What I am somewhat on the fence for and I believe similar for you, is more in frequency and amount going to be better? The 12 hour interval I am also doing to ensure that a down regulation mechanism, if there is any, may not have a chance to develop. The evening dose under the thinking that sleep is a good repair window and may be a period where the body uses supplements effectively. I don't have scientific fact for that. Overall I am seeing NR as the base layer supplement to keep the body healthy. Ontop, exercise, supplements to be used to trigger additional improvement which can now be fueled by the larger NAD+ pool. So how big should and can the NAD+ pool be made so all processes can be served.
Stefan
I don't necessarily believe more is better. I believe there is a certain saturation point which has yet to be identified and is different for all of us. I don't think we can push NAD levels higher than when we were young and at some point even with repeated conditioning and exersize our utilization curve will top out and adding more NAD precursors beyond that would be a waste of money.
I believe the most cost efficient approach is to break the daily dosage into evenly timed applications thru the day to stay near our maximum saturation point. If the ChromaDex/Brenner study was correct and the 300mg and 1000mg dosages produced an identical 50% NAD rise then there is a rate limiting process along the path. I think its tied to our utilization. If this is indeed true than surpassing the 300mg dosage has diminishing returns the higher you push the dosage because the unused portion will be eliminated thru the kidney's. As blood serum levels fall we have the opportunity supplement again to keep us near our saturation point. I believe its truly a use it our lose it scenario.
I liken the whole situation to a bucket with a leak. The older we get the bigger the leak. Fill the bucket to much and the excess splashes out. So in this scenario the amount needed differs with age and our infirmity's which helps drive demand beyond what's recycled and this recycle process gets worse with age.
So much like you I see the NAD precursors as a base supplement because we have this recycling/salvaging issue that diminishes our available NAD pool with age. But having said that there is also the theory that our NAD demand just raises with age. Either way the NAD pool needs supplementation to meet demand.
Down regulation mechanism. Hum . . . we know the whole NAD process is driven via feed back loops so yes there are several down regulation mechanisms. However NAD is central to your respiratory metabolism so its how our cell breaths and I don't see that being cut off. I look at this as a supply and demand scenario. Excess Nicotinamide along with the NAD NADH ratio from our NAD reactions tells the cell I'm nutritionally satisfied and this begins to inhibit Sirtuin processes that ramp down NAD production. Once those (NAM) levels eventually fall the Sirtuin activities become more active again. There are other sensors at work as well but together when NAD falls low enough those enzymes to produce more become active again.
Sleep is a good repair window but lets also consider our circadian rhythm and NAD is a central signaling metabolite. I thought this way as you and dosed prior to sleep but found many nights I had the urge to read and it wasn't putting me to sleep. This told me I was fooling my body into thinking to was time to be mentally active. So I'm now trying to respect this part of my cycle and compliment it with the sedative effects of Nicotinamide (Nam) instead of stimulating myself with (NR).
To each their own.
The press release also stated that:
"Average maximal increases in blood NAD+ were approximately 30% at the 100 mg dose and approximately 50% at the higher doses. Increases in blood NAD+ tended to be sustained for longer times at higher doses"
which correlates that there is absorption rate limit. Interestingly however it also indicates that NR then apparently keeps circulating till its needed so in that sense the evenly spread timing is good but may not need to be overly accurate and excretion speed not that high. Well either way multeple dosing seems a good approach.
Now you forced me to read about circadian rhythm :-)