Methods of assessment of selenium status in humans: a systematic review.
BACKGROUND
To understand the effect of selenium intake on health, it is important to identify sensitive and population-specific biomarkers of selenium status.


OBJECTIVE
The objective of this systematic review was to assess the usefulness of biomarkers of selenium status in humans.


METHODS
The methods included a structured search strategy on Ovid MEDLINE, EMBASE (Ovid), and Cochrane databases; formal inclusion and exclusion criteria; data extraction into an Access database; validity assessment; and meta-analysis.


RESULTS
The data from 18 selenium supplementation studies (of which 9 were randomized controlled trials and 1 was considered to be at low risk of bias) indicate that plasma, erythrocyte, and whole-blood selenium, plasma selenoprotein P, and plasma, platelet, and whole-blood glutathione peroxidase activity respond to changes in selenium intake. Although there is a substantial body of data for plasma selenium, more large, high-quality, randomized controlled trials are needed for this biomarker, as well as for the other biomarkers, to explore the reasons for heterogeneity in response to selenium supplementation. There was insufficient evidence to assess the usefulness of other potential biomarkers of selenium status, including urinary selenium, plasma triiodothyroxine:thyroxine ratio, plasma thyroxine, plasma total homocysteine, hair and toenail selenium, erythrocyte, and muscle glutathione peroxidase activity.


CONCLUSIONS
For all potentially useful biomarkers, more information is needed to evaluate their strengths and limitations in different population groups, including the effects of varying intakes, the duration of intervention, baseline selenium status, and possible confounding effects of genotype.
School of Medicine, Health Policy and Practice, the University of East Anglia, Norwich, United Kingdom.
Kate
K
Ashton
Lee
L
Hooper
Linda J
LJ
Harvey
Rachel
R
Hurst
Amélie
A
Casgrain
Susan J
SJ
Fairweather-Tait
D015415:Biomarkers / Q000097:blood*; D002986:Clinical Trials as Topic; D019587:Dietary Supplements; D005979:Glutathione Peroxidase / Q000097:blood*; D006801:Humans; D008722:Methods; D015596:Nutrition Assessment; D009752:Nutritional Status; D012643:Selenium / Q000097:blood*; D051140:Selenoproteins / Q000097:blood*; D014131:Trace Elements / Q000097:blood* / Q000494:pharmacology
D015415:Biomarkers; D051140:Selenoproteins; D014131:Trace Elements; D005979:Glutathione Peroxidase; D012643:Selenium