It's not the beta carotene, it's the carrot.

Biotechnology offers a better, cheaper, and more feasible solution Golden Rice, which incorporates beta carotene into the genetically altered rice grains.

The golden color produced by beta carotene bound to the fat in the milk was the main marketing point and the source of the brand name.

The concept is simple. Although rice plants do not normally synthesize beta carotene in the endosperm (seeds), they do make it in the green portions of the plant.

By using gene splicing techniques to introduce the two genes that express these enzymes, the pathway is restored and the rice grains accumulate therapeutic amounts of beta carotene.

The review also questioned the possible harm of such supplements, given the increased risk of lung cancer in smokers with high intakes of beta carotene, and the increased risk of heart failure in at risk populations who consume high levels of vitamin E supplements.