Vitamin C appears to convert sodium selenite (a form of selenium used for supplementation) to elemental selenium, making it unavailable for absorption. This interaction occurred when 1 g of vitamin C was taken with sodium selenite on an empty stomach, but not when these nutrients were taken together with a meal. Vitamin C does not appear to interact with selenomethionine, another commonly used form of supplemental selenium.
- Robinson MF,Thomson CD,Huemmer PK. Effect of a megadose of ascorbic acid, a meal and orange juice on the absorption of selenium as sodium selenite. The New Zealand medical journal. 1985 Aug;98(784):627-9
- Ip C. Interaction of vitamin C and selenium supplementation in the modification of mammary carcinogenesis in rats. Journal of the National Cancer Institute. 1986 Jul;77(1):299-303