Ok – I’m excited!! A recent meta-analysis of seventeen epidemiological studies (n=1,643 depressed individuals and 804 controls) investigating zinc levels and depression found that depressed individuals had lower plasma/serum zinc levels than non –depressed people (Swardfager et al., 2013) While the actual difference in plasma/serum zinc was found to be small, approximately -1.85 umol/L lower in depressed compared with control individuals, the effect size increased in individuals with more severe depression, inpatients and studies with more robust methodology.
It is important to note that the lower levels seen in depressed patients were typically still within the established reference range….and this is the bit where I get excited because in fact, all 16 studies that found a correlation between lower plasma/serum zinc and depression found a mean zinc level i.e. 10-14mmol/L that according to the reference range used here in Australia (9-19 umol/L) – would be deemed adequate!
This research suggests that a) the reference range for zinc testing needs serious review and b) when some health professionals insist that there’s nothing wrong with your patient’s zinc result because “it’s within range” – we now have a great piece of very significant evidence to support our different interpretation and the need for zinc supplementation.
If you want to hear more about these new findings and the key things you need to know about plasma and serum zinc testing and interpretation then have a listen to the latest premium audio here