Deconstructing the vanilla milkshake: the dominant effect of sucrose on self-administration of nutrient-flavor mixtures

Appetite. 2008 Jan;50(1):128-38. doi: 10.1016/j.appet.2007.06.011. Epub 2007 Jul 18.


Rats and humans avidly consume flavored foods that contain sucrose and fat, presumably due to their rewarding qualities. In this study, we hypothesized that the complex mixture of corn oil, sucrose, and flavor is more reinforcing than any of these components alone. We observed a concentration-dependent increase in reinforcers of sucrose solutions received (0%, 3%, 6.25%, and 12.5%) in both fixed ratio and progressive ratio procedures, but with equicaloric corn oil solutions (0%, 1.4%, 2.8%, and 5.6%) this finding was replicated only in the fixed ratio procedure. Likewise, addition of 1.4% oil to 3% or 12.5% sucrose increased fixed ratio, but not progressive ratio, reinforcers received relative to those of sucrose alone. Finally, addition of 3% vanilla flavoring did not change self-administration of 3% sucrose or 3% sucrose+1.4% oil solutions. These data suggest that, calorie-for-calorie, sucrose is the dominant reinforcing component of novel foods that contain a mixture of fat, sucrose, and flavor.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Corn Oil / administration & dosage
  • Dairy Products / analysis
  • Dietary Fats / administration & dosage*
  • Dietary Sucrose / administration & dosage*
  • Dietary Sucrose / analysis
  • Energy Intake
  • Flavoring Agents / administration & dosage*
  • Food Preferences
  • Male
  • Rats
  • Self Administration
  • Solutions
  • Vanilla / chemistry*


  • Dietary Fats
  • Dietary Sucrose
  • Flavoring Agents
  • Solutions
  • Corn Oil