It’s a question we get a lot: can you take fish oil on an empty stomach? That’s the topic we’re covering in this blog—and we think you’re going to like the answer to the question because it serves up some options.

Before we get into the why’s and the when’s, let’s talk about the what’s.


What is Fish Oil? 

Fish oil is a polyunsaturated fatty acid (PUFA) recommended by scientific experts and healthcare practitioners globally for a whole host of health benefits.

Fish oil is one source, arguably the best source, of omega-3 fatty acids. There are other ways to get omega-3s, but today we’re going to focus on fish oil. And to take it one step further, we’ll be talking about omega-3 EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), the two main and most important of the omega-3s. The third is ALA (alpha linolenic acid) but we won’t be talking about ALA today as it is found mainly in plant, not fish, oils.

Fish oil is derived from the oil or the oily tissue found in fatty fish, including salmon, tuna, halibut, sardines, anchovies, herring and others. Fatty fish is the richest source of fish oil and is often recommended as the best way to get your benefits from omega-3 EPA and DHA.

BLOG: Can Athletes Benefit from Taking More EPA and DHA?

Unfortunately, we know two things: 1) not enough people, especially Americans, are eating the recommended amount of fatty fish—for example, the American Heart Association calls for two (3-ounce) servings of fatty fish per week—and 2) most people are falling short of the amount of omega-3 EPA and DHA needed to reach sufficient or, better still, optimal blood levels of this important nutrient.

While we would like to see more people eat more fatty fish to get their blood levels into the range where omega-3 EPA and DHA can do the most good, from a realistic standpoint, fish oil supplements are a reasonable option to consider as a means to raise your Omega-3 Index, the test that measures your omega-3 EPA and DHA blood levels.


What are the Benefits of Fish Oil?

Though not quite as plentiful as the number of fish in the sea, the benefits from fish oil are varied and extensive.

For example, the omega-3 EPA and DHA help reduce inflammation, making fish oil a strong heart health contender (especially for helping lower cholesterol, reduce blood pressure and prevent hardening of the arteries) and a potential way to lessen the symptoms of joint pain and rheumatoid arthritis.

There are numerous reasons for moms-to-be to get omega-3 EPA and DHA, both for herself and for the developing fetus. Some research suggests that fish oil during pregnancy may reduce the risk of pre-term and early pre-term birth or low birth weight.

BLOG: Does Taking a Supplement Increase DHA Concentrations in Breast Milk?

Omega-3 EPA and DHA are also crucial for a baby from the time of conception to age two, as this is considered a key time for brain growth and development of the eyes, and immune and nervous systems and studies have shown that these nutrients are vital in these areas.

Other research has found positive (but not conclusive) results for fish oil in the areas of brain function and mood support, helping reduce the risk of age-related macular degeneration, potential improvement for sports performance and muscle recovery.

And if you haven’t already guessed, omega-3 EPA and DHA are among the most studied nutrients. Read more here, here and here.


Can Fish Oil Upset Your Stomach?

Now we’re getting to the meat of this blog.

Yes, for some people, fish can cause an upset stomach, but generally that’s because your fish has gone bad or was improperly handled, in other words, you’ve suffered from fish poisoning.

But more commonly, the concern about stomach upset is from fish oil supplements. If you’re taking too much fish oil, you may end up with diarrhea or acid reflux or heartburn. One possible solution is to lower the amount you’re taking. (But before doing that, consider a simple, at-home blood test to determine whether your EPA and DHA blood levels are actually too high.)

BLOG: Omega-3 and Omega-6 Foods

You might be taking an amount that’s perfectly suitable for you—and that will be determined too by the O3I test. If you are in the right range, be aware that there are other common reasons why you’re experiencing an upset tummy, nausea, or burping from your fish oil supplement.

And the good news is there may be some simple solutions.

Some vitamins are water soluble while others are fat soluble. Fatty acids, like fish oil, fall into the category of fat soluble, which simply means you should be taking them with food, preferably a meal or a snack that contains some “good” fat of its own.

We’re not talking potato chips here, but rather a monosaturated fat (e.g., nuts such as almonds and pecans, avocados or olive or peanut oil) or another polyunsaturated fat (e.g., walnuts, flax seeds, sunflower or corn oil, and yes, it’s fine to eat fish with your fish oil supplement).

While we suggest avoiding trans fats (e.g., frozen pizza, fried foods, some cakes and pies), it’s okay to eat foods with saturated fat, in moderation (e.g., some cheese—we said “some!” or whole milk, coconut or palm oil, butter).

And just because omega-3 fish oil supplements aren’t water soluble vitamins, like B and C, if you’re taking your fish oil supplement in a form where you swallow (e.g., soft gels, capsules), you should swallow them with water. If instead, you take a fish oil supplement which you chew before you swallow (e.g., gummy or gel bites), the water is up to you.

VIDEO: Make Sure You Take Your Omega-3 Supplements with a Meal


Are Some Fish Oil Forms Better Absorbed Than Others?

There’s another reason that experts recommend taking your fish oil supplements along with a (healthy) meal or snack and that’s because some research has shown that doing so increases bioavailability, meaning that your body will better absorb the fish oil and the nutrients (i.e., EPA and DHA) within. You want better absorption, so that you can access the benefits of the dose you’re taking.

Some forms of fish oil supplements appear to be better absorbed than others. As this article explains, there are both natural and processed fish oil supplements and the manufacturing process can make a difference in the form, and therefore in the absorbability factor.

  • Natural fish oil—the oil is sourced from the tissues of oily fish, mostly in the form of triglycerides. Then these oils are capsuled or made available in liquid form. In addition to omega-3 EPA and DHA, these supplements frequently contain vitamins A and D. Free fatty acids (FFA) are found in whole fish, and natural fish oil is probably as close as you can come to fish in supplement form. And they are highly absorbable.


  • Processed fish oil—the lower price and capsule delivery method makes these the most common fish oil supplements in the market. With processed fish oil, the oil is purified and/or concentrated. The purification process eliminates some contaminants, such as mercury and PCBs. It may also increase the EPA and DHA levels. Processed fish oil is available in these forms:


  • Ethyl esters or triglycerides, with the former possibly more prone to problems like rancidity or oxidation than the latter. Some research also shows that ethyl esters are not as bioavailable as the other forms, including triglycerides.However, this post makes for an interesting read if you’re trying to decide between an ethyl ester or a triglyceride. It suggests that after reviewing the scientific literature in terms of bioavailability, safety or efficacy, that the differences are minor and cannot be considered to be significantly different.


  • Reformed or re-esterified triglycerides. In this case, the oil is processed even further so it transforms into a synthetic triglyceride form. Reformed triglycerides are said to be better absorbed than ethyl esters. They also represent a small percentage of the fish oil supplement market and are considered to be among the most expensive option.

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


Tips for Taking Fish Oil

While some supplements are best taken in the morning (and others at night), there’s no real rule for when to take your fish oil supplements.

 As much as science shows that taking your fish oil supplements accompanied by a low-fat snack or a low-fat meal will help with absorption and also counter any temporary gastrointestinal issues associated with the supplement, taking your fish oil supplement at mealtime may not be an option for everyone.

In other words, the best schedule for taking all (and some people take a lot) of their medications and supplements is an individual thing, best worked out on an individual basis, preferably with your healthcare practitioner.

As it turns out, some people end up taking their fish oil supplements before bedtime for any number of reasons. In that case, you’re probably not eating a meal or a snack just before you get into bed? (And certainly not after you’ve brushed your teeth.)

BLOG: How to Tell if Fish Oil Capsules are Rancid

So, we say if you’re not having a gastro-related reaction to your fish oil supplements, and it works better for you to take them just before your head hits the pillow, it may be okay to take them without food. However, you’ll want to test your Omega-3 Index to ensure that your body is properly absorbing the omega-3s.

Here are few other tips related to fish oil supplements and avoiding gastro-intestinal discomfort:

  1. There’s no right or wrong time of day to take your supplements. If your dose includes more than one capsule, ask your doctor or registered dietitian (RD) if it makes sense to split your dose (not your capsules!). In other words, instead of taking your capsules at the same time, take one serving at one meal and the other at another meal. In that case, try to have a low-fat meal or low-fat snack accompany both doses, for instance, taking one capsule with breakfast or lunch, and the other with dinner. This may help reduce any stomach-related issues.
  2. Brand matters. Not all fish oil supplements are created equal. Some are more expensive for a good reason. Quite simply, it may cost more to make a higher quality product, in part because the company may invest more money and extra care to help ensure stricter standards and a better processing method. If that’s the case, it may be worth spending a little more. And especially, if you’re experiencing gastro discomfort, you might want to switch fish oil supplement brands.
  3. There are so many fish oil supplement brands on the market. Do your research to better understand the differences. Your doctor or registered dietitian may have a recommendation. You also may want to check the list of members on the Global Organization for EPA and DHA Omega-3s (GOED) website as member companies commit to the trade association’s strict omega-3 quality and ethics standards.

Bottom line: Take your fish oil supplements with a low-fat snack or a low-fat meal if you can. If you can’t, don’t sweat it. In either case, testing to determine your blood levels of omega-3 EPA and DHA tells you whether your fish oil is being absorbed or not. This is the best way to know if you actually need a fish oil supplement, or a different dose of a fish oil supplement. Involve your healthcare practitioner in the process. And if you have stomach distress that doesn’t go away or gets worse, see your doctor for advice.

VIDEo: Tips for Choosing an Omega-3 Supplement

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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