Soda mostly consists of empty sugar calories (see also here). Cola actually appears to raise our cholesterol, and Coca-Cola has been found to be very low in antioxidants. Gum arabic, found in some sodas, is harmless. But sodium benzoate, also found in some sodas, is harmful (see also here). And the high fructose corn syrup found in sodas may be contaminated with mercury. Studies funded by the soda (and dairy) industry appear to be even more biased than studies funded by drug companies. Industry influence is likewise seen in the USDA Dietary Guidelines, which did not go as far as other countries to advise against soft drink consumption.
Topic summary contributed by Jerry.