How do I prevent workitem change email notifications?

Is there any way to prevent the workitem change notification when updating a workitem via RESTful services?

I am modifiying a custom field on several thousand workitems on a regularly scheduled basis and the genartion of the email notifications is causing both performance issues with the tool as well as confusion for our users who are receiving the emails.

The services are written in C# and follow the guidance provided here : https://jazz.net/library/article/352#cm_and_rm.

Any help would be greatly appreciated.