Objective: Examine the relationship between food monitoring and change in fruit and vegetable, low-fat dairy, and DASH unfriendly food servings and in relative blood pressure in youth participating in a nutrition intervention focused on the DASH diet.
Subjects: A subset of the participant's data reported by Couch et al. (2008) was used. Only participants who were in the DASH intervention group who completed the intervention or through the follow-up were considered. Participants were adolescents aged 11 to 18 with diagnosed pre-hypertension or hypertension.
Study Design: Participants were randomly assigned to a behavioral nutrition intervention focused on the DASH diet or routine nutrition care.
Methods: Participant food trackers were coded and six components of food self-monitoring were derived: actual days of food recording, foods described, foods with an amount, recording sufficiency for foods recorded, recording sufficiency for foods described and recording sufficiency for foods with an amount. Changes in servings of fruits and vegetables, low-fat dairy foods, and unfriendly foods were assessed using 3 multi-pass 24-hour food recalls. Relative blood pressure change was calculated as post-treatment (or follow-up) blood pressure minus baseline blood pressure divided by baseline blood pressure.
Results: There was a significant negative correlation between actual days of food recording and change in intake of unfriendly food servings (r=-0.56, p=0.01). Correlations that trended towards significance included: actual days of food recording, recording sufficiency for foods with an amount and foods described and change in intake of fruit and vegetable servings (r=0.36, p=0.09; r=0.35, p=0.10; r=0.34, p=0.10). There was a non-significant trend toward a difference between high versus low recording sufficiency for foods recorded and relative change in systolic blood pressure (p=0.09) and change in intake of low-fat dairy servings (p=0.06) post- intervention. There was a non-significant trend toward a difference between high versus low recording sufficiency for foods described and relative change in systolic blood pressure (p=0.09) and change in intake of low-fat dairy servings (p=0.06) post- intervention. There was also a non-significant trend toward a difference between high and low recording sufficiency for food amounts and change in low-fat dairy servings (p=0.09) and change in DASH unfriendly food servings (p=0.10) post-intervention.
Conclusion: The concept of DASH unfriendly foods was hard for subjects to understand, but repeatedly recording foods drew awareness to and understanding of this food category. More days of recording some foods appeared to be related to increasing intake of fruits and vegetables (two food groups important in lowering blood pressure). Describe and giving amounts for foods was important in helping adolescents increase intake of fruits and vegetables too. A more complex level of recording was necessary to effect changes in blood pressure and changes in low-fat dairy servings likely because in order to effect these outcomes subjects needed a good understanding of the DASH diet, and recording and describing 5 or more foods more frequently enabled this understanding.