Everything in life has side effects. Take oxygen for example. Our cells wouldn’t survive without it and yet it’s the biggest generator of free radicals, potential chemical poisons that have the capacity to initiate massive destruction if left unchecked. Nicotinamide adenine dinucleotide (NAD) is a similar molecule. As we age our bodies manufacture less of this substance which might lead to ageing and degeneration. Boosting NAD might help to slow down ageing and it just so happens that there is a supplement which does just that called Nicotinamide mononucleotide (NMN). But there is a potential downside to ramping up NAD with NMN. Cancer cells also need NAD to grow and therefore taking NMN to augment NAD might inadvertently help cancer cells to multiply. Like oxygen NMN might be life preserving but also possibly dangerous.
What we don’t yet have is the technology which would allow us to peek into our cells and find out if we have any cancer growth in its early stages which might make supplementing with NMN an unwise choice. This is why taking NMN is potentially fraught.