Gum usually contains sugar or artificial sweeteners, which allows coating your teeth with sugar while you chew the gum leading to plaque buildup and tooth decay.
Chewing also signals your body that you are about to swallow food, so the acids that are used in the digestion of food are activated, causing all sorts of problems in your stomach.
When one consumes a chewing gum, the physical movement of the teeth and jaw goes up by 40% which if continued for a longer span of time can cause splitting headache, that can be very painful.
Lanolin is the ingredient which keeps chewing the gum soft. This ingredient is also found in skin care products. It is just as bad as it sounds; it is a yellow waxy substance which is secreted by the sebaceous glands of the sheep.
Chewing gum can release the mercury from these fillings into your system. High levels of mercury in your system can cause neurological issues as well as chronic illnesses and mental disorders.