Krill oil is a substitute for fish oil that has been shown to reduce stress, lower cholesterol and improve depression. Krill are small crustaceans that you will find in the waters around the antarctic. They feed on phytoplankton and swim in large schools of 30,000 (1).
Krill oil is specifically extracted from a species of antarctic krill called euphausia superba. Krill oil is very similar to fish oil in that it is high in omega-3 fatty acids, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).
The main difference between the two is that krill oil contains high levels of choline while regular fish oil does not (2).
Krill oil is also better at being absorbed by the body (has higher bioavailability) which means that you can use a lower dose compared to fish oil while getting the same results. But other than that, a lot of the benefits of krill oil are going to be identical to those of omega-3 fish oil, so we will use the two interchangeably throughout this article.
One of the biggest factors in the effectiveness of krill oil is your current diet. A healthy diet requires a balance of omega-6 and omega-3 fatty acids. You can find omega-6 in meat, dairy, nuts, cereals, and many vegetable oils, because of this omega-6 is often high in most diets (even relatively poor diets). Omega-3 on the other hand is only available in fish, flax seeds, hemp, and in red meat (but it is negligible).
Because of this most people tend to have a lot of omega-6 fatty acids in their diet, while having relatively low omega-3 fatty acids. This can be addressed by adding more omega-3 rich foods.
If you are in a country with a high fish diet (Japan, Italy, Sweden are all examples) then you are probably getting enough already, but in other countries it can be quite expensive to purchase the right type of fish. Also, you’d have to drastically alter your diet to accommodate the huge increase in oily fish.
Because of this omega-3 supplements are very popular, cod liver oil has been around for decades, and fish oil is also common (in fact, a lot of the time fish oil and cod liver oil are the same product just with different names). Krill oil is not nearly as common, but this has changed in recent years.
Krill oil can help to reduce stress and ease premenstrual syndrome. A 2003 study looked at the effect of krill oil on premenstrual syndrome management (3).
The study had 70 volunteers, split into two groups. One group took 2g of krill oil daily (in two 1g doses) eight days before their menstrual cycle, the other group did the exact same thing but using fish oil. The study found a significant between group difference, with krill oil being more effective at reducing stress.
Interestingly enough, a different study that just looked at fish oil, found that it was able to reduce stress in overweight women who were 30-44 years old (4).
This demonstrates that while krill oil is more effective than fish oil (according to the 2003 study), both are capable of reducing stress.
The 2003 study was primarily based on premenstrual syndrome, and it seems to indicate that krill oil may be useful as a way to reduce the symptoms. Breast tenderness was reduced, stress (as mentioned) and irritability were also lowered.
Krill oil may help reduce c-reactive protein levels. A 2007 study in the Journal of the American College of Nutrition found that taking krill oil for 30 days led to a slight reduction in c-reactive protein levels in people suffering from rheumatoid arthritis (5).
C-reactive protein is a plasma protein that is produced in the liver (6).
It rises in response to inflammation, and often it is seen as a marker for inflammation-related conditions such as cancer or cardiovascular disease (7).
It’s not just krill oil that appears to have an effect on c-reactive protein levels though, fish oil may also have an effect, though there are more studies that didn’t find a link then there are ones that did (8, 9, 10, 11).
Even krill oil has had mixed results, so far the study we mentioned above is the only one that saw a difference (though the difference was significant) and that was only in people with rheumatoid arthritis.
Another study, this time on 115 healthy volunteers, failed to find any significant difference in c-reactive protein levels after 1-6 months (12).
It might just be the case that krill oil reduces inflammation in people with arthritis and similar joint issues, which in turn reduces c-reactive protein levels.
Krill oil can have a huge effect on cholesterol levels. Cholesterol can be split up into two types; high density lipoprotein (HDL) and low density lipoprotein (LDL) cholesterol, also known as “good cholesterol” and “bad cholesterol”, combined together they make your total cholesterol levels. Increasing your HDL levels can help to lower your LDL cholesterols, because one of the main functions of HDL cholesterol is to clear LDL from your artery walls.
Therefore increasing HDL will help to lower LDL levels. This may reduce total cholesterol levels, but provided you are increasing good cholesterol and lowering bad cholesterol it doesn’t matter so much if your total cholesterol levels change.
A 2004 study found that 1-3g of krill oil per day for a period of 1-6 months led to significant reductions in total cholesterol, LDL cholesterol, and triglycerides. HDL cholesterol was also increased (13).
The study also claimed that krill oil was much more effective than regular fish oil. Which has also been found to increase HDL cholesterol reduce LDL cholesterol, and also reduce total cholesterol (14, 15, 16.)
The fact that krill oil is more effective than fish oil is probably just down to it having a higher bioavailability.
Krill oil can help reduce the symptoms of depression. Depression has been linked with inflammation and increases in c-reactive protein in some studies (17).
So it is perhaps no surprise that fish oils have been shown to reduce the symptoms of depression. Krill oil hasn’t specifically been linked, but that is most likely down to a lack of studies. But there are many studies that link fish oil, so it is fair to assume that krill oil will produce the exact same results.
A 2011 study found that omega-3 fatty acids were an effective treatment for depression (18).
Another study in 2002 noticed a significant effect of omega-3 fatty acids on recurrent unipolar depressive disorder (19).
Of course depression has been linked with high cortisol levels due to stress (20).
As we have already discussed, fish oil and krill oil have been linked with reduced stress, and there are many studies linking fish oil to reduced cortisol (21).
Krill oil may help improve birth weight and reduce preterm birth incidence. Taking fish oil while pregnant seems to have a few benefits, though more evidence is definitely needed before we can say for certain.
An article in 2011 stated that omega-3 fatty acids can “increase gestation length and improve infant cognitive and visual performance” (22).
He went on to state that “adequate levels of omega-3 fatty acids have also been shown to reduce the incidence of preterm birth in some populations”.
Krill oil can help to reduce blood pressure in people with high blood pressure. High blood pressure, also known as hypertension is a serious medical condition which can lead to heart disease, strokes, and heart failure (to name a few).
The evidence of fish oil reducing high blood pressure is mixed. We’ve already looked at the effect of krill oil on total cholesterol and LDL cholesterol levels. Reducing cholesterol is one way of reducing hypertension, so there is definitely a connection.
One study found that 2.5g of fish oil per day for six weeks led to a reduction in triglycerides and in blood pressure (23).
A meta-analysis in 2013 found that there was a significant reduction in blood pressure seen in people who were hypertensive (24).
The study also found that there was a small (non-significant) reduction in blood pressure in regular healthy people.
A 2012 study gave either fish oil or a soya product to women with metabolic syndrome over a 90-day period. The study found that there was a statistically significant drop in diastolic blood pressure (25).
Krill oil may reduce inattention and hyperactivity in children with ADHD. Attention deficit hyperactivity disorder (ADHD) may be improved by omega-3 fatty acids. A 2003 study found that 4 months of omega-3 fatty acid supplementation led to a reduction in hyperactivity and disruptive behaviorr in children with hyperactivity disorder (26).
Another study published found that dietary omega-3 supplementation (using margarine with added omega-3) in boys with ADHD and boys without ADHD led to an improved score in the child behavior checklist (CBCL) (27).
The study also found that boys with ADHD had slightly improved attention.
This study has some funding issues however. It was bankrolled by Unilever, a well known consumer goods company that happens to sell margarine as one of its products. That does not mean that the results are worthless though, particularly when you consider that other studies like the one we mentioned earlier found similar results. But it should definitely be mentioned.
Krill oil may help reduce joint pain. We’ve already covered this somewhat by talking about the effect that krill oil has on inflammation and c-reactive protein. But it is important to distinguish this as omega-3 supplements are often taken for joint health.
A meta analysis on omega-3 supplements and the effect they have on inflammatory joint pain was completed in 2007 (28). It found that omega-3 supplements “are an attractive adjunctive treatment for joint pain associated with rheumatoid arthritis”.
There aren’t any real side effects to taking krill oil, but there are a couple of things to look out for. Firstly, there is a tiny risk of mercury being present. A lot of fish that are high in omega-3 fatty acids are also high in mercury (29).
Which sounds scary until you realize that this correlation is mostly noticeable in shark and whale, not in krill (30).
Also, many of the dangers of high levels of mercury are protected against by omega-3’s such as heart disease.
Something that you should consider is whether you have a seafood allergy or not, because this is something that people forget about when it comes to krill oil. It’s not a definite that if you have a seafood allergy you will have an allergic reaction to krill oil, but it is a possibility. This is also something to consider if you avoid seafood for moral or religious reasons.
Since krill oil can slow blood clotting it should be avoided for two weeks after surgery (31).
But as with most advice given by webmd, it is usually being overly cautious. The likelihood of you having any issues with 2g of krill oil a day is probably microscopic, but perhaps not worth the risk.
According to examine.com the correct dosage for krill oil is around 1-3g per day (32).
As we have seen in the studies we have looked at in this article, most use around 2g per day taken in two doses of 1g. Remember that krill oil has a higher absorption rate than fish oil, so you need less of it to see results.
Q: Are Krill oil and fish the same thing?
A: Krill oil comes from small crustaceans, not fatty fish, and typically contains more EPA. And unlike conventional fish-oil pills, krill oil’s omega-3s are linked to an antioxidant and other potentially beneficial substances called phospholipids, which makes it just a little bit better.
Q: Is Krill Oil good for your joints?
A: Yes, just 300 mg a day of krill oil has been shown to relieve joint pain.
Q: Does Krill oil have any side effects?
A: At high dosages, krill oil can cause some side effects similar to fish oil such as bad breath, heartburn, fishy taste, upset stomach, nausea, and loose stools.
Q: Can Krill oil cause weight loss?
A: Yes, krill oil has been shown to help support weight loss in combination with a proper exercise and diet regimen.
Q: Can I take Krill oil if I’m allergic to shellfish?
A: Krill oil does not contain the proteins from the flesh of the shellfish, but can have traces of tiny molecules of the proteins. Because there is a chance of developing an allergic reaction, you should avoid the use of fish oil supplements.
Q: Which is better krill or fish oil?
A: Both fish-oil pills and krill-oil supplements supply the healthful omega-3 fatty acids DHA and EPA. But there are differences. Krill oil comes from small crustaceans, not fatty fish, and typically contains more EPA.
Q: Is Krill oil safe for pregnancy?
A: Because some studies indicate that the fatty acid DHA may benefit a developing child’s brain, krill oil is sometimes taken by pregnant women or given to children. Experts do not recommend this, however, since safety or efficacy of krill oil in pregnant women and children has not been proven.
Q: Is krill oil a blood thinner?
A: Krill Oil, and other omega-3 supplements, stop platelets from clumping together and will often cause thinning in the blood. If you duplicate the blood-thinning effect by taking blood-thinners with Krill Oil, it could lead to negative reactions if not monitored properly.
There seem to be many benefits to taking krill oil as a supplement, it appears to reduce inflammation and therefore has many health benefits related to that. For example a reduction in joint pain and rheumatoid arthritis, a reduction in blood pressure and total cholesterol in hypertensive patients. It can also lower c-reactive protein levels.
Krill oil may also help to reduce depressive symptoms, and help treat stress. The effect that it has on cortisol could help explain that. As a treatment for childhood attention hyperactivity disorder, krill oil may have some benefits. But it is too soon to say.
However experts claim that because omega-3 levels are often low in children taking fish oil or krill oil is a good idea anyway, the improved behaviour and attention would just be an added bonus.
As its fish based, a lot of people may be worried about levels of mercury, but this is pretty much a non story. Of greater concern should be whether krill oil can cause an allergic reaction in people who are allergic to shellfish.
The only real issue regarding krill oil is a moral one. Krill are not an endangered species, but they are a vital food source for many marine species such as whales, and their numbers are dropping due to global warming and fishing.
Many experts warn that over-fishing of krill could be causing damage to whales and other species that eat krill. This is not too relevant to their effectiveness as a supplement, but potential food for thought.