These trials showed golden rice could stimulate vitamin A uptake but at a low level.
Indigo Sun said it was fact that UV exposure from sunbeds stimulated vitamin D production.
And it appears that many people don't get enough -- especially in the winter months when there's less sunlight available to stimulate vitamin D production in the body.
In cultured cell lines β-catenin can bind to unligated VDR, but complex formation is enhanced by vitamin D, and β-catenin stimulates vitamin D dependent transcription [10].
Transient transfection of a stabilised β-catenin mutant (S37A) stimulated vitamin D dependent transcription in a dose dependent manner in wild type cells (Figure 1D).
With shorter winter days and insufficient solar radiation in the UVB wavelengths needed to stimulate vitamin D synthesis, dietary sources such as fatty fish became increasingly important.
Indeed, leptin addition to normal Ob stimulated vitamin D3-dependent alkaline phosphatase activity, however, neither anti-Rb nor AG490 had any effect on this activity, indicating no cytotoxic effects of these treatments on normal Ob.
PTH has an important role in calcium homeostasis, as it stimulates vitamin D activation in the kidney, increases renal calcium reabsorption in the distal tubules and affects bone cells such as osteoblasts, osteoclasts and stromal cells [ 16].
It can be argued that our stratification into the low, moderate and high UV regions would have been more accurate in terms of ability of the UV light to stimulate vitamin D synthesis, if we had stratified the country using the vitamin D action spectrum weighted UV rather than the UV index.
Race/ethnicity potentially exaggerates dependency on food sources of vitamin D for those living in northern latitudes and/or low solar load regions, as dark complexion impairs the ability for low levels of ultraviolet light to penetrate the skin and stimulate vitamin D synthesis [ 2].
