Print Friendly, PDF & Email

Disclaimer: This post is currently being reviewed because it does not fit our standards for quality.

People often lack a sufficient amount of omega-3 fats (especially DHA), which causes an imbalance in the body’s omega-3 to omega-6 fat ratio. Fish oil is an excellent source of omega-3 fats that also provides many health benefits.

Introduction to Fish Oil

Fish Oil

Fish oil contains two omega-3 fatty acids known as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

The ideal omega-3 to the omega-6 ratio in the body is 1:1, which is associated with a lower lipid count, healthier blood vessels, and reduced risk of diabetes and some forms of cancer [R].

DHA is highly concentrated in the brain, retina, testicles, and semen.

I’m a big proponent of fish consumption as a source of DHA.  I’m such a big fan of fish that I made the cover of my cookbook have Salmon in it.

Fish Oil Snapshot


  • Great for brain health
  • Great anti-inflammatory
  • Good for the heart
  • Great for mood
  • Dose-dependently lowers heart rate
  • Good for skin, eyes, and fertility
  • Good for a wide array of conditions
  • Important for fertility and pregnant women
  • Helps with weight


  • May increase oxidative stress if fish oil is rancid

Health Benefits of DHA and EPA

1) Fish Oil Reduces Inflammation

Fish Oil Reduces Inflammation

In one study, men who took DHA supplements for 6–12 weeks decreased the concentrations of several inflammatory markers in their blood by approximately 20% [R].

One study found that fish oil higher in EPA than DHA lowered inflammatory cytokines, such as IL-6 and IL-1β, associated with neurodegenerative and autoimmune diseases [R].

EPA and DHA produce molecules known as “resolvins”, which are named for their ability to “resolve” inflammation [R].

Resolvin molecules are responsible for the cooperation between fish oil and aspirin. When aspirin is introduced to the body, it allows EPA and DHA to be converted into resolvins [R].

This suggests that fish oil and aspirin are a good synergy and should be taken together.

DHA produces NPD1 molecules, which have anti-inflammatory properties in the brain in response to strokes [R].

NPD1 also has anti-Alzheimer’s properties that prevent the inflammatory response caused by the disease [R].

Studies show that a dietary supplementation of fish oil lowers the activity of chronic inflammatory and autoimmune diseases including rheumatoid arthritis, Crohn’s disease, ulcerative colitis, psoriasis, lupus erythematosus, multiple sclerosis, and migraine headaches [R].

Fish oil may prevent or slow disease progression in individuals with mild inflammatory diseases [R].

2) DHA Improves Cognition

DHA Improves Cognition

Higher levels of DHA are correlated with improved verbal fluency in older people [R].

A study on healthy young adults suggested that after six months of daily doses of fish oil (Lovaza) improved working memory [R].

Other studies have demonstrated that youth who have a dietary intake of fish have experienced improved reaction time and memory retention [R].

Algal DHA taken for six months decreased heart rate and improved memory and learning in healthy, older adults (over 50) with mild memory complaints [RR].

In another study, low doses of DHA supplementation improved memory and attention [R].

Higher DHA levels in middle-aged adults are related to better performance on tests of nonverbal reasoning, mental flexibility, working memory, and vocabulary [R].

3) DHA and EPA Benefit Mood

DHA and EPA Benefit Mood

Both 1 g and 2 g of ethyl-EPA helped alleviate symptoms of depression in bipolar patients [R].

There is evidence that suggests that taking fish oil alongside a proven anti-depressant could have significant effects [R].

A regular intake of fish oil reduces the rate of developing dementia and other cognitive decline diseases in adults and elderly individuals [R].

DHA activates the Cannabinoid system, which may be one mechanism by how it improves mood.

However, 220 mg/day DHA or DHA + arachidonic acid had no effect on depression symptoms during pregnancy (study with 119 women) [R].

4) Reduces Risk of Stroke and Improves Blood Flow to Brain

Reduces Risk of Stroke and Improves Blood Flow to Brain

Fish oil appears to improve blood flow to the brain in healthy individuals [R].

A high dietary intake of fish reduces the risk of stroke in elderly individuals [R].

The reduced risk of stroke is thought to be related to omega-3 fats, especially DHA [R].

5) DHA Prevents Aggression

The presence of DHA normalizes aggression [R].

DHA reduces aggression during relaxation following periods of high stress [R].

A 6-month study on schoolchildren ages 8-16 years old demonstrated a reduction in several measures of aggression [R].

6) Fish Oil Lessens Joint Pain

Fish Oil Lessens Joint Pain

Resolvins found in EPA and DHA appear to prevent certain inflammatory cytokines such as TNF-α from inducing pain [R].

Human studies have shown the supplemental fish oil reduces inflammatory joint pain [R].

Omega-3’s are effective in reducing pain caused by arthritis [R].

In patients with rheumatoid arthritis, high doses of fish oil decrease disease activity and a number of tender joints [R].

7) Fish Oil Reduces Triglycerides and Increases HDL

Fish Oil Reduces Triglycerides and Increases HDL

Both EPA and DHA have the ability to reduce triglyceride levels, most effectively after several weeks of supplementation [R].

Reduction levels range between 15-30% [R].

Elevated triglycerides are a risk factor for many cardiovascular diseases and can also cause leptin resistance [R].

Other sources of DHA, such as algae oil and krill oil, tend to have the same benefits [R].

Fish oil reduces the activity of cholesteryl ester transfer protein (CETP). This inhibition reduces triglycerides and increases high-density lipoprotein (HDL-C) levels [R].

8) Omega 3’s Promote Cardiovascular Health

Omega 3's Promote Cardiovascular Health

High triglyceride levels, a risk factor for various cardiovascular diseases, are reduced by EPA and DHA [R].

Normalizing the omega-3 to omega-6 ratio is linked to cardiovascular protection [R].

Studies show that higher intakes of DHA and EPA reduce the risk of cardiovascular disease [R].

Fish oil supplementation is associated with a significant reduction in deaths from cardiac reasons [R].

Studies demonstrate that an omega-3 to the omega-6 ratio of 1:1 is associated with a 70% decreased risk of dying from cardiovascular disease [R].

However, one study found that, overall, omega-3 supplementation was not associated with a lower risk of all-cause mortality, cardiac death, sudden death, myocardial infarction, or stroke based on relative and absolute measures of association [R].

9) Fish Oil Decreases Risk of Diabetes

Fish Oil Decreases Risk of Diabetes

A 1:1 omega-3 to omega-6 ratio is linked to a reduced risk of diabetes [R].

Some studies show that taking high doses of fish oil supplementation is associated with increased insulin sensitivity [R].

10) Fish Oil Promotes Weight Loss

Fish Oil Promotes Weight Loss

EPA and DHA have the ability to activate receptors in the body that increase metabolic rate [R].

DHA is correlated with weight loss in humans [R].

Fish oil’s anti-inflammatory effects have the ability to indirectly aid in fat metabolism in people with high inflammation or metabolic syndrome [R].

Fish oil can increase the secretion of adiponectin, which is responsible for breaking down fats [R].

High doses of fish oil can reduce abdominal and fat weight gain [R].

Fish oil increases enzymes in muscle cells, which is associated with fat loss [R].

Combining fish oil supplements with exercise and a proper diet is effective in weight loss [R].

11) Omega-3’s Speed Up the Healing Process

Omega-3's Speed Up the Healing Process

Fish oil reduces the rate of muscle degeneration [R].

Some studies suggest that lean body mass is better retained after surgery when increasing EPA in the diet [R].

There is evidence suggesting that fish oil aids muscle growth [R].

12) EPA and DHA Benefit Fertility and Fetal Development

Data suggests that fish oil may contribute to reduced reproductive aging and extended reproductive lifespan [R].

High doses of fish oil supplementation improve markers of the female reproductive lifespan in women of normal weight [R].

The fetus of a pregnant woman can benefit from EPA and DHA for development [R].

There is evidence that fish oil may reduce the risk of premature birth and birth complications [R].

Fish oil is associated with larger birth weights [R].

One study suggests that women who take DHA supplements during pregnancy give their babies some degree of added protection against getting common colds [R].

DHA is very likely important in the formation of the acrosome, an arc-like structure on the top of sperm, which is critical in fertilization because it houses a variety of enzymes that sperm use to penetrate an egg [R].

Higher visual acuity after DHA supplementation is a consistent finding in infants born preterm. For infants born at term, the results are less consistent and are better explained by differences in sensitivity of the visual acuity test (electrophysiologic tests being more sensitive than subjective tests) or by differences in the amount of DHA included in the experimental formula.

Omega-3 fats are able to pass from mother to fetus, which assists with nervous system development [R].

DHA plays a significant role in the neural development of a fetus. The fetus is dependent on the mother to provide DHA, either through supplementation or diet [R].

DHA is critical for development in the first three months of life [R].

Breast milk is a significant source of DHA. A higher concentration of DHA in breast milk is connected to a mother’s diet and supplementation [R].

DHA supplementation should also be added to the formula to promote cognitive development [R].

13) DHA Protects the Eyes

DHA Protects the Eyes

A 1:1 omega-3 to omega-6 ratio protects against retinal angiogenesis, the development of new blood vessels in the eye [R].

DHA is a key component to this protection. With a regular intake of dietary fish oil, protection is nearly definite [R].

14) Omega-3’s Benefit the Kidneys

Omega-3's Benefit the Kidneys

Omega-3 fats prevent the progression of kidney disease [R].

Supplementation promotes kidney function in those with diabetes [R].

The intake of omega-3 fats is correlated with protection from kidney disease associated with diabetes [R].

15) Fish Oil Protects the Skin

Fish Oil Protects the Skin

A high intake of dietary fish products is linked to a reduced risk of skin cancer [R].

It is believed that this prevention is due to fish oil lessening the suppression of the immune system caused by sunlight [R].

Fish oil reduces the risk of sunlight on the skin and can protect against burns [R].

Fish oil decreases inflammation caused by UV light [R].

There is some evidence that fish oil supplementation reduces the severity of acne, especially in individuals with moderate to severe acne [R].

16) Fish Oil Helps Manage Gastrointestinal Diseases

The anti-inflammatory effects of omega-3 fats can assist in managing Inflammatory Bowel Disease (IBD) and other gastrointestinal diseases causing inflammation [R].

Fish oil has a significant therapeutic role in individuals with ulcerative colitis [R].

17) Omega-3’s Promote Thyroid Health

EPA and DHA decrease blood lipids and cholesterol, which benefit thyroid hormones [R].

Studies suggest that omega-3 fats increase thyroid hormone signaling pathways in the liver [R].

18) Fish Oil Decreases Infection

Fish Oil Decreases Infection

There is evidence that fish oil benefits individuals affected by Klebsiella pneumonia bacterial infection [R].

19) Fish Oil Decreases Muscle Fatigue

Fish oil reduces the oxygen consumption of muscles, which promotes resistance to muscle fatigue (R).

EPA and DHA improve contractile recovery in muscles (R).

Fish oil lowers heart rate and oxygen demand during exercise without interfering with performance (R).

20) Fish Oil Reduces the Risk of Some Cancers

DHA was shown to increase the efficacy of chemotherapy in prostate cancer cells in vitro, and a chemoprotective effect in a mouse model was reported (R).

DHA measured in blood was associated with an increase in high-grade prostate cancer risk (R).

There is evidence that fish oil supplementation reduces the risk of prostate cancer in elderly men (R).  However, another study found an increased risk of prostate cancer from fish oil (R, R).

Fish oil is associated with a decreased risk of skin cancer (R).

In mice, DHA was found to inhibit the growth of human colon carcinoma cells, more than other omega-3 PUFAs (R). The anti-cancer effect of DHA was caused by a decrease in cell growth regulators.

Fish oil is associated with improvements in clinical and functional parameters in advanced cancer patients experiencing weight loss (R).

Medical studies found that people taking fish oil received higher scores on assessments measuring the quality of life (R).

In addition to DHA’s possible anticancer effect, it may also be used as a non-toxic adjuvant to increase the efficacy of chemotherapy (R).

21) EPA Decreases the Effects of ADHD in Children

Fish oil supplementation is effective in managing symptoms in children with ADHD (R).

There is evidence that both DHA and EPA are useful in treating ADHD (RR).

22) Fish Oil Helps Alleviate Migraine Headaches

Fish oil supplementation reduces the frequency, duration, and severity of headaches (R).

There is evidence supporting that fish oil is beneficial in the treatment of migraine headaches in adolescents (R).

23) DHA is Neuroprotective

Preliminary studies showed that a high intake of DHA was associated with reduced risk of developing Alzheimer’s disease (R) and Parkinson’s disease (R).

Preclinical studies indicate that DHA improves memory and can slow the progression of Alzheimer’s disease in mice (R).

Neuroprotective effects of dietary DHA have been described in animals models of Parkinson’s disease (R).

It was found that a diet rich in DHA might protect stroke victims from brain damage and disability and aid in a speedier recovery (R).

Accordingly, dietary administration of DHA reduces stroke-induced neuroinflammation in animal models (R).

However, clinical trials show that DHA does not slow the decline of mental function in elderly people with mild to moderate Alzheimer’s disease (RR2).

24) DHA Helps Epilepsy

The use of DHA by persons with epilepsy could decrease the frequency of their seizures. Studies have shown that children with epilepsy had a major improvement, i.e. decrease in the frequency of their seizures, but another study showed mixed results with 57 adults taking DHA supplementation. The 57 subjects demonstrated a decreased frequency of seizures for the first six weeks of the study, but for some, it was just a temporary improvement (R).

25) DHA Helps Detox

DHA helps mount the body’s antioxidant NRF2 response, which helps us detox.

26) DHA Helps Psoriasis

Supplementary treatment with omega-3 fatty acids complements topical treatment in psoriasis, and makes a significant contribution to improving symptoms (R).

27) DHA May be Anti-Aging

A new study found that higher intake of DHA was associated with slower rates of telomere shortening, which is a basic DNA-level marker of aging (R).


Fish Oil/DHA helps inhibit Epstein-Barr Virus (R).

Fish oil (DHA, EPA) inhibits CD40 and CD86, which are costimulatory molecules (R).

Fish Oil/DHA+EPA suppresses proinflammatory cytokines including TNF-a and IL-1b (R).

Fish oil /DHA increases the T-regulatory cells (Tregs) (R, R2).

Fish oil/DHA exert anti-inflammatory activity by the activation of AMPK (R).

Fish oil/DHA provide oral tolerance by activating the CD25 T-regulator cells (R, R2).

Both DHA and EPA increased PPAR-gamma mRNA and protein activity in HK-2 cells (R).

DHA also activates RXR (Retinoid X Receptors) (R).

Fish Oil/DHA increase BDNF and/or normalize BDNF levels after traumatic brain injury in rats (R, R2).

Fish oil/DHA can prevent the negative effects of a high-fat diet on the 5HT1A receptor (R).

Fish oil/DHA and EPA are cardiovascular prevention after myocardial arrest possibly by stimulating the vagus nerve (R).

DHA activates SIRT1 (R).


Since Omega-3’s are potent anti-inflammatories, they can increase mortality and decrease the immune response to influenza and viral infections in animals (R).

One study found that long-term intake of fish oil increases oxidative stress and decreases lifespan in senescence-accelerated mice (R).

Buying Fish Oil

When buying fish oil, the main thing to look out for is that it’s not oxidized, because that can easily happen.


The recommended daily dosage of fish oil supplements is 1000mg-1200mg. Adults should get at least two servings of oily fish per week, which is equivalent to about 500mg of omega-3 fats. Maximal results occur after approximately three weeks of taking supplements (R).

However, some people respond to high dosages of fish oil.


Seafood is a great source of DHA and EPA.  I like to eat wild salmon often, but I still supplement with fish oil.

Health Tools I Wish I Had When I Was Sick

At SelfHacked, it’s our goal to offer our readers all the tools possible to get optimally healthy. When I was struggling with chronic health issues I felt stuck because I didn’t have any tools to help me get better. I had to spend literally thousands of hours trying to read through studies on pubmed to figure out how the body worked and how to fix it.

That’s why I decided to create tools that will help others cut down the guesswork:

  • Lab Test Analyzer – a software tool that will analyze your labs and tell you what the optimal values are for each marker — as well as provide you with actionable tips and personalized health and lifestyle recommendations to help you get there.
  • SelfDecode – a software tool that will help you analyze your genetic data from companies such as 23andme and ancestry. You will learn how your health is being impacted by your genes, and how to use this knowledge to your advantage.
  • SelfHacked Secrets – an ebook where we examine and explain the biggest overlooked environmental factors that cause disease. This ebook is a great place to start your journey if you want to learn the essential steps to optimizing your health.
  • SelfHacked Elimination Diet course – a video course that will help you figure out which diet works best for you
  • Selfhacked Inflammation course – a video course on inflammation and how to bring it down
  • Biohacking insomnia – an ebook on how to get great sleep
  • Lectin Avoidance Cookbook – an e-cookbook for people with food sensitivities
  • BrainGauge – a device that detects subtle brain changes and allows you to test what’s working for you
  • SelfHacked VIP – an area where you can ask me (Joe) questions about health topics

FDA Compliance

The information on this website has not been evaluated by the Food & Drug Administration or any other medical body. We do not aim to diagnose, treat, cure or prevent any illness or disease. Information is shared for educational purposes only. You must consult your doctor before acting on any content on this website, especially if you are pregnant, nursing, taking medication, or have a medical condition.


1 Star2 Stars3 Stars4 Stars5 Stars (8 votes, average: 4.38 out of 5)


  • Marco

    Hi there,
    just wanted to ask you, what is your take on CO2 distillation process?.
    I heard temperatures are much lower than the 200° C implied when adopting molecular distilled procedures.
    Normally if temperatures are much lower, quality should be also higher correct?.



  • Curtis

    Long-term fish oil consumption can cause liver damage? Specifically, non-alcoholic steatohepatitis (NASH). This just came out a few days ago. Thoughts?

  • Rich Geldreich

    Dose seems to matter a lot when treating mood disorders with fish oil. The EPA to DHA ratio matters too, although there doesn’t seem to be a firm consensus yet on the best ratio. More EPA vs. DHA seems to be necessary for mood problems.

    I was taking 1 gram/day, off and on, and I mentioned my low moods to my chiropractor and he suggested I try 4 grams/day. Wow! I got an instant improvement.

  • Kerry

    What about Fukushima? BP Oil Spill? Our oceans are polluted.

  • carol close

    I was super shocked to see 4 studies regarding fish oil increasing intestinal permeability pointed out here. [functionalalps]

    “Ingestion of (n-3) fatty acids augments basal and platelet activating factor-induced permeability to dextran in the rat mesenteric vascular bed.”

    “Lipid peroxidation induced by DHA enrichment modifies paracellular permeability in Caco-2 cells: protective role of taurine.” We conclude that hydrogen peroxide and peroxynitrite may be involved in the DHA-induced increase in paracellular permeability and that the protective role of taurine may be in part related to its capacity to counteract the effects of hydrogen peroxide.

    “Intestinal permeation and gastrointestinal disease.”

    “The type of dietary fat modulates intestinal tight junction integrity, gut permeability, and hepatic toll-like receptor expression in a mouse model of alcoholic liver disease.” Essential” polyunsaturated fat linoleic acid also increase intestinal permeability. Saturated fats had no such effect.

  • Ash

    While I love supplements and have had many benefits from many kinds, Fish Oil has always been a question for me. I do seem to concentrate better on it, but after a few days use, my stomach becomes irritated/inflamed and the benefits seem to be lost. I don’t understand why that happens, but it does, consistently.

    Ray Peat seems to hate Fish Oil, claims it’s nothing more then seafood industry trying to sell a waste product. Have you read his work? Thoughts?

  • K

    from “information is beautiful”, via IFLscience, this infographic displays a different story for the review of research on fish oil with clear detriment indicated by the majority of studies. that doesn’t mean there aren’t legit uses for fish oil, but it certainly isn’t the snake oil it’s purported to be.


  • john seville

    I have been a long time user of Fish Oils for their anti-inflammatory action, unfortunately I have not really obtained much benefit in that area, though the benefits of eye health have been very good. I have been thinking of dropping this supplement for a number of reasons, first, I read a while back the possibility of “sudden death” in those that supplement in larger quantities, I use 1-2 tablespoons since I have an autoimmune issue. Now that you have brought forth the information that Fish Oil suppresses CD8+ counts I will definitely do so, reason being CD8+ T cells are very much at the forefront of containing the Epstein Barr virus and this virus has been implicated in most autoimmune issues. I doubt it will make a difference with my AI, but perhaps it will help prevent other issues down the line. Keep up the great work, very informative!

  • Alan

    Do you think softgels are better than liquids in terms of protection from oxidation?

    1. Joseph M. Cohen


  • Tim

    Hi Joe,

    Have you looked into Brian Peskin’s research? He claims that fish oils of any kind are detrimental, and that he recommends consuming parent essential oils that have a higher omega 6 to omega 3 ratio.

  • anna burns

    I’m curious what your opinion is of fermented cod liver oil. Will you share please?

    1. Joseph M. Cohen

      Oxidized, not good. Just good marketing.

  • BB

    Algal oil is available as well as a dietary DHA EPA supplement, for those that are vegan, allergic to fish, etc..

  • Leave a Reply

    Your email address will not be published. Required fields are marked *

    This site uses Akismet to reduce spam. Learn how your comment data is processed.