NR is a precursor to NAD, which is the central catalyst of metabolism. Metabolism is the set of processes that converts everything that we eat into everything that we are and everything that we do. And it turns out that our metabolism gets stressed by sunlight, oxygen, and many of the inevitable stresses of life. By boosting our NAD with NR, we can try to maintain resiliency through life as we age. NR is not only for people who are elderly, because sun and oxygen and other common disturbances are intrinsic to our lives.

Much of what we know is from animal research. It’s been observed that as organisms get older, NAD declines in various tissues, like the liver. In fact, I think it may be episodic rather than on a simple timer. There are young people, twenty-year-old athletes, who take NR because they do a lot of physical activity. When you play football on Sundays—suit up and have a lot of collisions—there are many repair processes that tax the NAD system. Inflammation and infection can also tax the NAD system. So my point of view is that most of the attacks on the NAD system are episodic. They may be correlated with aging but are not necessarily caused by aging itself. But the idea is that we can boost our resiliency as we go through our lives by maintaining NAD.

The body does have mechanisms to try to maintain NAD. However, the NAD system comes under attack in a lot of different conditions. For example, when DNA gets damaged, which happens all the time because of sunlight and environmental exposures, NAD is deployed to repair DNA. When NAD is in use to play defense, it’s less available for all the other metabolic processes.

One of the fun things that I used to do when people got together in an auditorium to learn about NAD was to ask for a show of hands: How many people would love to get on a jet, fly to Ibiza, be outside in the sunlight, listening to music and eating great food and drinking wine into the evening? Everybody of course raised their hand, right? It turns out that all of those things can attack the NAD system. The time zone disruption, oxygen, sunlight, alcohol, and eating to excess will attack the NAD system. Not necessarily music, but sufficient noise to produce hearing loss can also do this.

Imagine a cat lady who has lots of cats, and we have a series of pictures of her hands. We could order those pictures on the basis of scars on the back of her hands. But the scars were not caused by time. The scars were caused by cats. So there’s an episodic nature to what you’re observing. When people say that NAD declines in aging, I don’t know that this is due to time. The evidence is stronger that NAD is disturbed episodically by conditions of metabolic stress, many being of the inevitable variety.

There are several other vitamin precursors to NAD. High-dose niacin causes flushing, so there are not many people who enjoy taking that. There are some limitations in using higher-dose nicotinamide, and NAD and NMN supplements have to be broken down to NR before they can go into a cell. The NR pathway gets turned up in cells that are stressed. This makes NR a very attractive NAD precursor vitamin.

A higher NAD status is known to be protective of skin. When DNA is being damaged by the sun, NAD is deployed to do repair processes. Boosting NAD status will support skin cells that are doing DNA repair.

I’m not all that fancy really. I think that the key to wellness is eating well and being physically and mentally active and socially engaged. I try to be positive. But do I do intermittent fasting? No. Do I have a trendy diet? No. Am I keto? No. People have to find enjoyable and sustainable practices for themselves. Clearly matching energy expenditure to energy intake is important—which means not eating too much and staying physically active are important. I think working out hard enough to get a good sweat and elevate one’s heart rate is important. But I don’t think it’s evidence based for nondiabetics to wear continuous glucose monitors, and I don’t go in for a lot of things that are the latest fads.

I like to get up and have breakfast. And while I personally don’t eat very late in the day, I would not prescribe someone else’s time interval for eating. In my view, orthorexia—a kind of compulsiveness about eating practices—is promoted when people are too prescriptive about their health practices, so I’d like to suggest that people worry less and do more.