Abstract
BACKGROUND: Vitamin D deficiency is common in many countries, including Saudi Arabia. Various population-level preventive measures have been implemented, including milk fortification with vitamin D. OBJECTIVES: The main objective of the study was to determine vitamin D levels in fortified low fat cow milk on the Saudi Arabian market and to compare it with the label claims. DESIGN: Cross-sectional study. SETTING: Academic research center. MATERIALS AND METHODS: Five milk batches from five major producers were purchased in five replicates from five major retail stores in Riyadh, Saudi Arabia. We used a validated liquid chromatography assay to measure vitamin D levels. All samples were producer labeled to contain 400 IU/L (10 ng/mL) vitamin D and were analyzed within the first 40% of their validity period. Intra-batch, inter-batch, and inter-producer variations were determined as a coefficient of variation. MAIN OUTCOME MEASURES: Intra-batch, inter-batch and inter-producer variations in vitamin D level. RESULTS: Overall, mean (SD) measured vitamin D level was 10.2 (1.6) with a range of 7.1-13.9 ng/mL. In 25 of 125 samples (20%), the vitamin D level was outside +/- 20% of the label claim (10.4% under-fortified, 9.6% over fortified). Intra-batch, inter-batch, and intra-producer variations were 1.6 -20.8%, 8.2-20.8%, and 16.1%, respectively. CONCLUSIONS: Vitamin D content in fortified low fat cow milk on the Riyadh market matches label claim in 85% of the samples of major retailers. Variations from label claim in 15% of the samples are small and may not be clinically important. LIMITATIONS: This study was limited to five major retailers in the Riyadh area and did not examine full-fat or non-fat milk samples.