Methods of Assessment of Zinc Status in Humans: An Updated Review and Meta-analysis

Area of Science:

• Nutritional Biochemistry
• Human Physiology
• Biomarker Research

Background:

• Accurate zinc status assessment is vital for identifying deficiency and evaluating intervention effectiveness.
• Previous systematic reviews (SR) have explored biomarkers of zinc status, with the last comprehensive update by the EURRECA network in 2009.
• This study addresses the need for an updated assessment of biomarkers reflecting short-term changes in zinc intake.

Purpose of the Study:

• To update the 2009 EURRECA SR on biomarkers of zinc status.
• To determine which biomarkers of zinc status effectively reflect changes in zinc intake within a minimum of two weeks.

Main Methods:

• A systematic literature search was conducted from January 2007 to September 2022 across major databases (MEDLINE, Embase, Cochrane).
• Data from identified articles were extracted and combined with data from the previous SR.
• A random-effects model meta-analysis was employed to analyze pooled data, assessing risk of bias and certainty of evidence.

Main Results:

• Pooled data analysis confirmed that plasma/serum zinc concentration and urinary zinc excretion respond to changes in zinc intake in healthy participants.
• Significant mean effect sizes were observed for both plasma/serum zinc (controlled studies: 2.17 µmol/L; before-and-after studies: 2.87 µmol/L) and urinary zinc (0.39 mmol/mol creatinine; 3.09 µmol/day).
• Forty new putative biomarkers were identified, but further research is required to validate their sensitivity and reliability.

Conclusions:

• Updated meta-analyses confirm that plasma/serum zinc and urinary zinc are responsive biomarkers to changes in zinc intake in healthy populations.
• While new potential biomarkers have been identified, their utility requires further investigation.
• These findings support the use of plasma/serum and urinary zinc as indicators of recent zinc intake changes.