Differences in Consumption of NASEM Priority Nutrients and Food Groups by Race/Ethnicity Among Women Living in WIC-Participating Households

Abstract

Purpose:

To examine racial/ethnic differences in dietary intake of women in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC).

Design:

Cross-sectional study.

Setting:

Data from the US National Health and Nutrition Examination Survey.

Participants:

Women 19 to 50 years of age living in WIC-participating households.

Measures:

Nutrient/food group intake from one 24-hour dietary recall.

Analysis:

Multivariable linear regression was used to evaluate the relationship between race/ethnicity and nutrient/food group intake.

Results:

Compared to non-Hispanic white women, Hispanic women had lower dietary energy density (1.7 ± 0.1 vs 2.2 ± 0.1 kcal/g, P < .001), and better nutrient intake, including more folate (429 ± 20 vs 364 ± 29 µg, P = .024), fiber (20.1 ± 0.9 vs 13.6 ± 0.9 g, P ≤ .001), and potassium (2575 ± 78 vs 2251 ± 66 mg, P = .012). This may be related to greater consumption of total vegetables (1.67 ± 0.16 vs 1.17 ± 0.17 cup equivalents [c-eq], P = .029), including more red and orange vegetables (0.64 ± 0.11 vs 0.32 vs 0.09 c-eq, P = .013) and more legumes (0.17 ± 0.04 vs 0.07 ± 0.02 c-eq, P = .006). Both Hispanic and non-Hispanic black women consumed more sodium (Hispanic: P = .015; non-Hispanic black: P = .008), but less added sugars (Hispanic: P ≤ .001; non-Hispanic black: P = .015), than non-Hispanic white women.

Conclusion:

These findings highlight differences in dietary intake by race/ethnicity and can inform nutrition messages of WIC nutrition educators and dietitians.

Keywords

NHANES WIC maternal nutrition dietary intake nutrient intake

Purpose

The Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) is a federal nutrition assistance program that provides supplemental, nutrient-dense foods and beverages, nutrition education, and referrals to social/medical services for eligible pregnant, post-partum, and breastfeeding women up to their fifth birthday.¹ A limited number of studies have explored the relationship between race/ethnicity and dietary intake among WIC women,^2
-4 but these studies are limited in generalizability, and differences in nutrients/food groups commonly under-/overconsumed by WIC women remain unknown. Therefore, the objective of this study was to use nationally representative data to examine racial/ethnic differences in dietary intake of women living in WIC-participating households, with a focus on the priority nutrients and food groups described in the 2017 report by the National Academies of Sciences, Engineering, and Medicine (NASEM).⁵

Methods

Design

This national cross-sectional study was conducted using data from the National Health and Nutrition Examination Survey (NHANES). The NHANES is a continuous survey conducted by the National Center for Health Statistics (NCHS) using a complex, multistage, probability cluster-sampling design and is representative of the US civilian, noninstitutionalized population. The NHANES collected dietary data via 24-hour recall assessments,⁶ using the USDA Automated Multiple Pass Method.⁷ The NHANES collects 2 days of diet recall. The first recall is collected in-person at the Mobile Examination Center, and the second is collected via phone 3 to 10 days later.⁸ The first day of dietary recall was used for this study. Additional NHANES procedures can be found elsewhere.⁹ The NCHS Research Ethics Review Board reviewed and approved all study protocols for the NHANES. Since all NHANES data were deidentified and did not contain sensitive information, this study was exempt from further review at the university level.

Sample

Data from 2 cycles (2011-2012 and 2013-2014) of the NHANES were combined to create a sample of the most current national dietary estimates that included information on WIC participation status. The sample included women 19 to 50 years of age from households participating in the WIC program. Women with missing, incomplete, or unreliable day-1 dietary recall status were excluded from the analysis. WIC participation status was defined at the household level due to larger sample size and to account for potential spillover effects from family members participating in WIC.^10,11

Measures and Analysis

The primary measure for this study was population mean nutrient/food group intake. The variables selected for analysis included nutrients and priority food groups under-/overconsumed by WIC-participating women, as described in the 2017 NASEM report.⁵ Wald χ² test was used to assess distribution of sociodemographic characteristics. Multivariable linear regression was used to compare nutrient/food group intake of non-Hispanic black, Hispanic, and other/mixed race women to non-Hispanic white women. The model was adjusted for all relevant covariates: age, income, household size, and total energy intake. The NHANES day-1 dietary sample weight was also included in the model. All data were analyzed using SAS 9.4 survey procedures (SAS Institute, Cary, North Carolina), accounting for the differential probabilities of selection, nonresponse, and oversampling associated with the NHANES. For all statistical analyses, a P value of <.05 was considered statistically significant. Subanalyses by pregnancy status were not performed because the NHANES discontinued oversampling of pregnant women after 2006, which limited the number of pregnant, low-income, WIC-participating women surveyed.

Results

The final sample comprised 488 women 19 to 50 years of age living in WIC-participating households, including 130 non-Hispanic white, 131 non-Hispanic black, 174 Hispanic, and 53 other/mixed race women. Table 1 shows the results of the linear regression comparing nutrient/food group intake of women in different racial/ethnic groups. Hispanic women had lower dietary energy density (1.7 ± 0.1 vs 2.2 ± 0.1 kcal/g, P < .001) and better dietary nutrient distribution, including more folate (429 ± 20 vs 364 ± 29 µg, P = .024), fiber (20.1 ± 0.9 vs 13.6 ± 0.9 g, P ≤ .001), and potassium (2575 ± 78 vs 2251 ± 66 mg, P = .012), compared to non-Hispanic white women. Conversely, the diets of non-Hispanic black women had less calcium (802 ± 52 vs 930 ± 46 mg, P = .047) compared to non-Hispanic white women. Interestingly, both Hispanic and non-Hispanic black women consumed more sodium (Hispanic: P = .015; non-Hispanic black P = .008) but less added sugars (P ≤ .001 Hispanic, P = .015 non-Hispanic black) than non-Hispanic white women.

Table 1.

Racial/Ethnic Differences in Nutrient and Food Group Intake of Women 19 to 50 Years of Age Living in WIC-Participating Households.^a,b

	N-H White, n = 130		N-H Black, n = 131			Hispanic, n = 174			Other/Mixed, n = 53			Recommended Amount^d
Nutrient category^c	Mean	SE	Mean	SE	P Value	Mean	SE	P Value	Mean	SE	P Value	Recommended Amount^d
Energy density (kcal/g)	2.2	0.1	1.9	0.1	.038	1.7	0.1	<.001	2.0	0.1	.121	–
Nutrients to increase	Mean	SE	Mean	SE	P Value	Mean	SE	P Value	Mean	SE	P Value
Calcium (mg)	930	46	802	52	.047	1005	49	.259	883	68	.530	1000 (RDA)
Iron (mg)	13.4	1.5	13.0	1.0	.771	15.4	0.7	.111	15.4	1.3	.281	18 (RDA)
Folate (µg)	364	29	305	26	.141	429	20	.024	403	35	.394	400 (RDA)
Vitamin D (µg)	4.2	0.5	3.2	0.4	.127	4.4	0.4	.869	6.0	1.2	.187	600 IU^e (RDA)
Fiber (g)	13.6	0.9	14.2	0.9	.549	20.1	0.9	<.001	17.9	2.8	.140	28/25.2 (DGA)
Potassium (mg)	2251	66	2195	58	.551	2575	78	.012	2497	156	.163	4700 (AI)
Nutrients to limit	Mean	SE	Mean	SE	P Value	Mean	SE	P Value	Mean	SE	P Value
Added sugars (tsp-eq)	26.0	2.8	18.5	1.5	.015	15.3	2.3	<.001	17.9	3.6	.085	<10% kcal
Saturated fat (g)	26.4	1.0	24.9	1.0	.248	25.5	0.8	.421	24.6	1.4	.317	<10% kcal
Sodium (mg)	3125	117	3411	77	.008	3459	121	.015	3251	171	.508	2300 (UL)
Food group category^f	Mean	SE	Mean	SE	P Value	Mean	SE	P Value	Mean	SE	P Value	Recommended Amount^e
Total fruit (c-eq)	0.83	0.29	0.72	0.28	.786	0.94	0.14	.732	0.44	0.22	.299	2.0
Total vegetables (c-eq)	1.17	0.17	1.22	0.15	.848	1.67	0.16	.029	1.42	0.20	.299	3.5
Dark green vegetables (c-eq)	0.02	0.03	0.04	0.05	.736	0.05	0.04	.540	0.02	0.03	.946	0.4
Total red and orange vegetables (c-eq)	0.32	0.09	0.51	0.14	.225	0.64	0.11	.013	0.48	0.13	.194	1.0
Total starchy vegetables (c-eq)	0.46	0.07	0.35	0.07	.251	0.29	0.08	.132	0.38	0.17	.601	1.0
Legumes computed as vegetables (c-eq)	0.07	0.02	0.07	0.03	.998	0.17	0.04	.006	0.14	0.09	.416	0.4
Other vegetables (c-eq)	0.37	0.10	0.31	0.09	.620	0.69	0.09	.023	0.53	0.09	.140	0.8
Nuts and seeds (oz-eq)	0.41	0.12	0.26	0.09	.165	0.28	0.14	.324	0.97	0.60	.337	0.7
Total protein foods (oz-eq)^d	3.87	0.33	5.60	0.74	.032	4.67	0.64	.137	5.40	0.80	.096	6.5
Whole grains (oz-eq)	1.29	0.40	1.59	0.57	.501	0.71	0.30	.013	1.53	0.37	.613	4.5
Total grains (oz-eq)	6.02	0.60	6.90	0.62	.175	8.19	0.49	.004	5.96	0.54	.930	9.0
Total dairy (c-eq)	1.66	0.19	1.40	0.22	.420	1.90	0.30	.526	1.72	0.44	.899	3.0

Abbreviations: AI, adequate intake level; c-eq, cup equivalents; DGA, Dietary Guidelines for Americans 2015-2020; N-H black, non-Hispanic black; N-H white, non-Hispanic white; NASEM, National Academies of Sciences, Engineering, and Medicine; oz-eq, ounce equivalents; RDA, recommended dietary allowance; tsp-eq, teaspoon equivalents; UL, upper intake level; WIC, Women, Infants, and Children.

^a Least square means from linear regression models are presented with standard error (SE), representing population mean intake on a given day. Non-Hispanic white women are the reference group. Dietary recommendations are included for reference, statistical comparisons were not made to recommended intake.

^b N = 488.

^c Nutrients represent nutrient inadequacies and excesses linked to adverse health consequences relevant to pregnant, breastfeeding, or postpartum women, as described in the NASEM report.⁵

^d Recommendations represent daily nutrition goals derived from DGA 2015-2020. Source of goal noted in parentheses.¹²

^e DGA recommendations made on a per-week basis have been converted to a per-day basis in order to promote comparability between results and dietary recommendations.

^f Food groups selected for analysis represent higher and lower priorities for pregnant, breastfeeding, or postpartum women, as described in the NASEM report on the WIC Food Package.⁵

Racial/ethnic differences in food group intake were also observed. Hispanic women reported consuming more total vegetables (1.67 ± 0.16 vs 1.17 ± 0.17 c-eq, P = .029), including more red and orange vegetables (0.64 ± 0.11 vs 0.32 vs 0.09 c-eq, P = .013) and more legumes (0.17 ± 0.04 vs 0.07 ± 0.02 c-eq, P = .006), compared to non-Hispanic white women. However, Hispanic women consumed fewer whole grains (0.71 ± 0.3 vs 1.29 ± 0.40 ounce equivalents [oz-eq], P = .013), despite consuming more total grains (8.19 ± 0.49 vs 6.02 ± 0.60 oz-eq, P = .004), compared to non-Hispanic white women. Only one difference in food group intake was observed between non-Hispanic white and non-Hispanic black women; non-Hispanic black women consumed more protein (5.60 ± 0.74 vs 3.87 ± 0.33 oz-eq, P = .032).

Discussion

Summary

The findings demonstrate that Hispanic women had lower dietary energy density than their non-Hispanic white counterparts, which is consistent with findings that Hispanic women consume empty calories in moderation.² Additionally, Hispanic women had better dietary nutrient distribution, including greater intake of folate, fiber, and potassium compared to non-Hispanic white women. Interestingly, these findings are consistent with national trends for WIC-participating children. Hispanic WIC children also have lower dietary energy density and greater potassium and fiber intake compared to non-Hispanic white counterparts,¹³ which suggests similar dietary habits between WIC children and women.

The high fiber and potassium intake of Hispanic women may be related to greater vegetable intake than their non-Hispanic white counterparts. Compared to non-Hispanic white counterparts, Hispanic women reported greater intake of total vegetables including legumes, red and orange vegetables, and other vegetables. These findings are consistent with a study that reported variation in vegetable consumption among WIC women by race/ethnicity.⁴ Similarly, we observed lower added sugar intake among Hispanic WIC women compared to their non-Hispanic white counterparts, which confirms findings from a study conducted in WIC clinics in the Southeastern United States that also found lower added sugar intake among Hispanic women.³

Non-Hispanic black women had lower calcium and higher sodium intake than their non-Hispanic white counterparts, and these trends have also been reported for children living in WIC-participating households.¹³ The Dietary Guidelines for Americans recommend reducing sodium intake, and women in all racial/ethnic groups exceeded the Recommended Dietary Allowance.¹² Higher sodium intake among non-Hispanic black women and children is of particular concern because the non-Hispanic black population experiences disproportionally high rates of hypertension.¹⁴ Since the relationship between sodium intake and blood pressure varies with energy intake,¹⁵ dietary intervention may be useful in addressing both blood pressure and nutrition health status of this racial group.

Limitations

Although associations between nutrient/food intake and race/ethnicity are presented for women living in WIC-participating households, NHANES data are cross-sectional and preclude causal inferences. Additionally, WIC participation status was defined at the household level rather than individual level due to small sample size, so the results may not reflect dietary intake of WIC recipients directly. Although 24-hour recalls are frequently used in dietary assessment, these retrospective, self-reported data have limitations such as recall bias.¹⁶ The results reported here represent population mean dietary intake on a given day, and therefore, are not an estimation of long-term usual intake.¹⁷ Lastly, nutrient and food group intake among racial/ethnic groups were compared in order to study differences in dietary intake of women living in WIC-participating households. Further research statistically comparing intake estimates for each racial/ethnic group to dietary guidelines is important for influencing further recommendations for the WIC food package.

Significance

This study highlighted differences in nutrient and food group intake between racial/ethnic groups for women in WIC-participating households. Findings can be used to inform culturally tailored nutrition messages delivered by WIC nutrition educators and dietitians. Additionally, since the nutrients/food groups selected for analysis represent priorities for future food package revisions,⁵ the findings can inform WIC food package policy change.

So What?

What is already known on this topic?

Participation in WIC is associated with improved dietary intake among low-income children.

What does this article add?

This article reports racial/ethnic differences in nutrient/food group intake of women living in WIC-participating households using nationally representative data.

What are the implications for health promotion practice or research?

These findings can be used to inform culturally tailored nutrition messages delivered by WIC nutrition educators and dietitians. Additionally, since the nutrients/food groups selected for analysis represent priorities for future food package revisions, the findings can inform WIC food package policy change.

Footnotes

Authors’ Note

M.C.Z. and V.R. conceptualized the study. M.C.Z. and K.W.K. contributed to study design. M.C.Z. performed statistical analyses and wrote the manuscript. C.B., K.W.K., and V.R. reviewed and edited the manuscript. All authors approve of the final version of the manuscript.

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

Meghan C. Zimmer

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