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Omega-3 fatty acids are are good for your heart, brain, joints, vision and even your mood.Getty Images/iStockphoto


I don't like fish, but I want to make sure I am not missing out on its healthy oils. What's the difference between omega-3 capsules, fish oil and krill oil? Is one better for you than another?


There's good reason to up your intake of omega-3 fatty acids. Research suggests that doing so is good for your heart, brain, joints, vision, even your mood.

A higher intake of omega-3 fats is also thought to help guard against Type 2 diabetes, stroke, Alzheimer's disease and possibly prostate cancer.

If you don't eat fish, a key source of these healthy fats, it's important to know how to navigate the supplement aisle. Depending on the potential health benefits you're searching for, some types of omega-3 pills won't deliver.

What are omega-3 fatty acids?

The body can't make omega-3 fats on its own, so you have to get them from food or supplements.

There are three kinds of omega-3 fatty acids: EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) plentiful in fish and seafood, and ALA (alpha-linolenic acid) found in flax, chia and hemp seeds, flax oil, canola oil, walnuts, pecans, soybeans, tofu and many fortified foods (e.g., eggs, soy milk).

Omega-3 fatty acids are vital components of cell membranes, allowing nerve impulses to pass easily between cells. They're also the building blocks for hormones that control inflammation, blood clotting and relaxation and contraction of artery walls.

The strongest evidence for the beneficial effects of omega-3 fats revolves around heart disease, and that's especially so for DHA and EPA in fish and seafood. Higher intakes and higher blood levels of DHA and EPA appear to help lower elevated blood pressure, prevent arrhythmias (abnormal heart beats), improve blood vessel function and lower triglycerides (blood fats).

Fish oil versus krill oil

Fish oil and krill oil supplements both provide heart-healthy DHA and EPA, but there are differences. Fish oil supplements are derived from salmon or a blend of fatty fish, including sardines, mackerel, herring, anchovies and/or menhaden. Krill oil doesn't come from fish; it's made from tiny shrimp-like crustaceans.

Perhaps the more meaningful difference, though, is the chemical structure of krill and fish oil and how it affects the absorption of omega-3 fatty acids.

Much of the DHA and EPA in krill oil is bound to phospholipids – fatty substances that dissolve easily in water and, therefore, may enhance the absorption of DHA and EPA into the bloodstream. The omega-3 fats in conventional fish oil supplements, on the other hand, are attached to triglycerides, fats that don't readily dissolve in water.

Despite claims by manufacturers, the absorption of DHA and EPA from krill oil has not been proven to be superior to omega-3's in fish oil. Recent studies have found little or no difference in blood levels of omega-3 fats after consuming identical amounts of the two supplements.

It seems that both krill oil and fish oil, when provided in equal doses, are equally effective at raising DHA and EPA levels in the body. Keep in mind, however, that the krill oil supplements typically provide smaller amounts of DHA and EPA than fish oil products.

Supplementing with krill oil may prevent "fishy burps," a side effect that often occurs with fish oil. If you take fish oil and experience a fishy aftertaste, freezing the capsules can reduce the problem. Taking fish oil at the beginning of a meal, rather than after, can also help.

What about "omega-3" capsules?

A supplement labelled "omega-3" may contain omega-3 fats from fish oil or krill oil (DHA and EPA) or flax oil (ALA). If the source of omega-3 fatty acids is not clear on the front label, check the ingredient list.

While there is less research on the health benefits of ALA compared with fish oil, higher intakes of ALA have been tied to a lower risk of hypertension and heart attack.

It also may protect against Type 2 diabetes.

That said, it's easy to add ALA to your diet without resorting to supplements. One tablespoon of ground flax delivers 1,200 milligrams of ALA, one teaspoon of flax oil has 2,400 mg and seven walnut halves supply 1,280 mg. Not bad considering women require 1,100 mg per day and men need 1,600 mg.

Flax oil is not a substitute for fish or krill oil, though.

EPA and DHA in fish and seafood are better known for supporting heart, brain and eye health.

How much DHA & EPA?

There are no official recommended intakes for DHA and EPA.

Heart experts typically recommend consuming at least 500 mg of DHA plus EPA (combined) each day, an amount obtained by eating six ounces of salmon a week.

The American Heart Association advises people with heart disease to consume a combined 1,000 mg of DHA plus EPA a day from fish, omega-3 supplements or a combination of the two.

Read the ingredient list on fish and krill oil supplements to determine the amount (in mg) of DHA and EPA contained in one 500 mg or 1,000 mg capsule.

Bottom line

If you like fish, include it in your diet twice a week. In addition to DHA and EPA, oily fish – such as salmon, trout and sardines – is an excellent source of protein, B vitamins, vitamin D, magnesium, potassium and selenium.

(Yes, smoked salmon counts, too. It's higher in sodium than fresh salmon, but it's still an excellent source of omega-3 fats.)

If you don't eat fish, consider taking a fish oil or krill oil supplement each day. Fish oil capsules vary in the amount of DHA and EPA they contain. Most 1,000 mg fish oil capsules contain 300, 500 or 600 milligrams of DHA and EPA combined. Liquid fish oil can contain as much as 1,300 milligrams of DHA and EPA a teaspoon.

DHA supplements made from algae are also available for vegans and people who are allergic to fish.


Fishing for omega-3s

Healthy people should consume at least 500 milligrams of DHA and EPA (combined) each day; individuals with heart disease are advised to get 1,000 mg daily. Since omega-3 fats store in the body, it isn't necessary to eat fish every day.

Daily recommended intakes for ALA are 1,100 mg for women and 1,600 for men.

DHA + EPA (milligrams), per 3 ounces

  • Salmon, Atlantic: 1,825
  • Salmon, Chinook: 1,476
  • Herring, Atlantic: 1,712
  • Mackerel, Atlantic: 1,022
  • Salmon, sockeye, canned: 982
  • Trout, rainbow: 981
  • Sardines, Atlantic: 835
  • Tuna, skipjack: 733
  • Krill oil, 500-mg capsule: 80-120
  • Krill oil, 1,000-mg capsule: 160-190
  • Fish oil, 1,000-mg capsule: 300-600
  • Fish oil, 1 tsp: 1,000 to 2,400

ALA, milligrams

  • Flaxseed oil, 1 tsp: 2,416
  • Flaxseed, ground, 2 tbsp: 2,400
  • Flax oil, 1,000 mg capsule: 500
  • Chia seeds, ground, 2 tbsp: 3,400
  • Hemp seeds, 2 tbsp: 1,700
  • Walnuts, 7 halves: 1,280
  • Soybeans, ½ cup: 514
  • Canola oil, 1 tsp: 419

Leslie Beck, a registered dietitian, is based at the Medisys clinic in Toronto.