Insufficient Muscle Development Level Associated with Serum Zinc, Manganese and Cobalt Levels in Children Aged 6 to 9 Years in Shenzhen, China.

Some trace elements have been found to be associated with muscle mass and muscle function; however, evidence in children is limited, and it remains unclear which trace elements are more relevant. We aimed to explore the association of levels of individual and combined essential trace elements and muscle development level (MDL) in young children. Muscle mass was measured by body composition analysis, and trace elements were determined by using inductively coupled plasma mass spectrometry (ICP-MS). Logistic regression, restricted cubic spline (RCS) and weighted quantile sum regression (WQS) were used to assess the individual and joint associations between trace element levels and MDL. We enrolled 2851 children: 1595 boys (55.9%) and mean age 7.1 years (range 6.8-7.3). The proportion of insufficient muscle mass in the whole body, limbs, upper and lower limbs was 1.9%, 6.5%, 44.9% and 4.6%, respectively. The odds of insufficient MDL decreased with the fourth versus first quartile of zinc (OR = 0.67, 95% CI: 0.51-0.89), manganese (OR = 0.80, 95% CI: 0.65-1.00), and cobalt (OR = 0.89, 95% CI: 0.81-0.99) and was increased with the fourth quartile of nickel (OR = 2.23, 95% CI: 1.72-2.89) and selenium (OR = 1.51, 95% CI: 1.14-1.98). The RCS yielded similar results, except for the discrepancy in high cobalt levels. The odds of insufficient MDL decreased with the combination of nine trace elements (OR = 0.84, 95% CI: 0.73-0.97), primarily zinc (weight = 0.297), manganese (weight = 0.198) and cobalt (weight = 0.173). Insufficient MDL in young children was mainly in upper limbs. Low levels of zinc, manganese, and cobalt, individually or combined, were significantly associated with risk of insufficient MDL. Further foods rich in zinc, manganese, and cobalt should be suggested to supplement in diet, and increase exercise of upper limbs to improve insufficient MDL in the young children should be needed.