NAD+, NR, and the Longevity Conversation

Interest in NAD supplements, longevity supplements, and NMN vs NAD continues to grow. The reason is clear: modern longevity science is centred on cellular health, and NAD+ sits at the core of how our cells produce energy, repair damage, and age.

So what does NAD+ actually do, how can you increase NAD naturally, and what are the best NAD supplements?

What is NAD+?

NAD+ is a coenzyme found in every cell, essential for:

• Energy production (mitochondrial function)
• DNA repair
• Cellular resilience and ageing pathways
• Sirtuin activation linked to longevity

NAD+ levels naturally decline with age. This is associated with reduced energy, impaired repair, and increased cellular stress, all key drivers of ageing.

NAD+ and ageing

There is now over a decade of research linking NAD+ to the biology of ageing.

• Levels decrease steadily over time
• Mitochondrial function declines
• DNA repair becomes less efficient
• Cellular stress increases

This is why NAD+ is central to supplements for cellular health.

Can you take NAD+ directly?

Despite the rise in NAD IV drips and direct NAD supplements, the evidence is limited:

• NAD+ is not easily absorbed in its full form
• There is no clear proof that IV or oral NAD significantly increases intracellular levels
• High-dose IV approaches may carry risks such as metabolic strain and oxidative stress

Current clinical thinking suggests IV NAD should be reserved for specific medical contexts, not general longevity.

NMN vs NAD vs NR

If the goal is to support NAD+, the more effective approach is through precursors.

This is the core of the NMN vs NAD discussion.

The two main NAD precursors are:

• NMN (nicotinamide mononucleotide)
• NR (nicotinamide riboside)

Both can increase NAD levels, but NR stands out:

• Stronger human clinical evidence
• Well-established safety profile
• Efficient conversion into NAD+

This is why NR is increasingly considered among the best NAD supplements available.

Why delivery matters

Many supplements for cellular health overlook absorption.

• Capsules can degrade in the digestive system
• Bioavailability is reduced through first-pass metabolism

In contrast, liquid or sublingual formats:

• Absorb more efficiently
• Bypass parts of digestive breakdown
• Improve utilisation of NAD precursors

A more effective longevity approach

The evidence is consistent:

• Direct NAD supplementation is not the most effective strategy
• Precursors like NR offer a more credible pathway
• Absorption and delivery format matter

Marathon Not A Sprint is built on this approach, using NR to support cellular health and longevity pathways in a format designed for efficient absorption.