Wild or Farmed Salmon: Which Can be Dangerous to Health

Wild salmon is caught in natural environments such as oceans, rivers, and lakes. Salmon is valued for its health benefits. This fatty fish is rich in omega-3 fatty acids, which most people lack. However, not all salmon are the same.

Today, most of the salmon you buy is not caught in the wild but is raised on fish farms. This article explores the differences between wild and farmed salmon and whether one is healthier than the other.

Different environments

Wild salmon are caught in natural environments such as oceans, rivers, and lakes. But half of the salmon sold worldwide comes from fish farms that use a process known as aquaculture to raise fish for human consumption. Annual global production of farmed salmon has increased from 27,000 to more than 1 million metric tons over the past two decades.

While wild salmon eat other organisms found in their natural habitat, farmed salmon are given processed, fatty and high-protein food to produce larger fish. Wild salmon is still available, but global stocks have halved in just a few decades. Differences in nutritional valueFarmed salmon eat processed fish feed, while wild salmon eat a variety of invertebrates.

For this reason, the nutritional composition of wild and farmed salmon varies greatly. Obviously, the differences in the nutrition of wild and farmed salmon can be significant. Farm-raised salmon contains much fatter, slightly more omega-3, much more omega-6, and three times more saturated fat. In addition, it has 46% more calories, mostly from fat.

Conversely, wild salmon contains more minerals, including potassium, zinc, and iron. Polyunsaturated fat contentThe two main polyunsaturated fats are omega-3 and omega-6 fatty acids. These fatty acids play an important role in your body. They are called essential fatty acids or essential fatty acids because they are necessary for your diet.

However, the right balance must be maintained. Most people today consume too much omega-6, upsetting the delicate balance between these two fatty acids. Many scientists speculate that this can cause increased inflammation and may play a role in today’s pandemics of chronic diseases such as heart disease.

Although farmed salmon contains three times more fat than wild salmon, most of these fats are omega-6 fatty acids. For this reason, the ratio of omega-3 to omega-6 is about three times higher in farmed salmon than in wild salmon. Nevertheless, the ratio of farmed salmon (1:3-4) is still excellent – it is just worse than that of wild salmon, which is 1:10.

Both farmed and wild salmon should lead to a significant improvement in omega-3 intake for most people – and is often recommended for this purpose. In a four-week study of 19 people, eating farmed Atlantic salmon twice a week increased blood levels of omega-3 DHA by 50%.

Farmed salmon may contain more pollutants

Fish tend to absorb potentially harmful pollutants from the water they swim in and the food they eat. Studies published in 2004 and 2005 showed that farmed salmon have much higher concentrations of pollutants than wild salmon. Some of these contaminants include polychlorinated biphenyls (PCBs), dioxins, and several chlorinated pesticides.

Perhaps the most dangerous contaminant found in salmon is PCBs, which are closely linked to cancer and various other health problems. One study published in 2004 found that PCB concentrations in farmed salmon were on average eight times higher than in wild salmon. These levels of contamination are considered safe by the FDA, but not by the US Environmental Protection Agency.

Researchers have hypothesized that if EPA guidelines were applied to farmed salmon, people would be advised to limit their salmon consumption to no more than once a month. That said, one study found that levels of common contaminants such as PCBs in Norwegian farmed salmon dropped significantly from 1999 to 2011. These changes may reflect lower levels of PCBs and other contaminants in fish feed (21).

In addition, many argue that the benefits of eating omega-3s from salmon outweigh the health risks associated with contaminants.

Mercury and other trace metals

The current evidence for trace metals in salmon is conflicting. Two studies have shown very little difference in mercury levels between wild and farmed salmon. However, one study found that wild salmon had levels three times higher.

In general, arsenic levels are higher in farmed salmon, but cobalt, copper, and cadmium levels are higher in wild salmon. In any case, traces of metals in any of the salmon varieties are present in such low amounts that they are unlikely to cause concern.

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Written by Emma Miller

I am a registered dietitian nutritionist and own a private nutrition practice, where I provide one-on-one nutritional counseling to patients. I specialize in chronic disease prevention/ management, vegan/ vegetarian nutrition, pre-natal/ postpartum nutrition, wellness coaching, medical nutrition therapy, and weight management.

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