Canned sardines: healthier than tuna and safe for mercury

Canned sardines are among the healthiest preserved fish — they contain high levels of omega-3 fatty acids, calcium and protein, and are inexpensive and widely available. Unlike tuna, they accumulate only minimal amounts of mercury and heavy metals because they are small fish that feed on plankton. Dietitians recommend them as a safe alternative for people concerned about toxins in canned fish.