How to prevent Office apps from launching executables

I posted the following in an Office forum and they recommended that I post it
here. Please let me know your thoughts.

"I noticed that Word and other Office apps will allow a user to execute any
file type. All you have to do is click File, Open...select view all file
types,
right click the file to execute and then select "Run As" and bingo,
the file executes.

From a security perspective, this is a major issue for our company.
Is there any way to limit the file types that can be viewed or
designate the directory that the File Open option can only view or disable
the Run As option that is displayed when you right click the file?"

Thanks
-Don