Are Omega-3 Fatty Acids a Factor?
Studies have long linked deficiencies of beneficial omega-3 fatty acids to depression, as well as to SAD specifically. A 2011 study in Nature Neuroscience has even demonstrated—albeit in mice—how lower omega-3 levels change brain activity. The omega-3 deficient mice had decreased function of specific brain receptors involved in pain and appetite regulation, which are found in regions of the brain associated with mood disorders. The behavioral changes seen in the mice were all typical of depression. Other studies have shown that omega-3s appear to help maintain healthy levels of the brain chemicals dopamine and serotonin. Researchers note that cell membranes are partly made up of omega-3 fats. Higher omega-3 levels may make it easier for serotonin—a chemical that enables brain cells to communicate—to pass through cell membranes. Low levels of serotonin are linked with depression, aggression and suicidal tendencies, while dopamine is a “reward” chemical that the brain releases in response to pleasurable experiences, such as eating or having sex.
Some results suggest that SAD is less common in those who consume more omega-3 fatty acids, such as Icelandic people, who eat plenty of coldwater fish. One of the largest studies ever conducted assessing omega-3s’ effectiveness in treating major depression (published in 2010 in the Journal of Clinical Psychiatry) looked at 432 people with major depression. Half the participants took a high-concentration fish oil supplement (1,050 mg of EPA and 150 mg of DHA); the other half took a similar-looking placebo. The researchers found the omega-3 supplements effective, comparable to results with conventional antidepressants. Although this study looked at depression in general and not specifically at patients whose depression is caused by SAD, its strong results are encouraging.
Food Sources of Omega-3 Fats: Because our bodies cannot make these essential omega-3 fatty acids, we’ve got to eat them. Oily, fatty fish (mackerel, herring, salmon, sardines, anchovies) are the best sources of omega-3s because they contain the “more potent” forms of omega-3s: eicosapentaenoic (EPA) and docosahexaenoic acid (DHA). Flaxseed, hemp, canola and walnut oils are all rich sources of another omega-3, alpha-linolenic acid (ALA). Our livers metabolize ALA into EPA and DHA. But our livers are limited in their abilities to convert ALA. It is estimated that only 5 to 15 percent of ALA is ultimately converted to EPA and DHA .
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