Oily Fish: Health Benefits, Best Choices and How Much to Eat

Oily fish are fish with higher fat content that provide long-chain omega-3 fatty acids, which support cardiovascular, brain, and metabolic health. This article explores the key health benefits of consuming these nutrient-dense fish regularly.

They include fish like salmon, trout, mackerel, sardines, herring, and anchovies, which are defined by their higher fat content compared to white fish. Specifically, it’s all about the long-chain omega-3 fatty acids. These fats are largely absent from typical Western diets and difficult to obtain in meaningful amounts from other foods.

Unlike white fish (like cod, flatfish, or tilapia), which primarily store fat in their liver, oily fish distribute fat throughout their flesh. This is why they provide a reliable and concentrated source of omega-3s in a normal portion size.

Is fish high in omega-3?

Oily fish stand out, nutritionally, because they supply two omega-3 fatty acids: eicosapentaenoic acid ('EPA') and docosahexaenoic acid ('DHA'), which are difficult to find anywhere else in nature. While small amounts of omega-3s are found in some plant foods, these do not provide the same compounds, quantities or benefits.

Because EPA and DHA are not efficiently produced by the body and are not found in many other foods, oily fish represent one of the most efficient ways to increase intake through diet alone. Some plant foods, such as flaxseed, walnuts, and chia seeds, contain another omega-3 called alpha-linolenic acid ('ALA'). 

While ALA is beneficial by itself, the body converts ALA into EPA and DHA very inefficiently. As a result, relying on plant sources alone typically leads to low levels of EPA and DHA. For most people, oily fish remain the most practical dietary source of these fats. 

Health effects

EPA and DHA are incorporated into the 'cell membranes' throughout your body, where they help control inflammation, brain health and cardiovascular health¹. This is why you need them.^[1]

Regular consumption of oily fish is associated with a lower risk of cardiovascular disease and major cardiovascular events such as heart attack and stroke, even at relatively modest intakes. These benefits appear strongest in people who don't get a lot of omega-3 from their diet.^[2]

DHA is also a major structural component of your brain. It makes up a large proportion of the polyunsaturated fats found in brain tissue and plays a role in maintaining normal brain structure, brain function and brain health. 

Thus, higher intakes of oily fish have been associated with better cognitive performance in older adults and a lower risk of cognitive decline, dementia, and Alzheimer’s disease. Researchers believe these effects are partly due to substances derived from EPA and DHA that help protect brain cells from damage and support brain cell maintenance as you age.^[3]

Additional benefits

In addition to omega-3s, oily fish also provide a range of other nutrients and health benefits. A typical 100g (3.5 oz) serving of oily fish can provide: 50-100% of your vitamin D, 20–25 grams (1 oz) of high-quality protein, vitamin B12, niacin and selenium. 

Smaller species, such as sardines and anchovies, are often eaten with their soft, edible bones, which can also provide calcium. You won't get that from the supplements. 

How much do you need?

Recommendations vary slightly, but most experts suggest eating fish at least twice per week, with at least one serving being oily fish. In practical terms, this equates to 200–250 grams (7–9 ounces) of fish per week. Most oily fish provide 1.3–2.5 grams of EPA and DHA per 100 grams, meaning that even one or two servings per week can substantially increase your omega-3 intake.

How to increase your intake of fish