Tuna does have a fairly significant among of iron in it which is definitely important to the body for a number of reasons. This particular type of fish also has a significant amount of protein as well as vitamin K, E, B12, and B6 in it. In tuna you will also find that there is niacin, riboflavin, folate, and pantothenic acid.
A lot of the nutrients that are found in tuna are especially good for those who are on a diet because they help to metabolize fat in the body much faster which can in turn assist with weight loss. Tuna does not however contain any vitamin D or thiamin. There is no trans fat in tuna and only 1 gram of saturated fat per serving of 100 grams which is not a very significant amount at all and once again makes for a great diet food.