The more frequently cells replicate the faster they accumulate transcription error. Mice have a cell doubling rate far FAR higher than humans, so we would expect a wildly different pattern in encoding.
But I was wondering if that even was a wise thing to do given that it simply accelerate cell turnover in the epidermis if I'm not mistaken.
If so, doesn't it mean premature aging of the skin? (a bit of a tangent :o)
If someone else knows more...?
What they do is preempt extra-environmental stress and the resultant write error. This is less protective and more avoidive.
IE, if you have less Retinol then you are genetically optimized for you will accrue slightly more oxidative stress as a result of your deficiency. Supplements can prevent this particular stress by alleviating deficiency, but they can't reduce it beyond whatever your base rate is.
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.