Fish Oil versus Krill Oil: Is One Better Than the Other?


fish oil vs krill oil


Fish oil versus krill oil – which is the better choice? By now, you’ve probably heard about the importance of eating fish. Fatty fish like wild salmon is an excellent source of heart-healthy fats called omega-3s that have anti-inflammatory properties.


Those anti-inflammatory benefits may lower the risk for heart disease and stroke, although more research is still needed since a recent study didn’t show the same benefits as previous studies.

Still, many experts believe that research will ultimately show the heart health benefits of omega-3s and, possibly, other benefits as well. There’s even some evidence that omega-3s positively impact mood and can help people who suffer from depression.


If you want to add more omega-3s to your diet and you don’t like the taste of fish, you may have considered taking a fish oil supplement. Fish oil supplements offer a way to get omega-3s without the fishy taste – but that’s not your only option these days.


There’s another source of omega-3s that’s growing in popularity – krill oil. Krill oil is available online and in many health food stores. It is more expensive than fish oil supplements – but is the extra expense worth it?


How Krill Oil and Fish Oil Differ


Fish oil and krill oil are both a source of long-chain omega-3 fatty acids, healthy fats that have anti-inflammatory benefits. The two long-chain fatty acids that studies have focused on are DHA and EPA.


You may have also read about short-chain omega-3 fatty acids called alpha-linolenic-acid or ALA in sources like walnuts, flaxseed and sesame seeds. Although these may have some benefits, it’s not clear whether they have the SAME health benefits as long-chain omega-3s in fatty fish, krill oil and fish oil.


Plus, your body can only convert a small percentage of the ALA you get from foods like walnuts and flaxseed into long-chain omega-3s, so you ’re better off getting omega-3s from marine sources like fish, fish oil or krill oil.


The Pros and Cons of Krill Oil


Unlike fish oil that comes from fatty fish, krill oil comes from a small crustacean that lives at the bottom of the ocean and feeds on phytoplankton. Since krill are so small and low on the food chain they don’t accumulate mercury and toxins like larger fish do.


That’s certainly a benefit, but mercury and toxin contamination usually isn’t a problem with fish oil supplements as long as you buy them from a reputable manufacturer. That’s because the omega-3s in fish oil comes from smaller fish that are less likely to accumulate mercury.


Plus, most reputable brands are molecularly distilled to remove any mercury or toxins. Neither krill oil nor fish oil should contain significant levels of toxins.


Krill oil does have something fish oil supplements don’t. It’s a source for a compound called astaxanthin. This antioxidant may offer additional benefits due to its ability to fight free-radical damage to cells. Plus, it can cross the blood-brain barrier and may have benefits for brain and eye health.


Should you buy krill oil for this added feature? Probably not since you can get the same benefits by eating more fruits and vegetables.


Another argument for taking fish oil over krill oil is that krill oil capsules are typically a less concentrated source of omega-3s, meaning you have to take more to get the same amount of omega-3s as you’d get from a fish oil supplement. It’s also not clear whether krill oil is absorbed as well as fish oil supplements.


Some studies show it’s BETTER absorbed while others show fish oil is better absorbed. Based on this, there probably isn’t a huge difference between the two in terms of absorption.


Another thing to consider is most of the studies showing the benefits of omega-3s have used fish oil not krill oil. It’s likely that krill oil has similar benefits since it contains long-chain omega-3s, but studies using it are fewer.


The few studies that have been done have shown benefits like a reduction in LDL-cholesterol, improvement in pre-menstrual syndrome symptoms and improvement in arthritis symptoms, but these studies were sponsored by makers of krill oil. That raises questions about their credibility.


Fish Oil versus Krill Oil: The Bottom Line?


Should you rush out and buy krill oil? I would hold off on switching to krill oil until there are more studies supporting its benefits. Fish oil is less expensive, but always confirm that the brand you buy uses molecular distillation to remove impurities.


If you like the taste of fish, we usually recommend getting long-chain omega-3s from sources like wild salmon rather than a supplement. Fish is a good source of protein and low in calories so it’s a good choice for the dinner table.


It’s best to get your nutrients from dietary sources rather than supplements whenever possible since whole foods have nutrients that work together as a “team” for maximal benefits. But if you don’t like the taste of fish, fish or krill oil supplements are an alternative.


Based on price and current research, stick with a quality fish oil supplement until more data on krill oil comes out. Save the extra pennies and dollars to buy more fruits and vegetables.



Medscape Family Medicine. “How Does Krill Oil Compare With Fish Oil?”
Today’s Dietician. Vol. 14, No. 1, page 22.
Consumer Reports. “Krill Oil versus Fish Oil Supplements”

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.

2 thoughts to “Fish Oil versus Krill Oil: Is One Better Than the Other?”

  1. How many times a week can I eat sardines? I love them. And also what type of salmon is lowest in mercury? Thank you,

    1. Jeff, sardines, being small fish, are quite low in mercury. It’s a fish that you can safely eat every day. Salmon is also a fish relatively low in mercury. Wild-caught salmon is usually a little higher in mercury, but I would still choose it over farm-raised salmon. Farm-raised salmon has higher levels of other impurities like PCBs and dioxins. It’s harder to find wild-caught salmon, but canned salmon is usually wild. Check to make sure on the label. Hope this helps. 🙂

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