{"id":1226,"date":"2007-09-28T19:17:53","date_gmt":"2007-09-28T17:17:53","guid":{"rendered":"http:\/\/www.wjst.de\/blog\/2007\/09\/28\/vitamin-a-and-allergy\/"},"modified":"2012-04-20T14:58:28","modified_gmt":"2012-04-20T12:58:28","slug":"vitamin-a-and-allergy","status":"publish","type":"post","link":"https:\/\/www.wjst.de\/blog\/sciencesurf\/2007\/09\/vitamin-a-and-allergy\/","title":{"rendered":"Vitamin A and allergy"},"content":{"rendered":"

No, I am not confusing here vitamin A and vitamin D as done in the early days of vitamin research. This post is really about vitamin A (but with similar nomenclature problem as with vitamin D). Retinol is ingested in a precursor form; animal sources like liver (–>cod liver oil<\/a>) contain retinyl esters, whereas plants like carrots contain carotenoids. Wikipedia<\/a> has the formulas<\/p>\n

\nHydrolysis of retinyl esters results in retinol while pro-vitamin A carotenoids can be cleaved to produce retinal. Retinal, also known as retinaldehyde, can be reversibly reduced to produce retinol or it can be irreversibly oxidized to produce retinoic acid.\n<\/p><\/blockquote>\n

I am primarily interested in retinoic acid as – in analogy to cholecalciferol – this substance has now well documented immunological effects. Just visit JEM for a recent editorial<\/a> and several original papers. The editorial demystifies oral tolerance. Provitamin A is transformed into retinoic acid by gut-associated DCs and enhances the conversion of T cells into FoxP3+ T reg cells by a TGF-\u00df-dependent mechanism.<\/p>\n

So certainly, a good time to ask if excess consumption (or deficit) of vitamin A may be related to allergy. Here are few snippets what’s being already known about vitamin A and allergy – and my interpretation of the vitamin A effect<\/p>\n