Giving male mice a supplement called NMN every day for a year seems to help their eyes work better as they get older, especially in a type of mouse prone to eye problems.

What we've found so far suggests that long-term NMN supplementation may support eye function in aging male C57BL/6N mice with the rd8 mutation. Our analysis of the available evidence shows that daily NMN intake over a year appears to help maintain better eye function in this specific group of mice as they age [1]. We looked at one key assertion based on 11.0 supporting studies, with no studies refuting the idea [1]. This means the evidence we've reviewed leans toward a positive effect of NMN on eye health in these mice. The rd8 mutation makes these mice more prone to eye issues, so any support for function is notable. Still, all the data we have comes from studies on this single mouse type, and only male mice were studied. We can't say how this might apply to other animals or humans, or even female mice, because the evidence doesn't cover that. We also don’t have details on *how much* improvement occurs or which specific aspects of vision are affected. Our current analysis is limited to what’s been studied so far — long-term, daily NMN use in this particular mouse model. Because this is based on one assertion backed by multiple supporting studies, we’re confident there’s a pattern worth noting. But science builds over time, and new evidence could change how we understand these results. Practical takeaway: In this specific type of aging male mouse with a genetic tendency for eye problems, giving NMN every day for a year seems to help their eyes work better. We don’t know yet if this applies to other cases or what it means for humans.