Canned Tuna May Not Be as Healthy as You Thought

Tuna fish is ideal for a quick lunch or dinner and makes a great snack between meals. According to the National Fisheries Institute, one in four Americans enjoys canned tuna at least once a week. Low in calories and high in protein, this treat fills you up quickly and satisfies your cravings without adding inches to your waist. But is it really that healthy?

Rich in protein and low in calories, canned tuna fits into most diets and makes a healthy snack or meal. (Image: Yulia_Davidovich/iStock/GettyImages)

Tip

Canned light tuna is lower in mercury than raw, boiled and grilled tuna fish. Choose low-sodium varieties that come packaged in BPA-free cans.

Canned Tuna Nutrition Facts

Compared to other canned foods, tuna is less processed and packs a hefty nutritional punch. Most brands use only salted fish and vegetable oil or water. This means you don't have to worry about hidden sugars, additives and potentially dangerous chemicals.

The nutritional value of tuna fish varies among brands. Water-packed tuna, for example, boasts more than 42 grams of protein and just 191 calories per can. It also provides 1.4 grams of fat, 464 milligrams of omega-3s, 14.8 milligrams of omega-6s, and 190 percent of the recommended dietary allowance of selenium. It's a good source of phosphorus, iron, magnesium, vitamin A and B-complex vitamins, such as niacin and riboflavin.

Oil-packed tuna, by comparison, has approximately 339 calories per can. Some varieties are higher in protein than others, depending on the amount and type of fish. In general, the most popular canned varieties are skipjack and albacore tuna. Bluefin and bigeye tuna are typically sold fresh or frozen.

Is Canned Tuna Safe?

Experts agree that tuna fish promotes health and well-being, but they also warn about the high mercury levels in canned varieties. According to a 2015 review published in the journal Environmental Research, eating canned tuna once a week is unlikely to cause any adverse reactions. Raw and cooked tuna fish are higher in mercury and should be consumed only once a month or so.

As the Environmental Defense Fund notes, air pollution is a major contributing factor to mercury contamination. With a few exceptions, canned light tuna appears to be lower in mercury than canned white and albacore tuna. Consumer Reports points out that around 20 percent of the dietary mercury exposure comes from canned albacore and 37 percent from canned tuna. Researchers advise pregnant women to completely avoid this fish.

Mercury is a metal that occurs naturally in the environment. However, this doesn't mean it's safe for human consumption. As Medical News Today notes, exposure to mercury may cause anxiety and depression, memory problems, difficulty walking, numbness, vomiting, nausea and muscle weakness. In the long run, it may lead to nerve damage, infertility and cardiovascular disease.

Potential Health Benefits

Clinical research confirms the potential health benefits of canned tuna. Due to its high content of omega-3s, this fish supports brain function. According to a 2014 article featured in Human Psychopharmacology, these dietary fats enhance cognitive performance. They also support the proper functioning of the immune, cardiovascular and endocrine systems; promote cardiovascular health; and reduce inflammation.

Canned tuna is also an excellent source of protein. Your body needs this nutrient to build and preserve lean mass, maintain bone mineral density and recover from exercise. Furthermore, a 2017 clinical trial published in the journal Obesity Facts has linked high-protein diets to weight loss, increased satiety and improved metabolic health.

This fish also provides large amounts of selenium, potassium, B vitamins and omega-6 fatty acids. Since it contains no carbs or sugars, it's ideal for ketogenic and low-carb diets. The mercury in tuna isn't a reason for concern as long as you don't go overboard — moderation is the key. Ideally, choose low-sodium varieties with a high protein content; purchase tuna fish that comes in BPA-free cans to reduce your exposure to bisphenol A, a potentially dangerous chemical.

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