Is coffee good or bad?

Caffeine may have some good effects if you are adult. But for kids it is certainly bad. Some effects on kids are given below.

Psychological and Physiological
The brain of a child tend to be a little bit more sensitive to caffeine`s effects than brain of adults that explains why It’s easier for children to develop caffeine dependency.
Caffeine inhibits the neurotransmitter Adenosine, which is responsible for sleep. Continuous uses of Caffeine can create sleep problems.
Caffeine increases release of Adrenaline and dopamine which make heart beat faster, can make them to be hyperactive, nervous, anxious.
It dilates the blood vessels making them pee more that causes the body to excrete Calcium.

Nutritional Deficiency
Beside decreasing appetite caffeinated beverages often contain empty calories ( calories that don’t provide any nutrient) and kids who fill up on them don’t get the vitamins and minerals they need, putting them at risk for nutritional deficiencies.
Serving your baby coffee or tea with meals can interfere with adequate absorption of Calcium and iron. (which is fundamental to growth of bones and teeth in kids.)

Dental Problem
Drinking too much sweetened caffeinated drinks could lead to dental cavities form the high sugar content and the erosion of tooth enamel from acidity.