What This Means
This research examined how blood levels of heavy metals (lead, cadmium, mercury, and manganese) and selenium relate to the risk of death in people with cardiovascular-kidney-metabolic (CKM) syndrome — a condition involving the interconnected problems of heart disease, kidney disease, and metabolic disorders like diabetes and obesity. The researchers followed 6,072 adults from a large U.S. national health survey (NHANES, 2011-2018), during which 409 participants died. The main finding was that people with higher blood selenium levels had a substantially lower risk of dying from any cause: those in the highest selenium group had a 38% lower mortality risk compared to those in the lowest selenium group. The relationship followed an 'L-shaped' pattern, meaning mortality risk dropped sharply with initial selenium increases and then leveled off.
The study also investigated whether inflammation might explain part of the selenium-mortality link. Using four different markers of systemic inflammation (NLR, MLR, NMLR, and SIRI), the researchers found that inflammation did partially mediate the relationship — meaning some of selenium's apparent protective effect may work through reducing inflammation. However, this mediating role was modest, with inflammation accounting for only about 3.6% to 5.3% of the total association, suggesting other biological pathways are also involved. The protective association between selenium and survival was consistent regardless of whether patients had early-stage or advanced CKM syndrome.
This research suggests that selenium status may be an important factor in survival outcomes for people with CKM syndrome, and that environmental or nutritional exposures to metals and selenium could be relevant to this high-risk population's prognosis. The findings highlight the potential value of monitoring trace element levels and inflammatory markers in people with CKM syndrome, though as an observational study it cannot prove that selenium directly causes reduced mortality.