Vitamin D dose response study in Canadian infants: 25-hydroxy-vitamin D status during a 20 week intervention

Sina Gallo1, Catherine A Vanstone1, Kathryn Comeau1, Sherry Agellon1, Celia Rodd2, Atul Sharma2 and Hope A Weiler1
FASEB (Federation of American Societies of Experimental Biology) Journal Vol 24 April 2010 537.11
1 Dietetics and Human Nutrition, McGill University, Ste. Anne de Bellevue, QC, Canada
2 Montreal Children’s Hospital, Montreal, QC, Canada

The Canadian Paediatric Society (CPS) recommends breastfed infants receive vitamin D supplementation (400 to 800 IU/d) in support of optimal plasma 25-hydroxy vitamin D (25(OH)D), defined as 75 nM.

The objective of this study was to establish a dosage of vitamin D that would support optimal status in 97% of young infants. Healthy term born infants from Montreal (32 girls, 46 boys) were randomized to 400, 800 or 1200 IU vitamin D3 daily from age 4 wk and plasma 25(OH)D (RIA, Diasorin Inc.) measured at baseline, 4, 8 and 20 wk (NCT00381914; clinicaltrials.gov). Blinded treatments were re-coded. Repeated measures ANOVA (by ITT) accounting for within-subject serial correlations demonstrated season of birth, weight, time, treatment and treatment-time interaction as significant (p<0.01) predictors of 25(OH)D. Table 1 shows estimated means by time and treatment.

Mean 25(OH)D concentrations were higher over time (p<0.01) in dose regimen A vs. other treatments.
Using 25(OH)D categories, overall 32% were above 75 nM after the 20 wk intervention.

These results suggest that daily dosages of vitamin D from 400 to 1200 IU support a mean 25(OH)D concentration above that associated with deficiency, but the majority do not reach optimal status by 20 wk of supplementation.