Omega-3 for Men: Fish Oil, Krill Oil and What Heart Research Shows

Fish Oil vs. Krill Oil for Heart Health: The Short Answer

Both fish oil and krill oil supply the same two heart-relevant omega-3s: EPA and DHA. The National Institutes of Health (NIH) Office of Dietary Supplements does not show one source working better than the other for heart health. What the research does show clearly is that eating fatty fish, and getting enough EPA and DHA overall, supports cardiovascular health more consistently than the specific supplement source you choose.

If you eat fatty fish once or twice a week, you may already be close to the American Heart Association’s (AHA) target. If you don’t, a supplement is one option, but it’s not automatically the better one.

Chest Pain or Heart Attack Symptoms: Don’t Wait for a Supplement to Help

No omega-3 product treats a heart attack or replaces emergency care. If you or someone near you has chest pain or pressure, shortness of breath, pain spreading to the arm or jaw, cold sweat, or sudden dizziness, call 911. Sort out supplements later.

What Omega-3 Fatty Acids Actually Are

Omega-3s are a family of fats your body needs for normal cell function. The three main types are ALA, EPA, and DHA. ALA comes mostly from plant oils like flaxseed, soybean, and canola. EPA and DHA come from fish and seafood.

Your body can turn a small amount of ALA into EPA and DHA, but the conversion rate is very low. That means eating fish, or taking a supplement that already contains EPA and DHA, is the more direct way to raise your levels of these two.

Omega-3s become part of the membrane surrounding every cell in your body, including cells in your heart and blood vessels.

What the Heart Research Shows

According to the NIH, eating fatty fish and other seafood as part of a healthy eating pattern is linked to a healthier heart and a lower risk of some heart problems. Getting more EPA and DHA, whether from food or supplements, has been shown to lower triglyceride levels.

The AHA recommends eating one to two servings of seafood a week to help lower the risk of some heart problems, especially when that seafood replaces less healthy food choices. For people who already have heart disease, the AHA points to about 1 gram per day of combined EPA and DHA, ideally from oily fish, with supplements used only under a health care provider’s guidance. The AHA does not recommend omega-3 supplements for people who are not at high cardiovascular risk.

A serving, per the AHA, is about 3 ounces cooked, or roughly ¾ cup of flaked fish. Fatty fish with the most omega-3s include salmon, mackerel, herring, sardines, and anchovies.

Evidence Limits Worth Knowing

Much of the heart-health link comes from studies of people who eat fish regularly, not from supplement trials alone. The NIH notes it isn’t always clear whether the benefit comes from the omega-3s themselves or from other parts of a fish-based diet.
The AHA’s supplement guidance is aimed at people already diagnosed with heart disease or at high risk, not the general population.
Neither official source reviewed for this article claims that a fish oil or krill oil supplement can prevent, treat, or cure heart disease.

Fish Oil vs. Krill Oil: How the Two Compare

The NIH lists fish oil, krill oil, cod liver oil, and algal oil as the main types of omega-3 supplements. All of them provide varying doses and forms of omega-3s. Here’s how fish oil and krill oil compare on what’s actually documented:

Fish Oil

Source: oily fish such as salmon, sardines, anchovies, and mackerel
Omega-3s provided: EPA and DHA
Amounts per serving vary widely by brand, so check the supplement facts panel rather than assuming
The most studied form in the cardiovascular research the NIH and AHA cite

Krill Oil

Source: krill, a small shrimp-like crustacean
Omega-3s provided: EPA and DHA
Amounts per serving also vary by brand — compare the label, not the marketing
Sometimes marketed as more absorbable due to its phospholipid structure. This is a manufacturer claim, not a comparison the NIH or AHA fact sheets make, and the evidence on absorption differences between krill and fish oil is limited and mixed

Bottom line: choose based on the total EPA plus DHA per serving on the label and how well you tolerate the product, not the marketing story attached to the source.

A Simple Checklist Before You Choose a Product

Check the label for total combined EPA plus DHA per serving, not just the total “fish oil” or “krill oil” weight.
Compare that number to the amount you’re already getting from fish in your diet.
If you have heart disease, ask your doctor what daily EPA and DHA target makes sense for you, rather than guessing.
If you take a blood thinner such as warfarin, talk to your doctor before starting any omega-3 supplement.
Decide between food and supplements based on how often you actually eat fatty fish, not on which supplement looks more advanced.

Extra Caution: Who Should Talk to a Doctor First

The NIH notes that omega-3 supplements can interact with medications you take. High doses in particular may increase bleeding risk when combined with warfarin or other blood-thinning medicines. Talk with your health care provider about your medications before starting any omega-3 supplement, and definitely before taking more than a standard consumer dose.

The FDA-referenced limit the NIH cites is no more than 5 grams per day of combined EPA and DHA from dietary supplements.

Frequently Asked Questions

Is fish oil or krill oil better for heart health?

Neither the NIH nor the AHA singles out one source as better for the heart. Both provide EPA and DHA. What matters more, based on their guidance, is the total EPA and DHA you get, how consistently you take it, and whether you have a diagnosed heart condition that changes your target.

How much omega-3 do I need for heart health?

The NIH has not set an official recommended amount for EPA and DHA specifically. The AHA suggests one to two servings of seafood a week for general heart health, and about 1 gram per day of combined EPA and DHA, under a doctor’s guidance, for people who already have heart disease.

Can I just eat fish instead of taking a supplement?

Yes, according to both sources. The AHA’s core recommendation is built around eating fatty fish, not taking a pill. Two servings of fatty fish a week can get you into a similar range as many supplement doses, and food sources come with other nutrients supplements don’t provide.

Are there risks to taking omega-3 supplements?

The NIH lists mild side effects like an unpleasant taste, bad breath, heartburn, nausea, and stomach upset. The more serious concern is a possible interaction with blood-thinning medications at higher doses. Anyone on a blood thinner, or with a heart condition, should check with a doctor before starting a supplement or increasing their dose.