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| Seafood Omega -3s and Mental Health Omega-3s are a unique type of polyunsaturated fatty acid that are abundant in fish and shellfish. The two main seafood omega-3s are EPA* and DHA*. These omega-3s benefit heart health, the immune system and brain function, and are essential for infant brain growth and development. DHA is highly concentrated in the brain and retina where it participates in vision, communication between cells, nerve impulse transmission, and the protection of brain cells. Details of how these fatty acids affect mental function are beginning to merge. In several mental disorders, these omega-3s are significantly below those observed in healthy people. Depression Serious mental disorders affect about one in 17 American adults and are the leading cause of disability in the U.S., according to the National Institute of Mental Health. Major depressive disorder—a prolonged period of feeling low or hopeless—affects about 14 million Americans at any given time. The condition interferes with a person’s ability to work, sleep, eat and experience pleasure and can be disabling. Depression is most common in countries with the lowest consumption of seafood, such as the U.S. and Germany. It occurs least often in countries such as Japan, Korea and Iceland, where seafood consumption is high. But this observation does not mean that low seafood consumption causes depression. However, we are learning that the omega-3s in fish may be helpful in treating patients with depression. Several studies in patients being treated medically for depression reported marked improvement in patients’ symptoms when small amounts of EPA were added to the treatment. Doses of 1 to 2 grams of EPA/day were more effective than larger amounts and were without harmful side effects. Results also suggest that EPA is more effective than DHA. How EPA might bring about these improvements is not known. While these results are encouraging, much more information from larger rigorous studies is needed before we can consider these findings conclusive. Postpartum depression: Serious depression also affects about 10% of women shortly after childbirth. Known as postpartum depression or “baby blues,” the condition is marked by sudden mood changes, crying, irritability and anxiety. It can be severe. Childbirth is accompanied by changes in hormones, nutrients, emotions, and stress. At this time, there is a sharp fall in omega-3s, particularly DHA. Because DHA is an important part of brain structure and function, the sudden loss in DHA may be related to postpartum depression. Women who consume seafood regularly during pregnancy and lactation or who have taken fish oil supplements during pregnancy have much smaller losses in DHA and are less likely to experience postpartum depression. Some studies have shown that women with this condition who consumed EPA and DHA had less severe postpartum depression than women not taking these fatty acids. Other studies have reported no benefits. Currently, there are too few studies to permit any conclusions about the usefulness of seafood omega-3s in preventing or easing this condition. As there are many other reasons to consume adequate amounts of these fatty acids during pregnancy and lactation, the possible chance of avoiding this condition is something to cheer the mind. Bipolar Disorder People with bipolar disorder, sometimes called manicdepressive illness, suffer large swings in mood, from very high to hopelessness and back again. Like major depression, this disorder can prevent a person from functioning normally and is also more common in countries where seafood consumption is low. People with bipolar disorder frequently have significantly lower levels of EPA and DHA than those without the condition. Although the condition often improves with medical treatment, some medicines have undesirable side effects. Several studies have reported that the addition of EPA to a patient’s usual therapy improves the symptoms. Only a few studies have reported no effect and none has found that the condition became worse. Severity of depression is usually reduced, without undesirable side effects. The most effective levels of EPA are moderate, 1 to 2 grams/day. Well controlled studies with more patients would improve the support for adding EPA to the treatment of bipolar patients. Now, however, studies are considered promising, but not conclusive. Hostile Behavior Aggressive, violent and hostile behavior may also be related, at least in part, to omega-3 status. Many of these behaviors have been associated with very low levels of EPA and DHA in tissues, but that does not mean low omega-3s cause hostility. Many other conditions affect violence toward others and oneself. However, as with depression and bipolar disorder, violent behaviors, homicide and suicide are higher in countries with the lowest consumption of seafood. A few studies have reported significant improvements in behavior and lower aggression in those with a history of violence who were treated with EPA and DHA supplements. This topic is currently being studied and firmer results can be expected in the coming years. It is worth bearing in mind that good health, resistance to many types of illness and behavior all have links to good nutrition. Including seafood sources of EPA and DHA is an important part of sound food choices. Written by Joyce A. Nettleton, DSc, RD, ScienceVoice Consulting, Denver, CO. 4/06 Are Fish And Plant Omega-3s The Same? Food labels and news stories mention omega-3s often—usually referring to the heart-healthy oils in fish. They are widely discussed because of the many health benefits associated with them. Omega-3s are a type of polyunsaturated fatty acid the body needs, but cannot make for itself. For that reason we need to obtain them from foods. There are three main omega-3 fatty acids. One, alphalinolenic acid, is found in some plant seeds and oils such as flax. The other two are EPA* and DHA*, and these occur almost exclusively in fish and shellfish. EPA and DHA are known as “long-chain” omega-3s because their structure is longer than alpha-linolenic acid. The body has a strong preference for the long-chain omega-3s. You may hear that you can get the same health benefits associated with eating fish from plant foods, such as flax seed. However, alpha-linolenic acid in plants does not have all the same properties as the omega-3s from fish. Does the difference matter? It may, depending on your needs. Fish Oil Omega-3s EPA and DHA have special functions in the body. DHA is highly concentrated in the brain, where it helps brain cells communicate with each other and protects them from harmful substances, such as those in Alzheimer’s disease. It is concentrated in the retina of the eye, where it is critical for visual function. EPA is important for healthy blood vessels, heart health, and brain function. It also has anti- inflammatory and anti-clotting properties that favor a healthy heart and brain. Plant Omega-3s Alpha-linolenic acid is the only omega-3 found in plants. It has some, but not all, the health benefits associated with EPA and DHA. Most of it is oxidized or “burned” for energy. A very small amount, less than 5%, is converted to EPA. Only a trace amount of this EPA is further converted to DHA. It is our limited ability to convert alpha-linolenic acid to EPA and almost no DHA that creates a dilemma. The body needs DHA for brain structure and function and for the retina of the eye. When DHA is not sufficiently available, substitutes made from other fatty acids do not function as well. This is of key importance for pregnant women who must supply DHA to the developing fetus. If they do not obtain DHA from the foods they eat, the fetus draws DHA from the mother’s tissues. Over several pregnancies, this process depletes the mother’s supply. DHA is important in the retina for optimum visual acuity, the ability to see clearly. Once depleted, the retina may not recover fully, even if plenty of DHA is provided later. Retinal DHA also participates in the cellular communication processes that eventually result in the ability to see. The retina has the highest concentration of DHA in the body, an indication of its importance. DHA is also important in protecting brain health. Recent research has shown that DHA is the basis for making a substance called neuroprotectin D1, which reduces the production of the harmful protein responsible for Alzheimer’s disease. Neuroprotectin D1 protects brain cells against other damaging cellular by-products, prolongs the life of brain cells, and reduces inflammation, processes that occur early in the development of Alzheimer’s disease. It is also a key substance in the communication between brain cells. The Body’s Preference for Fish over Plant Omega-3s When consumed in ready-made form, EPA and DHA from fish oils are taken up into tissues immediately. They are not used for energy. This means they are ready to go to work for us stabilizing heart rhythms, keeping over-active inflammatory responses in check, improving blood flow, and participating in brain function. In pregnancy and early infancy, the fetus and young infant readily incorporates DHA into its growing brain and developing visual system, whereas plant-based alphalinolenic acid is of limited use because so little is converted to DHA. Fish intake in most western countries, including the U.S., is very low, but consumption of vegetable oils rich in linoleic acid, another type of polyunsaturated fatty acid, is high. Americans consume at least 10 times as much linoleic acid as alpha-linolenic acid. High levels of linoleic acid further reduce the conversion of alpha-linolenic acid to EPA. Other polyunsaturates, including flax and fish oils, also reduce the amount converted. Thus, taking flax oil to boost omega-3 intake is likely to reduce the amount converted to EPA rather than boost it. In its favor, plant omega-3s help offset the large amounts of linoleic acid in western diets. It also has some positive effects on heart health and immune function. However, the health effects of fish oil omega-3s appear to be stronger, quickeracting, and more diverse. Foods Rich in Omega-3s EPA and DHA are found almost exclusively in fish and shellfish. They are most abundant in fatty fish such as salmon, rainbow trout, black cod (sablefish), sardines, mackerel, herring and pilchards. All seafoods have some EPA and DHA. Egg yolks from hens fed flaxseed have alpha-linolenic acid, EPA and DHA, because the chicken is better able to convert alpha-linolenic acid to EPA and DHA than we are. Eggs with omega-3s are usually marked as containing “omega-3s.” Small amounts of EPA and DHA are in poultry too. Plant-based sources of alpha-linolenic acid are flax seed and oil, walnuts, canola and soybean oils. New products such as yogurt, margarine, spreads and snack bars may have omega-3s added, but may not indicate which ones they have. Such foods nearly always have alphalinolenic acid from flax seed or oil. Unless the label specifically mentions “long-chain” omega-3s, or EPA, or DHA, it will not have fish oil omega-3s. Be sure to read the label. Written by Joyce A. Nettleton, DSc, RD, ScienceVoice Consulting, Denver, CO. 4/06 |
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