Date of Award:


Document Type:


Degree Name:

Doctor of Philosophy (PhD)


Nutrition, Dietetics, and Food Sciences

Department name when degree awarded

Nutrition, Dietetics and Food Science

Committee Chair(s)

Heidi J. Wengreen


Carrie Durward


Martha Archuleta


Greg Madden


Guifang Fu


People often base their behaviors on social norms—what they think others do or approve of. This is likely true of fruit and vegetable (FV) intake as well. College students typically don’t get enough FV. We attempted to encourage FV eating by providing students with messages or demonstrations that eating FV is normal. First, we tried to encourage FV intake by providing students with messages regarding the average skin carotenoid concentration and where they fit within their peers (Chapter II). Carotenoids are compounds found in FV that cannot be made by the body, making them an estimate of FV intake. We found that students did not increase their self-reported FV intake or skin carotenoids as a result of these social norms messages, messages about the recommendation for FV or no message at all. We then added an approval/disapproval message (as ☺︎, :| or ☹︎ ) to the average carotenoid scores and where a student fit within their peers’ scores (Chapter V). This resulted in small increases in self-reported FV intake and skin carotenoids for those receiving the approval/disapproval message and those who only got information about the average score of their peers and where they fit within the average. To test whether self-report was influenced by messages regarding social norms, we sent out messages telling students they were lower than average—whether this was true or not, higher than average, providing the recommendation for FV, no message. Those told they were lower than their peers reported a half-cup increase in FV intake immediately after receiving the message. Finally, we attempted to influence student’s FV intake by having other students come into a weekly class, pose as students in the class and eat vegetables (Chapter III). We found that those exposed to these vegetable-eating students were no more likely to increase FV than those not exposed to it. Overall, we found very small or no effects from any of the included studies and that self-reported FV intake should be interpreted with caution. Interventions that include other factors, such as time, cost, availability or knowledge/skills, might increase FV more than social norms alone.



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Nutrition Commons