Food price and diet and health outcomes: 20 years of the CARDIA Study.
BACKGROUND
Despite surging interest in taxation as a policy to address poor food choice, US research directly examining the association of food prices with individual intake is scarce.


METHODS
This 20-year longitudinal study included 12 123 respondent days from 5115 participants in the Coronary Artery Risk Development in Young Adults (CARDIA) Study. Associations between food price, dietary intake, overall energy intake, weight, and homeostatic model assessment insulin resistance (HOMA-IR) scores were assessed using conditional log-log and linear regression models.


RESULTS
The real price (inflated to 2006 US dollars) of soda and pizza decreased over time; the price of whole milk increased. A 10% increase in the price of soda or pizza was associated with a -7.12% (95% confidence interval [CI], -63.50 to -10.71) or -11.5% (95% CI, -17.50 to -5.50) change in energy from these foods, respectively. A $1.00 increase in soda price was also associated with lower daily energy intake (-124 [95% CI, -198 to -50] kcal), lower weight (-1.05 [95% CI, -1.80 to -0.31] kg), and lower HOMA-IR score (0.42 [95% CI, -0.60 to -0.23]); similar trends were observed for pizza. A $1.00 increase in the price of both soda and pizza was associated with greater changes in total energy intake (-181.49 [95% CI, -247.79 to -115.18] kcal), body weight (-1.65 [95% CI, -2.34 to 0.96] kg), and HOMA-IR (-0.45 [95% CI, -0.59 to -0.31]).


CONCLUSIONS
Policies aimed at altering the price of soda or away-from-home pizza may be effective mechanisms to steer US adults toward a more healthful diet and help reduce long-term weight gain or insulin levels over time.
Duffey
Kiyah J
KJ
Department of Nutrition, Carolina Population Center, University of North Carolina at Chapel Hill, 27516-3997, USA.
Gordon-Larsen
Penny
P
Shikany
James M
JM
Guilkey
David
D
Jacobs
David R
DR
Popkin
Barry M
BM
D000328:Adult; D001835:Body Weight; D002253:Carbonated Beverages; D003327:Coronary Disease / Q000209:etiology / Q000517:prevention & control*; D004032:Diet / Q000191:economics*; D002149:Energy Intake; D005247:Feeding Behavior; D005260:Female; D005502:Food / Q000191:economics*; D006291:Health Policy / Q000639:trends*; D006801:Humans; D007333:Insulin Resistance; D016014:Linear Models; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D040841:Resource Allocation; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D014481:United States; D055815:Young Adult