Lemon is rich in photosensitive substances, it is true, this kind of material in many citrus peel with, the content of about one-third of the essential oils used by everyone may contain this kind of material. If applied to the skin and then exposed to sunlight, then a photosensitization reaction will occur. The so-called photosensitization reaction is that the photosensitized substances enter the skin and combine with specific molecules, and finally, through a series of reactions, lead to the production of melanin.

But it is not eaten containing such substances will certainly produce photosensitive reaction, experts explain, want to produce photosensitive reaction, the need for conditions have three: first of all, the body specific, followed by the need to have enough light time, and finally the content of the photosensitive substances must also meet a requirement. These three conditions as long as one of them does not meet then photosensitive reaction will not happen, that is to say, want to produce melanin is not so easy.