The correct answer would be the third option. Phytochemicals are plant compounds with the ability to stabilize free radicals. These are substances produced by plants that functions in helping them to survive over their predators, pathogens and competitors. They can be produced through primary or secondary metabolism. These compounds are considered as research compounds instead of essential substances since they have not been established to have good effects. Some phytochemicals are beneficial to humans while some are toxic and can interfere with the absorption of nutrients in the body. Examples of these compounds are carotenoids, polyphenols, anthocyanins, flavanols, catechins, lignans, isoflavanones and proanthocyanidins.
Vaccinations exist for the flu and the chicken pox