Kidney stones (one of the most painful things you can get) are often made of calcium phosphate. The phosphate comes from the phosphoric acid flavouring in cola drinks and the calcium comes from your bones. The very high levels of phosphate in the blood you get from drinking cola dissolves the calcium from bone.

Cola is a common cause of osteoporosis for the same reason. Two diseases from one glass. And if it's diet cola, make that three. Aspartame is a common cause of incontinence in the elderly, and nothing gives you such a big dose of it as an artificially sweetened soft drink.