For sample adults who had taken any vitamin or mineral supplements during the past 12 months (VITANY), VITAMINA indicates whether they had taken any vitamin A during that period.
In 2000, interviewers were instructed to "read if necessary," "Do not include any Vitamin A in the multi-vitamins you told me about." Similar instructions are found in the 1987 and 1992 surveys.
Vitamin and Mineral Supplements in NHIS
Vitamin A 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, 1987, 1992, 2000, 2002, 2005)
- Vitamin C (VITAMINC, 1987, 1992, 2000, 2002)
- Vitamin E (VITAMINE, 1987, 1992, 2000, 2002, 2005)
- Multi-vitamin (VITAMULTV, 1987, 1992, 2000, 2002, 2005)
- Selenium (VITASELN, 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 1987, 1992 and 2000, respondents who gave an affirmative response to the question associated with VITAMINA were asked to report the number of months they had taken vitamin A supplements (VITAMINAMO).
In 2000 only, respondents who had taken vitamin A during at least one month in the past 12 months were asked how often they had taken vitamin A in those months (VITAMINANO), responding as desired in terms of days per week or days per month (VITAMINATP).
The National Center for Health Statistics recoded data from VITAMINANO and VITAMINATP to create two new variables with consistent time units: number of days per week took vitamin A during the relevant months of the past 12 months (VITAMINADWK), and number of days per month took vitamin A during the relevant months of the past 12 months (VITAMINADMO). VITAMINADMO is also available for 1987 and 1992, when it was asked as a direct question.
For more information on the full range of variables dealing with vitamins, see VITANY.
Apart from universe differences, VITAMINA is fully comparable for 1987, 1992 and 2000.
A somewhat related variable from 2002, VITYVITAD, reports respondents' use of vitamins A and/or D. Researchers wishing to combine or compare that variable with VITAMINA should exercise caution. VITAMINA reports the use of only vitamin A, and there is no way to determine whether a "Yes" response to VITYVITAD is an indication of a respondent's taking only vitamin A, only vitamin D, or both.
Moreover, VITYVITAD--and all other variables from 2002 pertaining to the use of particular vitamins/minerals in the past 12 months--indicates whether the respondent took vitamins A and/or D 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." By contrast, an affirmative response to VITAMINA indicates the use of any amount of vitamin A in the past 12 months.
- 1987: Half of sample persons age 18+ (excluded from CACT supplement) who took vitamin/mineral supplements in the past 12 months.
- 1992: Half of sample persons age 18+ in quarters 1 and 2, and in 2 weeks of quarter 3 (excluded from CACT supplement) who took any vitamin or mineral supplements in past 12 months.
- 2000: Sample adults age 18+ who took any vitamin or mineral supplements in past 12 months.
Codes and Frequencies
- 1987, 1992, 2000
- 1987, 1992, 2000 : SAMPWEIGHT