Canned tuna in oil typically contains more calories and fat than canned tuna in water. Additionally, canned tuna in oil may contain added salt but offer more vitamin D compared to canned tuna in water. It's important to note that both canned tuna in oil and water can be a healthy addition to a balanced diet, and that the health benefits will ultimately depend on how the tuna is prepared and consumed. In the end, the selection of tuna should be based on your personal preference or the recipe requirements. However, pregnant women and nursing mothers must keep in mind mercury levels. The FDA recommends these groups as well as young children, choose from the "best choices" fish, which includes canned light and skipjack tuna [2]. The FDA reports that fish from the "good choices" list, which includes albacore and yellowfin tuna are okay to consume once per week for individuals not in the aforementioned groups. Additionally, the FDA recommends avoiding big eye tuna, which contains high levels of mercury [2].