Purpose of review
In critical care, micronutrients remain perceived as ‘quantum’ part, that is, a little pertinent component of therapy. Some micronutrients have attracted more attention because of their antioxidant properties. During the last decade, some large size trials have tested their therapeutic potential, generally as ‘single high-dose micronutrient intervention’, with variable success. This review aims at taking stock of most recent.
Micronutrient blood levels are generally low in ICU patients, which has prompted the concept of replenishing or compensating deficits, or even realizing a pharmacological action. Single micronutrient trials have been conducted in large cohorts with selenium (≥1000 μg/day), with limited success but no harm. Other trials have tested high-dose vitamin D (>400 000 IU), with nonconvincing results despite selecting patients with very low blood levels. High-dose vitamin C has been tested in septic shock (+/- thiamine, hydrocortisone) with variable results. A problem encountered in all studies is definition of deficiency based on blood levels as majority of the patients suffer inflammation, which causes redistribution of the micronutrients away from the circulating compartment in the absence of real deficiency.
Micronutrients are essential in the ICU. Due to their antioxidant properties and to the high prevalence of low blood concentrations suggestive of deficiency, several large-size RCTs have been conducted with variable success. Further research must clarify the respective importance of deficiency and inflammation.