Randomized, Controlled Trial to Examine the Impact of Providing Yogurt to Women Enrolled in WIC

Article Outline

• Abstract
• Introduction
• Methods
  • Design
  • Study Sites and Staff Training
  • Participant Recruitment and Selection
  • Yogurt Intervention
  • Study Surveys and Dietary Records
  • Data Analysis
  • Sample Size
• Results
• Discussion
• Implications for Research and Practice
• Acknowledgments
• References
• Copyright

Abstract 

Objective

Examine the impact of providing yogurt to women enrolled in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC).

Design

Randomized, controlled intervention trial.

Setting

Two California WIC local agency sites.

Participants

511 pregnant, breast-feeding, or postpartum women.

Intervention

Substitution of part of the WIC milk allowance with yogurt accompanied with educational materials.

Main Outcome Measures

Participants' consumption and attitudes regarding yogurt provision.

Analysis

Chi-square, Fisher exact, and Student t test to compare pre- versus post-intervention responses. Nonparametric Wilcoxon, chi-square, and t test to compare changes in response in intervention versus controls. Analysis of covariance models to test the influence of language preference on outcomes.

Results

Over 86% of women wanted to substitute some of their milk vouchers with yogurt. Among these, 62% reported preferring yogurt to milk. The majority (89%) redeemed the yogurt coupons. Compared to controls, intervention women reported a trend (P = .09) toward an increase in yogurt intake of 1.0 fl oz/day while not decreasing other dairy consumption. Those in the intervention group with the lowest tertile of yogurt intake at baseline increased yogurt consumption by 2.8 fl oz/day (P = .003) relative to controls with lowest intake.

Conclusions

Yogurt is likely to be a popular substitute for milk and could contribute to increased dairy intake among women if it were an option in WIC.

Key Words: dairy, yogurt, women, WIC, low-income, nutrition education, dietary intake

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Introduction 

The Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) is a federal program that provides nutrition education and vouchers for nutritious food to low-income pregnant, breast-feeding, and postpartum women; infants; and children up to age 5 who are at nutritional risk. California has the largest state WIC program, which serves 1 in 5 of the nation's WIC participants.¹ The majority of California participants are Latino (78%), followed by Caucasian (8%), African American (6%), Asian (5%), and Native American (<1%).²

In December 2007 the United States Department of Agriculture (USDA) published the Interim Final WIC Food Package Rule for the WIC program, making substantial changes to the food items allowed. To make the WIC food package consistent with the 2005 Dietary Guidelines for Americans, the National Academies' Institute of Medicine (IOM) researched the current WIC food packages extensively and made recommendations to the USDA.³ One of the IOM recommendations was to add yogurt as a substitute for part of the milk allowance. The USDA asked states for assistance in exploring how yogurt could be provided.

The WIC program can measure only what is offered to the intended beneficiaries, not what is eaten, so evaluation using carefully designed research protocols is the only way to quantify changes in the diets of participants. The California WIC program sought to address the questions posed by the USDA as well as provide important information on the acceptability of yogurt, what WIC participants select and, ultimately, the potential dietary impact of the addition of yogurt to the WIC food provisions. The objectives of this WIC intervention trial were to document changes in women's: (1) preferences for yogurt; (2) perceived barriers to yogurt consumption; and (3) amount of dairy servings consumed. Our hypotheses were that the provision of yogurt coupons to the intervention group would increase their preference for yogurt, decrease their perceived barriers, and increase yogurt consumption compared to the control group.

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Methods 

Design 

A randomized, controlled pilot study was conducted with pregnant, breast-feeding, and postpartum women at 2 local WIC agencies in California from early March 2009 through the end of September 2009. This 7-month time period was necessary to obtain data from a sufficient sample size to document significant changes in total dairy intake, while accommodating the need to complete data collection prior to implementation of the new WIC food package on October 1, which included reductions in milk amount and fat content (only lower-fat milk allowed) provided to women. Completion of the study by this date also allowed for adequate time for data analysis prior to the deadline for public comment on the USDA's Interim Rule. Each study participant was randomized to either the intervention or control group and followed for approximately 2 months. The study protocol was reviewed and expedited approval obtained by the Institutional Review Board at the Children's Hospital & Research Center, Oakland, CA.

Study Sites and Staff Training 

Two WIC local agencies were identified for inclusion in the yogurt pilot study, the County of San Luis Obispo WIC program's Paso Robles site, and the Del Norte Clinics, Inc. WIC program's Colusa site. Two half-day training sessions, one at each participating local WIC site, were conducted with WIC staff to review study protocols, recruitment strategies, and data collection tools. Regular conference calls were used to facilitate study progress, and research staff provided in-person assistance at the local sites at critical junctures of the study.

Participant Recruitment and Selection 

All pregnant, breast-feeding, and postpartum women enrolled in WIC were invited to participate if they were over 18 years of age, planning to continue visits to the same WIC clinic at least 2 months following recruitment, and able to read English or Spanish. Eligible participants were asked to complete a baseline survey, which included a question about interest in substituting yogurt vouchers for part of their milk vouchers. Women not interested in making this substitution were not followed further in the study. Those interested in receiving yogurt were asked to sign a study consent form and were given instructions on completing a 3-day dairy food record. All tools developed for this study were provided in either English or Spanish, depending on the participants' language preference.

Women returning to the WIC site for the subsequent monthly appointment along with a completed baseline dairy food record were randomly assigned to either the intervention (received yogurt coupons and educational yogurt brochure) or control group (did not receive yogurt coupons or brochure). They were then instructed to keep a second 3-day dairy food record to bring to their subsequent monthly appointment (2 months after the baseline visit). At this second visit, completed follow-up dairy food records were collected, and a follow-up survey was administered to both the control and intervention groups. In this way, baseline and follow-up survey and food record data were collected on both intervention and control women interested in receiving yogurt coupons. Only baseline survey data were collected from women not interested in receiving yogurt coupons, and results were used to characterize these subjects. Women who completed the study were provided thank-you gift cards.

Yogurt Intervention 

Two coupons for free 32-fl oz containers of low-fat Yoplait yogurt (for a total of 64 fl oz) were provided to each participant in the intervention group to use during the 1-month intervention period. Yogurt coupons were also provided to women in the control group after completing the study. The yogurt provided to WIC participants reflected the nutritional requirements recommended by the IOM.³ Any of the following flavors were allowed, provided they were available at the store where the coupons were redeemed: plain, vanilla, peach, strawberry, or strawberry/banana. Oral instructions were provided by WIC staff on how to use the coupons, including which local vendors were stocking the yogurt, and how to redeem them along with their usual WIC vouchers.

Educational materials on yogurt were developed for use by WIC staff members and intervention participants. The purpose of the education materials for clients was to provide information on yogurt's nutritional quality, uses in meals and snacks, purchasing and handling, and use in recipes. The content for the staff guide contained information on the nutritional profile of low-fat yogurt and its potential health benefits.

Study Surveys and Dietary Records 

Participant surveys were developed for this protocol to capture WIC participants' stage of change (2 questions), preferences of type and flavor of dairy products (5 questions), as well as perceptions (nutritional value, spoilage; 4 questions) and barriers related to yogurt consumption (taste, cost, availability, lactose intolerance; 6 questions). A 4-point Likert scale was used for most survey questions, scaled from likes a lot to dislikes a lot or agrees a lot to disagrees a lot. Surveys were completed during the WIC visit. A dairy food record for participants to complete (3 days of records at baseline and again at follow-up) was used to capture and quantify dairy intake in women with low literacy (eg, included line drawings of standard portion sizes to facilitate record keeping). These records were completed at home by the participant reflecting intake on 1 weekend day and 2 weekdays. All tools were pilot-tested with women who participated in WIC at other sites in California and revised accordingly based on feedback.

Data Analysis 

For consistency, all participant surveys were entered by 1 of 2 research staff members, and all 3-day dairy food records were entered by 1 trained dietitian. Approximately 20% of all study forms were double entered to check for data entry errors, and further data queries were conducted to test for other errors and outliers.

Dependent variables included participants' preference for type, flavor, and container of yogurt typically consumed, perceptions regarding nutritional value, spoiling of yogurt, and barriers related to yogurt consumption including taste, cost, availability, and lactose intolerance. Independent variables included age, pregnant or breast-feeding status, race, education level, and language preference. To compare pre- versus post-intervention responses for intervention and control groups, the authors used chi-square or Fisher exact tests for categorical variables and the Student t test for continuous variables. Nonparametric Wilcoxon tests were used to compare the intervention and control groups for ordinal data. Changes in response in intervention versus control groups were also compared using chi-square, t tests, or Wilcoxon tests. In addition, linear modeling was used to compare the changes in the type of yogurt or milk usually consumed for the control and intervention groups. Analysis of covariance models were used to explore the change in daily servings of dairy consumed between groups controlled by breast-feeding status and ethnicity variables. To assess the effect of the intervention on women perceived to have the greatest benefit of adding yogurt substitution, subgroup analyses were also performed in those women with the lowest tertile of yogurt consumption at the beginning of the study. All data were analyzed using SAS (version 9.2, SAS Institute, Chicago, IL, 2007), using a significance level of .05 (2-tailed) for all statistical tests.

Sample Size 

The authors estimated that with 250-300 women in each group (intervention and control) and assuming a standard deviation of 2.0 (based on data from Fulgoni et al⁴) and a correlation of 0.6 between baseline and follow-up, a statistically significant (P < .05) difference in change in intake of 0.4 servings of yogurt or milk/day (3.2 fl oz) between the intervention and control groups could reasonably be detected.

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Results 

A total of 593 pregnant, breast-feeding, or postpartum women completed the initial pre-intervention survey, of whom 511 (86%) were enrolled in the study based on indicating an interest in substituting yogurt for some of their milk vouchers (Figure 1). There were no significant differences in sociodemographic characteristics between women who were versus those who were not interested in yogurt. There were, however, statistically significant differences in yogurt preference between the women interested versus not interested in yogurt, which did not seem to be explained by lactose intolerance, as a similar number of women in both groups reported trouble digesting dairy products (Table 1).

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• Figure 1 

  Enrollment, retention, and randomization of pregnant, breastfeeding, or post-partum women (> 18 years of age) enrolled in the WIC Yogurt Intervention Study.

Table 1. Comparison of Yogurt Preferences and Attitudes About Yogurt in Women Enrolled (Interested in Substituting Some of Milk Vouchers for Yogurt; n = 511) With Those Not Enrolled (Not Interested in Yogurt; n = 82) in the WIC Yogurt Intervention Study^a

Measure	Agree or Like It a Lot	Agree or Like It a Little	Disagree or Dislike It a Little	Disagree or Dislike It a Lot	P Valueb
Do you like plain yogurt?					.015
Not enrolled	8.2%	27.4%	17.8%	9.6%
Enrolled	19.2%	37.2%	10.8%	5.2%
Do you like flavored yogurt?					<.001
Not enrolled	56.9%	27.9%	0.0%	5.1%
Enrolled	91.9%	7.1%	0.6%	0.4%
Do you have trouble digesting things made with milk?					NS
Not enrolled	9.5%	13.5%	9.5%	67.6%
Enrolled	6.0%	13.7%	12.3%	67.9%
Do you like the taste of yogurt more than milk?					<.001
Not enrolled	9.0%	14.1%	37.2%	39.7%
Enrolled	31.3%	30.3%	26.9%	11.6%

Note: Values in rows may not sum to 100% because of rounding and exclusion of participants who responded, “Don't eat.”

NS indicates not statistically significant; WIC, Special Supplemental Nutrition Program for Women, Infants, and Children.

Fifty-five of the 511 who initially agreed to participate in the project subsequently dropped out for various reasons: 18 were not interested in participating after completing the baseline survey; 14 changed residence; 13 did not complete the follow-up survey and/or diet record collection; 3 were no longer enrolled in WIC; 2 transferred to another WIC agency; 3 felt it would take too much time; 1 could not come in for monthly appointments; and 1 was lost to follow-up. Compared to those who did not complete the study, completers were more likely to communicate in Spanish (55% for completers vs 36% for noncompleters, P = .01) and to have been on WIC for a longer duration (2.3 ± 2.4 y for completers vs 1.8 ± 2.2 y for noncompleters, P = .03).

For the 456 participants (89% of the initial group) who completed the study protocol, the control group had a higher percentage of women currently breastfeeding compared to the intervention group (35% vs 25%, P = .03). There were no other significant differences in baseline socioeconomic characteristics between the 2 groups (Table 2). At baseline, the majority of study participants reported eating yogurt at meals or snacks (69%) and buying yogurt to eat (66%). Less than 20% of participants reported liking plain yogurt a lot at baseline, whereas over 90% liked flavored yogurt a lot. There were no significant differences between groups in change in yogurt preference from baseline to follow-up.

Table 2. Age, Pregnancy, and Breast-feeding Status, Language Preference, and Socioeconomic Variables at Baseline for Control (n = 213) versus Intervention Women (n = 243) Enrolled in the WIC Yogurt Intervention Study

Characteristic	Control	Intervention	P Valuea
Age (y)	25.8 ± 5.4	26.6 ± 6.0	NS
Currently pregnant (%)	59.6	62.6	NS
Currently breast-feeding (%)	34.6	25.2	0.03
Main food shopper in household (%)	93.8	96.2	NS
Total number of people in household	3.6 ± 1.4	3.5 ± 1.4	NS
Duration of family on WIC (y)	2.5 ± 2.5	2.2 ± 2.2	NS
Spanish language preference (%)b	56.3	53.5	NS
Race/ethnicity (%)			NS
Hispanic	81.7	75.2
Non-Hispanic, white	16.0	20.3
Other race/ethnicity	2.4	4.6
Highest level of education (%)			NS
Not high school graduate	35.2	29.6
High school graduate	39.1	36.2
Some college or more	25.7	34.2

Note: When mean is provided, standard deviation is also included. Values in columns may not sum to 100% because of rounding.

NS indicates not statistically significant; WIC, Special Supplemental Nutrition Program for Women, Infants, and Children; y, years.

Perceived barriers to yogurt consumption and purchasing were also assessed using a 4-point Likert scale. The intervention and control groups were similar on all variables at baseline except for the question on the size of yogurt container usually purchased. More participants in the control group disagreed strongly that they purchased small (4-8 fl oz) containers (12% for control vs 10% for intervention, P = .01). Because of similarities between the intervention and control groups, responses were combined (Table 3). Study participants were roughly split on the question of liking the taste of milk more than yogurt and on liking to eat yogurt more than drink milk. Fewer than 1 in 5 participants thought that yogurt was not as healthful as milk, and yogurt was popular with nearly all families. Less than 20% reported that they had trouble digesting things made with milk. A majority (62%) thought that the cost of yogurt was too high. Nearly all participants (96%) found yogurt available where they shopped for food. More than half of participants (60%) agreed that they did not know how to include yogurt in recipes.

Table 3. Thoughts About Dairy Food at Baseline for Combined Group of Control (n = 213) and Intervention (n = 243) Women Enrolled in the WIC Yogurt Intervention Study^a

WIC indicates Special Supplemental Nutrition Program for Women, Infants, and Children.

When asked the same questions about barriers to consuming and purchasing yogurt at follow-up, there were only slight changes in responses in the intervention women and no significant differences between control and intervention groups, with the exception of the question on yogurt container size. After the intervention, more participants who received coupons for large containers of yogurt agreed that they usually purchased yogurt in large containers (22% for intervention vs 17% for control, P = .001).

Participant preference at baseline (control and intervention groups combined) for lower-fat yogurt (2% or 1% fat content) was similar to that for lower-fat milk (61% for yogurt, 64% for milk). However, more participants consumed nonfat yogurt at baseline (22%) compared to nonfat milk (10%). Fruit- and berry-flavored yogurts were the most popular (usually consumed by 94%), followed by vanilla (usually consumed by 34%). There were no significant differences between groups in observed changes from baseline to follow-up in preferences for yogurt type or flavor.

Three-day dairy-focused pictorial food records were completed at baseline and follow-up by all but 1 woman in the control group and all but 5 women in the intervention group. The majority of women (>98%) completed the records as instructed (2 weekdays and 1 weekend day) at both the baseline and follow-up time points. On average, one 8-fl oz serving of yogurt was consumed daily in both groups at baseline (Table 4).

Table 4. Change in Daily Intake (8 fl oz equivalents of milk^a) of Dairy Food at Baseline and Follow-up for Entire Sample (control vs intervention) and Change in Yogurt Consumption for Subset With Low Yogurt Consumption at Baseline (control vs intervention)

NS indicates not statistically significant.

In the intervention group, the only significant baseline to follow-up change in intake of dairy food was the increase in yogurt intake (1.0 ± 5.6 fl oz, P = .02). In the control group, the only significant change was the decrease in milk intake (-1.1 ± 6.4 fl oz, P = .01). There was a trend toward a small daily increase in yogurt consumption in the intervention compared to the control group (P = .09). The absolute difference was equivalent to a daily increase of 1.0 fl oz of yogurt (Table 4). There were no significant differences observed in the intake of other dairy food (milk, cheese, desserts) or in total dairy consumption.

In a multivariate model of change in intake of yogurt including language and breast-feeding status, the interaction for language (but not breast-feeding status) was significant (P = .03), meaning that change in yogurt intake differed between language subgroups. Change in yogurt intake was therefore examined by language preference. The increase in yogurt intake by the intervention group was slightly more significant when the Spanish-speaking participants were analyzed separately (P = .075), though the increase in consumption pattern was similar, a 1 fl oz increase in yogurt intake per day, whereas the change in the English speaking subgroup did not approach significance (data not shown).

A subgroup analysis was also performed including those women who were in the lowest tertile of yogurt consumption at the beginning of the study, less than 0.67 fl oz of yogurt per day (Table 4). When these low-yogurt consumers (n = 37) were compared to those in the control group who were also low-yogurt consumers (n = 27), the relative increase in yogurt consumption was significant, equivalent to 2.8 fl oz per day (P = .003).

Among those who received yogurt coupons (intervention group only), 90% used at least 1 coupon in the month after receipt (17% used 1, 74% used both). Among the 10% who did not use the coupons after receipt, 2% were not able to find the coupon variety of yogurt where they shopped, 7% could not find their coupons when they shopped, and <1% did not want the yogurt. Those who reported using the yogurt coupons were satisfied with the yogurt and education (Table 5). A majority responded that they ate the yogurt themselves, found the yogurt brochure helpful, and used the brochure to include yogurt in meals (84%) or snacks (85%). Only a minority agreed (a lot or a little) that the amount of yogurt they received was too much (16%) or too little (32%), and less than 5% said it spoiled before they could eat all of it. Intervention participants who used the coupons were more evenly split on the questions regarding preferences for different yogurts: over two-thirds would have liked different flavors and carton sizes, whereas nearly half would have liked different brands.

Table 5. Response (%) to Yogurt Coupon Provision After the Intervention by Intervention Group Participants Enrolled in the WIC Yogurt Study Who Used 1 or Both Coupons (n = 219)

Note: Values in rows may not sum to 100% because of rounding and participants checking “Does not apply.”

WIC indicates Special Supplemental Nutrition Program for Women, Infants, and Children.

Of those who used the yogurt coupons during the intervention period, 91% responded that in the future they would be interested in substituting yogurt for some milk, if that option were available in their WIC food package. Nearly the same proportion (88%) of the entire intervention group, whether they used the coupons or not, continued to be interested in yogurt at the end of the pilot.

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Discussion 

Little is known about the dairy preferences of WIC participants, and this is the first reported study to document the outcome of providing yogurt as a milk substitute to low-income women enrolled in WIC. Characterizing the women who opt to use yogurt coupons is important in extrapolating the findings to other WIC populations and, ultimately, determining the likely impact of offering yogurt vouchers on nutrient intakes. The authors did not find any differences on the basis of sociodemographic characteristics between those women who said they were vs were not interested in substituting yogurt for milk. Not surprisingly, it was primarily the women who did not like yogurt who stated that they would not want yogurt coupons.

The results of the study very clearly illustrate WIC participants' enthusiasm for yogurt. Over 86% of the women approached at entrance to the study were interested in substituting yogurt for milk. Nearly 70% of the women in both the intervention and control groups responded that they were already eating yogurt as part of their usual consumption patterns. Flavored yogurt was particularly popular (“liked a lot” by over 90% of study participants compared to slightly over 50% who reported liking lower-fat milk a lot).

The yogurt coupons and educational brochure were highly utilized. The yogurt coupons were redeemed at a rate similar to milk vouchers in WIC. The reported yogurt coupon redemption rate was 89%. From February-September 2009, the average redemption rate for WIC vouchers that included milk (without other food) and were distributed to either women or children was 88%.⁵ The redemption rate for combination food vouchers (includes food besides milk on the voucher) tends to be higher than for milk-only vouchers, suggesting that yogurt on WIC vouchers would be redeemed at a frequency similar to milk.

Many intervention participants (nearly 70%) indicated that they would prefer more choices in terms of available yogurt flavors. Not all WIC vendors appeared to stock the 5 flavors allowable by the coupons. Since this was a pilot involving a relatively small number of consumers, it is likely that stocking additional flavors of the 32-fl oz yogurts was not viable for most vendors. If yogurt was adopted by WIC, the increased demand for the 32-fl oz yogurt containers could make it more feasible for vendors to provide additional flavor options. Among the WIC women, the authors identified few barriers to including yogurt in their diet. Very few had trouble finding yogurt where they shopped for food or found that yogurt spoiled too quickly, and only 19% reported any lactose intolerance when consuming dairy products. The only major barrier (reported by 62% of the study sample) to yogurt purchase and consumption was the cost, suggesting that removing the cost barrier by provision of yogurt in the WIC food package would be beneficial for increasing intake.

Similar to how cheese has been a popular substitution for milk in many WIC food packages, yogurt may provide an additional option for WIC participants who are either lactose intolerant or are not regular milk consumers. This substitution has the additional benefit of providing a low-fat or nonfat option that is a rich source of calcium and vitamin D.

To be most economical, yogurt was provided to women in the intervention in 32-fl oz containers. According to AC Nielsen grocery store data,⁶ 84% of yogurt unit purchases are in 6- to 8-ounce cup sizes and 62% of households that purchase yogurt choose smaller size cups. Not unexpectedly, WIC participants typically purchased yogurt in smaller size containers. However, spoilage and finding the 32-fl oz containers at stores were not often reported as a problem among participants. Further, there was a significant shift away from using the smaller yogurt cup sizes in the intervention group, suggesting that women were able to adjust to using the larger container sizes. Most women in the intervention group liked both the yogurt flavors and the amount provided, suggesting that large containers would be acceptable to WIC participants. After the intervention, 90% of WIC participants continued to say that they would want to substitute yogurt in place of some of their milk.

The amount of yogurt provided by the intervention, 2 32-fl oz containers, would provide an additional 2 fl oz per day of yogurt to each participant if she were to use it entirely for herself over the period of 1 month, and if this amount of yogurt were simply added to current procurement and consumption patterns. The authors found a small (and nearly significant) increase in yogurt intake of approximately 1.0 fl oz/day, particularly among participants with Spanish language preference. Among women with the lowest yogurt intake at baseline, the authors found a significant increase in yogurt intake (nearly 3 fl oz/day) over those in the control group with similarly low intakes. These findings suggest that providing yogurt vouchers can result in increased yogurt consumption among low-income women, particularly for those who are low yogurt consumers. It is noteworthy that these increases in yogurt intake were achieved without any obvious impact on the intake of other dairy food, meaning that it did not appear that women compensated for an increase in yogurt by decreasing their intake of other dairy products. Provision of yogurt and education for longer than 1 month may further increase daily yogurt intake.

Intake of dairy generally contributes to higher intakes of minerals such as calcium, phosphorus, magnesium, potassium, and zinc and vitamins such as vitamins A, D, and B₁₂.⁷ Calcium is essential for attainment of optimal peak bone mass for the prevention of osteoporosis. Research also suggests that adequate dietary calcium is important for optimal blood pressure⁸ and maintenance of weight status.⁹ The Dietary Reference Intake for women of reproductive age is 1000 mg/day.¹⁰ Over 75% of women in the US fail to meet the recommendations for calcium intake.¹¹ If women who received yogurt in place of some of their milk averaged even a modest increase of 1 fl oz per day in yogurt, and no other changes in dietary intake occurred, on average calcium intakes would increase by 350 mg per week for adult WIC participants, representing a marked contribution to total calcium intakes.

On average women of reproductive age consume 1.1 servings of dairy per day,⁴ far below the 3 daily servings recommended.¹² The dietary tools selected for this study were not designed for determination of point estimates of dairy intake. Rather, results from these tools were used to examine relative change in dairy consumption from baseline to study end point. Even though the measured intakes likely overestimate actual dairy consumption, the data provide a systematic comparison of change over time.

There are several study limitations that should be noted. This pilot intervention lasted only 1 month and was conducted at only at 2 WIC sites. It is possible that had the intervention been conducted for a longer period and at more sites, the results might have been different. For example, with more education about yogurt at WIC visits, additional yogurt flavors at WIC vendors, and provision of yogurt coupons more than a single time, it is possible that women would be more likely to increase their intake. It is also possible that women who received yogurt coupons were more likely to report increases in intake because of social desirability.

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Implications for Research and Practice 

Because of the overwhelmingly positive reception of yogurt by pregnant, breast-feeding, and postpartum women participating in the WIC program and because of the positive nutrient contributions of yogurt that appear to add, rather than replace, nutrients in the diet, this pilot suggests that yogurt could be a viable addition to the WIC food package. Future studies to provide additional information on 2 topics outside the scope of the current pilot study, cost and sustained participant use of yogurt, are needed:

If the WIC food package regulations allow state agencies the flexibility to include yogurt as a substitute for milk, the variety of offerings, the educational messaging, and most importantly, the nutritional intake of participants, particularly those with lactose intolerance, could be enhanced.

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Acknowledgments 

Funding for this study was provided by the National Dairy Council^®. The authors gratefully acknowledge the following individuals for their numerous contributions to this study: Tammy Seitel, Lisa Spence, Karen Kafer, Douglas DiRienzo, Mary Anne Burkman, Linnea Sallack, Kim Frinzell, Linda McClure, Celena Crawford, Wendy Fertschneider, Margo Medina, Rose McIsaac, Marisol Chavez, Barbara Green, Rikki Ray, Marion Roan, and Lisa Calvelli. The authors also thank the study participants, without whom this study would not have been possible.

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