Offering “Dip” Promotes Intake of a Moderately-Liked Raw Vegetable among Preschoolers with Genetic Sensitivity to Bitterness

Published:November 24, 2011DOI:



      Evidence-based strategies for promoting vegetable consumption among children are limited.


      To determine the effects of providing a palatable “dip” along with repeated exposure to a raw vegetable on preschoolers' liking and intake.


      One hundred fifty-two predominately Hispanic preschool-aged children studied in Head Start classrooms in 2008.


      A between-subjects, quasiexperimental design was used. A moderately-liked raw vegetable (broccoli) was offered twice weekly at afternoon snacks for 7 weeks. Classrooms were randomized to receive broccoli in one of four conditions differing in the provision of dip. Bitter taste sensitivity was assessed using 6-n-propylthiouracil.


      Broccoli was provided in four conditions: with regular salad dressing as a dip, with a light (reduced energy/fat) version of the dressing as a dip, mixed with the regular dressing as a sauce, or plain (without dressing).

      Main outcome measures

      Mean broccoli intake during 7 weeks of exposure and broccoli liking following exposure.

      Statistical analyses

      Descriptive statistics were generated. Multilevel models for repeated measures tested effects of condition and bitter sensitivity on mean broccoli intake during exposure and on pre- and post-exposure liking while adjusting for classroom effects and potential covariates.


      The majority of Hispanic preschoolers (70%) showed sensitivity to the bitter taste of 6-n-propylthiouracil. Children's broccoli liking increased following exposure but did not vary by dip condition or bitter sensitivity. Bitter-sensitive children, however, ate 80% more broccoli with dressing than when served plain (P<0.001); effects did vary based on whether regular or light dressing was provided as a dip or sauce. Dip did not promote broccoli intake among bitter-insensitive children.


      Providing dip—regular, light, or as a sauce—increased raw broccoli intake among bitter-sensitive Hispanic preschoolers. Findings suggest that offering low-fat dips can promote vegetable intake among some children who are sensitive to bitter tastes.
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      J. O. Fisher is an associate professor, Department of Public Health, Center for Obesity Research and Education, Temple University, Philadelphia, PA; at the time of the study, she was an assistant professor, Department of Pediatrics, US Department of Agriculture/Agricultural Research Service (USDA/ARS) Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX


      J. A. Mennella is a member, Monell Chemical Senses Center, Philadelphia, PA


      S. O. Hughes is an assistant professor, Department of Pediatrics, USDA/ARS Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX


      Y. Liu is a statistician, Department of Pediatrics, USDA/ARS Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX


      P. M. Mendoza is a dietitian, Weatherhead PET Imaging Center for Preventing and Reversing Atherosclerosis, University of Texas Medical School at Houston; at the time of the study, she was a research coordinator, Department of Pediatrics, USDA/ARS Children's Nutrition Research Center, Baylor College of Medicine, Houston, TX


      H. Patrick is a health scientist and program director, Health Behaviors Research Branch, National Cancer Institute, Bethesda, MD; at the time of the study, she was a research assistant professor, Departments of Medicine and Clinical and Social Psychology, University of Rochester, Rochester, NY