Abstract
To promote fruit and vegetable (FV) intake among participants, the USDA Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) implemented a comprehensive food package revision in 2009. However, to our knowledge, no studies have systematically explored the factors related to FV purchases and/or consumption among WIC participants in the post-2009 revision era. To fill this knowledge gap, we conducted a systematic literature review using PubMed, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Cochrane Central Register of Controlled Trials, and Web of Science using key search terms. Studies published from January 1, 2007, through February 28, 2019, were included, since an interim rule for the WIC food package revision was issued in 2007. This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses format. The articles were grouped based on main themes or factors, settings, design, study years, and sample size. Thirty-nine articles met the inclusion criteria. Seven main themes or factors related to FV purchases and/or consumption in WIC participants were identified in these articles. The 2009 WIC food package revision was the most-studied factor (n = 9). National and state-level studies showed a consistently positive relation between the 2009 revision and FV purchases and/or consumption. However, some studies did not find a positive relation. State-level policy variations can be exploited as natural experiments to assess the causality of state-level factors in WIC participants' FV purchases or consumption. The majority of the included studies were limited in being local (n = 26, 66.7%), cross-sectional (n = 29, 74.4%), or having sample sizes <1000 (n = 25, 64.1%), which could explain the diverse results regarding the relation between FV purchases and/or consumption and various factors, including individual, store, and program characteristics.