Research Forum

Forum Navigation
You need to log in to create posts and topics.

Carotenoids are directly converted to toxic retinyl esters (including retinyl palmitate) in the skin

This can begin to explain my hunch that the carotenoids are just as toxic or possibly more toxic than retinol...because they can be directly converted to retinyl esters (including retinyl palmitate):

Topical beta-carotene is converted to retinyl esters in human skin ex vivo and mouse skin in vivo.

Human epidermis contains endogenous retinoids (retinol and retinyl esters) and carotenoids (mostly beta-carotene). Previous studies have shown that the enzymes involved in retinoid metabolism are present in human epidermis. There is still a controversy about the presence in the skin of the enzymes able to convert beta-carotene into vitamin A (retinol), although a recent study demonstrated the conversion of beta-carotene into retinol in human cultured epidermal cells. In this study, we addressed the question of the possible bioconversion of topical beta-carotene into vitamin A or derivatives by human and mouse skin. Surgically excised human abdominal skin was mounted on Franz perfusion chambers to assess the cutaneous penetration of topical beta-carotene as well as its metabolism, after a 24-h incubation period, whereas hairless mice received topical beta-carotene 24 h before assaying epidermal beta-carotene and retinoid concentrations. Epidermal retinoid and beta-carotene concentrations were determined by high-pressure liquid chromatography. Topical beta-carotene penetrated well into human and mouse epidermis and induced a 10-fold (human) and a threefold (mouse) increase of epidermal retinyl esters, which demonstrates that topical beta-carotene is converted into retinyl esters by human and mouse epidermis and thus appears as a precursor of epidermal vitamin A.

Beta-carotene can be converted directly into retinyl esters.  One can have a low serum retinol, yet have a high fraction/percentage of retinyl esters, and that alone will cause Poison/"Vitamin A" toxicity.  This is starting to explain the large numbers of diseases that appear to have "low serum retinol", yet have all the signs of Poison/"Vitamin A" toxicity...because the serum retinyl esters are not being accounted for!  This is huge.

Dr. Garrett Smith, the "Nutrition Detective"
Licensed Naturopathic Physician (NMD) in Arizona, home of the Love Your Liver program
YouTube - FaceBook - Instagram - Twitter