An increase in vitamin A status by the feeding of conjugated linoleic acid.


Banni S, Angioni E, Casu V, Melis MP, Scrugli S, Carta G, Corongiu FP, Ip C.




Nutr Cancer


Previous research indicated that conjugated linoleic acid (CLA) is a potent inhibitor of mammary carcinogenesis. The present study showed a progressive increase in retinol (vitamin A alcohol) in the liver in proportion to CLA intake in rats that were fed different levels of CLA (in increments of 0.5%) for 1 month. The escalation reached a magnitude of about fivefold over the control at 2% dietary CLA. In contrast, the increase in liver retinyl esters peaked at about twofold between 0.5% and 1% CLA. Only retinol was detected in mammary tissue; a maximal twofold increase was attained at 0.5% CLA, and no dose-response effect was evident. The above findings are discussed in relation to two important questions: 1) How does CLA raise vitamin A status in the animal? 2) Is the increase in vitamin A associated with the anticarcinogenic effect of CLA?