J Steroid Biochem Mol Biol. 2018 Jun;180:23-28. doi: 10.1016/j.jsbmb.2018.02.002. Epub 2018 Feb 9.
Al-Daghri NM1, Ansari MGA2, Sabico S2, Al-Saleh Y3, Aljohani NJ4, Alfawaz H5, Alharbi M6, Al-Othman AM7, Alokail MS2, Wimalawansa SJ8.
2 out of 4 of the milk brands decreased the Vitamin D levels
The word FAT does not occur once in the study
VitaminDWiki suspects the decreases occurred in brands with low-fat milk content
“A total of 889 apparently healthy Saudi adolescents aged 11–17 years were randomly enrolled from 34-different schools in Riyadh city during the months of November-May 2014–2015.”
It appears that different brands of milk were served to different high schools
It appears that the RCT occurred during the Winter, Spring, when Vitamin D levels normally drop
So, the drop observed may have been due to season - the brands with lower Vitamin D levels were not able to cancel the seasonal drop
Another possibility - the two brands may have supplemented with Vitamin D2 rather than D3
Vitamin D deficiency is rampant in the Middle East, even in children and adolescents. This study was designed to investigate the effects of different vitamin D repletion strategies commonly used on serum vitamin D levels of Saudi adolescents.
A 6-month multi-center, controlled, clinical study, involving 34 schools in the central region of Riyadh, Saudi Arabia. Different strategies of vitamin D supplementation were tested (200 ml fortified milk of different brands or vitamin D tablet (1,000IU). Anthropometrics were taken and fasting blood samples withdrawn at baseline and after intervention for the quantification of serum glucose, lipid profile and 25(OH) vitamin D. A significant increase in 25(OH)D level was observed in subjects supplemented with vitamin D tablet, milk brand 2 and milk brand 4, whereas subjects supplied with fortified milk brands 1 and 3 respectively, exhibited a significant decrease in 25(OH)D levels. Analysis of covariance showed that after adjusting for baseline 25(OH)D, age, gender and BMI, the mean 25(OH)D levels of children who were taking vitamin D tablet (9.1 ± 0.8 nmol/l) and milk brand 4 were significantly higher (7.3 ± 1.1 nmol/l) than children taking milk brand 2 (1.6 ± 1.0 nmol/l). Subjects supplied with milk brands 1 and 2 exhibited a significant increase in total cholesterol level, while it dropped significantly in subjects taking milk brand 3, while no changes were observed in other groups. Different strategies in vitamin D supplementation used in this clinical study elicited varying degrees of improvement in serum 25(OH)D level. The observed outcomes were dependent on the strategy and gender in the Saudi adolescent population, with oral tablet supplementation being favored in boys.