Omega-3s seem to be all over the place in the world of health-conscious people. They are known to benefit heart and brain health, help resolve inflammation, and even promote a healthy pregnancy. You will usually find them in stores as pure supplements, but they are also readily available in our diet.
Why are Omega-3s getting so much attention? Are there such things as “bad omega-3s”? Which foods are the highest sources of omega-3?
In this article, we give you the low-down on which foods are richest in Omega-3 fatty acids. First, however, we are going to review some of the basic information about Omega-3s, including what they are, where they come from, and how they benefit our health.
What are Omega-3s and Why Are They Important?
Omega-3s fatty acids (Omega-3s, for short) are a type of fat that is liquid at room temperature. These sorts of fats are called unsaturated fatty acids, and, more specifically, polyunsaturated fatty acids (PUFAs).
Omega-3s are usually called essential fatty acids, which means our body cannot easily make them. Instead, we must get them from the food we eat.
There are three main types of Omega-3s for human health: ALA, EPA, and DHA.
Out of the three Omega-3’s above, EPA and DHA are the most crucial, and the health benefits of Omega-3’s are attributed to the metabolism of EPA and DHA within the body. ALA (alpha-linolenic acid) is found mostly in plant-based oils, while both EPA and DHA are found in most abundance in seafood and grass-fed meats (as discussed shortly).
Omega-3’s are critical because both EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are used by the brain in consistent amounts, and thus we need a steady supply of it for normal neural function. Omega-3s are also important for cell structure, and they have key roles in keeping immune and hormone health.
The structures of EPA and DHA differ slightly; DHA has 22-carbon backbones and 6 double bonds at different positions, and EPA has a 20-carbon backbone and 5 double bonds and different positions.
If you don’t have a strong biochemistry background, it is likely that the differing structures won’t mean much. As with all chemical structures, the structure of the component determines its function. EPA and DHA are metabolized by the body with high efficiency. ALA is converted into EPA and DHA in the body, but this process is slow and inefficient. Thus, the easiest way to obtain the health benefits of Omega-3’s is to consume foods that contain EPA and DHA.
Essentially, since we cannot produce Omega-3s in the body we if we want to increase the Omega-3s in our body, we need to consume more foods that contain Omega-3s, and specifically, foods that contain EPA and DHA.
What are the Health Benefits of Omega-3s?
There are three main benefits of Omega-3s for our health: they promote brain and neural health, they can reduce the risk of cardiovascular disease, and they can reduce inflammation in the body. We will discuss each of them briefly below.
Brain Health and Cognition
Omega-3s are beneficial for brain development of the child during a woman’s pregnancy and lactation periods as well as for the maintenance of brain health throughout life.
In women who supplemented with Omega-3 during pregnancy and lactation, their children showed to have enhanced problem-solving skills and hand-eye coordination when compared to children whose mothers did not supplement with Omega-3 (especially DHA and EPA).
In adults, some research shows that supplementation with Omega-3 slowed cognitive decline in people with mild cognitive dysfunction associated with Alzheimer’s Disease.
Omega-3 fatty acids EPA and DHA are shown to reduce the risk of heart disease and circulatory blockages. Consuming more EPA and DHA is linked to a decrease in gene expressions that are involved in heart-damaging pathways.
Another study showed that EPA and supplementation decreased the risk of experiencing a heart attack and other cardiovascular risk factors.
Inflammation is the cause of many chronic diseases. EPA and DHA are thought to have important roles in in reducing oxidative stress that leads to inflammation, thus improving cellular function and gene expression. Inflammatory markers, like C-reactive protein, are linked to an increased risk of chronic diseases, like cardiovascular disease. Studies have shown that supplementation with EPA and DHA significantly reduced some types of C-reactive protein.
Additionally, Omega-3s are metabolized into components called resolvins. Resolvins, in addition to being powerful anti-inflammatory elements, also have free radical-scavenging properties that may help to suppress tumor growth and cancer.
Best Sources of Omega-3 in the Diet
Certain types of fish have the most Omega-3s of any other food in our diets. Cold water fish, like salmon, albacore tuna, trout, sardines, and warm-water fish like snapper, are the highest in EPA an DHA. Here are the approximate amounts of EPA and DHA per 150g serving:
- salmon (fresh Atlantic or Australian): more than 500 mg
- canned sardines: 1,500 mg
- trout (fresh rainbow): 300–400 mg
- gemfish: more than 500 mg
- canned tuna: 300–500 mg
- rainbow trout: 300–400 mg
- barramundi, snapper, John Dory: 200–300 mg
Additionally, fish is very low in saturated fat, making it a “lean meat”. The American Diabetes Association recommends that you choose lean meats over meats higher in saturated fat, like “red meats”. In fact, the ADA recommends everyone consume fish at least twice a week.
Because of the size and life-span of many of the types of fish highest in Omega-3, they also tend to be high in mercury. This is especially risky for pregnant women, since high levels of mercury exposure can lead to miscarriages and low birth weight.
Krill are very small organisms that resemble small shrimp, but are actually zooplankton. They eat phytoplankton. Because of their size, they don’t accumulate mercury like fish do. It is difficult to find krill as such to prepare in your food, but you can find krill oil in capsules.
About 30-65 percent of krill’s fatty acids are stored as phospholipids, whereas fish oil is stored as another type of fat called triglycerides. Our body may be able to absorb phospholipids more easily than triglycerides.
According to the study cited above, we may need more krill oil to get the same effect as taking fish oil or consuming fish.
3. Other Seafood
Omega-3s are also found in other non-fish seafood, but in lower quantities. Some of the seafood highest in Omega-3s include:
- Squid: 200-500 mg
- Lobster- 200-500 mg
- Crab: 100-500 mg
- Scallops: less than 200 mg
- Shrimp: less than 200 mg
The foods mentioned above have a lower density of Omega-3s when compared to their fishy counterparts.
4. Grass-Fed Beef
When compared to grain-fed beef, grass-fed beef is lower in overall fat content. This is beneficial for those looking to reduce saturated fat intake. Grass-fed beef is also higher in vitamin A.
Regarding Omega-3s, studies show that grass-fed cattle have an increase in Omega-3 fats and generally achieve a more favorable Omega-3 to Omega-6 ratio. However, cattle must be fed a pure grass diet to achieve these results.
Studies show that, while omega-3 profiles in some grass-fed beef may be slightly higher, in general, people who consume grass-fed or grain-fed food have similar intakes of both Omega-3.
5. Chia and Flaxseed
Chia and flaxseed and great options for vegetarians and vegans who aren’t getting Omega-3s from most of their foods in their diet. They are high in a type of Omega-3 fatty acid called alpha-linolenic acid (ALA). In general, ALA provides some of the anti-inflammatory and benefits for heart health. To some extent, our bodies can convert ALA to EPA (about 8%).
While our bodies can convert some ALA to EPA through enzymatic reactions, our cells have a much harder time converting it into DHA (between 0-4%). DHA is the Omega-3 fatty acid to which we attribute most benefits for brain health.
It is important to note, however, that the cells of people who follow vegan diets are likely more efficient at converting ALA in DHA. Even so, there is no evidence that a lower intake of DHA in vegetarians or vegans results in adverse health or cognitive function, suggesting that their bodies may be more efficient at converting ALA into DHA.
Seaweed and algae are good sources of DHA that are comparable to fish sources. In fact, DHA from algal oil is accumulated more in the body than DHA from fish oil.
Algae and seaweed could be good alternatives for vegetarians and vegans to get enough DHA in their diet.
Scientists who research the marine food chain have found that algae and seaweed also contain mercury.
Summary of Omega-3 Content in Selected Food Groups
Here is an in-depth list of the ALA, EPA, and DHA content in selected foods (info provided by the USDA):
Supplement Sources for Omega-3
If you feel you aren’t eating enough omega-3 food sources, you can take high-quality supplements. Supplements are equally effective to increase Omega-3 content in the blood and provide all of the health benefits of dietary Omega-3.
Not all Omega 3 sources are the same.
Fish oil is the most common omega-3 supplement. It is a natural source of both DHA and EPA. However, unfiltered fish oil could have mercury.
Algae oil is a good alternative for vegans and non-vegans alike. It is one of the only natural sources of vegan DHA.
Krill oil has several benefits over fish oil. Krill does not contain mercury, it resists oxidation to make sure you get the full amount of Omega-3 found on the label it is environmentally sustainable. You may have to take more krill oil than fish oil to get the same results, but this is a small change that you can make for the benefits.
The most important element to notice in the Omega-3 supplement you choose is the source of the omega-3s the supplement contains. Make sure most of the omega-3 oils are from both DHA and EPA, as these are much harder to come by than ALA in our diet. Additionally, regardless of the source, check to see if you supplement is free of hexanes, dioxins (check the ingredient label), and are filtered for mercury.
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Image Credit: DHA and EPA structure by Tao Yi et al.