Is diet soda bad for you?
Last updated September 3, 2026.
Approved sweeteners are safe at normal intakes, and diet soda beats sugary soda - but water is the better default, and people with phenylketonuria must avoid aspartame entirely.
What to do
- Prefer it over regular soda - swapping cuts ~150 calories and 40 g sugar per can.
- Keep water the default - seltzer covers the fizz without sweeteners.
- Watch the teeth - any soda is acidic; do not sip all day.
- Avoid aspartame with PKU - MedlinePlus flags this absolute exception.
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