The Lowdown on Omega-3s

What are omega-3s?

There are three different types of fatty acids: monounsaturated, polyunsaturated and saturated. Unsaturated fatty acids have double bonds in their structure and are liquid at room temperate, whereas saturated fatty acids do not have double bonds and are usually solid at room temperature. Omega-3 fatty acids are an example of a polyunsaturated fatty acid. “Poly” refers to having more than one double bond and “3” indicates that the first double bond is in the third position. Omega-6 fatty acids are another main type of polyunsaturated fatty acid.

There are three types of omega-3s that are found in foods:

  • Alpha-linolenic (ALA)
  • Eicosapentaenoic acid (EPA)
  • Docosahexaenoic acid (DHA)

EPA and DHA are the biologically active forms and confer the most health benefits. ALA can be converted to EPA and DHA, but the conversion rate is usually around 5-10% and 2-5%, respectively. The rate of conversion is influenced by diet, gender, age, and genetics.

Why are omega-3s important?

Omega-3s and omega-6s are essential fats, meaning our bodies cannot make them so we must get them from our diet. Omega-3s have anti-inflammatory effects in the body. They do this through reducing the production of inflammatory molecules such as cytokines, eicosanoids and reactive oxygen species, and by increasing resolvins and protectins, which are molecules that reduce inflammation. While omega-6s are generally known to be pro-inflammatory, they also play a role in resolving inflammation once it’s present in the body. It’s important to have both omega-3s and omega-6s in our diet.

Research shows that omega-3s are particularly important for heart, brain, eye, and prenatal health. Their role in helping with inflammatory conditions, like IBD, is less clear. However, it is still essential for people with IBD to get enough of them, either through diet and/or supplements.

How much omega-3s should you be eating?

Since ALA can be converted to EPA and DHA, Health Canada has only set an adequate intake level for ALA, not EPA or DHA. However, because this conversion rate is low, it can be beneficial to consume foods that contain EPA and DHA in them. In Canada, the adequate intake for ALA is 1.6 g per day for men and 1.1 g per day for women. This increases to 1.4 g in pregnancy and 1.1 g in lactation. Some sources recommend vegetarians should consume approximately double the recommended intake if they do not consume direct sources of EPA and DHA.

How to get omega-3s from food

EPA and DHA are found in fish, algae, omega-3 eggs and some fortified foods. ALA is found in plant-based foods, with the greatest sources being flaxseeds (ground or oil), hempseeds (whole seed or oil), chia seeds, walnuts and soy products. For individuals who consume fish, Health Canada recommends two servings (150 g or 5 ounces) every week. For individuals who do not consume fish, it is still possible to meet your omega-3 needs through plant-based foods. Listed below are the amounts of ALA typically found in omega-3 rich plant-based foods.



ALA (grams)

Ground flaxseeds 1 tbsp 2.5
Hemp seeds 1 tbsp 0.9
Chia seeds 1 tbsp 1.9
Walnuts ¼ cup 2.5
Flaxseed oil 1 tsp 2.6
Tofu ½ cup 0.5
Edamame ½ cup 0.3


To optimize the conversion of ALA into EPA and DHA, it’s recommended that you limit having concentrated sources of omega-6s. This is because omega-3s and omega-6s compete for the same metabolic pathways. Examples of concentrated sources are corn oil, soybean oil, safflower and sunflower oil (except high oleic varieties). Many of these oils are found in processed foods, like chips and store-bought baking. If you are not getting enough omega-3s from foods, it is recommended that you take an omega-3 supplement daily. This could be either a fish oil or algae oil-based supplement.

Does research support omega-3 supplementation in IBD?

Ulcerative Colitis

In terms of maintaining remission, results from studies have pretty consistently shown that supplementation was ineffective for helping to maintain remission. The exception was one study that showed that there was a decreased risk of relapsing in patients who were at really high risk of relapsing. For studies that looked at whether supplementation could help induce remission, some studies showed benefits, whereas other did not. No firm conclusions can be drawn about whether supplementation helps in active disease given the heterogeneity between studies.

Crohn’s Disease

Some research studies showed a slight benefit in omega-3 supplements helping to maintain remission, while other studies showed no benefit. There have only been a few studies evaluating the use of omega-3 supplements in active Crohn’s disease, all of which added omega-3s to nutrition supplements. There were no significant differences in rates of achieving remission between intervention and control groups.

Overall, there isn’t enough evidence to strongly support the use of omega-3 supplementation in inactive or active IBD with the studies that have been done so far.

Pregnant and lactating women would benefit from taking an omega-3 supplement (either fish- or algae-based) that has at least 200-300 mg of DHA in it if they are not eating fatty fish at least two times per week. More information about omega-3 intake during pregnancy can be found at Health Canada.

Potential harms of supplementation

When taking really high doses of omega-3 supplements, some people may experience diarrhea or indigestion. Caution should be taken for those who are on blood thinners or who are getting surgery; it is advised that you check with you doctor if you are thinking of starting supplementation. Pregnant women should not take fish liver oil, krill oil or flaxseed oil due to questions around safety.

Take-Away Points

  • Omega-3s have an anti-inflammatory effect in the body.
  • It is important to get enough omega-3s as they are essential fats.
  • Omega-3 supplements can be taken if adequate amounts cannot be consumed from dietary sources.
  • There is insufficient evidence at this time for routine high dose supplementation of omega-3s in IBD.


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 Written by: Gina Almasan, RD