IF statement pertaining to a SUM formula

I have created a spreadsheet that has a series of questions and an applicable drop down list beside each question with an appropriate numeric rating (e.g. 0, 1, 2, 3, 4 or 5). I have put in a formula to sum the total of all of those numbers. I would also like to add an additional statement to say that if any of those cells in the sum formula are equal to zero then the total value should equal zero.

Here is my current formula:

=SUM(B16,F16,D16,H16,J16,L16,N16,B29,D29,F29,H29,J29,L29,N29)