Efficacy of food fortification on serum 25-hydroxyvitamin D concentrations: systematic review.
BACKGROUND
Many residents of the United States and Canada depend on dietary sources of vitamin D to help maintain vitamin D status. Because few natural food sources contain vitamin D, fortified foods may be required.


OBJECTIVE
We aimed to determine the effects of vitamin D-fortified foods on serum 25-hydroxyvitamin D [25(OH)D] concentrations.


METHODS
We searched MEDLINE (1966 to June Week 3 2006), Embase, CINAHL, AMED, Biological Abstracts, and the Cochrane Central Register of Controlled Trials for randomized controlled trials (RCTs) comparing vitamin D-fortified foods with a control and reporting serum 25(OH)D concentrations. Two reviewers independently determined study eligibility, assessed trial quality, and extracted relevant data. Disagreements were resolved by consensus. Meta-analyses of absolute mean change in 25(OH)D were conducted by using a random-effects model, with evaluation of heterogeneity.


RESULTS
Nine RCTs (n = 889 subjects) were included, of which 8 consistently showed a significant beneficial effect of food fortification on 25(OH)D concentrations. Although 7 RCTs (n = 585 subjects) potentially were meta-analyzable, we were unable to combine the overall results because of significant heterogeneity. The individual treatment effects ranged from 14.5 (95% CIs: 10.6, 18.4) nmol/L to 34.5 (17.64, 51.36) nmol/L (3.4-25 microg vitamin D/d). Subgroup analyses showed a reduction in heterogeneity and significant treatment effect when 4 trials that used milk as the fortified food source were combined.


CONCLUSIONS
Most trials were small in size and inadequately reported allocation concealment, but results showed that vitamin D-fortified foods improved vitamin D status in adults.
O'Donnell
Siobhan
S
Clinical Epidemiology Program, Ottawa Health Research Institute, Ottawa, Canada.
Cranney
Ann
A
Horsley
Tanya
T
Weiler
Hope A
HA
Atkinson
Stephanie A
SA
Hanley
David A
DA
Ooi
Daylily S
DS
Ward
Leanne
L
Barrowman
Nick
N
Fang
Manchun
M
Sampson
Margaret
M
Tsertsvadze
Alexander
A
Yazdi
Fatemeh
F
D000293:Adolescent; D000328:Adult; D000368:Aged; D000818:Animals; D050071:Bone Density Conservation Agents / Q000008:administration & dosage*; D005260:Female; D005527:Food, Fortified; D006801:Humans; D008297:Male; D008875:Middle Aged; D008892:Milk / Q000737:chemistry*; D009747:Nutritional Physiological Phenomena; D009752:Nutritional Status; D016032:Randomized Controlled Trials as Topic; D016896:Treatment Outcome; D014807:Vitamin D / Q000008:administration & dosage* / Q000031:analogs & derivatives* / Q000097:blood; D055815:Young Adult
D050071:Bone Density Conservation Agents; D014807:Vitamin D; C104450:25-hydroxyvitamin D