TABLE 3.

Methods used for collection of food and nutrient intakes in NHANES¹

					Continuous NHANES
Characteristic	NHANES I: 1971–1974	NHANES II: 1976–1980	Hispanic NHANES: 1982–1984	NHANES III: 1988–1994	1999–2006	2007–2010	2011–2014
Dietary assessment method
24-h recall, d	1	1	1	12	1 (1999–2002); 2 (2003–2006)	2	2
FFQ	Yes	Yes	Yes	Yes (expanded version)	Yes (expanded version in 2003–2006)	Yes	Yes
Dietary recalls publicly available, n	1	1	1	12	1 in 1999–2002; 2 in 2003–2006	2	2
Database used for 24-h dietary recall	In-house	In-house	In-house	In-house	In-house (1999–2001); FNDDS version 1.0 (2001–2002); FNDDS version 2.0 (2003–2004); FNDDS version 3.0 (2005–2006)	FNDDS version 4.1 (2007–2008); FNDDS version 5.0 (2009–2010)	FNDDS 2011–2012
Dietary supplements during home interview3	Vitamin and mineral use; no question on duration; “regular” or “irregular” use reported	Vitamin and mineral use; no question on duration; “regular” or “irregular” use reported	Not collected	Vitamin and mineral use over the past month; name, manufacturer, duration, frequency, and amount taken	Vitamins, minerals, herbals, other types of dietary supplements; prescription and over the counter; use over past 30 d; full name, strength, manufacturer, duration, frequency, and amount taken	Vitamins, minerals, herbals, other types of dietary supplements; prescription and over the counter; use over past 30 d and past 24 h; full name, strength, manufacturer, duration, frequency, and amount taken in past 24 h; reason for taking product	Vitamins, minerals, herbals, other types of dietary supplements; prescription and over the counter; use over past 30 d and past 24 h; full name, strength, manufacturer, duration, frequency, and amount taken in past 24 h; reason for taking product
Dietary supplements database	NA	NA	NA	Database contracted out	NHANES Dietary Supplement Database	NHANES Dietary Supplement Database	NHANES Dietary Supplement Database

¹FFQ, food-frequency questionnaire; FNDDS, Food and Nutrient Database for Dietary Studies; NA, not applicable.

²The Supplemental Nutrition Survey for Older Americans was conducted on persons aged ≥50 y who provided 24-h recall in 1988–1991 as part of NHANES III. These individuals provided up to 2 additional 24-h recalls over the telephone to trained dietary interviewers ~8 and 6 mo after their first recall at the Mobile Examination Center. These data are publicly available on the NHANES website (14).

³Since the 1980s, dietary supplement use information has been collected during the household interview. Since 2007, information on dietary supplements consumed during the 24-h recall period also has been assessed during the dietary interviews.