Exactly correct, but perhaps not in the way you think. Having excess retinol does not offer 'protection' in the literal sense. It does not shield your DNA as i

Exactly correct, but perhaps not in the way you think. Having excess retinol does not offer 'protection' in the literal sense. It does not shield your DNA as it replicates to replace the cells that died at the elevated rate of death due to UV exposure. Rather, retinol is rare (% of bodymass) and is a key component of the chain of cell duplication. Having excess retinol available means your processes won't 'run out' of it when they need it. This protects from the biological equivalent of 'cutting corners' in manufacturing and THIS is how it reduces transcription error. It's preventative by way of avoiding a deprivation. If you are anticipating any excess cell death for any reason, it is better to have a slight oversupply of retinol as well as a variety of other antioxidants. The benefits are (literally) microscopic but are cumulative over a lifespan. Think of it a bit like brushing your teeth. You're not rebuilding enamel, you're preventing it's loss.