Offering “dip” promotes intake of a moderately-liked raw vegetable among preschoolers with genetic sensitivity to bitterness

J Acad Nutr Diet. 2012 Feb;112(2):235-45. doi: 10.1016/j.jada.2011.08.032.


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

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

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

Design: 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.

Intervention: 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.

Results: 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.

Conclusions: 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.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Brassica / chemistry
  • Child, Preschool
  • Energy Intake*
  • Feeding Behavior*
  • Female
  • Food Preferences*
  • Hispanic Americans
  • Humans
  • Male
  • Propylthiouracil / analysis
  • Taste / genetics*
  • Vegetables*


  • Propylthiouracil