Foods with omega-3

Which foods contain omega-3?

There are two separate groups. ALA (plant-based omega-3) is found in flaxseed, soybean and canola oil, chia seeds and walnuts. EPA and DHA are found in fish, fish oil and krill oil; oily cold-water fish (salmon, mackerel, tuna, herring, sardines) contain high amounts, while low-fat fish such as bass, tilapia and cod, and shellfish, contain low amounts. The amount of omega-3 in fish also depends on what the fish eats; farmed fish generally contain more EPA and DHA than wild fish, but this varies with the feed. NIH reports that in farmed Atlantic salmon in Scotland, EPA and DHA content fell significantly between 2006 and 2015 as feed composition changed. ^[1]

In the USA, DHA is added to some eggs, yogurt, juice, milk and soy beverages. ^[1] Beef is very low in omega-3; ALA is somewhat higher in grass-fed beef. ^[1]

NIH/USDA serving table: fish and seafood

The values below are US servings compiled by NIH from USDA data (3 ounces ≈ 85 g, cooked). The table uses US species names; rows such as “Atlantic mackerel” may not correspond exactly to species names sold in Türkiye. The total column is the sum of DHA and EPA.

Source: NIH ODS table (USDA FoodData Central data). ^[1] NIH notes that the USDA database does not specify whether most fish are farmed or wild. For reference: EFSA sets the adequate intake of EPA+DHA for adults at 250 mg (0.25 g) per day; this is far below the total in one serving of salmon listed in the table, but the value is set as a daily target, not as a limit per serving. ^[6]

Anchovy, bonito, bluefish: values for fish of Türkiye

In a review reporting data from the National Food Composition Database (TürKomp, 2014), EPA and DHA for a 150 g fish serving (the serving of the Türkiye-Specific Dietary Guidelines) are as follows. The table does not state the cooking status; canned products are labeled separately.

The values are reported from TürKomp. ^[2] Three points should be noted. First, EPA and DHA in the canned rows of the table are much lower than the values for the same fish given as separate rows in the table (anchovy: 5.788 g and 0.262 g). Second, these values were not obtained with the same method and the same serving (150 g versus 85 g) as those in the NIH/USDA table, so they cannot be compared directly; the species, season, fishing area and fat content of the fish change the content. Third, the table is taken from a secondary review. The Ministry of Health report also lists anchovy, young bluefish (çinekop), sardine, bluefish and Atlantic bonito as species rich in omega-3 in Türkiye, and salmon and herring among species of foreign origin. ^[5]

Walnuts, flaxseed and chia: plant-based omega-3 (ALA)

Source: NIH ODS table. ^[1] According to NIH, ALA can be converted in the body to EPA and then to DHA, but the conversion is very limited and reported rates are below 15%; the practical way to raise EPA and DHA levels is therefore to obtain them directly. ^[1] The review by Brenna et al. likewise reports that in healthy adults ALA supplementation raises blood EPA and DPA levels but has little effect on DHA, and that blood DHA level can be raised with preformed DHA. ^[7]

ALA itself is an essential fatty acid: NIH and EFSA set separate adequate intake values (NIH 1.6 g for adult men and 1.1 g for women; EFSA 0.5% of energy). According to 2011–2012 NHANES data, NIH states that most children and adults in the USA get the recommended amounts of ALA; this is US data. ^{[1] [6]}

How many servings of fish per week? What do institutions say?

The numbers belong to different purposes and populations (cardiovascular risk, mercury in pregnancy, general nutrition); one does not refute another, but they cannot be reduced to a single number. The FDA/EPA advice supports the Dietary Guidelines for Americans recommendation of at least 8 ounces of seafood per week (for a 2,000-calorie diet) and 8–12 ounces in pregnancy. ^[3]

Mercury in fish: which fish are lower?

The 2021 FDA and EPA advice classifies more than 60 fish and shellfish as “Best choices,” “Good choices” and “Choices to avoid” according to mercury level. Fish that FDA/EPA and the Dietary Guidelines for Americans list as “best choices” for children include anchovy, Atlantic mackerel, salmon, sardines, trout, shrimp, squid, oysters and tilapia. Those to avoid include king mackerel, shark, swordfish, marlin, orange roughy, bigeye tuna and Gulf of Mexico tilefish; in the list, Atlantic mackerel and king mackerel are separate rows. ^[3]

According to NIH, the Dietary Guidelines for Americans recommend avoiding king mackerel, shark, swordfish and tilefish in pregnancy and lactation and limiting albacore (white) tuna to 6 ounces per week; there are also studies showing that the benefits of moderate seafood consumption in pregnancy outweigh the risks. These results are based on observational data and a systematic review. ^[1] The Ministry of Health report also states that some fish may contain excessive mercury and that canned tuna should be consumed at less than 180 g per week. ^[5]

How much fish is consumed in Türkiye?

The review by Öksüz et al., based on TÜİK (2016) data, reports that annual per-capita fish consumption was 8.0 kg in 2000 and 6.1 kg in 2015; the same review says that this amount is far below the world average (the world average was about 20 kg in 2016). This data is from 2015; it does not replace a current national measurement. ^[2]

This guide does not recommend personal nutrition or doses; in people with a medical condition, pregnancy or a special diet, the amount and type of fish are determined with a physician or dietitian.