Tuna in Oil Vs. Tuna in Water

Canned tuna is great for a quick and convenient lunch, and is also the perfect store cupboard standby for family favorites like a pasta bake or crowd-pleasing tuna cakes. But whether you should buy tuna in oil or tuna in water is a conundrum.

If you're concerned about calories, tuna in water is certainly better for your waistline. According to the USDA, 1/2 cup of canned tuna in oil contains 145 calories, while 1/2 cup of canned tuna in water has only 66 calories.

When it comes to omega-3 fats — healthy fats that the American Heart Association says may reduce the risk of heart attacks and strokes — canned tuna in water is also the better bet.

A November 2011 study — the only one of its kind — published in Public Health Nutrition found water-packed tuna has about three times more of the beneficial EPA and DHA omega-3 fats as tuna in oil. This is because when you drain oil from oil-packed tuna, some of the omega-3s in the fish go with it. But water and oil don't mix, so when you drain the liquid from water-packed tuna, it does not reduce the omega-3.

However, in some cases, tuna in oil scores better. For instance, 1/2 cup of canned tuna in oil has 55.5 micrograms of selenium compared to 48.7 micrograms in the same amount of tuna in water. According to the National Institutes of Health Office of Dietary Supplements, selenium is important for reproduction, thyroid gland function and protecting the body from infection.

In regard to fat-soluble vitamin D, there's a big difference: One-half cup of tuna in oil has 4.9 micrograms of the nutrient, while 1/2 cup of tuna in water has only 0.83 micrograms. So the tuna in oil is a more bone-friendly food.

Separate from the issue of canned tuna in oil vs canned tuna in water, you've probably noticed that there are two other main varieties of the fish on sale in the grocery store. These are "light" tuna (largely skipjack) and "white" (also known as albacore) tuna.

These two types of tuna differ in their toxin content — in particular how much mercury they contain. According to the Food and Drug Administration (FDA), canned light tuna is a "best" choice when it comes to mercury content. However, canned and fresh white or albacore tuna only rates as a "good" choice. It's recommended that people limit their consumption of fish types that fall into the latter category to one portion a week.

The FDA also says that pregnant and breastfeeding women should choose the types of fish lowest in mercury, so if you are in this group and are shopping for canned fish, you would be better buying light, and not white/albacore tuna.

Read more: Canned Tuna May Not Be as Healthy as You Thought

The best advice if you are not pregnant or breastfeeding and aren't eating more than a portion (4 ounces) of tuna a week, is to choose the tuna that best suits your personal taste or the recipe you are using. You might find drained oil-packed tuna more appetizing eaten as a snack with cut up veggies for example. Plus, choosing tuna in oil might mean you don't need to add mayonnaise.

State-registered UK dietitian Helen Bond tells LIVESTRONG.com: "Though there are waistline advantages to tuna in water, tuna in oil is not an unhealthy option. This is because the oil that tuna is packed in almost always an unsaturated oil, like sunflower oil or soybean oil, so isn't bad for your heart health like a saturated oil can be."

Perhaps more relevant health-wise is how high your can of tuna is in sodium, which the Centers for Disease Control and Prevention says can increase blood pressure. Compare labels and try to choose a lower sodium variety; Harvard Health Publishing also says rinsing canned tuna to is an easy way to cut down on sodium.

Read more: 5 Foods That Serve Up More Antioxidants When You Buy Them Canned