Exhibit 16 August 1, 2007 U.S. Securities and Exchange Commission Office of the Chief Accountant 100 F Street, NE Washington, DC 20549 Re: USANA Health Sciences, Inc. File No. 0-21116 Dear Sir or Madam: We have read Item 4.01 of Form 8-K/A of USANA Health Sciences, Inc. dated August 1, 2007, and agree with the statements concerning our Firm contained therein. Very truly yours, /s/ Grant Thornton LLP GRANT THORNTON LLP