What is Fish Oil for and Do You Really Need It?

what is fish oil for


What is fish oil for? Next to vitamin D and multivitamins, which we’ve discussed in previous articles, fish oil is one of the most popular supplements. Yet, research looking at the benefits of fish oil have been inconsistent, leading many of us to wonder whether we need it or not.


We, too, have pondered the same question – does fish oil really offer the benefits the supplement companies claim and is it safe? After all, fish oil comes from fish, and fish swim in waters where they’re exposed to pollutants and heavy metals.


If you ask a health expert about the safety of fish, they’ll likely tell you, depending upon the type of fish, that you should eat the actual fish itself no more than twice a week, and for some larger fish, only once a week or less.


Larger fish that are higher on the food chain are more likely to accumulate high levels of toxins as opposed to tiny fish like anchovies and sardines that get devoured by a large fish before they have time to build up toxins.


In this article, we hope to clarify the question of what is fish oil for as well as help you decide whether you should take it. We took it for years, but after one study linked it with prostate cancer, we discontinued it temporarily. 


That study has since been widely criticized and disputed. First, let’s look at why you might consider taking a fish oil supplement in the first place.


How Fish Oil Grew in Popularity


You might think fish oil is a relatively recent supplement phenomenon but as far back as 16th century England, fishermen used fish oil to treat a variety of health issues, including the common cold, wounds, and skin problems.


It wasn’t until the 1970s that fish oil really made inroads into the supplement market. The impetus was a study looking at why the Eskimos living in Greenland had such a low rate of heart disease despite eating a high-fat diet.


The fats in their diet, as you might expect, came from the fish they had such ready access to. Fish that live in cold, deep waters, have high levels of fatty acids called omega-3s. This long-chain omega-3s are called Eicosapentaenoic acid (EPA) and Docosahexaenoic acid (DPA).


This study opened up a whole line of research looking at the health benefits of fish oil, particularly the omega-3s, EPA and DHA. Not all fish are high in omega-3s. Here are examples of fish that are:


  • Sardines
  • Anchovies
  • Tuna
  • Salmon (Wild Caught)
  • Mackerel
  • Herring
  • Lake Trout
  • Whitefish
  • Black Cod


As we’ll get to later, not all of these fish are necessarily healthy to eat due to concerns about toxins. We just want to make you aware that not all fish have enough omega-3s to be significant.


What is Fish Oil For, Anyway?

The reason people are excited about fish oil and the omega-3s it contains has to do with their anti-inflammatory properties. As you know, inflammation is a driving force in a number of diseases, including heart disease, autoimmune disease, type 2 diabetes, and even some types of cancer.


By calming inflammation, omega-3 fatty acids from fish oil might lower the risk for a number of health problems – all well and good, but how does this play out in real life?


Fish Oil for Brain Health


One recent area where omega-3s failed to show benefits was for delaying age-related cognitive decline. Since omega-3s are so concentrated in the brain and are essential for normal brain development in children, the hope was that fish oil supplements might slow down brain aging or even prevent Alzheimer’s disease.


While some early studies showed benefits, the most recent research looking at omega-3s and brain aging did not. One such study was published last year in the Journal of the American Medical Association.


What makes this study more credible is they actually gave participants omega-3 supplements for five years and monitored their cognitive function. This gives the study more legitimacy than the typical study where participants recall how much fish they ate etc.


One thing to keep in mind, the participants in this study were older, which may have skewed the results. Plus, a number of previous observational studies DID show the omega-3s in fish oil benefits brain health. It’s possible that getting omega-3s from eating fish has benefits that taking a supplement doesn’t.


Conclusion: There’s more evidence that eating fatty fish supports brain health as opposed to taking fish oil supplements. 


Fish Oils and Your Heart


You may have heard that fish oils are heart healthy – but are they really? Some studies show fish oils lower blood triglyceride levels and slightly raise HDL, both of which bode well for heart health.


Yet a large review of 20 studies spanning a period of 13 years showed taking long-chain omega-3s as a supplement was NOT linked with a lower risk of heart attack or stroke.


Sounds discouraging, doesn’t it? Before assuming fish and fish oils have no heart health benefits – research does show that eating 2-4 servings of fish weekly was linked with a modestly reduced risk of stroke. Other good news – a study also showed fish oil seems to reduce the risk of blood clots.


When you take all the research into account, there’s no strong evidence that taking a fish oil supplement will lower your risk for heart disease or heart attacks, although it may modestly reduce your risk of stroke. It also may lower the risk of blood clots.


On the other hand, EATING fish high in omega-3s twice a week may offer some heart-protective benefits.


Conclusion: Again, fatty fish itself seems to offer more benefits than supplements, although fish oil supplements may reduce the risk of stroke and blood clots. 

Inflammation and Omega-3s


We know that long-chain omega-3s in fish oil seems to reduce inflammation. One disease marked by inflammation is rheumatoid arthritis. Some studies show long-chain omega-3s relieves the symptoms of rheumatoid arthritis and may even lower your risk for getting the disease, although it doesn’t slow the progression of the disease once it’s established.


In addition, fish oil shows promise for treating other inflammatory conditions such as inflammatory bowel disease. If you have arthritis or another inflammatory condition, you may benefit from taking a fish oil capsule.


Most of the time, people with arthritis take non-steroidal anti-inflammatory medications that have numerous side effects. Fish oils are a safer alternative. If you can get relief from fish oils without taking non-steroidals, take that route.


Combining fish oils with other supplements with anti-inflammatory activity like curcumin, the active ingredient in turmeric, and tart cherry may give you additional relief.


Conclusion 2: Omega-3s in fish oil have anti-inflammatory activity that may help some inflammatory diseases, including arthritis. 


What about Cancer?


Where fish oil shows the most promise from a cancer perspective is for breast cancer prevention. A number of studies show fish oil supplements reduce breast cancer risk by as much as 30%. Research also shows it may lower the risk of breast cancer recurrence.


Another common cancer that fish oils may lower the risk of is colon cancer. We should mention that one study in 2013 found men who had the highest levels of long-chain omega-3s in their bloodstream had a HIGHER risk for prostate cancer.


Although this study has been widely criticized, it’s something to keep in mind if you’re male. Here’s a link to an article we wrote on that study. Keep in mind that some research now shows omega-3s LOWER the risk of prostate cancer. 


Conclusion: Fish oil supplements may be more beneficial for women than men in terms of cancer prevention. 


Fish Oil - Salmon
Wild-caught salmon is high in protein, low in calories, and a good source of omega-3s.

Mental Health Benefits?


If you suffer from anxiety or depression, there’s evidence that the omega-3s in fish oil may help. In fact, research suggests long-chain omega-3s may help you better deal with stress, although exactly how it does this is unknown.


According to David Mischoulon, MD, PhD, director of research in the Depression Clinical and Research Program at Boston’s Massachusetts General Hospital, long-chain omega-3s are as active in the brain as antidepressants. In addition, low levels of omega-3s are linked with a higher risk of suicide.


Conclusion: Growing evidence suggests long-chain omega-3s are beneficial for depression and anxiety. 


Other Potential Health Benefits


One thing that happens as we age, among many, is we lose muscle mass. Just recently, a study showed healthy adults over the age of 60 who took fish oil supplements lost less muscle mass over time. That’s important! The main reason people become frail, fall, and fracture a hip is because they lose muscle mass.


  • If you don’t want to lose muscle mass, here’s your prescription:
  • Check your vitamin D level and make sure it stays in the normal range. Take supplements if necessary. 
  • Make sure you’re getting enough long-chain omega-3s in your diet.
  • Resistance train.


If you do these three things, you WILL lose less muscle as you age. If you still want to be fit enough to do the things you enjoy during retirement, there’s your blueprint.


Should You Take a Fish Oil Supplement?


We believe you SHOULD get long-chain omega-3s by eating fatty fish twice a week. Wild-caught salmon is your best bet, not farm-raised. If you buy wild salmon, levels of mercury and toxins are low enough that you can safely eat it twice weekly. Here’s an article on selecting salmon


If you don’t eat fatty fish at all and you’re female, we recommend taking a fish oil supplement as it may lower your risk for breast cancer. If you’re male, at this point, we recommend eating fatty fish and approaching fish oil supplements with caution until more information comes out about the prostate cancer connection.


Before taking a fish oil supplement, talk to your doctor. Omega-3s can interact with some medications. You also shouldn’t take it before surgery or if you’re undergoing chemotherapy.


Choosing a Fish Oil Supplement and How Much Fish Oil Do You Need?


When choosing fish oil supplement, you have to be concerned with how fresh the product is. The fats in fish oil are unstable and become rancid quite easily. Depending on how the fish oil is processed, it may be rancid, or oxidized, before it even reaches you.


Rancid fish oil produces free radicals that are potentially damaging to cells, tissues, and blood vessels. Plus, as you know, supplements aren’t highly regulated by the FDA, so you don’t know which supplements are oxidized and even if what’s in the capsule is pure fish oil. Some companies add fillers.


Plus, fish oil capsules are more highly concentrated than others. The concentration can be as high as 90% to as low as 10%. Prescription fish oil capsules have the highest concentration of fish oil, 80% and above.


That doesn’t mean you can’t get a high-quality fish oil capsule without a prescription. At the end of the article, we listed several fish oil supplements that have been independently tested and deliver a good combination of suitable concentration, free of contamination, and likely to be fresh.


How much fish oil do you need? If you’re taking 1,000 milligram capsules, most data suggest 2 capsules are enough to offer benefits. This assumes that the capsule you’re taking has a concentration of fish oil of at least 50%.


Other Tips


If you take fish oil capsules, take them with a meal to improve absorption. Also, store them in a dark, cool place to protect them from rancidity.


The other concern is contamination with toxins like heavy metals and substances called PCBs, linked with cancer. Fortunately, most fish oil supplements, because they come from smaller fish and the way they’re processed, don’t contain heavy metals or toxins.


Plant-Based Omega-3s


Wondering whether eating fish is the only way to get your omega-3s? Flaxseed, chia seeds, walnuts, and sesame seeds, and some types of algae have omega-3s that differ from those in fish oil. The omega-3s in fish oil are called long-chain fatty acids while those from plant-based sources have short chains.


The problem with short-chain omega-3s is your body has to convert them to the long-chain form to get the proposed benefits. Unfortunately, your body doesn’t make this conversion efficiently. In fact, less than 5% of the short-chain omega-3s you get from plant sources, like flax and chia, makes it into the long-chain form.


Not that short-chain omega-3s DON’T have health benefits, it’s just that the benefits are unproven. Still, chia seeds and flaxseeds have other health advantages. Chia is high in fiber and protein and flaxseed is rich in fiber and lignans. Enjoy them in your diet but don’t count on them as a dependable source of omega-3s.


The Bottom Line


If you can, get your omega-3s by eating wild-caught salmon. Eating it twice a week is enough to give you benefits. I’m hit or miss about eating salmon, so I take two 1,000 milligram fish oil capsules a day.


Dr. A gets his omega-3s by eating Mahi or salmon for lunch but also takes 1,000 milligrams of fish oil daily. 


If you take a fish oil supplement, here are some we recommend. We tried to choose ones that are reasonable in cost too:





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Ann Rheum Dis doi:10.1136/annrheumdis-2013-203338.
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Kristie Leong M.D.

Dr. Kristie Leong and Dr. Apollo Leong are physicians helping you to lead a healthy lifestyle by sharing nutrition and fitness tips and keeping you abreast of the latest health news.