Linking ASA24 and NHANES Data with the Nova Classification System for Industrial Food Processing

On this page...

• Description
• Development
• Use
• Data Requests
• References
• Contact

Description

The Nova Classification System of Industrial Food Processing was initially developed in 2009 [5] and since then further refined [1, 2] by a team at the University of São Paulo under the view that the extent and purpose of industrial food processing contributes to explain the current relationships between dietary patterns, health, and disease.

The Nova Classification System of Industrial Food Processing classifies foods into four groups:

• Group 1 - Unprocessed or minimally processed foods
• Group 2 - Processed culinary ingredients
• Group 3 - Processed foods
• Group 4 - Ultra-processed foods [1, 2].

See Table 1 from Martinez-Steele et al, 2023 (3) for more detailed descriptions for each Nova group.

The resources described on this web page provide researchers with a standardized method described by Martinez-Steele et al, 2023 for using the Nova Classification System with dietary data collected via the National Cancer Institute (NCI)’s Automated Self-Administered 24-hour (ASA24) Dietary Assessment Tool, as well as the National Health and Nutrition Examination Survey (NHANES). Both ASA24 and NHANES use the same food composition data from the USDA’s Food and Nutrient Database for Dietary Studies (FNDDS).

Development

Researchers at the University de São Paulo and the NCI collaborated to standardize application of Nova to major data sources that connect to the USDA’s FNDDS, including the NHANES and dietary data collected via NCI’s ASA24. In brief, FNDDS food codes are disaggregated into their smallest components (similar to ingredients) and the corresponding gram weight and energy (kcal) for each component are assigned to one of the four Nova groups and one of the 37 Nova subgroups [4].

The Nova classification was determined by considering the qualitative descriptions of the underlying food codes or SR codes. The decision to use an SR code rather than a food code depended on whether there was any indication that the food code could have been homemade. Food codes that were likely to be homemade or artisanal and linked to a list of scratch ingredient SR codes were classified at the SR code level. Conversely, foods likely purchased as ready-to-eat/heat/drink items were classified at the food code. Mixed dishes were assumed to be homemade unless the food item description or SR codes clearly suggested that it was ready-to-eat.

Details of how this method is applied to individual-level intake data from NHANES is previously published [4], and this method was adapted to the food codes available in ASA24 to merge into respondent reported data.

Use

For NHANES, respondents’ food and beverage intake reported in the 2001-2002 through 2017-2018 NHANES data cycles is currently classified with the Nova Classification System. The available data files present total daily grams and energy from each Nova group and subgroup, both absolute and proportion values, for each NHANES respondent on day 1 and day 2 of dietary data collection. Additional data files present all food codes that respondents recorded during an NHANES dietary recall for each NHANES cycle. These variables represent the proportion of grams and energy from each Nova group and subgroup for each food code available in that NHANES cycle.

For ASA24, the data files present all possible food codes that respondents could record during an ASA24 dietary recall or record for versions starting from ASA24 2011. These variables represent the proportion of grams and energy from each Nova group and subgroup for each food code available in that version of ASA24. These files do not provide absolute gram or energy amounts as this will vary based on the portion size that a respondent reports. These variables can be merged into the ITEMS file for any ASA24 study. Please refer to the ASA24 Sample Analysis Files and Data Dictionaries web page for more information.

Data Requests

Database files that link to FNDDS food codes by version of ASA24 and cycle of NHANES are available upon request via a proposal process. Please send an email to RFAB@mail.nih.gov to request the proposal form. The proposal will be reviewed by the Steering Committee members once received and the appropriate datasets will be released to the proposal lead. Each proposal should result in only one analysis or manuscript. Second or follow-up analyses or manuscripts will require an additional proposal.

References

1. Monteiro CA, Cannon G, Moubarac JC, Levy RB, Louzada MLC, Jaime PC. The UN Decade of Nutrition, the NOVA food classification and the trouble with ultra-processing. Public Health Nutr. 2018 Jan;21(1):5-17. doi: 10.1017/S1368980017000234. PMID: 28322183.
2. Monteiro CA, Cannon G, Levy RB, Moubarac JC, Louzada ML, Rauber F, Khandpur N, Cediel G, Neri D, Martinez-Steele E, Baraldi LG, Jaime PC. Ultra-processed foods: what they are and how to identify them. Public Health Nutr. 2019 Apr;22(5):936-941. doi: 10.1017/S1368980018003762. PMID: 30744710
3. Martinez-Steele E et al. Best Practices for applying the Nova food classification system. Nature Food. 2023. Jun;4(6):445-448.
4. Martinez-Steele E, O'Connor LE, Juul F, Khandpur N, Galastri Baraldi L, Monteiro CA, Parekh N, Herrick KA. Identifying and Estimating Ultraprocessed Food Intake in the US NHANES According to the Nova Classification System of Food Processing. J Nutr. 2023 Jan;153(1):225-241.
5. Monteiro CA. The issue is not food, nor nutrients, so much as processing. Public Health Nutr. 2009. 12, 729–731.

Contact

Please send any questions to the Risk Factor Assessment Branch at RFAB@mail.nih.gov.