Salmon
This versatile fish is a fan-favorite for a reason. It can be served at any time of day (think: a lox bagel for breakfast, a salmon Caesar salad for lunch, a filet for dinner), and a three-ounce piece contains 447 IU, per the USDA. Rifkin adds that it also provides protein and important omega-3 fats. Limited research shows that wild-caught salmon may contain higher amounts of vitamin D than farmed fish.