Here's What Happens When You Eat Fish Every Day

Fish is an incredibly versatile and broad food that can be prepared enough ways, that eating it every day wouldn't even seem like a challenge. Low in fat but high in protein, fish can easily serve as a center-of-the plate main focus of the meal (think a pan-fried filet), or can be used as an appetizer (think sardines on toast).

While intensely-flavored species such as mackerel, herring, anchovies, and sardines might put off some more picky eaters, you would be hard-pressed to find many people who aren't fans of more mild fish such as red snapper, cod, or sea bass. Even salmon, an oily and "fishy" option is more often than not a crowd-pleaser.

Eating fish every day will have a positive effect on a number of different systems in the body, although depending on the type of fish being consumed, it may come with a drawback as well.

A study of 40,000 men in the United States found that those who consumed at least one serving of fish every week decreased their risk of heart disease by 15 percent (via The National Library of Medicine). Other studies have also found that the risk of heart attacks and other heart disease is lessened among those who eat fish regularly (via Healthline).

While it may seem counterintuitive, the fattier the fish, the better it is for your heart. Fatty fish such as salmon, sea bass, and sardines are high in omega-3 fatty acid, which is optimal for heart health. These fatty fish actually contain two kinds of omega-3 fatty acids: DHA and EPA, both have which have been shown to have a number of wide-ranging health benefits (via Medical News Today). In addition to being heart-healthy, they have been shown to minimize inflammation in the body, and combat anxiety (via Harvard Health Letter).

Mercury is a metal found in both freshwater and saltwater water systems. It's caused by both natural sources as well as pollutants (via The United States Geological Survey). High levels of mercury have been associated with lung and kidney problems, and issues with the nervous, digestive, and immune systems. High levels of mercury intake can be deadly. 

Meanwhile, bigger fish such as tuna, swordfish, and king mackerel generally have the highest levels of mercury because they consume smaller fish, which have small amounts in their systems (via National Resources Defense Council). We, in turn, eat those larger fish and the mercury begins to build up in our own bodies. Mercury is particularly impactful on developing babies, which is why pregnant women are warned against eating fish with a high mercury content (via March of Dimes).

While cognitive decline is a natural occurrence during the aging process, the consumption of fish has been shown to slow the rate of mental decline (via The National Library of Medicine).

Fish consumption is also shown to help with improving the functional tissue of the brain, in areas that deal with memory. Another benefit of the previously mentioned omega-3 fatty acids is that they help with brain health. Specifically, they aid in building the membranes around the brain cells, which improves their structure and function (via Medical News Today). A study from 2017 carried out by a number of California university research centers found that omega-3 fatty acids are able to increase the blood flow to the brain as well (via The National Library of Medicine). The same study found that there was a connection between omega-3 intake and improved cognitive function.

The body creates vitamin D from exposure to direct sunlight. In sunny part of the world, humans ought to be able to soak up all of the vitamin D the body needs solely from the sun's rays, especially during the warmer months of the year (via The National Health Service). However, in regions without ample amounts of sun or during cloudy periods of the year, the body still needs vitamin D because the vitamin helps in regulating the amount of calcium in the body, and is essential in keeping the bones, teeth, and muscles in good shape (via The National Health Service).

Fish can provide a source of vitamin D year round, and you don't need to eat much of it either. A single 4-ounce serving of salmon can get you 100 percent of the recommended daily value. Nearly half of the United States population is vitamin D deficient, but a couple of outings to the fishmonger would put that problem to rest right away.