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Omega-3 Fatty Acids and Depression: A Fishy Situation

Sh’Nese Townsend

October 10, 2008

What is Depression?

It was really hard to get out of bed in the morning. I just wanted to hide under the covers and not talk to anyone. I didn't feel much like eating and I lost a lot of weight. Nothing seemed fun anymore. I was tired all the time, and I wasn't sleeping well at night. But I knew I had to keep going because I've got kids and a job. It just felt so impossible, like nothing was going to change or get better (National Institute of Mental Health).

 The personal story above is representative of the symptoms that can occur for the over 20 million people who suffer from depression in the United States (MedlinePlus).  Most people have felt “down in the dumps” at one point or another, but for people with depression these feelings last for extended periods of time.  People with depression are so consumed with feelings of hopelessness, worthlessness, and pessimism that it interferes with their ability to carry out the normal functions of everyday life.  It is not uncommon for them to have suicidal thoughts (or suicide attempts).  The irritability, insomnia, and changes in eating habits, whether it be overeating or a loss of appetite, can be distressing not only to the person living with depression but also the loved ones who are concerned for his or her wellbeing (National Institute of Mental Health).

How do we treat depression?

Depression is most commonly treated with psychotherapy and medication.  In psychotherapy people work to change negative ways of thinking and behaving and understand and work through personal relationships that may be causing their depression (National Institute of Mental Health).  This is often all the treatment necessary for those with mild to moderate depression, but for those with major depression medication is incorporated as an additional form of treatment.  There are chemicals in the brain called neurotransmitters.  Though scientists are unsure of exactly how these chemicals work, but they believe depression occurs when certain neurotransmitters (such as dopamine, serotonin, and norepinephrine) are out of balance (National Institute of Mental Health).  Antidepressant medications work by blocking the reuptake of certain neurotransmitters by the brain (depression.com).  Each antidepressant has possible side effects which include insomnia, headaches, nausea, irritability, sexual dysfunction, weight gain, and dry mouth.   In addition, people who take antidepressants known as MAOIs have to avoid several foods and medications or face the possibility of severe reactions and stroke in some cases (Mayo Clinic).

The possible alternative…

For those who have concerns about the side effects associated with antidepressants, there may be an alternative under the sea: fish, or fish oil more specifically.  Fish began to be thought of as an option for alleviating the symptoms of depression after researchers began noticing lower rates of depression amongst people who often ate fish.  Ten years ago, the results of a cross-national study were published that showed a negative correlation between annual fish consumption and prevalence of major depression (Hibbeln 1998).   Another study proposed a link between deficiencies in omega-3 fatty acids, the type of fat found in fish thought to alleviate depressive symptoms, and postpartum depression (Hibbeln & Salem, 1995).  Researchers found that when they fed piglets omega-3 fatty acids the amount of the neurotransmitter serotonin in the brain increased, which are the same effects produced by the popular antidepressant Prozac (ABC News).  These studies, and others like them, are a part of the growing body of research on the effectiveness of omega-3 fatty acids as a possible treatment for depression, eicosapentaenoic acid and docosahexaenoic acid in particular.

More about omega-3

When trying to understand depression, the typical route that has been taken has been to think about neurons, neurotransmitters, and hormones, but after studies such as the ones previously mentioned fat came into the forefront.  Over half of the brain’s dry weight comes from fat, and omega-3s help form cell membranes, keep membranes flexible, and regulate the flow of hormones and other chemical messengers, which may affect mood (AHealthyMe.com). Omega-3 fatty acids are a form of polyunsaturated fat, which is considered “good” fat.  There are three types of Omega-3 fatty acids: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA).  ALA can be found in dark green leafy vegetables, flax seed oil, and certain vegetable oils.  The body uses ALA to synthesize EPA and DHA, but EPA and DHA can also be received directly from oily cold water fish such as salmon, tuna, or mackerel (Advance Health & Life Extension).

Omega-3 fatty acids, along with Omega-6 fatty acids, are essential fatty acids.  Our body does not manufacture these fatty acids but they are essential for good health, so we have to get them from the food we eat or supplements.  Omega-6 fatty acids are found in grains, plant-based oils, poultry, and eggs (Advance Health & Life Extension).  Omega-3 and Omega-6 should be in equally proportions in our bodies, but this ratio is extremely unbalanced for many people living in today’s developed nations.  People get plenty of Omega-6 from all of the fried, over processed fast food cooked in oils high in omega 6s, but they do not get as much Omega-3 (Advance Health & Life Extension, AHealthyMe.com).   The amount of omega-6s in the average individual’s body is estimated to be anywhere from 20 to 50 times higher than the amount of omega-3s (Truthaboutomega3.com).  Some believe that this imbalance may be lead to depression.   

Fish oil supplements

As has already been mentioned, the body can convert ALA into DHA and EPA, so it would seem that even if someone is not a fish eater she would still be able to get enough DHA and EPA from eating lost of dark green veggies.  Advocates for fish oil supplements do not think ALA produces EPA and DHA in sufficient amounts.  Others even go so far as to say it is hard to get enough omega-3s by simply eating fish (AHealtyMe.com).  Dr. Chris Hart, who endorses a supplement called XTend-Life, says “the only way to ensure that you get the benefits of DHA and EPA is to take it directly in the form of fish oil” (Truthaboutomega3.com).  

There are many pharmaceutical grade fish oils on the market such as AMB Well PGFO, Sealogix, and WINOmeg3complex. The reasoning behind taking fish oils is that they have larger amounts of DHA and EPA than a piece of fish would, and they have less contaminant because the supplements go through an intense filtering process.  Fish oil goes well with most medicines except for blood thinners, because omega-3s are anti-inflammatory and therefore block blood platelet clumping (AHealthyMe.com).  There are only a few risks associated with taking fish oil. One is that loose stools or diarrhea are common, but this can be minimized by taking a small dose with each meal rather than taking one big dose (AHealthyMe.com).  Fish oil should not be confused with cod liver oil.  Cod liver oil comes from the liver of the fish whereas fish oil comes from the body of the fish (Truthaboutomega3.com).    Digesting cod liver oil too frequently can result in hazardous doses of vitamin A (AHealthyMe.com).

What research says:

There is research both supporting and disputing the claims by fish oil companies.  Peet, Murphy, Shay, and Horrobin (1998) hypothesized that the depletion of omega-3 fatty acid in the cell membrane may be important in understanding the etiology of depression.  The results of their study did support their hypothesis.  The fatty acid levels in the cell membranes of the red blood cells of depressed patients were lower that the control.  This may seem to indicate that omega-3 fatty acids are the solution to the problem, but there are also studies with negative results.  For example, Grenyer et al. (2007) assessed the effectiveness of administering a tuna fish oil supplement to patients with major depression who were receiving traditional outpatient treatment through a double-blind placebo-controlled study.  They found no greater benefit of fish oil compared to the placebo when added to standard outpatient treatment.

Conclusions

When one searches through the literature on fish oil and depression, there are so many publications the support both sides of the issue.  Many show evidence of the benefits of fish oil, but there are enough the studies with inconclusive results to take note. 

Presently, I would not recommend a depressed person throwing away their current medication for fish oil.  The FDA has not approved fish oil supplements as a treatment for depression since it came up as a potential treatment ten to fifteen years ago, and maybe there is a reason for that.  More large scale studies need to be done before any definite decisions can be made on the effectiveness of fish oil in curing depression. 

On the other hand, we do know that essential fatty acids are necessary for our bodies to function properly.  For that reason, it may be a good idea to lay off of the processed food and eat some fish every now and then…just in case.

References

Grenyer, B.F.S., Crowe, T., Meyer, B., Owen, A.J, Grigonis-Deane, E.M., Caputi, P. et al.  Fish oil supplementation in the treatment of major depression: A randomised double-blind placebo-controlled trial.  Progress in Neuropsychopharmocology and Biological Psychiatry, 31(7), 1393-1396. 

Hibbeln, J.R.  (1998).  Fish consumption and major depression.  The Lancet, 351, 1213.

Hibbeln, J.R. & Salem, N, Jr.  (1995).  Dietary polyunsaturated fatty acids and depression: when cholesterol does not satisfy.  American Journal Clinical Nutrition, 62, 1-9.

Peet, M., Murphy, B., Shay, J., & Horrobin, D.  (1998).  Depletion of omega-3 fatty acid levels in red blood cell membranes of depressive patients.  Biological Psychiatry, 43(5),  315-319.

 

 

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