I have a friend who drinks a lot of seltzer water and I worry this is adding acidity to his body. What’s your opinion about this?
Be aware that “soda water" is slightly different. In soda water, generally, an alkalizing agent such as sodium bicarbonate, or a potassium-based alkaline compound, is added to the artificially carbonated water. This reduces the acidity of the water to some degree and can add a slight salty taste.