Development of a tool for the assessment of calcium and vitamin D intakes in clinical settings.
The study aim was to develop a tool (software and ruler) to assess the dietary calcium and vitamin D intakes in Portugal, and evaluate the usefulness of non-dietary variables as intake predictors. Our findings indicated that is possible to estimate both using three and six food items, respectively, and non-dietary predictors.


BACKGROUND
The study aim was to develop a tool to assess the dietary calcium and vitamin D intakes in Portugal, and evaluate the usefulness of non-dietary variables as predictors.


METHODS
Trained interviewers collected information of 2,414 adults of Porto, Portugal, using a structured questionnaire and a validated semi-quantitative food frequency questionnaire (FFQ). Food items with the highest contribution to the total intake and non-dietary predictors (gender, age and body mass index (BMI)) were selected for the tool. Different statistical approaches were used to predict the intake. A Bland-Altman plot compared the predictions from the tool and the full FFQ.


RESULTS
The items selected to predict intake were milk (38%), cheese (12%), yogurt (10%) and gender for calcium and oily fish (39%), canned fish (9%), white fish (7%), eggs (5%), red meat (5%), age and BMI for vitamin D. The Bland-Altman plot showed that the mean differences were 0.0 (limits of agreement = [-220.67; 220.77]) mg/day and 0.0 (limits of agreement = [-1.03; 1.05]) microg/day, respectively for calcium and vitamin D.


CONCLUSIONS
The equations estimated by the best statistical model to predict the calcium and vitamin D intake allowed for the design of a software and a circular ruler useful in clinical settings.
Department of Hygiene and Epidemiology, University of Porto Medical School, Alameda Prof. Hernani Monteiro, Porto, Portugal. milton@med.up.pt
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D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D002136:Calcium, Dietary / Q000008:administration & dosage*; D015930:Diet Records; D005247:Feeding Behavior; D005260:Female; D005502:Food; D006801:Humans; D008297:Male; D008875:Middle Aged; D011174:Portugal; D012737:Sex Factors; D012984:Software; D011795:Surveys and Questionnaires; D014807:Vitamin D / Q000008:administration & dosage*
D002136:Calcium, Dietary; D014807:Vitamin D