 10 percent in some people. Furthermore, information found on Medline suggests that fish oil supplements may either lead to an increase or decrease in blood sugar levels of diabetics, yet there is no noticeable impact on overall glucose control as recorded on the hemoglobin A1c test. [source: Medline Plus].

The action of fish oil on the blood may lead to an increased risk of bleeding, especially at high- dose levels. Those taking blood thinning medication (including herbs like gingko biloba as well as drugs like Coumadin) or NSAIDs should use caution and consult their physicians before adding fish oil to their diets [source: Medline Plus].


Fish Oil and Skin Health


­The health-promoting qualities of essential fatty acids can be good for the body's largest organ, the skin. Omega-3 fats improve the health and beauty of human skin in several ways. They improve cellular health and functioning, and help skin maintain a smooth, elastic texture. Some research has found that they prevent wrinkles and work against the aging process.


The deficiency of omega-3 in the diet of most North Americans probably contributes to skin conditions such as dandruff, eczema and psoriasis, as well as plain old dry skin. Without the essential fatty acids, too much moisture leaks out through the skin. In short, taking fish oil internally as a supplement may be as good as or better than applying cosmetic moisturizers [source: Healthy Oil Planet].

Again, fish oil's key mechanism appears to be the reduction of inflammation. Scaly, red skin, acne and eczema are all symptoms of inflamed tissue, so it sounds logical that these conditions may be helped by restoring the balance of fats in your system through fish oil supplementation. In fact, several European studies found fish oil to be an effective intervention against psoriasis [source: Healthy Oil Planet]. However, there are other studies that indicate fish oil supplements have no real effect on psoriasis [National Psoriasis Foundation].

In many countries, skin cancer is the most commonly diagnosed form of cancer, due to overexposure to UV radiation. UV is known to degrade the skin's immune response, allowing cancerous cells to multiply and develop into tumors. Some research done on animals suggests that fish oil supplementation can protect against immune suppression due to UV radiation, and, thus, against contracting skin cancer. In early 2009, British scientists initiated what may be the first human study to test for this effect [source: University of Manchester].

Another demonstrated benefit of fish oil is reduced blood pressure. Read on for more information.


Fish Oil and Blood Pressure


­Many studies confirm that regular consumption of fish and fish oil contributes to a drop in blood pressure. This effect goes along with the prevention of artherosclerosis and the reduction of triglyceride levels. Reportedly, the reduction is dose-dependent -- that is, the more you take, the greater the effect you're likely to see. Even with robust supplementation, the decrease will probably be a modest one, though. People with elevated blood pressure may see a more significant drop. Blood pressure in the normal range has been found unaffected by fish oil [source: Morris, Sacks and Rosner].


Combining supplementation with other dietary changes may enhance the effect on blood pressure. In an Australian study, overweight patients who dieted (that is, restricted their caloric intake) while taking fish oil saw a drop in blood pressure. This group also enjoyed a 38 percent reduction in triglycerides and a 24 percent increase in HDL or "good" cholesterol [source: Mori, et al.].

High blood pressure is a concern for many heart transplant patients. In one study, doctors at the University of Oslo treated several heart transplant recipients with fish oil, and found it an effective means of preventing the hypertension that frequently accompanies the heart transplant process [source: Holm, et al.].

Bear in mind that taking fish oil, especially in higher dosages, can bring with it an increased risk of bleeding. If you are already on medication to lower your blood pressure or reduce coagulation, consult your physician before taking fish oil supplements. To learn more about fish oil, visit the links on the following page.


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Related HowStuffWorks Articles

  • Environmental Defense Fund. "Seafood Selector: Mercury in Fish and Shellfish." (Accessed 3/12/09)
  • FishOil4Health. "What You Need to Know Before Buying Fish Oil Supplements." (Accessed 3/12/09)
  • Healthy Oil Planet. "How Your Skin Benefits from Fish Oils." (Accessed 3/12/09)
  • Holm, T. Andreassen, AK., Aukrust, P., Andersen, K., Geiran, OR., Kjekshus, J., Simonsen, S., Gullestad, L. "Omega-3 fatty acids improve blood pressure control and preserve renal function in hypertensive heart transplant recipients." European Heart Journal, 2001 March 22(5): 428-36, PubMed (Accessed 4/01/09)$=relatedarticles&logdbfrom=pubmed
  • Larsen, Hans R. "Fish Oils: The Essential Nutrients." (Accessed 3/10/09)
  • Maroon, Joseph C., and Jeffrey Bost. Fish Oil: The Natural Anti-Inflammatory (Basic Health Publications, 2006). (Accessed 3/11/09)
  • Medline Plus. "Omega-3 Fatty Acids, Fish Oil, Alpha-Linoleic Acid." (Accessed 3/10/09)
  • Morris, MC., Sacks, F., Rosner B. "Does fish oil lower blood pressure? A meta-analysis of controlled trials." Circulation 1993 Aug; 88(2): 523-33 Pub Med (Accessed 4/01/09)
  • Mori, TA., Bao DQ., Burke, V., Puddey, IB., Watts, GF., Beilin, LJ. "Dietary fish as a major component of a weight-loss diet: effect on serum lipids, glucose, and insulin metabolism in overweight hypertensive subjects." American Journal of Clinical Nutrition 1999; 70(5): 817-25. PubMed (Accessed 4/01/09)
  • Oil of Pisces database. "Health Benefits of Fish Oils." (Accessed 3/10/09)
  • National Psoriasis Foundation (Accessed 4/01/09)
  • University of Manchester. "Fish Oils to Boost Skin Health." (Accessed 3/10/09)
  • Weil, Andrew. "Why I Still Take My Daily Fish Oil." Time, June 20, 2006. (Accessed 3/10/09),9171,1205361,00.html