In the immortal words of everyone from Fargo, the answer to that question is “you betcha.” However, that’s only because there can be side effects to everything in life from breathing to not breathing and everything in between.

So, before you get the least bit worried, be aware that when it comes to omega-3 fish oil, whether you’re getting them from fatty fish or dietary supplements, are generally safe. Not to mention they come with a lot of potential health benefits.

BLOG: Can You Take Fish Oil on an Empty Stomach?

Having said that, it’s important that you make informed decisions about your  own health, including omega-3s. In this blog, we’re going to address the kinds of mostly mild side effects that could occur from omega-3s. And we’ll be focusing on specific types of omega-3s, namely eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). We won’t be sharing much information today about the third main type of omega-3—alpha-linolenic acid (ALA), because even though your body converts ALA to EPA and DHA, as it’s not an efficient process.


Why Do You Need Omega-3 EPA and DHA?

Omega-3s are polyunsaturated fats (PUFAs) known for their work in fighting inflammation, helping to lower blood pressure and very high triglycerides, and taking part in other heart-related work. In addition, omega-3s may help reduce the risk of dry eye, lubricate your joints, brighten your mood, improve your focus and cognitive function, aid in muscle recovery and sports performance, and support immune function and your nervous system. And the benefits begin early, with omega-3 EPA and DHA playing a vital role for infants’ health, starting in vitro with brain growth and vision development.

Now to be fair, while there is an extensive (seriously extensive—over 40,000 published studies on omega-3 EPA and DHA) body of research that supports benefit in many of these areas and others, not all the research shows consistent benefit and some is still emerging. That’s the nature of scientific research.

In the meantime, there’s enough strong evidence to consider obtaining these important nutrients from food (like fatty fish) and/or from dietary supplements. To help you figure out if you’re getting the right amount, test your omega-3 EPA and DHA blood levels. In other words, are your blood levels of this important nutritional combo optimal or sufficient or, sadly, insufficient or deficient? (Keep reading.)


Where Do Omega-3s Come From?

You can get omega-3 EPA and DHA from food, in dietary supplements and in some fortified foods.

Let’s take the food first: the richest source of EPA and DHA is found in fatty fish, specifically in the oil or oily tissue. We’re talking about salmon, mackerel (these tasty, tiny fish pack a wallop of the good stuff!), herring, sardines, anchovies, caviar (yes, please!), halibut, tuna and trout—just to name a few. In addition to oysters, you’ll find lesser amounts of omega-3 EPA and DHA in these shellfish: mussels, squid, crab and shrimp.

BLOG: Do All Fish Have Omega-3?

As for fortified foods, the options aren’t as many and you’ll need to check the label to confirm whether the food is fortified with omega-3 EPA and DHA, just DHA or a different type of omega-3. Most often, if a food—like orange juice, milk, cereal, pasta and margarine—is fortified with omega-3s, those nutrients will be from omega-3 ALA, the plant-based source favored by vegetarians and vegans.

As an aside, there’s also omega-3 EPA and DHA in prescription formulations for which you’ll need a doctor’s order and a reason to take the high doses found in that medication. We’re not addressing fish oil prescription medication in today’s blog.

On the other hand, dietary supplements are a popular, widely used option for getting omega-3s EPA and DHA, in part because not everyone likes the taste of fish. In fact, most people, especially in the U.S., are not getting enough omega-3s from diet alone, making the addition of supplements an acceptable—and mainstream—option.

One advantage of getting your EPA and DHA from supplements is it’s easy to keep track of how much you’re getting in a serving size—as it’s right on the label.

But regardless of where you get your omega-3 EPA and DHA, the only way to know if you’re actually getting enough is to check your blood levels. At OmegaQuant, we offer a simple, easy to use, at-home finger prick test to determine if your omega-3 EPA and DHA blood levels are in what we like to call “the goldilocks range”—not too little, not too much, but just right.


What are the Different Forms of Omega-3 EPA and DHA?

Some forms of fish oil supplements appear to be better absorbed than others. The manufacturing process can make a difference in the form, and therefore in the absorbability factor. Thus, it’s interesting to look at the options.

In actual fish, omega-3 fatty acids are present as free fatty acids (FFA), phospholipids, and triglycerides, according to this piece.

When it comes to dietary supplements, the omega-3 EPA and DHA form that comes closest to whole fish is natural fish oil which presents in the form of triglycerides. Sourcing the oil from the tissues of fatty fish, the oils are capsuled or sold as a liquid. Triglycerides, also used in conventional fish oil supplements, are generally well-absorbed.

BLOG: Omega-3 and Omega-6 Foods

A more expensive option is reformed, also known as re-esterified, triglycerides, whereby the oil is processed even further, resulting in a synthetic triglyceride form of omega-3 EPA and DHA supplements that is highly absorbable and among the most expensive option of fish oil supplements.

Ethyl esters is another form of processed fish oil commonly found in fish oil supplements, and like its triglyceride cousins, this form is purified and/or concentrated, helping to eliminate some of the contaminants found in fish, including mercury and PCBs.

On the other hand, ethyl esters appear to be more susceptible to issues such as rancidity or oxidation when compared to the triglyceride form. And some research shows that ethyl esters are not as highly absorbed as the triglyceride form (especially reformed triglycerides).

However, the jury is not yet out on bioavailability comparisons showing ethyl esters fall short. This article says that the scientific literature shows the absorbability differences between ethyl esters and triglycerides are not significantly different.

You may have heard about phospholipids, another form of long-chain omega-3 PUFAs. Phospholipids can come from vegetable sources or marine sources. In actuality, marine phospholipids are not a fish oil form, but rather an alternative to fish oil known as krill oil. So that’s a discussion for another time.


What are Some of the Side Effects of Omega-3?

While you can have serious side effects from omega-3s found in fish, for example, too much mercury or other contaminants or food poisoning in general, or maybe choking on a fish bone. Likewise, with dietary supplements, you can have serious consequences from fish oil supplements with choking hazards, rancid fish oil, or purchasing from companies selling supplements but ignoring the legal regulations that require execution of good manufacturing practices (GMPs) that help protect consumers from safety issues.

And if you have a fish allergy, both fish and fish oil supplements can result in a serious problem.

By and large, though, the side effects we’ll focus on today are more likely found from taking fish oil supplements—possibly in higher doses than recommended. While some of these side effects can be of concern (and we’ll address those), even the government’s National Institutes for Health’s National Center for Complementary and Integrative Health (NCCIH) says that when it comes to the safety of omega-3 supplements, “omega-3s usually produce only mild side effects, if any.”

VIDEO: Making Sense of the Different Omega-3 Forms in Supplements


Potential Mild to Moderate Side Effects, and a Few More Severe

Here are some of the mild to moderate side effects that you may experience when taking fish oil supplements, ranging from mild to moderate to potentially severe:

  • Bad taste/bad breath
  • Burping
  • Diarrhea
  • Nausea
  • Heartburn
  • Rash
  • Blood Pressure Reaction
  • Bleeding Gums or Bloody Nose
  • Blood Not Properly Clotting
  • Allergic Reaction


What to Do if You Experience Side Effects?

The mild side effects associated with fish oil supplements can often be lessened, or eliminated, by making some modifications to your fish oil supplement regimen. For example, if the fishy smell bothers you or those close to you, look for a supplement that is odorless, coated and/or adds a flavor, like peppermint.

Lowering your dose or splitting up the servings (e.g., if two capsules make up the serving size, try taking them at separate times) may just work for you. Did you know that switching up the time of day could also be helpful? Some people find that taking their omega-3 supplements just before bedtime helps lessen tummy issues like nausea, or maybe you’re just sleeping through them.

Here’s one suggestion that may help with gastrointestinal concerns and also with  bioavailability. Take your fish supplements with a healthy snack or meal that also includes some of the “good” fats. Like an avocado or a handful of nuts or a salad with an olive-oil based dressing—you get the picture, yes? Omega-3s are fat soluble, meaning that in addition to taking with water, in an ideal world, they should also be taken along with some other “good” fat.

Switching your brand, even moving to one that serves up a different form of omega-3 EPA and DHA, may make the difference.

If your mild side effects don’t go away and are bothersome, talk to your doctor. It could be the fish oil, but it could be something else.

BLOG: Can You take Fish Oil Instead of Eliquis?

For more serious concerns such as an unwanted change in blood pressure, abnormal bleeding, blood not properly clotting, or an allergic reaction (e.g., trouble breathing, swallowing or talking; swelling in your tongue, throat, mouth, lips or face; tightness in your chest or throat, rash or hives) talk with your healthcare practitioner right away.

Since some of these serious reactions could be related to adverse interactions between fish oil and certain prescription medications, let your doctor or pharmacist know about all your medications, over-the-counter products, and even other dietary supplements you are taking. That’s always a good idea to do with all things you take orally.

Here are some examples of medications—and certain conditions—that could be problematic. As fish oil could have a blood thinning effect, if you’re already taking a blood-thinner prescription medication the combination could potentially increase the risk of bleeding. Because fish oil could help (slightly) reduce blood pressure, if you’re already on a blood pressure medication, be aware that the combination might result in blood pressure that is too low. Taking fish oil supplements could increase some symptoms of bipolar disorder; and high doses of fish oil could mess with controlling your blood sugar levels if you have diabetes. Read more here.


Bottom line: Omega-3 EPA and DHA offer numerous benefits from fish and from fish oil supplements. Omega-3 EPA and DHA supplements not only offer health benefits, they have a wide margin of safety. Choose your brand carefully. Remember to ask your doctor or pharmacist if you are taking anything else that could cause problematic interactions with fish oil supplements. If you have an allergy to fish or shell fish, then not only fish but also fish oil supplements are probably not for you.

Finally, the best way to determine whether you could be benefitting from fish oil is to start by knowing your numbers. Test your blood levels either through a doctor’s order for an in-lab test or through an at-home self-test of your omega-3 EPA and DHA blood levels. Once you know your baseline numbers, test on a regular basis to make sure you remain in that ideal “goldilocks” level. Learn more about self-testing here.

These statements have not been evaluated by the Food and Drug Administration. This test is not intended to diagnose, treat, cure, prevent or mitigate any disease. This site does not offer medical advice, and nothing contained herein is intended to establish a doctor/patient relationship. OmegaQuant, LLC is regulated under the Clinical Laboratory improvement Amendments of 1988 (CLIA) and is qualified to perform high complexity clinical testing. The performance characteristics of this test were determined by OmegaQuant, LLC. It has not been cleared or approved by the U.S. Food and Drug Administration.

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