Top 27 Science-Based Health Benefits of Fish Oil (DHA & EPA)

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.

What is 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 [1].

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

Pros

• 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

Cons

• May increase oxidative stress if fish oil is rancid

Health Benefits of DHA and EPA

1) 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% [2].

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 [3].

EPA and DHA produce molecules known as “resolvins”, which are named for their ability to “resolve” inflammation [4].

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 [5].

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

DHA produces NPD1 molecules, which have anti-inflammatory properties in the brain in response to strokes [6].

NPD1 also has anti-Alzheimer’s properties that prevent the inflammatory response caused by the disease [7].

Studies show that 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 [8].

Fish oil may prevent or slow disease progression in individuals with mild inflammatory diseases [9].

2) DHA Improves Cognition

Higher levels of DHA are correlated with improved verbal fluency in older people [10].

A study on healthy young adults suggested that after six months of daily doses of fish oil (Lovaza) improved working memory [11].

Other studies have demonstrated that youth who have a dietary intake of fish have experienced improved reaction time and memory retention [12].

Algal DHA taken for six months decreased heart rate and improved memory and learning in healthy, older adults (over 50) with mild memory complaints [13, 14].

In another study, low doses of DHA supplementation improved memory and attention [12].

Higher DHA levels in middle-aged adults are related to better performance on tests of nonverbal reasoning, mental flexibility, working memory, and vocabulary [15].

3) DHA and EPA Benefit Mood

Both 1 g and 2 g of ethyl-EPA helped alleviate symptoms of depression in bipolar patients [16].

There is evidence that suggests that taking fish oil alongside a proven anti-depressant could have significant effects [17].

A regular intake of fish oil reduces the rate of developing dementia and other cognitive decline diseases in adults and elderly individuals [18].

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) [19].

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

Fish oil appears to improve blood flow to the brain in healthy individuals [20].

A high dietary intake of fish reduces the risk of stroke in elderly individuals [21].

The reduced risk of stroke is thought to be related to omega-3 fats, especially DHA [22].

5) DHA Prevents Aggression

The presence of DHA normalizes aggression [23].

DHA reduces aggression during relaxation following periods of high stress [24].

A 6-month study on schoolchildren ages 8 – 16 years old demonstrated a reduction in several measures of aggression [25].

6) Fish Oil Lessens Joint Pain

Resolvins found in EPA and DHA appear to prevent certain inflammatory cytokines such as TNF-α from inducing pain [26].

Human studies have shown the supplemental fish oil reduces inflammatory joint pain [27].

Omega-3’s are effective in reducing pain caused by arthritis [28].

In patients with rheumatoid arthritis, high doses of fish oil decrease disease activity and a number of tender joints [29].

7) 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 [30].

Reduction levels range between 15 – 30% [31].

Elevated triglycerides are a risk factor for many cardiovascular diseases and can also cause leptin resistance [32].

Other sources of DHA, such as algae oil and krill oil, tend to have the same benefits [33].

Fish oil reduces the activity of cholesteryl ester transfer protein (CETP). This inhibition reduces triglycerides and increases high-density lipoprotein (HDL-C) levels [30].

8) Omega 3’s Promote Cardiovascular Health

High triglyceride levels, a risk factor for various cardiovascular diseases, are reduced by EPA and DHA [30].

Normalizing the omega-3 to omega-6 ratio is linked to cardiovascular protection [34].

Studies show that higher intakes of DHA and EPA reduce the risk of cardiovascular disease [35].

Fish oil supplementation is associated with a significant reduction in deaths from cardiac reasons [36].

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 [34].

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 [37].

9) Fish Oil Decreases Risk of Diabetes

A 1:1 omega-3 to omega-6 ratio is linked to a reduced risk of diabetes [38].

Some studies show that taking high doses of fish oil supplementation is associated with increased insulin sensitivity [39].

10) Fish Oil Promotes Weight Loss

EPA and DHA have the ability to activate receptors in the body that increase metabolic rate [40].

DHA is correlated with weight loss in humans [41].

Fish oil’s anti-inflammatory effects have the ability to indirectly aid in fat metabolism in people with high inflammation or metabolic syndrome [42].

Fish oil can increase the secretion of adiponectin, which is responsible for breaking down fats [43].

High doses of fish oil can reduce abdominal and fat weight gain [44].

Fish oil increases enzymes in muscle cells, which is associated with fat loss [45].

Combining fish oil supplements with exercise and a proper diet is effective in weight loss [46].

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

Fish oil reduces the rate of muscle degeneration [47].

Some studies suggest that lean body mass is better retained after surgery when increasing EPA in the diet [48].

There is evidence suggesting that fish oil aids muscle growth [49].

12) EPA and DHA Benefit Fertility and Fetal Development

Data suggests that fish oil may contribute to reduced reproductive aging and extended reproductive lifespan [50].

High doses of fish oil supplementation improve markers of the female reproductive lifespan in women of normal weight [51].

The fetus of a pregnant woman can benefit from EPA and DHA for development [52].

There is evidence that fish oil may reduce the risk of premature birth and birth complications [52].

Fish oil is associated with larger birth weights [53].

One study suggests that women who take DHA supplements during pregnancy give their babies some degree of added protection against getting common colds [54].

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 [55].

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 [56].

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 [56].

DHA is critical for development in the first three months of life [57].

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 [57].

DHA supplementation should also be added to the formula to promote cognitive development [57].

13) 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 [58].

DHA is a key component of this protection. With a regular intake of dietary fish oil, protection is nearly definite [58].

14) Omega-3’s Benefit the Kidneys

Omega-3 fats prevent the progression of kidney disease [59].

Supplementation promotes kidney function in those with diabetes [60].

The intake of omega-3 fats is correlated with protection from kidney disease associated with diabetes [61].

15) Fish Oil Protects the Skin

A high intake of dietary fish products is linked to a reduced risk of skin cancer [62].

It is believed that this prevention is due to fish oil lessening the suppression of the immune system caused by sunlight [63].

Fish oil reduces the risk of sunlight on the skin and can protect against burns [64].

Fish oil decreases inflammation caused by UV light [65].

There is some evidence that fish oil supplementation reduces the severity of acne, especially in individuals with moderate to severe acne [66].

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 [67].

Fish oil has a significant therapeutic role in individuals with ulcerative colitis [67].

17) Omega-3’s Promote Thyroid Health

EPA and DHA decrease blood lipids and cholesterol, which benefit thyroid hormones [68].

Studies suggest that omega-3 fats increase thyroid hormone signaling pathways in the liver [68].

18) Fish Oil Decreases Infection

There is evidence that fish oil benefits individuals affected by Klebsiella pneumonia bacterial infection [69].

19) Fish Oil Decreases Muscle Fatigue

Fish oil reduces the oxygen consumption of muscles, which promotes resistance to muscle fatigue [70].

EPA and DHA improve contractile recovery in muscles [70].

Fish oil lowers heart rate and oxygen demand during exercise without interfering with performance [71].

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 [72].

DHA measured in blood was associated with an increase in high-grade prostate cancer risk [72].

There is evidence that fish oil supplementation reduces the risk of prostate cancer in elderly men [73]. However, another study found an increased risk of prostate cancer from fish oil [74].

Fish oil is associated with a decreased risk of skin cancer [62].

In mice, DHA was found to inhibit the growth of human colon carcinoma cells, more than other omega-3 PUFAs [75]. 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 [76].

Medical studies found that people taking fish oil received higher scores on assessments measuring the quality of life [77].

In addition to DHA’s possible anticancer effect, it may also be used as a non-toxic adjuvant to increase the efficacy of chemotherapy [72].

21) EPA Decreases the Effects of ADHD in Children

Fish oil supplementation is effective in managing symptoms in children with ADHD [78].

There is evidence that both DHA and EPA are useful in treating ADHD [79, 80].

22) Fish Oil Helps Alleviate Migraine Headaches

Fish oil supplementation reduces the frequency, duration, and severity of headaches [81].

There is evidence supporting that fish oil is beneficial in the treatment of migraine headaches in adolescents [81].

23) DHA is Neuroprotective

Preliminary studies showed that a high intake of DHA was associated with a reduced risk of developing Alzheimer’s disease [82] and Parkinson’s disease [83].

Preclinical studies indicate that DHA improves memory and can slow the progression of Alzheimer’s disease in mice [84].

Neuroprotective effects of dietary DHA have been described in animals models of Parkinson’s disease [85].

It was found that a diet rich in DHA might protect stroke victims from brain damage and disability and aid in a speedier recovery [72].

Accordingly, dietary administration of DHA reduces stroke-induced neuroinflammation in animal models [86].

However, clinical trials show that DHA does not slow the decline of mental function in elderly people with mild to moderate Alzheimer’s disease [87, 87].

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 major improvement with a decrease in the frequency of their seizures, but another study showed mixed results with 57 adults on 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 [88].

25) DHA Helps Detox

DHA helps to 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 [89].

27) DHA May Be Anti-Aging

A new study found that higher intake of DHA slowed rates of telomere shortening, which is a basic DNA-level marker of aging [90].

Other

Fish Oil/DHA helps inhibit Epstein-Barr Virus [91].

Fish oil (DHA, EPA) inhibits CD40 and CD86, which are costimulatory molecules [92].

Fish Oil/DHA+EPA suppresses proinflammatory cytokines including TNF-a and IL-1b [93].

Fish oil /DHA increases the T-regulatory cells (Tregs) [94].

Fish oil/DHA exerts anti-inflammatory activity by the activation of AMPK [95].

Fish oil/DHA provide oral tolerance by activating the CD25 T-regulator cells [94].

Both DHA and EPA increased PPAR-gamma mRNA and protein activity in HK-2 cells [96].

DHA also activates RXR (Retinoid X Receptors).

Fish Oil/DHA increase BDNF and/or normalize BDNF levels after traumatic brain injury in rats [97, 98].

Fish oil/DHA can prevent the negative effects of a high-fat diet on the 5HT1A receptor [99].

Fish oil/DHA and EPA are cardiovascular prevention after myocardial arrest possibly by stimulating the vagus nerve [100].

DHA activates SIRT1.

Drawbacks

Since Omega-3’s are potent anti-inflammatories, they can increase mortality and decrease the immune response to influenza and viral infections in animals [101].

One study found that long-term intake of fish oil increases oxidative stress and decreases lifespan in senescence-accelerated mice [102].

Dosage

The recommended daily dosage of fish oil supplements is 1,000mg – 1,200mg. 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 [103].

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

Sources

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

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

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