Nutritional Value of Fresh Sardines or Canned Sardines

Those little cans of sardines, perfect for packing a lunch, offer more nutrition than you might imagine. Sardines' nutrition rivals that of many foods that are more expensive and require more preparation.

Sardines and good nutrition go hand-in-hand. These little fish are full of omega-3 fatty acids. A four-ounce serving contains 1,100 to 1,600 milligrams of omega-3s, according to Harvard Health.

To give you some context, a four-ounce portion of Atlantic, chinook or coho salmon contains from 1,200 to 2,400 milligrams of omega 3s. So on a per-ounce basis, there's not much difference between sardines and wild-caught salmon.

A 3½-ounce serving of sardines, or 100 grams, is equivalent to a typical can of sardines. There are 208 calories in a can of sardines of that size, according to the USDA Nutrient Database. This serving of sardines provides 24 grams of protein and 11.45 lipids of fat.

The same 3½-ounce serving contains 302 milligrams of calcium, about 25 percent of the recommended daily value. It provides 3 grams of iron, about a sixth of the daily recommended dose. It delivers more than three times the daily recommended dose of potassium, about 10 percent of the daily recommended dose of magnesium and slightly more than a third of the recommended daily dose of phosphorus.

Sardines as food also contain far more than the daily dose value of vitamin B12. These tiny fish boast significant amounts of vitamin A, vitamin D and vitamin E. They contain 142 milligrams of cholesterol, which is about half of the USDA daily recommended intake, but the fatty acids tend towards the monounsaturated and polyunsaturated, in line with the USDA fat guidelines. Sardines can truly be considered a superfood.

Read more: Are Canned Sardines Bad For You?

Other than salmon and mackerel, sardines contain one of the highest concentrations of omega-3s of any seafood, ounce for ounce, according to Harvard Health. Omega-3s are fatty acids, but they're not the kind of fatty acids that clog your arteries. Red meat and processed meats don't have the same kind of omega-3 content, according to the American Heart Association (AHA).

The AHA recommends eating fatty fish at least twice a week. These include sardines, salmon, mackerel, herring, lake trout and albacore tuna. Omega-3s benefit the hearts of healthy people and also of those who are at high risk for heart disease. They may decrease the risk of abnormal heartbeats, reduce triglycerides (a fatty lipid) and slow the growth of artery-clogging plaque.

Eating sardines also helps with the AHA's suggestion of getting your omega-3s through food, if possible. If you have heart disease, you may want to take a regular supplement as well, but talk with your doctor about this first.

Read more: 17 Reasons Why You Need More Omega 3s in Your Diet

Eating sardines can boost your fish intake, especially if you eat them in place of red meat. These fish are a staple in many parts of the Mediterranean region and can be combined with fruits, vegetables, beans, nuts, other types of seafood, olive oil and dairy products.

According to Harvard Health, some of the benefits of a Mediterranean diet include:

• An emphasis on healthy fats and unprocessed foods that helps improve cardiovascular health
• Antioxidants in the diet that combat cell stress and lead to longer DNA telomeres, protecting against chronic disease and early death
• The prevention of age-related chronic diseases

The Nurses Health Study, a long-term study of more than 10,000 women aged 57 to 61, was chronicled in the November 2013 issue of the Annals of Internal Medicine. Researchers assessed the effect of Mediterranean dietary patterns on aging. They have found that increased intakes of plants, whole grains and fish and moderate alcohol consumption contribute to healthy aging with no chronic diseases or major decline in mental health or physical function.

Read more: 7 Myths About Dietary Fats You Should Stop Believing Right Now

Sardines are tiny, compared to most fish. They grow to a maximum of just under eight inches, according to Food & Wine, although canned sardines are often no more than half that size. Sardines are named for the Mediterranean island of Sardinia, where they were once found in large numbers, and are a member of the same family as herring.

These fish have white flesh and, when you see them swimming, they have a lower jaw that juts out slightly. You might find them fresh at fish markets in the summer, but according to Food & Nutrition, you're more likely to see them canned. The skin and bones, sometimes included, are also edible. Sardine bones are soft and provide high doses of calcium.

They're often packed in oil, water or sauce, and sometimes they're smoked or salted. Sardines don't cost a lot, making them appealing to thrifty shoppers. You can eat them from the can, and Food & Nutrition suggests mashing them with mustard and onions as a spread on crackers or toast. They can be added to salads, or sauteed with herbs as a pasta topping.

You may see them on restaurant menus in summer. European coastal regions often feature freshly grilled sardines in during this season. Fresh sardines are perishable and hard to find, but you can find them frozen from some seafood producers.

There aren't many downsides to sardines, according to the AHA. If you're worried about mercury, sardines have one of the lowest concentrations of mercury of any seafood, at 0.012 parts per million, according to the Food and Drug Administration. The FDA labels sardines as the best choice.

Sardines are typically packed in aluminum cans, some of which are lined with bisphenol A, or BPA. According to the Center for Environmental Health (CEH), 38 percent of the cans tested had BPA linings.

BPA can migrate into the food inside the can. The problem with this compound, according to CEH, is that it can lead to serious reproductive health problems. Other studies cited by the CEH indicate possible connections to diabetes, heart disease and other health problems.

If you're concerned about the aquatic environmental implications of eating sardines, the Monterey Bay Aquarium's Seafood Watch has a list of which types of sardines to avoid and which to buy. The National Oceanic and Atmospheric Administration states that some populations are over-fished, but that there are large fluctuations in sardine populations, which helps the fish to rebound quickly when heavily fished in a given region.