Currently, most experts in the US agree that concentrations ≥75 nmol/L (≥30 ng/mL) define vitamin D sufficiency, concentrations between 50 and 72.5 nmol/L (20 29 ng/mL) define vitamin D insufficiency, and concentrations <50 nmol/L (<20 ng/ml) defines vitamin D deficiency.
It means that above this concentration, sufficiency of vitamin D does not interfere with PTH secretion.
These differences were more evident in plants grown at low Fe concentrations (iron limiting conditions) than at high iron concentrations (sufficiency conditions), such that G19833 had its highest iron reductase activity when grown at 0 μM Fe, while DOR364 exhibited very low iron reductase activity when grown at 0 or 1 μM Fe, but achieved higher rates when grown at 2 μM Fe.
Only two of 10 donors had mean iodide levels that met the standard of iodide sufficiency when iodide concentrations were averaged.
From associations between 25(OH) D concentrations with PTH concentrations and fractional calcium absorption rates, researchers have proposed that plasma 25(OH D values greater than 50 and 75 nmol/L should define vitamin D sufficiency and "optimal" concentrations (Dawson-Hughes, 2008; Heaney, 2008).
Prior to the N additions, the plants were most likely N-limited as the shoot N concentration was below sufficiency levels (mean = 1.94% for water control) [ 49].
Mineral nutrient analysis [23] revealed a low but not critical status for P (0.23 0.3 %) and Mg (0.17 0.19 %), and Ca and K concentrations in the sufficiency range, without significant treatment differences (Table 2).
All treatments had P concentrations within the sufficiency ranges of spring wheat (0.2 0.5%%) proposed by Mills and Jones [31]; however, the C-a and CPB-a were at the lower end of the sufficiency range (0.2), which together with the low yield indicated P stress.
Folate sufficiency or optimal blood folate concentrations that are directly linked to risk of neural tube defects are needed and could be used as a benchmark to enhance the biomarker based monitoring of prevention efforts and as a tool for needs assessments of such efforts (for example, implementing or modifying fortification programs).
The new miniaturised and automated 1,728 multiwell Screen format presented here has enabled the analysis of a large multidimensional space (Screen 1: N and P full factorial; Screen 2: ten elements at three concentrations) for nutrient sufficiency (and minimisation of toxic effects) at three levels.
