You may not be so quick to turn up your nose at sardines once you learn more about these nutritional powerhouses. "Sardines are a low-mercury, sustainable seafood that are an abundant source of omega-3 fatty acids (which have shown promising benefits for heart health), vitamin B12, vitamin D, calcium, iron, magnesium, and phosphorus," Maya explained. These tiny fish can be added to salad, served as part of a starter, or even eaten as a snack with crackers.