Science

Phytochemicals / Phytonutrients
Both can be used interchangeably. The word 'phyto' in Greek means plant.

They are not necessary for our body and so it would not result in diseases due to deficiency. They are unlike vitamins and not vitamins.

Unlike vitamins and enzymes, they will not be destroyed by the preparation methods. Chances are the preparations could cause them to be more readily available.

Oxidation / Free radicals
Both stand the same.

Oxygen is Zeus and oxidation is the Devil.

Oxygen
--chemically reactive and unstable upon biochemical reactions
--oxidizes its other molecules like rusting iron and sliced apple turns brown

Oxidation
--molecule with a lost electron, rendering it unstable
--damage cells with toxin as end product
--eg. cancer-causing free radicals are called carcinogenic

Antioxidant
--most powerful phytochemical
--molecule with several detachable electrons and stable after releasing
--donates 1 electron to free radicals, neutralizing it to be harmless

Carotenoid
--beta carotene ( contains pigment)
--absord + convert to vitamin A and antioxidant
--taken in excess will decolourised your skin