LONGECITY

A recent placebo controlled trial tried to figure out effects of NR in humans undergoing exercise.

The study setup:

participants were supplied with 1 gram of NR or placebo for 1 week

One hour of endurance exercise was carried out after 7 days and metabolic parameters were assessed directly afterwards and 3 hours later. This involved muscle biopsies (so taking muscle tissues samples of the participants) - while invasive for the participants, this gives a much better picture of the impact on real humans than studies with tissues in a petri-dish or mice. The study can be found using tjese links:

Nicotinamide riboside supplementation does not alter whole‐body or skeletal muscle metabolic responses to a single bout of endurance exercise

https://physoc.onlin...0.1113/JP280825

https://www.biorxiv....446v1.full-text

Their findings, quote:

"There was no effect of NR supplementation on substrate utilisation at rest or during exercise or on skeletal muscle mitochondrial respiration."

"NR supplementation did not increase skeletal muscle NAD+ concentration, but it did increase the concentration of deaminated NAD+ precursors nicotinic acid riboside (NAR) and nicotinic acid mononucleotide (NAM) and methylated nicotinamide breakdown products (Me2PY and Me4PY), demonstrating the skeletal muscle bioavailability of NR supplementation."

This could point to different interpretations:

- 1 week is not sufficient to develop the necessary adaptions

- 1 gram is insufficient to increase NAD+ sufficiently

- it doesn't work (for example because of feedback reduction in endogenous NAD+ cycling)

age: 23 ± 4 years

age: 23 ± 4 years

Yes, try this with people that are 55 or older. Not with kids.

Yes, try this with people that are 55 or older. Not with kids.

I guess your point is, that the NAD+ pool is declining with age - and that this could be a reason to boost it at older age.

I in principle agree with that logic.

The question is: would we therefore expect a zero effect on younger people?

Or would they still get raised NAD+ levels, but with not much impact on their physiologic functioning?

If the latter: this did not happen in this study, despite NR-metabolites being present in the muscle tissue.

I would expect no effect on younger people.

Further, I would expect little or no effect on anyone that did not take it for at least 90 days. as recommended by the manufacturer.

Unfortunately, this can be cheating. It is important how people ate throughout the study. It is very easy to mislead people here.