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Published on April 26, 2021

Krill Oil vs Fish Oil: Which Should You Take?

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Krill Oil vs Fish Oil: Which Should You Take?

Omega 3 fats are essential in our diet, and there are lots of different sources, such as oily fish, nuts, seeds, and also supplements. There are pros and cons of both food sources and also supplements. So, in this article, I will guide you through the advantages and disadvantages of Krill oil vs fish oil supplements. I’ll also cover who needs to take these supplements, and if krill oil is better than fish oil, and cod liver oil.

What Are Omega Fatty Acids?

There are two types of fats or fatty acids that are essential and can’t be produced in our bodies. These are omega 3 and omega 6. Omega 3 can be broken down into three main forms: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA).

Where Are Omega Fatty Acids Found?

ALA is found in plant oils, such as flaxseed, soybean, and canola oils. DHA and EPA are found in oily fish, fish oils, and krill oils. DHA and EPA are actually synthesized by microalgae—not by the fish—but accumulate in the tissue when they are eaten by fish and shellfish further up the food chain.

Why Are Omega Fatty Acids So Important?

Omega-3 and -6 fatty acids have an important structural role needed for cell membranes. They are also energy sources and are used to form signaling molecules called eicosanoids, comprised of prostaglandins, thromboxanes, and leukotrienes.

There are many different prostaglandins with wide-ranging roles, such as the sensation of pain, inflammation, regulation of pregnancy and birth, control of blood pressure, secretion of stomach acid, contraction, and relaxation of smooth muscle.

Thromboxanes regulate blood clotting by causing constriction of blood vessels and the aggregation of platelets (so they stick together), which are early steps in blood clotting.

Leukotrienes are involved in immune function by attracting immune cells such as neutrophils to sites of inflammation. They also constrict bronchioles in the lungs and make capillary walls permeable.

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This is thought to be because the metabolic products of omega-3 fatty acids are less inflammatory than those produced from omega 6 fatty acids. Western diets are associated with an imbalance of omega-3, -6 such that instead of levels of omega 3 being higher than 6, the reverse is more commonly seen. This is associated with an increased risk of chronic inflammation.[1]

A large systemic review that combined 86 trials involving over 162,000 people looked at the effect of higher omega-3 intake versus lower omega-3 intake for at least a year. This was provided mostly by omega-3 supplements while a few trials gave oily fish. Omega-3 fatty acids have been shown to reduce blood pressure and can be incorporated into your diet by eating oily fish or seeds, such as chia seeds, flax seeds, and nuts.[2]

There are three types of omega-3: those found in oily fish called EPA and DHA and the plant-based ALA.

What Is Krill Oil?

Krill oil is extracted from the bodies of Antarctic krill, a tiny shrimp-like shellfish. Krill oil, fish oil, and cod liver oil are similar in that they all contain DHA and EPA.

Fish oil is extracted from the body of the fish and contains some vitamin A and vitamin D as well. Cod liver oil is extracted from the liver of the fish and contains higher levels of vitamin A and D.

High doses of vitamin A can be toxic as it is a fat-soluble vitamin that is stored by your body. This is why omega 3 supplements that contain vitamin A are to be avoided in pregnancy because high levels of this vitamin may damage the fetus.

Krill Oil Vs Fish Oil

Evidence surrounding krill oil is limited compared with fish oils and cod liver oils. A large portion of the EPA and DHA in krill comes in phospholipid form (whereas fish oil fatty acids are contained in triacylglycerols), which some claim has a higher rate of absorption in the body than fish oil.

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Previously, it was thought that Krill oil was more bioavailable than fish oil, but there were problems with this research with regards to dosing.[3] More recently, a randomized controlled trial in 66 people was performed to answer this question and compared the bioavailability of krill oil compared with fish oil. It found that there was no difference between blood measurements of DHA and EPA. Therefore, the evidence does not support krill oil being “better” or needing lower doses than fish oil.[4]

Krill Oil Vs Fish Oil in Terms of Cholesterol

A study in animals looked at gene expression after supplementation with either krill oil or fish oil. They found that fish oil upregulated (increased gene expression) the cholesterol synthesis pathway more than krill oil. Krill oil was found to upregulate (increase gene expression) more metabolic pathways than fish oil. This suggests that there might be different biological effects between krill and fish oil but more research is needed.[5]

In group (meta) analysis of seven trials totaling 662 participants, Krill oil supplementation was found to reduce low-density lipoprotein cholesterol and triglycerides but not total cholesterol.[6] Whether this translates to decreased risk of cardiovascular disease needs further research.

However, when directly compared, krill oil was not superior to fish oil supplementation and had very similar effects on cholesterol.[7]

Krill Oil Vs Cod Liver Oil

Cod liver oil contains higher levels of vitamin D and vitamin A, which may be toxic in excess. If you want to take a high dose of omega-3, this means you will also end up having higher doses of vitamin A and D. Both of these are fat-soluble vitamins that are stored by the body and can become toxic. Vitamin A supplementation should be avoided during pregnancy due to risks for the baby.

There is a risk that since the liver is used to filter out toxins, there is the possibility that cod liver oil contains more environmental contaminants than fish oil or krill oil.

Are There Risks With Krill Oil?

Less research has been performed on krill oil and although no side effects have been reported, the safe maximum dose of natural astaxanthin has not been determined.

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Krill make up a vital part of the Antarctic food chain and a huge number of species higher up the food chain depend on them. Fishing krill has the potential to catastrophically destabilize this important food chain. Therefore, fish oils are more sustainable than krill oil.

Why Is Krill Oil Red?

The deep red color of krill oil is due to a compound called astaxanthin found in krill. Astaxanthin is also found in other more sustainable sources such as red trout, crab, lobster, and wild salmon. Astaxanthin is a carotenoid antioxidant compound that mops up harmful free radicals.

When to Take Omega-3 Supplement

A large review of 86 trials combined—totaling over 162,000 people—looked to see what the effect of increased omega-3 had on cardiovascular risk. Increasing ALA made no significant difference to blood clots of the coronary arteries supplying the heart (coronary events) but slightly reduced cardiovascular events (diseases related to blood vessels such as clots and rhythm problems) while EPA and DHA reduced serum triglycerides and also reduced the risk of coronary heart disease, such as heart attacks.[8]

They found that EPA and DHA decreased triglycerides (a type of fat) by about 15% and reduced the risk of coronary artery death and coronary events, which are illnesses of arteries supplying the heart. However, they did not affect cardiovascular events (e.g., strokes, heart irregularities).[9]

While increasing ALA made no significant difference to coronary events, it slightly reduced cardiovascular events. This means that the three combined (ALA, EPA, and DHA combined) may reduce the risk of coronary, cardiovascular disease, and lower triglyceride levels, but the effects are small.

One of the ways of decreasing your risk of cardiovascular disease is by lowering your cholesterol—reducing saturated fats in your diet and eating ALA omega-3 (e.g., from walnuts). A grouped meta-analysis has not found any link between omega-3 and dementia, but more information is needed to see if omega-3 can prevent cognitive decline.[10]

Overall, if you aren’t pregnant or intending to get pregnant, then omega 3 supplements are probably unlikely to do you harm and might benefit your long-term cardiovascular risk. It isn’t possible to tell the difference in general between eating enough omega-3 in your diet versus supplementing, but whole foods have other benefits as well.

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Omega-3 supplements often have high levels of vitamin A, which can be harmful in pregnancy. Therefore, you should avoid supplementing or choose a pregnancy-safe version.

If you are vegan, you may consider taking an omega-3 supplement made from algae or seaweed, but these are unregulated and can contain significant quantities of iodine, which can be harmful. Therefore, it is better, where possible, to optimize your diet. There are concerns that part of the benefit of omega-3 is from a whole food effect that isn’t seen with taking a supplement instead.

Tips on How to Get Enough Omega-3 in Your Diet

  • Aim to have oily fish twice a week if you aren’t pregnant or once a week if you are, as the benefit of omega-3 has to be offset by the risk of contamination with heavy metals.
  • Algae and seaweed are the only plant-based sources of EPA and DHA, but ALA can be converted in your body into EPA and DHA.
  • Vegan sources of omega-3 are chia seeds, linseed, hemp seeds, walnuts, and vegetable oils, such as rapeseed. To meet the current guidance for omega-3, you would need to eat about a tablespoon of chia or ground linseeds, or two tablespoons of hemp seeds, or six walnut halves a day.
  • Algae oil is an alternative to fish oil, which makes it an attractive option for vegetarians. But while algae oils do contain large amounts of DHA, most don’t contain any EPA fatty acids at all.

In Summary

Krill oil supplements appear to be safe and as effective as fish oil. They also have the bonus of containing the antioxidant astaxanthin.

However, harvesting krill is not sustainable, and there are risks regarding destabilizing the Antarctic food chain. Instead, aim to include foods rich in omega-3 in your diet to benefit from the “whole food effect,” and eat foods that are naturally rich in carotenoids, such as vegetables, crab, and lobster. Avoid taking high doses of cod liver oil, and avoid it completely during pregnancy due to the risk of vitamin A.

Featured photo credit: Anshu A via unsplash.com

Reference

More by this author

Dr. Harriet Holme

Registered Nutritionist, and doctor

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Published on October 19, 2021

13 Fish Oil Benefits For Women And Men

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13 Fish Oil Benefits For Women And Men

Fish oils are great sources of omega-3 and -6 fatty acids. Omega fats are essential, meaning that they can’t be synthesized in your body and have to be eaten in your diet. Omega-3 is synthesized by microalgae—not by fish—but accumulates in the tissue when they are eaten by fish and shellfish further up the food chain. Oily fish contains about 30% fat in their tissues, and this is where the omega fatty acids are found. There are many claims about omega-3 fatty acids in fish oils. But what is the evidence of the real benefits of fish oil for men and women? Can fish oils really improve your brain health, reduce your cholesterol, or help your heart?

Learn about the role of omega-3 as signaling molecules, in cell membranes, arthritis, and even eye disease. Find out the main benefits of fish oil for men and women and how to get enough.

What Are Omega Fatty Acids?

There are two types of fats or fatty acids that are essential and can’t be produced in our bodies: omega-3 and omega-6. Omega-3 can be broken down into three main forms: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). Fish oils contain DHA and EPA omega fatty acids and are a good source of these essential fats.

13 Benefits of Fish Oil (Omega Fatty Acids)

There are several different health benefits of omega fatty acids. Below are the 13 most common fish oil benefits for men and women.

1. Structural Role in Cells

Omega-3 and -6 fatty acids have an important structural role, as they are needed for cell membranes. You have an estimated 724 trillion cells in your body, and that is a lot of cell membranes to keep healthy.

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2. Energy Source

Both omega-3 and -6 are sources of energy, just like any other fat source. This means they can be used alongside energy from carbohydrates to power your body, providing energy for essential functions and exercise.

3. Signaling Molecules

Omega fatty acids are used to form signaling molecules called eicosanoids, comprised of prostaglandins, thromboxanes, and leukotrienes that have extremely important functions within our bodies.

Prostaglandins

There are many different prostaglandins with wide-ranging roles, such as the sensation of pain, inflammation, regulation of pregnancy and birth, control of blood pressure, secretion of stomach acid, contraction, and relaxation of smooth muscle.

Thromboxanes

Thromboxanes regulate blood clotting by causing constriction of blood vessels and the aggregation of platelets (so they stick together), which are early steps in blood clotting.

Leukotrienes

Leukotrienes are involved in immune function by attracting immune cells, such as neutrophils, to sites of inflammation. They also constrict bronchioles in the lungs and make capillary walls permeable.

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4. Prevent Heart Diseases

Cardiovascular events are diseases related to blood vessels, such as clots, rhythm problems, and heart attacks. Studies have found that ALA may reduce the risk of cardiovascular events.[1][2]

5. Decrease Cholesterol and Triglycerides

Triglycerides are part of your cholesterol profile. Higher levels are associated with an increased risk of atherosclerosis and heart disease. Studies have found that there is an inverse relationship between omega-3 and triglyceride levels.[3] This means that an increased intake of omega-3 led to a decrease in triglycerides and that higher doses of omega-3 led to a greater effect. This effect was stronger in people who already had raised triglycerides.

One of the ways of decreasing your risk of cardiovascular disease is by lowering your cholesterol. One study found that EPA and DHA decreased triglycerides by about 15% and reduced the risk of coronary artery death and coronary events, which are illnesses of arteries supplying the heart.

6. Improve Brain Health

A grouped meta-analysis has not found any link between omega 3 and dementia, but more information is needed to see if omega-3 can prevent cognitive decline. Learn more about this here: How Fish Oil Boosts Your Mental Clarity And Brain Power

7. Help With Rheumatoid Arthritis

Omega-3 supplements have been found to benefit the clinical outcomes of rheumatoid arthritis and may even delay the need for medications.[4][5]

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8. Decrease Progression of Osteoarthritis

A large prospective study in patients with wear and tear (osteoarthritis OA) found that a higher intake of total and saturated fat was associated with an increased risk of worsening OA, whereas a higher intake of unsaturated fats was associated with decreased progression of OA measured via X-rays.[6]

The current opinion is that the metabolic products of omega-3 fatty acids are less inflammatory than those produced from omega6 fatty acids. Western diets are associated with an imbalance of omega-3 and -6 such that instead of levels of omega-3 being higher than omega-6, the reverse is more commonly seen.

9. Prevent Autoimmune Diseases

There is also limited evidence that omega-3 supplementation may benefit people with other types of autoimmune arthropathies like systemic lupus erythematosus (SLE), but more research is needed.

10. Good For Eye Health

The macula is part of the retina at the back of the eye, and although it is tiny—only about 5mm across—it has a very important role in vision. It is responsible for our central vision, most of our color vision, and the fine detail of what we see. Getting enough omega-3 is linked to a reduced risk of macular degeneration, one of the world’s leading causes of permanent eye damage and blindness.[7][8]

11. Boost Your Mood

It is suggested that omega-3 may play a role in the prevention and treatment of depression. However, meta-analyses of the data have not confirmed clear benefits. Instead, more research looking at the effect of supplementing omega-3 in people with depression is needed.[9]

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12. Lower Blood Pressure

The evidence of the benefit of omega-3 fatty acids on high blood pressure (hypertension) is mixed with large-scale studies showing either no effect or a small reduction in risk of hypertension.[10][11] Omega-3 fats do have other health benefits, though. They are unlikely to do harm and are easily incorporated into your diet by eating oily fish twice a week and seeds, such as chia seeds, flaxseeds, and nuts.

13. Help With Fertility

Omega-3 appears to have a role in a healthy gamete (eggs and sperm) formation with consumption associated with increased probability of pregnancy and live birth rate.[12][13][14]

Where Are Omega Fatty Acids Found?

If you are allergic to fish or don’t eat it, how can you get enough omega-3? There are other sources of ALA is found in plant oils, such as flaxseed, soybean, and canola oils. DHA and EPA are found in oily fish, fish oils, and krill oils. DHA and EPA are synthesized by microalgae, not by the fish, but they accumulate in the tissue when they are eaten by fish and shellfish further up the food chain.

Final Thoughts

While there is evidence of the benefits for eye health, arthritis, improved cholesterol, and heart health, evidence to support the benefits of fish oil in helping high blood pressure, protecting brain health, and preventing dementia are less convincing.

Studies have found a “whole food effect” where eating oily fish appears to be more beneficial than supplementing with a fish or cod liver oil. There are also other plant-based sources of omega-3. Although some of these studies suggest that the more omega-3 the better, there is a limit to the recommended dose of supplements unless prescribed by your doctor.

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Omega-3 supplements may interfere with warfarin, due to its anti-platelet role in clotting, so it’s best to check with your doctor before starting a supplement.

Featured photo credit: Louis Hansel via unsplash.com

Reference

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