Is tea worse than diet coke?

Depends: Depends on what you put into your tea. Usually, diet coke is worse.

That depends: Are we talking black tea, green tea, herbal tea? How much is being ingested. Green, red & white teas can be healthy in moderation (especially if decaffeinated). Many herbal teas are fine - but need to know which ones. In general the Diet Coke would be worse for health. Regularly drinking soda has been linked to Non-Alcoholic Fatty Liver Disease, Diabetes, heart disease & metabolic syndrome.