Research published in the Journal of Biological Chemistry showed that there could be hazards to consuming excessive amounts of beta carotene. It could paradoxically produce insufficient vitamin A. Beta carotene is composed of two vitamin A molecules. When enzymes cleave them apart properly both molecules of vitamin A are effective. However, when cleaved at the wrong place, one molecule still takes up the receptor site, but deactivates. This, ironically, can lead to one molecule working as an anti-vitamin A and lead to a vitamin A deficiency! Blood levels of this anti vitamin A are detectable in all people becausethey are found in what we eat.
Studies a couple of decades ago showed that people who smoked who took beta carotene supplements had a greater chance of getting lung cancer than those not taking the supplement. We know that oxidants such as environmental pollutants and tobacco smoke increase the production of defective vitamin A. If we continue genetically engineering for higher levels of beta carotene, we need to be certain that the right form of beta carotene is what is engineered...another reason why genetic engineering is a very bad idea!
