Healthy Eating

Dec 26, 2005

Depression Linked to Fatty-Acid Levels

Study Links Brain Fatty Acid Levels To Depression
Bethesda, MD — A group of researchers from Israel has discovered that rats exhibiting the signs of depression have increased levels of the omega-6 fatty acid, arachidonic acid, in their brains. The details of their findings appear in the June issue of the Journal of Lipid Research, an American Society for Biochemistry and Molecular Biology journal.
During recent years, omega-3 fatty acids have enjoyed increased popularity as numerous studies have shown that supplementing diets with fish oil (a natural source of this polyunsaturated fatty acid) does everything from reducing the risk of heart disease to preventing arthritis. There is also evidence that depression may be associated with a dietary deficiency in omega-3 fatty acids. This "phospholipid hypothesis" of depression has been supported by research showing that omega-3 fatty acid concentration in the blood of depressed patients is lower than that in control patients.
"The "phospholipid hypothesis" of depression postulates that decreased omega-3 fatty acid intake, and hence, perhaps decreased brain omega-3 fatty acid content, could be responsible for the disease," explains Dr. Pnina Green of Tel Aviv University. "In humans, because of high dietary variability and the obvious inability to examine brain tissue, the theory is backed up mainly by indirect evidence. The availability of the Flinders Sensitive Line rat, an animal model of depression, overcomes both these obstacles."
In the Journal of Lipid research study, Dr. Green in collaboration with Dr. Gal Yadid of Bar-Ilan University, Ramat Gan, used the Flinders Sensitive Line rats to investigate the link between omega-3 fatty acids and depression. They examined the brains of the depressed rats and compared them with brains from normal rats. Surprisingly, they found that the main difference between the two types of rats was in omega-6 fatty acid levels and not in omega-4 fatty acid levels. Specifically, they discovered that brains from rats with depression had higher concentrations of arachidonic acid, a long-chain unsaturated metabolite of omega-6 fatty acid.
Arachidonic acid is found throughout the body and is essential for the proper functioning of almost every body organ, including the brain. It serves a wide variety of purposes, from being a purely structural element in phospholipids to being involved in signal transduction and being a substrate for a host of derivatives involved in second messenger function.
"The findings that in the depressive rats the omega-3 fatty acid levels were not decreased, but arachidonic acid was substantially increased as compared to controls is somewhat unexpected," admits Dr. Green. "But the finding lends itself nicely to the theory that increased omega-3 fatty acid intake may shift the balance between the two fatty acid families in the brain, since it has been demonstrated in animal studies that increased omega-3 fatty acid intake may result in decreased brain arachidonic acid."
Although far less attention has been paid to dietary requirements for omega-6 fatty acids, which can be found in most edible oils and meat, perhaps in the future, depression may be controlled by increasing omega-3 fatty acid intake and decreasing omega-6 fatty acid intake.
The American Society for Biochemistry and Molecular Biology (ASBMB) is a nonprofit scientific and educational organization with over 11,000 members in the United States and internationally. Most members teach and conduct research at colleges and universities. Others conduct research in various government laboratories, nonprofit research institutions, and industry.
Founded in 1906, the Society is based in Bethesda, Maryland, on the campus of the Federation of American Societies for Experimental Biology. The Society’s primary purpose is to advance the sciences of biochemistry and molecular biology through its publications, the Journal of Biological Chemistry, the Journal of Lipid Research, Molecular and Cellular Proteomics, and Biochemistry and Molecular Biology Education, and the holding of scientific meetings.
This story has been adapted from a news release issued by American Society For Biochemistry And Molecular Biology.
New York, NY (November 1, 2004) — There is mounting evidence that a diet containing omega-3 fatty acids, already known to help prevent cardiovascular disease, may also prevent depression. In light of the Food and Drug Administration (FDA)’s recent ruling that antidepressants will be labeled with a "black box"warning about the drugs’ higher potential suicide risk in children, NewYork-Presbyterian Hospital/Weill Cornell Medical Center nutrition experts call for further study of the mental health benefits of omega-3 fatty acids.
"Given recent findings of serious risks linked with antidepressants, we should prioritize the study of natural antidepressants contained in dietary sources — specifically, omega-3 fatty acids, found most abundantly in fish and seafood," says Dr. Barbara Levine, associate professor of nutrition in clinical medicine at Weill Cornell Medical College and director of the DHA Information Center at New York-Presbyterian/Weill Cornell. Dr. Levine has been studying DHA (docosahexaenoic acid — a component of omega-3s) and its effects on lowering triglycerides and raising HDL (high-density lipoproteins) in overweight and obese patients with metabolic syndrome.
"Omega-3 consumption in the U.S. is lower than in any other country; the U.S. also has one of the highest depression rates in the world," says Dr. Jeffrey Borer, chief of the division of cardiovascular pathophysiology at New York-Presbyterian/Weill Cornell and Gladys & Roland Harriman, Professor of Cardiovascular Medicine at Weill Cornell Medical College. "New research has linked omega-3 consumption inversely with incidence of neurological and immune disorders. However, further research among all age groups and populations is necessary in order to confirm these findings and to further educate the public."
The relation of omega-3s — principally DHA and EPA (eicosapentaenoic acid) and depression has been revealed in several studies worldwide. In a large Finnish study of fish consumption and depressive symptoms, published in Psychiatric Services in April 2001, Tanskanen, et al. demonstrated that the likelihood of having depressive symptoms was significantly higher among infrequent fish consumers than among frequent fish consumers. They theorized that the human brain is adapted to Paleolithic diets of our ancient ancestors, whose diet comprised equal proportions of omega-3 fatty acids and omega-6 fats (found in corn and soy seed oils). In the past 100 years, Western diets have lowered the ratio of omega-3 to omega-6 to about 1:25; simultaneously, the prevalence of major depression has increased.
In the 2003 Rotterdam study, published in the American Journal of Clinical Nutrition, Tiemeir, et al. found that elderly persons with depression had a fatty acid composition different from that of non-depressed persons. Percentages of omega-3 polyunsaturated fatty acids (PUFAs) were significantly lower, and the ratios of omega-6 to omega-3 PUFAs were significantly higher in subjects with depressive disorders than in control subjects.
Dr. Jospeh R. Hibbeln of the National Institute on Alcohol Abuse and Alcoholism, part of the National Institutes of Health (NIH) discovered that omega-3 may influence serotonin functionality in the brain. In a letter published in The Lance in April 1998, he reported that among healthy volunteers, low plasma concentrations of DHA predict low concentrations of a marker of brain serotonin turnover. Low concentrations of serotonin are strongly associated with depression and suicide.
DHA is a primary building block in the gray matter of the human brain and in the retina of the eye, and is present in every cell in the body. It is essential at every state of human life, beginning in utero, DHA, like EPA, must be derived from foods because the body cannot produce its own supply. It is available in fish and as a pure pharmaceutical–grade nutritional supplement, with an ideal ratio of omega-3s to omega-6s (10:1).

At the Food and Drug Administration’s Psychopharmacologic Drugs and Pediatric Advisory Committees meeting on September 13 and 14, committee members and relatives of children with depression heard testimony based on an analysis by an international panel of pediatric suicide experts of data from 15 clinical studies on the use of SSRI )Selective Serotonin Reuptake Inhibitor) antidepressants in children and teens with major depressive disorder (MDD). The also heard from industry representatives of the companies who manufacture the medications. Dr. Tarek Hammad, a Senior Medical Reviewer in the Department of Neuropharmacological Drug Products, Center for Drug Evaluation and Research, Food and Drug Administration, reported that there was a consistent link between antidepressants and suicidal thoughts and behavior (suicidality) among 2 to 3 percent of the subjects in the studies.
As a result of the hearings and recommendations by the joint committees, on Friday, October 15, 2005, the FDA announced that it will direct manufacturers to add a "black box" warning to the health professional labeling of all SSRI antidepressant medications to describe this risk and emphasize the need for close monitoring of patients started on these medications. The FDA will also develop a Patient Medication Guide (MedGuide), which will be given to patients receiving the drugs to advise them of the risk and precautions that should be taken.
Http://www.news.cornell.edu/releases/Nov04/omega-2.html

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