David Cohen said:"WillBrink" wrote
Quoted message said:DZ said:WillBrink wrote:
> JMW <[email hidden]> wrote:
>> WillBrink wrote:
>> > DZ wrote:
>>>> Can you post the summary here? I know that SAMe needs to be taken
>>>> with B vitamins to protect from the increase of
>>>> homocysteine. Anything else?
>>
>>>I didn't know SAMe raised homocysteine. Is it not also a methyl
>>>donor(?), which in theory, should lower homocysteine.
>>
>> No elevation of homocysteine in fifteen test subjects at
>> 1600mg/day of SAMe.
>> Giulidori P, Galli-Kienle M, Catto E, Stramentinoli G.
>> Transmethylation, transsulfuration, and aminopropylation
>> reactions of S- adenosyl-L-methionine in vivo. J Biol Chem
>> 1984;259:4205-11
>
> As a methyl donor, I would have expected to see a drop in homocysteine
> as you do with other methyl donors.
The effect can be opposite if they are a part of the methionine cycle
(methionine -> SAMe -> SAH <-> homocysteine -> back to
methionine). For example, it would make sense that methionine, which
is also a methyl donor, would raise homocysteine. But those methyl
donors that speed up re-methylation of homocysteine back to methionine
can reduce its concentration.
As John pointed out, it does not appear to increase homocysteine. I was
under the impression it lowered it, but perhaps it has no effects either
way. Have not looked into it much.
There was actually some increase in that study, measured at both week
2 and week 4 during the experiment. They say that it wasn't
statistically significant (baseline: 6.93 +- 1.52; week 2: 7.58 +-
2.10; week 4: 7.29 +- 1.91).
As they report, the difference week 2 vs. baseline has the p-value of
0.05; and week 4 vs. baseline has the p-value of 0.115. They probably
thought that because of the 2 comparisons made here, the 0.05 level
needs to be 2 times more stringent or so. But this is not the case,
because they're testing the same hypothesis. If we're interested in
the overall effect, baseline vs. supplementation, we can in fact
combine p1=0.05 and p2=0.115 values. Here is a handy formula that me
and Lev derived. It's a reduction from a more general case that we
published :-)
Denote w=p1*p2. Then the overall "significance" is
p12 = w*(1-ln(w)) = 0.035.
In this case, p12 is smaller than either p1 or p2. That is, there is a
statistically significant increase in homocysteine levels. Of course,
the magnitude of the increase might be too small to be of any
practical importance.
Quoted message said:Quoted message said:Quoted message said:So, I have some vague interest in SAMe but I'm undecided on pros and
cons. There is some evidence that methionine reduces lifespan.
Are there any SAMe life span studies in animals perhaps?
Allow me to add my cheap Jew comment at this point: SAMe is freakin'
expensive!!
Certainly, putting rats on calorie restriction is a lot cheaper then
giving them extra anything!