Observational studies consistently show that teetotallers have worse life expectancy than people who drink in moderation.
However there are other differences that may explain this - the teetotallers may be poorer - they may be recovering alcoholics - they may be on medication for other health issues that prevent them drinking.
Or it may be a genuine effect - alcohol can help with heart and stroke risk in very moderate quantities, and heart and stroke are such huge killers that even small benefits can outweigh the negative effects on eg cancer risk.