Fish Oil (Omega 3 Fatty Acids)


Fish oil is a name for omega-3 fatty acids. There are 3 major types of omega-3s. First, are EPA and DHA. These come mostly from eating fish, although vegetarian options are available because the fish get these from eating marine algae! The third major type is ALA. This can be obtained from nuts, flaxseeds, and leafy greens. The body cannot produce omega-3s, and omega-3s cannot be converted from omega-6s, which are popular in the western diet.

One of the current controversies is determining how the ratio of omega-6s to omega-3s influences health. Many Americans eat a lot more omega-6s from fast foods and processed foods, as compared to omega-3s.

How does this relate to depression? There is some old evidence that suggests that a deficiency of omega-3s fatty acids is correlated with depression. Lipid concentrations were drawn in 34 depressed patients and 14 normal volunteers. They found that in depression, there is a deficiency of omega-3 polyunsaturated fatty acids and a compensatory increase in omega 6s in the cell walls. There may also be an abnormal metabolism of omega-3s in depression.¹

Another study screened 3,884 adults older than 60 years old for depressive symptoms. The subjects also had their blood drawn to measure plasma phospholipid concentrations. Again, it was found that people with depression had higher ratios of omega-6 to omega-3 polyunsaturated fatty acids. This was independent of inflammation, atherosclerosis or other confounders, which suggested a direct effect on mood.²

Finally, a study from Finland looked at 1,767 people. Frequent lake fish consumers (2 or more times per week) had a lower risk of depression and suicidality. This was after adjusting for sex, age, marital status, education, employment status, ability to work, financial status and more.³

Mechanism of action:

 Omega-3s might help to alter cell membrane fluidity and therefore regulate neurotransmission.


1 gram of EPA+DHA daily. Of that gram, 600mg should be from EPA.


(4) A study in Taipei compared added omega-3 polyunsaturated fatty acids or placebo to standard treatment. Hamilton Rating Scale for Depression decreased from an average of 22 to 8.9 in the fish oil group and 15.7 in the placebo group.

(5) A study from Israel looked at 6-12 year-olds with depression. 20 children were randomized. 10 received placebo and 10 received omega-3s. 7/10 children in the omega-3 group had a 50% reduction in their depression scores while 0/10 in the placebo group had a 50% reduction.

But the evidence isn’t all positive …

(6) A study of 122 patients was conducted in St Louis, Missouri. The patients had both depression and coronary heart disease. Sertraline was started in all patients and then either placebo or omega-3s were started. No difference was seen between the omega-3 and placebo group in depression scores.

(7) A trial looked at 59 women with perinatal depression. The patients received psychotherapy and either placebo or omega-3s. Depression scores dropped significantly in both groups, and a difference was not seen between the placebo and the omega-3 group.


Natural medicines database deems fish oil to be likely safe in adults and possibly safe in children.

Medication interactions:

At high doses, fish oil can have an antiplatelet effect and could potentially interact with blood-thinning medications. Fish oil may lower blood pressure as well and interact with blood pressure medications. Fish oil is a fat and any medications that bind to fats could bind to fish oils.

Side effects:

Fish oil is generally well tolerated. Some people state that they have fishy burps after taking fish oils.

My experience:

I bought a vegan omega-3 capsule. It has 150mg of EPA and 300mg of DHA per capsule. I started by taking a capsule twice daily. I would have one in the morning with breakfast and my second one when I got home from work. The capsules are fairly small and go down easily enough. I have been taking them for over one month. I have unfortunately not noticed much of a change in my mood. This could be due to a few things. I already eat flaxseed in my morning smoothie every day and I do not eat fast foods or other foods that have a lot of omega-6s. So my cell membranes might already be the “correct” composition. Also, since diving into the evidence, it seems that the EPA component is what potentially provides more of the mental health effects. Since this capsule only provides 150mg per dose, I may need to take a much higher dose to notice any effects. I have not noticed any side effects or negative effects so I have continued to take the omega-3s

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1. Maes M, Christophe A, Delanghe J, et al. Lowered omega3 polyunsaturated fatty acids in serum phospholipids and cholesteryl esters of depressed patients. Psychiatry Res. 1999 Mar 22;85(3):275-91.

2. Tiemeier H, Van Tuijl H, Hofman A, et al. Plasma fatty acid composition and depression are associated in the elderly: the Rotterdam Study. Am J Clin Nutr. 2003 Jul;78(1):40-6.

3. Tanskanen A, Hibbeln JR, Hintikka J, et al. Fish consumption, depression, and suicidality in a general population. Arch Gen Psychiatry. 2001 May;58(5):512-3.

4. Su KP, Huang SY, Chiu CC, et al. Omega-3 fatty acids in major depressive disorder. A preliminary double-blind, placebo-controlled trial. Eur Neuropsychopharmacol. 2003 Aug;13(4):267-71.

5. Nemets H, Nemets B, Apter A, et al. Omega-3 treatment of childhood depression: a controlled, double-blind pilot study. Am J Psychiatry. 2006 Jun;163(6):1098-100.

6. Carney RM, Freedland KE, Rubin EH, et al. Omega-3 augmentation of sertraline in treatment of depression in patients with coronary heart disease: a randomized controlled trial. JAMA. 2009 Oct 21;302(15):1651-7. doi: 10.1001/jama.2009.1487.

7. Freeman MP, Davis M, Sinha P, et al. Omega-3 fatty acids and supportive psychotherapy for perinatal depression: a randomized placebo-controlled study. J Affect Disord. 2008 Sep;110(1-2):142-8. doi: 10.1016/j.jad.2007.12.228. Epub 2008 Feb 21.

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