X-Message-Number: 22450
From: "michaelprice" <>
References: <>
Subject:  NAD & Sir
Date: Mon, 1 Sep 2003 11:42:11 +0100

Doug Skrecky  wrote:

>> NAD (the coenzyme form of vitamin B3) is a
>> substrate for sirtuins, which consequently 
>> up-regulates sirtuin activity.
> I'm told it does not. 

Perhaps you're thinking of PMID: 12297502 ?
This subject has been extensively knocked about on 
sci.life-extension, where it continually resurfaces every
few months.  I advise anyone who wishes to investigate
in depth to google on the sci.life-extension archives
using the PubMed indices I've given in this post.

I'm surprised that Doug, as a committed life-extensionist,
doesn't make more use of the sci.life-extension 
newsgroup himself.

> NAD is not a limiting factor for Silent Information 
> Regulator activity under normal circumstances. 

Not according to PMID: 11884393, and I quote:

"This finding suggests that yeast life span extension may be 
facilitated by an increase in the availability of NAD(+) to Sir2, "

> Nicotinamide can reduce SIR activity by 
> blocking the NAD site, 

Correct.  As we would expect since nicotinamide is
a product, not a substrate, of SIR.

> but niacin has no effect.

Wrong.  Extra oral niacin, over and above RDA levels, 
typically increases intracellular NAD levels by a factor of 
2 or 3 and, in mammals, lowering the incidence of 
cancer by >40% (PMIDs 6213941, 11773517, 10453439)
and reduced human long-term mortality (PMID: 3782631).

Michael C Price

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