Food patterns, flour fortification, and intakes of calcium and vitamin D: a longitudinal study of Danish adults.

STUDY OBJECTIVE Deficiencies in calcium and vitamin D intakes are involved in the aetiology of osteoporosis, and health authorities recommend that the population consume a diet providing sufficient calcium and vitamin D. However, in 1987 the Danish Government withdrew a mandatory fortification of flour with calcium. This study examines intakes of calcium and vitamin D over time, in relation to food patterns, recommendations, and legislation. DESIGN Food and nutrient intakes were measured by a short food frequency questionnaire (FFQ) and a thorough diet history interview, in 1987/88, and again six years later. SETTING Copenhagen County, Denmark. PARTICIPANTS 329 men and women, aged 35-65 years at first examination in 1987/88. RESULTS At both examinations the non-enriched median intakes of calcium in men as well as women were above the recommended 600 mg/day. However, apparently the fortification of flour supplied up to 30% of the total calcium intake, and without the mandatory fortification, the percentage of adults with intakes below this recommendation increased from 6% to 22%. This group of subjects consumed cheese, milk, and oatmeal less often than those who had calcium intakes over 600 mg/day. During the study period the median intakes of vitamin D, which were well below the recommended 5 micrograms/day, did not change significantly. Associations between foods and vitamin D intakes were, in general, weak and insignificant, except for a positive association with fish intake. CONCLUSIONS Data on calcium intakes suggest that the decision to stop the mandatory fortification of flour with calcium may have been premature. The short FFQ may be used for a rough classification of people in relation to their calcium intake, while this method seems insufficient for ranking vitamin D intakes.