The 2002 Field Representative's Manual defines "high dose or megavitamin therapy" as:

This definition was not routinely shared with respondents.

Sample adults with an affirmative response to VITEV could also report that they had ever used:

• Multi-vitamins such as One-A-Day (VITMULTEV)

• Individual vitamin supplements (VITSUPEV)

However, only those who had used megavitamin therapy (i.e., with a "Yes" response in VITMEGAEV) were asked further questions about their use of vitamins in 2002.

Respondents who had ever used high dose or megavitamin therapy were asked follow-up questions including: whether they had used such therapy in the past 12 months; which vitamins were taken in high dose; whether megavitamin therapy was used to treat a specific health problem or condition and which condition(s) such therapy was used to treat; other reasons for using megavitamin therapy; the importance of megavitamin therapy to their well-being; whether they were seeing a practitioner for megavitamin therapy; and whether they had told a conventional health care practitioner about their use of megavitamin therapy.

For more information on the aforementioned variables related to high dose or megavitamin therapy, see VITYR.