Codes and Frequencies
VITASELN reports whether sample adults had taken a selenium supplement during the past 12 months. In 2002, VITASELN was asked of sample adults who had used high dose or megavitamin therapy for their own health or treatment in the past 12 months (VITYR). In 2005, VITASELN was asked of all sample adults who had taken vitamin or mineral supplements in the past 12 months (VITANY).
In 2002, respondents were asked, "During the past 12 months, did you use high dose or megavitamin therapy for your own health or treatment?" Those with an affirmative response (i.e., a "Yes" response in VITYR) were shown a flash card containing a list of vitamins and minerals. They were asked, "During the past 12 months, did you take any of the following vitamins in high dose? You may choose more than one."
In 2005, interviewers asked, "During the past 12 months, did you take selenium?" Interviewers were instructed to "read if necessary," "Do not include any selenium in the multi-vitamins you told me about."
Vitamin and Mineral Supplements in NHIS
Selenium is one of 12 vitamin/mineral supplements in the NHIS that respondents could report using during the past 12 months.
The other such supplements, along with the years these variables are available, are:
- Beta carotene (VITABETA, 2005)
- Calcium (VITACALC, 1992, 2000, 2002, 2005)
- Vitamin A (only) (VITAMINA, 1992, 2000)
- Vitamin C (VITAMINC, 1992, 2000, 2002)
- Vitamin E (VITAMINE, 1992, 2000, 2002, 2005)
- Multi-vitamin (VITAMULTV, 1992, 2000, 2002, 2005)
- Coenzyme Q-10 (VITYCOEN, 2002)
- DHEA (VITYDHE, 2002)
- Vitamins A and/or D (VITYVITAD, 2002)
- Vitamin B complex (VITYVITB, 2002)
- Zinc (VITYZINC, 2002)
In 2005, information was also collected on how long respondents had taken selenium.
Respondents who gave an affirmative response to the question associated with VITASELN were asked the number of months they had taken selenium supplements (VITASELNMO).
Those who had taken selenium during at least one month in the past 12 months were asked how often they had taken selenium in those months (VITASELNNO), responding as desired in terms of days per week or days per month (VITASELNTP).
For more information on the full range of variables dealing with vitamins and minerals, see VITANY.
Because of differences in the question wording for VITASELN, researchers should exercise caution when comparing responses between 2002 and 2005.
All variables from 2002 pertaining to the use of particular vitamins/minerals in the past 12 months--including VITASELN--indicate whether the respondent took the vitamin/mineral as part of high dose or megavitamin therapy.
The 2002 Field Representative's Manual defines such therapy as "the use of vitamins in excess of the Recommended Daily Allowances (RDA) established by the National Academy of Sciences, Food and Nutrition Board."
Thus, an affirmative response to VITASELN in 2002 indicates that the sample adult took selenium in high doses. A negative response to VITASELN in 2002 indicates that the respondent did not take high doses of selenium, but does not indicate that he/she took no selenium at all in the past 12 months.
By contrast, an affirmative response to VITASELN in 2005 indicates that the respondent took any amount of selenium in the past 12 months.
- 2002: Sample adults age 18+ who have used high dose or megavitamin therapy for their own health or treatment during the past 12 months.
- 2005: Sample adults age 18+ who took any vitamin or mineral supplements in past 12 months.
- 2002, 2005
- 2002, 2005 : SAMPWEIGHT