What’s the Deal With Fish Oil?

Kelly Hogan, MS, RD
by Kelly Hogan, MS, RD
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What’s the Deal With Fish Oil?

Among the supplements lining grocery store shelves, you’ve likely come across fish oil. Thanks to its high content of omega-3 fatty acids (found in the diet via fatty fish) for centuries, research links fish oil to health benefits, including better heart health, cognitive function and reduced risk of certain cancers. Like other supplements, it can be confusing to determine whether or not to take fish oil, especially if you do not consume fatty fish regularly. Here’s what you need to know about fish oil before deciding if a supplement is right for you.


Fish oil is derived from the tissues of fatty, oily fish like salmon, mackerel, tuna, anchovies, sardines and trout. Just like these fish, fish oil is rich in omega-3 fatty acids, specifically EPA and DHA. Omega-3 fats are important components in the structure of our cells, especially in the brain and eyes. They’re also an energy source for the body and an anti-inflammatory agent. Health organizations have varied recommendations on omega-3 fats, but the recently updated 2020-2025 Dietary Guidelines recommend adults and children consume fish 2–3 times per week (with one serving equating to 4 ounces). However, most Americans are far from meeting this goal.

The updated guidelines on fish consumption are greater than ever before, and children are included for the first time, likely due to the growing body of research on the benefits of omega-3 fats. The literature tends to favor a few different health categories, where it is thought to have the most benefits: fetal growth and development, cardiovascular health and cognitive function, though various cancers and inflammatory conditions are also being researched.


Because omega-3’s, especially DHA, is an important component in the structure of brain cells, it has been hypothesized that fish oil may be protective against cognitive decline and promote overall brain health. Several studies on this topic have mixed findings, ranging from a reduced risk of Alzheimer’s disease and dementia among individuals who supplemented with DHA versus those who did not, to several reviews and meta-analyses showing omega-3 supplementation did not significantly affect cognitive function.


Fish oil is commonly thought to have a cardio-protective effect, but the research has also been somewhat mixed. Studies have found a reduced risk of cardiovascular death and significant reductions in rates of heart attack and heart disease in individuals taking fish oil supplements compared to those who did not. However, a meta-analysis found omega-3 supplementation did not reduce the risk of heart attack, stroke or cardiovascular death. Another study using high-dose omega-3 supplementation (available only by prescription) found individuals taking the supplement had a significantly lower risk of stroke. Prescription, high-dose omega-3 supplements have also been found to reduce triglycerides in individuals with high levels.


Omega-3 fatty acids, especially DHA, are essential for fetal growth and development because they play such an important role in the structure of cells in the brain and eye. The current dietary guidelines recommend pregnant women consume 8–12 ounces of low-mercury, high-DHA/EPA seafood per week, such as salmon, sardines and trout. This equates to around 200–300mg of DHA, and the recommendation for breastfeeding women is similar. Studies are mixed and inconclusive on improvements in a child’s cognitive function, language and conceptualization whose mothers were supplemented with omega-3’s when pregnant. However, omega-3 supplementation may help reduce the risk of low birth weight. Most prenatal vitamins contain DHA.


Fish oil is also known to produce molecules that work to reduce inflammation in the body, which may help reduce the risk of chronic disease and even some cancers. It may also be beneficial to help reduce painful symptoms of inflammatory diseases such as rheumatoid arthritis.


If you like and consume fatty fish regularly (2–3 times per week), fish oil supplementation isn’t typically necessary. You can also get omega-3’s from other sources such as grass-fed beef and free-range eggs.

If you’re not quite there yet, working to include more fish in your diet is a great goal. A couple of delicious ways to incorporate more fatty fish into your diet include:


Supplementing with fish oil can help those who dislike the taste of fatty fish, but it’s not strictly necessary if you’re eating a well-balanced diet. A good place to start is by tracking your intake with an app like MyFitnessPal so you can get a sense of the types of fats you’re consuming.

If you’re thinking of supplementing, always discuss it with your dietitian or doctor and make sure you’re purchasing from a reputable brand that does third-party testing. It’s also a good idea to store the bottle in the refrigerator to slow oxidation. Avoid buying large bottles of capsules or liquids. While the price per capsule may be enticing, buying in bulk could lead to accidental oxidation — smaller bottles are open for, and used up, in a shorter time.

Ultimately, the best way to reap the most benefits from fish oil is to combine your intake (either via supplementation or fish) with a diet rich in fruits, vegetables, whole grainsbeans and legumes.

Originally published August 2014, updated with new information

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About the Author

Kelly Hogan, MS, RD
Kelly Hogan, MS, RD

Kelly Hogan, MS, RD is an NYC-based registered dietitian specializing in women’s health, sports nutrition and plant-based eating. She is passionate about helping people develop a positive relationship with food and their bodies, and uses a non-diet approach in her practice. When she’s not talking or writing all things nutrition, Kelly can be found running in Central Park – she’s run 11 marathons and counting! – cooking recipes new and old, handstanding at the yoga studio or hanging with friends and/or her rescue dog, Peanut.


29 responses to “What’s the Deal With Fish Oil?”

  1. Avatar devans00 says:

    Fish oil was recommended to me by my eye doctor. I mentioned that my eyes were uncomfortably dry while wearing contact lenses and he thought the fish oil would help. I can’t say that it has.

    Maybe I’ll cut back the daily dosage to a few times a week after reading this article.

  2. Avatar Nobam2012 says:

    It’s good, it’s bad, it’s good, it’s bad. That’s what all health advice is turning into. Just eat within your calorie range and workout.

    • Avatar scott says:

      Don’t worry abut calories and get on board with the ketogenic diet. Read Fat For Fuel. Get your EFA’s from flax,chia,hemp. Then get lots of coconut,butter. I had 85 grams of fat/30grams of protein with some low carb veggies and greens for breakfast. Now it’s time for my bulletproof coffee

  3. Avatar Merle says:

    How about fermented cod liver oil?

  4. Avatar InLimine says:

    Fish oil alleviated the tendinitis in my big toe down to almost nothing. I don’t believe in miracle cures but a $10 bottle of fish oil did what a $1000 set of custom orthotics, religious stretching, and staying off of my feet didn’t.

  5. Avatar Dan says:

    Whenever I take fish oil, I feel a bit confused and it becomes slightly hard for me to think clearly. I figured that I don’t really need this supplement.

    • Avatar scott says:

      The essential fatty acids are ALA and LA. get those from flax,chia,hemp,walnuts. Then add the DHA/EPA with bone broth and greens.Blend all together. Get on board with the ketogenic diet. Say goodbye to all grains and sugar. You will surprisingly have more enrgy. For mental clarity you need phospholipids from sunflower lecithin/RAW eggs and choline+inositol supplement. You can even try piraracetam

  6. Avatar mrcreigs says:

    Thinking fish oil would be good for trigliserides and healthy lifestyle I bought a 6 month supply 3000 mg a day. But have been reading articles that are making me second guess. So I’ve stopped taking them after my 6 month trial.

    • Avatar Alexa says:

      Is there any positive result after taking the supplement for 6 months? or was it a negative results that is why you stopped taking em after 6 mos?

  7. Avatar koom2014 says:

    Was on statins for cholesterol reduction so started taking krill oil as a supplement for heart health. Since then came off the statins so not sure if the krill helped reduce it, I’ve also found joint health seems better although this could be in my head too!

  8. Avatar Bobbie says:

    Way too much mercury….Dr. Oz was told by his Doctors to STOP eating so much fish…high in mercury….all of them….And do we really know what is in the capsule???

  9. Avatar Ben Bonarigo says:

    Check with American College of Cardiology. Fish oil is passe.
    LDLs are the 90% target. No nutritionist has ever truly been responsible for the health of an individual, though they are tangentially involved.

    • Avatar Brian T says:

      Ben I would disagree with you. I’ve been a nutritionist for over 17 years. Spent several years in academia as well. Many times I’ve been responsible for an individuals health after a patient has had zero success addressing their cardiovascular issues with allopathic medicine. This is not to say that drugs are never the answer, butost often, blood pressure, lipids and other risk factors are easily addressed with nutrition and exercise.

  10. Avatar MsMermaid says:

    Lifetime fitness staff are all pushing the fish oil supplements big time. 6-8 per day. Never made it past a couple, so glad to hear that may be a bit overboard.

  11. Avatar Janet says:

    I take Krill oil supplements because I’ve had my gall bladder removed and, therefore, do not digest and absorb fat – healthy Omega-3 and 6 included – as readily anymore. My doctor has suggested that I supplement my diet with Krill oil to make sure that I give my body a little extra to try and absorb so that I’m getting the amount my body needs.

  12. Avatar knotfreak says:

    Nobam2012, that’s the way science works. Knowledge builds as research progresses. That’s why science literacy is important, to help know the difference between the types of studies and their relative importance. Early studies often don’t stand up to larger, better work, so recommendations have to change. Your bottom line is correct and has stood the test of time 🙂

  13. Avatar Flash says:

    High cholesterol and taking meds to reduce numbers. Lowered but still slightly on the high side with meds for several years. Added two fish oil pills a day and cholesterol is now in the normal range and has stayed there. It worked for me.

    • Avatar Sylvia Solution says:

      Switch from butter, animal fat, cheeses, to olive oil, avocado, nuts, seeds and omega fish oil, d-tocopherol E and evening primrose oil to keep the wrinkles away and your insides from drying out as you age. Also follow the Mediterranean diet for a statistically proven healthy way of eating !

  14. Avatar Katanlin says:

    I have had high triglycerides most of my life. When I started taking 2 fish oil capsules a day, my numbers came down 1000 points in about 6 months. I continue to use fish oil capsules and changed to olive oil and watch what I buy/eat. Using low fat/fat free products, fish oil capsules, and olive oil I have lowered my numbers a few hundred more points. I am just about in a more normal range now. In my experience, it has worked for me and I can tell the difference when I don’t use fish oil in my triglyceride numbers,

  15. Avatar Keith says:

    Responding to research reported in The Economist, I began taking a daily capsule of fish oil to treat my arthritic knee, a source of constant pain. While the pain has not gone entirely, it has been much reduced.

  16. Avatar DanT says:

    I’ve been taking omega 3 capsules for over ten years to treat genetic hypertryglceridemea and they do work to lower triglycerides, the capsules are heavy metal free and this is something to check for when taking them over long periods.
    I’ve also found that using the capsules as well as a small amount of Apple cider vinegar everyday really helps to lower triglycerides as well, the vinegar needs to have the mother in it and will therefore probably be organic, also eating healthy and avoiding saturated fats will make a difference too.

  17. Avatar RYAN says:

    Why does someone with a degree in public health writing like they have a degree in physiology or nutrition… A lot of what is wrote here is crap; he has no knowledge of physiology. MyFitnessPal, please use qualified writers next time.

    • Avatar Sylvia Solutions says:

      Doctors have a degree, but surprisingly have rarely in my experience mentioned vitamins or food cures..they usually write a prescription for a medicine. Hippocrates said “Let food be your medicine, and your medicine be your food”. He was from the Mediterranean and self taught. ! !

  18. Avatar V says:

    Fish oil makes me dizzy. So I switched to flaxseed oil.

  19. Avatar Behealthy says:

    I am a very active, very healthy 55 year old. I exercise 1-2 hours, 4-5 times weekly, eat right, weigh 123 lbs, Take my vitamins, calcium daily. I was taking 1200 mg of fish oil supplements daily and earlier this year, I had a brain hemorrhage. Doctors can not figure out what caused the hemorrhage. Now after reading this article, I’m wondering if it could have been from taking too much fish oil supplements. I’ve stopped taking the supplements.

  20. Avatar Mikael Vitally Vyachesl says:

    polyunsaturated oils are toxic ..any oil extracted by high steam temperatures and then are put in a capsule and shipped to a warehouse and to the stores ?are rancid and toxic ..its a billion dollars business for the vitamin industry ,..do people in Okinawa Japan pop fish oil pills and vitamins shit pills all day ? Why Americans are mostly obese and they blow money in toxic pills ?,,,they should be slim and healthy ?

  21. Avatar scott says:

    Start with flax,chia,hemp,coconut and lecithin or 3 raw eggs then add your cod liver/fish oil. Throw in some bone broth and whey. Then add some greens. Put that in your vitamix and your off to the races. Go ketogenic diet. That was 85 grams fat 30 grams protein and very little carbs. Then have your bullet proof coffee

  22. Avatar Rhona Hall says:

    I suffer with depression and since I’ve started supplementing with fish oil, my mood is noticibly better. I will stay on it.

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