Dieting And Depression
by Connie Guttersen, RD PhD,
author of the Sonoma Diet
Scientific studies have linked a low dietary intake of omega 3 fatty acids and dieting with growing rates of depression in the United States. Depression affects more than 19 million Americans over the age of 18 every year. Furthermore, the incidence of major depression has been increasing while the age of onset has decreased. Interestingly, the risk of developing depression has increased at a rate similar to the rise in consumption of omega 6 fatty acids (vegetable seed oils) and relative to the decrease in omega 3 fatty acids (fish, walnuts, flaxseed.) Many nutritionists feel that this is a direct result of the increased consumption of processed foods among Americans.
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Omega 3 As An Antidepressant.
The association of omega 3 fatty acids as an antidepressant stems from a handful of epidemiological studies, which established that rates of depression among different countries were directly related to fish consumption. Hibbeln et al. published in the Lancet Journal a strong relationship of fish consumption with lower rates of depression in countries such as Japan, Korea, and Taiwan. He has also reported that high fish consuming nations have the lowest rate of post-partum depression. A more recent study by Nemets et al, studies the effects of the omega 3 fatty acid, EPA (eicosapentaenoic acid) in twenty people with recurrent depression. These individuals received either a fish oil capsule or a sugar pill in addition to antidepressant medication. As soon as two weeks into the study, there was an improved sense of well being and sleeping patterns in the EPA group. By four weeks into the study, 6 of the ten individuals taking the EPA had a significant reduction in the symptoms of depression as compared to only one of the ten taking the sugar pill.
The study concluded that the fatty acid EPA may boost the antidepressant effect of the medication in depressed individuals.
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There is sound scientific rationale to help explain the antidepressant effects of omega 3 fatty acids. More than half of the brain is comprised of fat, thus making brain function sensitive to the dietary composition of fatty acids consumed. The brain also requires that a certain amount of these fatty acids come from omega 3 to supply EPA and DHA fatty acids.
EPA and DHA are derived from omega 3 rather than the omega 6 derivative, arachidonic acid. EPA and DHA are important for proper communication between the neurotransmitters in the brain and are necessary for structural and functional roles in the brain cells. Omega 3 fatty acids also affect cellular function.
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Potential Mechanisms for Omega 3 as an Antidepressant.
- EPA and DHA regulate neuronal activity to prevent mood disorders.
- Omega 3 fatty acids are anti-inflammatory. EPA, the strongest of the omega 3 fatty acids, competes with arachidonic acid (omega 6 derived) to prevent the formation of specific pro-inflammatory compounds (cytokines), which are associated with depression.
- Once incorporated into the cell membrane, EPA and DHA affect the structure and fluidity of the cells. This has an influence on neurotransmitter balance and communication. All of these affect mood and depression.
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The Role of Serotonin.
Researchers have also attributed the antidepressant effects of EPA and DHA to be related to serotonin, an important chemical messenger responsible for a positive mood and an overall sense of well-being. EPA and DHA make it easier for serotonin to pass through the cell by influencing receptor activity. The way EPA and DHA affect serotonin levels is very similar to how many of the antidepressants and mood stabilizers work in the body. This relationship of serotonin with EPA and DHA is only one manner in which omega 3 fatty acids exert antidepressant effects.
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1. Identify and provide ideas of omega 3 sources in the diet. Fish sources as compared to the plant sources are different in their structure of fatty acids and therefore may be better sources of EPA and DHA. What this means is that it takes larger amounts of the plant sources of omega 3 to be equivalent to the fish sources. Flaxseed provides one of the highest concentrations of omega 3 within the plant sources.
2. Replace excessive amounts of seed / vegetable oils with monounsaturated fatty acids for a healthier balance and ratio of omega 6 to omega 3 intake. The dietary intake of olives, olive oil, canola oil, nuts, and avocados increase the concentration and activity of omega 3 fatty acids in the cells as compared to the intake of excessive amounts of omega 6 fats.
3. Limit the amount of highly processed or refined foods. Many of the best sources of healthy fats are found in natural wholesome foods which have not undergone refinement or classified as snack food / convenience foods.
4. There is no current specific recommendation for dietary intake levels of omega 3 fatty acids. However, The American Heart Association’s new guidelines include a recommendation for “ at least two servings of omega 3 rich fish per week”. According to the International Society for the Study of Fatty Acids and Lipids, the minimal daily intake of DHA and EPA should be 0.65 gm per day. It is estimated that in the United States our current intake is 0.1 to 0.2 gm of EPA and DHA daily.
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Low Fat Diets And Depression.
A separate but related issue involves the consequences of dieting, in particular, dieting with a low fat diet and or by caloric restriction alone. It is conceivable that dieting provokes stress, anxiety, and even depression. However, recent studies conclude that these feelings may also be related to the actual amount and type of fat consumed and that a low fat diet (approximately 25 % of total caloric intake from fat) does indeed promote the symptoms of depression. Dieting and weight cycling decrease serotonin levels by decreasing the blood levels of the amino acid precursor, tryptophan. Dieting also results in alterations or depletion of total membrane essential fatty acids. Omega 3 fatty acids were one of the groups to be depleted. These changes in the membrane distribution of fatty acids alter the balance of saturated, monounsaturated, omega 3 and omega 6 levels, potentially leading to a neurochemical imbalance conducive to depression. These compositional changes in membrane properties directly influence the activity of the neurotransmitter serotonin.
This information raises the question on whether the conventional way to lose weight and even lower cholesterol may have deleterious effects. The conventional dietary approach typically replaces the saturated fats with omega 6 fats, rather than emphasizing monounsaturated for a healthier balance and ratio to omega 3 intakes. Given the recent findings of the scientific publications concerning omega 3 fatty acids, it becomes even more important to address the type and balance of dietary fat consumed. The average ratio of omega 6 to omega 3 intake is approximately 15 : 1, far from the recommended 1-4 : 1 estimate. EPA and arachidonic acid (omega 6 derived) are intended to be consumed in balance. Without sufficient EPA, arachidonic acid derived eicosanoids will overwhelm and dominate many responses in the body, ultimately affecting more than just depression, but immune function and heart disease as well. For many consumers, this subject is confusing and challenging, especially when it comes to identifying foods to eat on a daily basis. The dietary advice, to increase the intake of omega 3 fatty acids, while moderating the intake of omega 6 fatty acids, can be achieved by several approaches.
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