Efficacy of fish intake on vitamin D status: a meta-analysis of randomized controlled trials.
BACKGROUND
It is well known that fish is the major natural source of vitamin D in the diet; therefore, this meta-analysis investigated the influence of fish consumption in randomized controlled trials (RCTs) on serum 25-hydroxyvitamin D [25(OH)D] concentrations.


OBJECTIVE
A literature search was carried out in Medline, Embase, Web of Science, and the Cochrane Library (up to February 2014) for RCTs that investigated the effect of fish consumption on 25(OH)D concentrations in comparison to other dietary interventions.


RESULTS
Seven articles and 2 unpublished study data sets with 640 subjects and 14 study groups met the inclusion criteria and were included in this meta-analysis. Compared with controls, the consumption of fish increased 25(OH)D concentrations, on average, by 4.4 nmol/L (95% CI: 1.7, 7.1 nmol/L; P < 0.0001, I(2) = 25%; 9 studies).The type of the fish also played a key role: the consumption of fatty fish resulted in a mean difference of 6.8 nmol/L (95% CI: 3.7, 9.9 nmol/L; P < 0.0001, I(2) = 0%; 7 study groups), whereas for lean fish the mean difference was 1.9 nmol/L (95% CI: -2.3, 6.0 nmol/L; P < 0.38, I(2) = 37%; 7 study groups). Short-term studies (4-8 wk) showed a mean difference of 3.8 nmol/L (95% CI: 0.6, 6.9 nmol/L; P < 0.02, I(2) = 38%; 10 study groups), whereas in long-term studies (∼6 mo) the mean difference was 8.3 nmol/L (95% CI: 2.1, 14.5 nmol/L; P < 0.009, I(2) = 0%; 4 study groups).


CONCLUSIONS
As the major food source of vitamin D, fish consumption increases concentrations of 25(OH)D, although recommended fish intakes cannot optimize vitamin D status.
Institute of Agricultural and Nutritional Sciences, Martin Luther University of Halle-Wittenberg, Halle, Germany; Clinical Medicine, and.
Ulrike
U
Lehmann
Departments of Clinical Science.
Hanne Rosendahl
HR
Gjessing
Institute of Agricultural and Nutritional Sciences, Martin Luther University of Halle-Wittenberg, Halle, Germany;
Frank
F
Hirche
Institute of Inland Fisheries, Potsdam-Sacrow, Germany;
Andreas
A
Mueller-Belecke
Clinical Medicine, and.
Oddrun Anita
OA
Gudbrandsen
Bevital AS, Bergen, Norway;
Per Magne
PM
Ueland
Departments of Clinical Science.
Gunnar
G
Mellgren
Department of Nutrition, Exercise, and Sports, Faculty of Sciences, University of Copenhagen, Copenhagen, Denmark;
Lotte
L
Lauritzen
Department of Internal Medicine and Clinical Nutrition, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden;
Helen
H
Lindqvist
Psychosocial Science, University of Bergen, Bergen, Norway;
Anita Lill
AL
Hansen
Institute of Public Health and Clinical Nutrition, University of Eastern Finland, Kuopio, Finland; and.
Arja T
AT
Erkkilä
Diabetes and Nutritional Sciences Division, King's College London, London, United Kingdom.
Gerda K
GK
Pot
Institute of Agricultural and Nutritional Sciences, Martin Luther University of Halle-Wittenberg, Halle, Germany;
Gabriele I
GI
Stangl
Clinical Medicine, and jutta.dierkes@med.uib.no.
Jutta
J
Dierkes
D000818:Animals; D016208:Databases, Factual; D004032:Diet; D005399:Fishes; D006801:Humans; D009752:Nutritional Status; D016032:Randomized Controlled Trials as Topic; D012307:Risk Factors; D017747:Seafood; D014807:Vitamin D / Q000008:administration & dosage* / Q000097:blood*; D014808:Vitamin D Deficiency / Q000097:blood
D014807:Vitamin D
25(OH)D; fish intake; intervention studies; meta-analysis; randomized controlled trial; vitamin D; vitamin D status