Soft drinks, candy, cookies, snack crackers, and ice cream are food items and are therefore eligible items
Seafood, steak, and bakery cakes are also food items and are therefore eligible items
Since the current definition of food is a specific part of the Act, any change to this definition would require action by a member of Congress. Several times in the history of SNAP, Congress had considered placing limits on the types of food that could be purchased with program benefits. However, they concluded that designating foods as luxury or non-nutritious would be administratively costly and burdensome. Further detailed information about the challenges of restricting the use of SNAP benefits can be found here:
http://www.fns.usda.gov/snap/retailers/eligible.htm