Fish oil & omega-3s

January 17, 2008

 2008 study published in the Canadian Medical Association Journal casts doubt on the health benefits of fish oil.

Dr. David Jenkins, a professor of medicine and nutritional science at the University of Toronto, and his co-authors analyzed three major studies that looked at heart patients and fish-oil supplements. One found benefits to fish oil, another found that taking fish oil actually left heart patients in worse shape, and the third found that the supplements had no effect. (They didn’t consider fish oil’s effect on joint pain, Alzheimer’s disease or depression.)

An article about the study in The Globe and Mail stated that: “Omega-3 fats in oily fish make the blood less likely to form clots, lower blood fat levels and protect against irregular heartbeats that cause sudden death from cardiac arrest. But fish oil can also have harmful effects, such as an increased risk of bleeding, especially at high doses.”

Perhaps the wonder-food status of fish oil will be a passing fad like oat bran, low-carb diets and pomegranate juice. Jenkins told the Globe that his suspicions were aroused by the near-universal acclaim for fish oil and the omega-3 fatty acids it contains.

Comments left by readers of the Globe article included:

  • “Snake oil has been replaced by fish oil, it appears.”
  • “It may not help your health, but it sure makes you stinky and very important to cats.”
  • “…while our bodies need a basic amount of omega 3′s to survive, as our own metabolism cannot synthesize these fatty acids, taking anything beyond this is not proven. Do we wish to further deplete our oceans’ fish stocks chasing another fountain of youth rainbow?”

Fish and mercury

Another health risk to consider is contamination from mercury and other industrial pollution. A controversy erupted recently in the U.S. when a group called the National Healthy Mothers, Healthy Babies Coalition started urging pregnant women and new mothers to eat more seafood in order to get Omega-3s. The advice conflicted with government guidelines limiting mercury intake. It turned out that the group was getting funding from the National Fisheries Institute — an industry group that promotes seafood. MSNBC also has a good article entitled: Debate rages over what level of mercury in tuna is considered harmful.

Vegetarian sources of Omega-3 fatty acids

Omega-3 essential fatty acids include ALA, EPA and DHA. Alpha-linolenic acid (ALA) is found mainly in the oil of flaxseeds, chia seeds, hemp seeds, walnuts, rapeseed (canola oil), andsoybeans. ALA reduces blood clotting, and is good for the heart. Over time, the body converts some of the ALA into EPA and, to a lesser extent, DHA. These two are also found to a small degree in seaweeds, and there are vegan DHA supplements made from micro-algae. Low levels of DHA have been associated with depression. Two tablespoons of ground flaxseeds or two teaspoons of flax oil per day will provides plenty of ALA. It is best not to over-heat flax, as high temperatures can damage the omega-3s.

Unrefined Algae DHA 90 CapsulesDirect forms of fish-free DHAinclude supplements and flax oils containing DHA derived from algae. The best value is Udo’s Choice Unrefined Algae DHA that provides 250mg of DHA per capsule. Two other examples include: Flora’s DHA Flax Oil that provides 100mg of DHA per tablespoon and North Coast Naturals 369+DHA that provide 50-60mg of DHA per capsule. These are available at natural food stores. Ask them to order some if you don’t see it. Or try a google search to locate online suppliers and similar products.

Balancing Omega-3 and Omega-6s

Unlike Omega-3s, Omega-6 fatty acids are numerous in modern diets. They are especially prevalent in refined vegetable oils (from soy, corn, sunflower, safflower, soy, and cottonseed) used in most of the snack foods, cookies, crackers, sweets and fast food common in the North American diet.

According to an article at DrWeil.com, the typical Western diet has an excess of omega-6s, especially in ratio to omega-3s. This imbalance may be responsible for much of the chronic inflammatory diseases seen today. Humans used to consume omega-3 and omega-6 fatty acids in roughly equal amounts. Today, Western diets typically have ratios of omega-3 to omega-6 in excess of 1 to 10, some as high as 1 to 30. The optimal ratio is thought to be 1 to 4 or lower.

Approx. Omega-3 to Omega-6 ratio in select plant foods/oils
(In brackets is the ratio expressed in grams per 100 grams – omega-3 to omega-6)

Flaxseed oil 4:1 (55g : 15g)
Flaxseeds 4:1 (20.3g : 5g)
Chia seeds 3:1 (21g : 7g)
Canola oil 1:2 (11g : 22g)
Hemp seeds 1:3 (7g : 21g)
Walnuts 1:5 (10.4g : 53g)
Soy 1 : 7.5 (7g : 53g)

Macadamia Nut 1:1 (1.5g : 1.5g)
Avocado 1 : 12.5 (1g : 12.5g)
Olive 1 : 13 (0.7g : 9g)

In general, all other common nuts and seeds (and their oils) have only trace amounts of omega-3s and relatively high amounts of omega-6. But you can balance these to some extent with high omega-3 content foods such as flax.

Note: Coconut oil has no omega-3 but only 3 grams of omega-6 per 100 grams.

Links to more information on Omega-3

• The Vegetarian Position Paper (view as a 20-page pdf) by the American Dietetic Association and Dietitians of Canada has a section titled “N-3 fatty acids” on page 7.
• Making Sense of Fats and Oils by Brenda Davis, RD.
• Detailed article on Omega-3s by Jack Norris, RD, VeganHealth.org.
• Essential Fatty Acids by Physicians Committee for Responsible Medicine
• Plant based sources of vegan & vegetarian DHA and EPA, by Yvonne Bishop-Weston, Nutritionist

See our vegetarian nutrition page for information about other nutritional concerns.