Possible Interaction: Vitamin A and Vitamin D

“ Vitamin A acts in synergy with vitamin D , and the immunological homeostasis ensured by these vitamins should not be unbalanced in favour of only one of them.”

“The hypothesis further proposes that vitamin A protects against the toxicity of vitamin D by decreasing the expression of vitamin K-dependent proteins and thereby exerting a vitamin K-sparing effect.”

“The "in vitro" lytic effect of retinol (35 microM) on various animal species erythrocytes is partially inhibited by cholecalcipherol.”

“These results are discussed and related to tocopherol metabolism in A-hypervitaminotic rats and to the well-known antagonism between retinol and cholecalcipherol , whose prolipoperoxidative action "in vivo" is recorded.”

“Conclusions: VA and VD co-deficiency may exacerbate AD symptoms in children, but the specific mechanism underlying this relationship requires further study.”

“Additionally, VA and VD co-deficiency impacts more on the symptoms and development in autistic children.”

“Conclusions: We found that children with autism have more VA and VD deficiencies than control children, and VA and VD co-deficiency may exacerbate the symptoms of children with ASD.”

“Vitamin A intakes reach potentially toxic levels in about 30% of adults in high-income countries, but are often grossly … low-income and middle-income countries, whilst vitamin D defi ciency remains common in all settings, and associations of human vitamin D status with mortality … modified by vitamin A ….”

“A possible interaction between vitamin A exposure and 25(OH)D concentration appears to be associated with an attenuation of the inverse association between risk of death and quartile of 25(OH)D concentration.”

“We report a study testing the hypothesis that high vitamin A levels may reduce the protective effect of vitamin D on outcome.”

“A high retinol level together with vitamin D deficiency/insufficiency is an additional risk factor for osteoporosis.”