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Alpha Lipoic Acid causes massive S-adenosylmethionine (SAM) depletion


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#31 Blue

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Posted 24 October 2009 - 02:28 AM

While also the animal studies show greater effect from RALA than SALA unfortunately the racemic mixture is seldom tested against them. Here is one where it seems better than RALA alone:

This study revealed a marked stereospecificity in the prevention of buthionine sulfoximine-induced cataract, and in the protection of lens antioxidants, in newborn rats by alpha-lipoate, R- and racemic alpha-lipoate decreased cataract formation from 100% (buthionine sulfoximine only) to 55% (buthionine sulfoximine + R-alpha-lipoic acid) and 40% (buthionine sulfoximine + rac-alpha-lipoic acid) (p<0.05 compared to buthionine sulfoximine only). S-alpha-lipoic acid had no effect on cataract formation induced by buthionine sulfoximine. The lens antioxidants glutathione, ascorbate, and vitamin E were depleted to 45, 62, and 23% of control levels, respectively, by buthionine sulfoximine treatment, but were maintained at 84-97% of control levels when R-alpha-lipoic acid or rac-alpha-lipoic acid were administered with buthionine sulfoximine; S-alpha-lipoic acid administration had no protective effect on lens antioxidants. When enantiomers of alpha-lipoic acid were administered to animals, R-alpha-lipoic acid was taken up by lens and reached concentrations 2- to 7-fold greater than those of S-alpha-lipoic acid, with rac-alpha-lipoic acid reaching levels midway between the R-isomer and racemic form. Reduced lipoic acid, dihydrolipoic acid, reached the highest levels in lens of the rac-alpha-lipoic acid-treated animals and the lowest levels in S-alpha-lipoic acid-treated animals. These results indicate that the protective effects of alpha-lipoic acid against buthionine sulfoximine-induced cataract are probably due to its protective effects on lens antioxidants, and that the stereospecificity exhibited is due to selective uptake and reduction of R-alpha-lipoic acid by lens cells.
http://www.sciencedi...af2d60160f94f21

This may simply be due to much better bioavailbility of racemic mixture compared to pure RALA (non-Na- or K-RALA). Or maybe not since intermediate lens concentrations were reached with this form.

Edited by Blue, 24 October 2009 - 03:01 AM.


#32 Blue

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Posted 24 October 2009 - 02:46 AM

All the test tube experiments showing different effects may not be that interesting since in the body ALA is rapidly eliminated unlike in test tubes. The good effects may be due to something done during its brief existence before elimination. Furthermore, since we do not know exactly how ALA is causing its effects it may well be that SALA is actually more effective for that effect. Only animal or human studies with the different isomers really count.

It is my understanding that the oxidized S isomer is not cleared from t cell as is the R isomer, and it "clogs" the machinery.

I know lipoic acid has been touted for a decade and a half for health and longevity, but I have still not seen definitive human trials showing a positive effect (or a negative one, for that matter) in healthy, non-diabetic human subjects. I mean definitive, not a single study. It does nothing for my blood sugar, energy levels or anything else I can determine. I find this sadly disappointing.

Lack of studies showing any significant disease modifying effect, or in the healthy, has certainly not stopped a lot of people from taking resveratrol based on animal studies.

But there are human studies on non-diabetics (granted, not many). These tend to support the neuroprotective effects seen in numerous animal studies. Some examples.

Oxidative stress and neuronal energy depletion are characteristic biochemical hallmarks of Alzheimer's disease (AD). It is therefore conceivable that pro-energetic and antioxidant drags such as α-lipoic acid might delay the onset or slow down the progression of the disease. In a previous study, 600 mg α-lipoic acid was given daily to nine patients with AD (receiving a standard treatment with choline-esterase inhibitors) in an open-label study over an observation period of 12 months. The treatment led to a stabilization of cognitive functions in the study group, demonstrated by constant scores in two neuropsychological tests (the mini mental state exam, MMSE and the Alzheimer's disease assessment score cognitive subscale, ADAScog). In this report, we have extended the analysis to 43 patients over an observation period of up to 48 months. In patients with mild dementia (ADAScog < 15), the disease progressed extremely slowly (ADAScog: +1.2 points/year, MMSE:-0.6 points/year), in patients with moderate dementia at approximately twice the rate. However, the progression appears dramatically lower than data reported for untreated patients or patients on choline-esterase inhibitors in the second year of long-term studies. Despite the fact that this study was not double-blinded, placebo-controlled and randomized, our data suggest that treatment with α-lipoic acid might be a successful 'neuroprotective' therapy option for AD. However, a state-of-the-art phase II trial is needed urgently.
http://www.springerl...78k401k7205050/

BACKGROUND: Impaired mitochondrial phosphorylation potential may play a role in migraine pathogenesis. Metabolic enhancers, such as riboflavin or coenzyme Q, are effective in migraine prophylaxis and quasi-devoid of adverse effects. Thioctic acid (-lipoic acid) is another substance known to enhance energy metabolism in mitochondria and to be beneficial in diabetic neuropathy. OBJECTIVE: After an open pilot study suggesting its therapeutic antimigraine potentials, we embarked therefore in a randomized controlled trial of thioctic acid (Thioctacid) in migraine prophylaxis steered by the Belgian Headache Society. METHODS: Five Belgian centers recruited 54 migraineurs (43 migraine without aura, 11 with aura; mean age 38 +/- 8 years; 7 males). After a 1-month single-blinded run-in period, 44 patients received either placebo (n = 18) or thioctic acid 600 mg p.o./day (n = 26) for 3 months. RESULTS: Statistical analysis was carried out on an intention-to-treat basis. Monthly attack frequency tended to be reduced between run-in and the 3rd month of treatment in the thioctic acid group compared to placebo (P= .06). The proportion of 50% responders was not significantly different between thioctic acid (30.8%) and placebo (27.8%). Within-group analyses showed a significant reduction of attack frequency (P= .005), headache days (P= .009), and headache severity (P= .03) in patients treated with thioctic acid for 3 months, while these outcome measures remained unchanged in the placebo group. No adverse effects were reported. For logistical reasons this trial was interrupted before the planned 80 patients were enrolled. CONCLUSION: Albeit underpowered, this study tends to indicate that thioctic acid may be beneficial in migraine prophylaxis. Before any firm conclusion can be drawn, however, a large multicenter trial is necessary.
http://www.ncbi.nlm....pubmed/17355494

Lipoic acid (LA) is an antioxidant that suppresses and treats an animal model of multiple sclerosis (MS), experimental autoimmune encephalomyelitis. The purpose of this study was to determine the pharmacokinetics (PK), tolerability and effects on matrix metalloproteinase-9 (MMP-9) and soluble intercellular adhesion molecule-1 (sICAMP-1) of oral LA in patients with MS. Thirty-seven MS subjects were randomly assigned to one of four groups: placebo, LA 600 mg twice a day, LA 1200 mg once a day and LA 1200 mg twice a day. Subjects took study capsules for 14 days. We found that subjects taking 1200 mg LA had substantially higher peak serum LA levels than those taking 600 mg and that peak levels varied considerably among subjects. We also found a significant negative correlation between peak serum LA levels and mean changes in serum MMP-9 levels (T = -0.263, P =0.04). There was a significant dose response relationship between LA and mean change in serum sICAM-1 levels (P =0.03). We conclude that oral LA is generally well tolerated and appears capable of reducing serum MMP-9 and sICAM-1 levels. LA may prove useful in treating MS by inhibiting MMP-9 activity and interfering with T-cell migration into the CNS.
http://www3.intersci...518036/abstract

Edited by Blue, 24 October 2009 - 03:09 AM.


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#33 health_nutty

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Posted 24 October 2009 - 04:54 AM

Here is how I see it:

The main reason for taking ALA for me is gone (to counteract supposed pro-oxidant effect of ALCAR). However, we find this is unnecessary at sane doses of ALCAR. Top that off with some big warning bells like this one and it just isn't worth it for me.

Edited by health_nutty, 24 October 2009 - 04:55 AM.


#34 nowayout

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Posted 24 October 2009 - 01:18 PM

I know lipoic acid has been touted for a decade and a half for health and longevity, but I have still not seen definitive human trials showing a positive effect (or a negative one, for that matter) in healthy, non-diabetic human subjects.

But there are human studies on non-diabetics (granted, not many). These tend to support the neuroprotective effects seen in numerous animal studies. Some examples.


The examples are indeed in non-diabetic patients. But they were not healthy.

#35 pycnogenol

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Posted 24 October 2009 - 01:52 PM

It does nothing for my blood sugar, energy levels or anything else I can determine. I find this sadly disappointing.


This unfortunately also mirrors my experience with taking ALA; it does not (for me) lower blood sugar which is the primary reason why I started taking this supplement in the first place. Oh well.

#36 Blue

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Posted 24 October 2009 - 02:37 PM

I know lipoic acid has been touted for a decade and a half for health and longevity, but I have still not seen definitive human trials showing a positive effect (or a negative one, for that matter) in healthy, non-diabetic human subjects.

But there are human studies on non-diabetics (granted, not many). These tend to support the neuroprotective effects seen in numerous animal studies. Some examples.


The examples are indeed in non-diabetic patients. But they were not healthy.

Very few supplements (beside the essential vitamins and minerals against deficiency diseases) shows effects in healthy, young people.
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#37 Blue

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Posted 24 October 2009 - 02:57 PM

There is a very large number of animal studies showing that lipoic acid, often in combination with carnitine, strongly reduces the normal age related decline in the brain. That, in addition to safety from human multi-year placebo controlled studies and long term-use in my opinion makes the risk:reward ratio excellent to protect the organ I most do not wish to decline with age. Some examples:

Abstract We have identified a group of nutrients that can directly or indirectly protect mitochondria from oxidative damage and improve mitochondrial function and named them “mitochondrial nutrients”. The direct protection includes preventing the generation of oxidants, scavenging free radicals or inhibiting oxidant reactivity, and elevating cofactors of defective mitochondrial enzymes with increased Michaelis–Menten constant to stimulate enzyme activity, and also protect enzymes from further oxidation, and the indirect protection includes repairing oxidative damage by enhancing antioxidant defense systems either through activation of phase 2 enzymes or through increase in mitochondrial biogenesis. In this review, we take α-lipoic acid (LA) as an example of mitochondrial nutrients by summarizing the protective effects and possible mechanisms of LA and its derivatives on age-associated cognitive and mitochondrial dysfunction of the brain. LA and its derivatives improve the age-associated decline of memory, improve mitochondrial structure and function, inhibit the age-associated increase of oxidative damage, elevate the levels of antioxidants, and restore the activity of key enzymes. In addition, co-administration of LA with other mitochondrial nutrients, such as acetyl-l-carnitine and coenzyme Q10, appears more effective in improving cognitive dysfunction and reducing oxidative mitochondrial dysfunction. Therefore, administrating mitochondrial nutrients, such as LA and its derivatives in combination with other mitochondrial nutrients to aged people and patients suffering from neurodegenerative diseases, may be an effective strategy for improving mitochondrial and cognitive dysfunction.
http://www.springerl...10161628604736/

Beagle dogs between 7.6 and 8.8 years of age administered a twice daily supplement of alpha-lipoic acid (LA) and acetyl-L-carnitine (ALC) over approximately 2 months made significantly fewer errors in reaching the learning criterion on two landmark discrimination tasks compared to controls administered a methylcellulose placebo. Testing started after a 5 day wash-in. The dogs were also tested on a variable delay version of a previously acquired spatial memory task; results were not significant. The improved performance on the landmark task of dogs supplemented with LA + ALC provides evidence of the effectiveness of this supplement in improving discrimination and allocentric spatial learning. We suggest that long-term maintenance on LA and ALC may be effective in attenuating age-associated cognitive decline by slowing the rate of mitochondrial decay and cellular aging
http://www.ncbi.nlm....pubmed/17622567.

Brain function declines with age and is associated with diminishing mitochondrial integrity. The neuronal mitochondrial ultrastructural changes of young (4 months) and old (21 months) F344 rats supplemented with two mitochondrial metabolites, acetyl-L-carnitine (ALCAR, 0.2%[wt/vol] in the drinking water) and R-alpha-lipoic acid (LA, 0.1%[wt/wt] in the chow), were analysed using qualitative and quantitative electron microscopy techniques. Two independent morphologists blinded to sample identity examined and scored all electron micrographs. Mitochondria were examined in each micrograph, and each structure was scored according to the degree of injury. Controls displayed an age-associated significant decrease in the number of intact mitochondria (P = 0.026) as well as an increase in mitochondria with broken cristae (P < 0.001) in the hippocampus as demonstrated by electron microscopic observations. Neuronal mitochondrial damage was associated with damage in vessel wall cells, especially vascular endothelial cells. Dietary supplementation of young and aged animals increased the proliferation of intact mitochondria and reduced the density of mitochondria associated with vacuoles and lipofuscin. Feeding old rats ALCAR and LA significantly reduced the number of severely damaged mitochondria (P = 0.02) and increased the number of intact mitochondria (P < 0.001) in the hippocampus. These results suggest that feeding ALCAR with LA may ameliorate age-associated mitochondrial ultrastructural decay and are consistent with previous studies showing improved brain function.
http://www.ncbi.nlm....pubmed/18373733
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#38 EmbraceUnity

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Posted 24 October 2009 - 08:59 PM

I know lipoic acid has been touted for a decade and a half for health and longevity, but I have still not seen definitive human trials showing a positive effect (or a negative one, for that matter) in healthy, non-diabetic human subjects.

But there are human studies on non-diabetics (granted, not many). These tend to support the neuroprotective effects seen in numerous animal studies. Some examples.


The examples are indeed in non-diabetic patients. But they were not healthy.

Very few supplements (beside the essential vitamins and minerals against deficiency diseases) shows effects in healthy, young people.


I recently learned that Amla has shown an cholesterol lowering effect in healthy young people, although it might be for similar reasons as green tea.... hard to say, since amla has a lot of nutrients.

http://www.ncbi.nlm..../pubmed/3250870

I believe this was also found to lower blood glucose. This might be something to try for those who were interested in lowering blood sugar.

Other non-human studies were more detailed, and showed reduced lipid peroxidation. It seems to be quite effective at preventing oxidation of LDL.

Edited by progressive, 24 October 2009 - 09:02 PM.


#39 Blue

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Posted 24 October 2009 - 11:40 PM

I know lipoic acid has been touted for a decade and a half for health and longevity, but I have still not seen definitive human trials showing a positive effect (or a negative one, for that matter) in healthy, non-diabetic human subjects.

But there are human studies on non-diabetics (granted, not many). These tend to support the neuroprotective effects seen in numerous animal studies. Some examples.


The examples are indeed in non-diabetic patients. But they were not healthy.

Very few supplements (beside the essential vitamins and minerals against deficiency diseases) shows effects in healthy, young people.


I recently learned that Amla has shown an cholesterol lowering effect in healthy young people, although it might be for similar reasons as green tea.... hard to say, since amla has a lot of nutrients.

http://www.ncbi.nlm..../pubmed/3250870

I believe this was also found to lower blood glucose. This might be something to try for those who were interested in lowering blood sugar.

Other non-human studies were more detailed, and showed reduced lipid peroxidation. It seems to be quite effective at preventing oxidation of LDL.

Well, if you are only talkning about likely beneficial laboratory changes with ala in healthy humans then there are a several of studies.

The aim of this study was to compare the indices of glutathione antioxidant system and oxidative damage level inresistance trained and untrained subjects and to assess the antioxidant action of α-lipoic acid in trained men exposed tomuscle-damaging exercise. Thirteen trained and twenty untrained men (NT) participated in the comparative study. Thentrained men were randomly assigned to TCON group (control) or TALA group (α-lipoic acid, 600 mg . day-1, for 8 days)and performed isometric/isokinetic effort of quadriceps muscles. The study has shown the significantly highererythrocyte levels of glutathione (GSH), glutathione reductase (GR) and glutathione peroxidase (GPx) in TCON than NTbut no differences in plasma lipid peroxidation (TBARS) and protein carbonylation (PC). However, total thiol (TT)concentration was two-fold lower in TCON than NT group. α-Lipoic acid variously influenced the post-exercise levels of GSH (+40%), GR (-24%) and GPx (+29%), but markedly reduced by over 30% the resting and post-exercise TBARS and PC in TALA compared with TCON. TT concentration significantly increased in TALA but it did not reach the high levelwhich was found in untrained group. It is concluded that α-lipoic acid supplementation diminishes oxidative damage. Itdoes not abolish differences in glutathione antioxidant system between untrained and trained subjects but modulates apro-antioxidant response to the muscle-damaging exercise.
http://www.jpp.krako...609_article.pdf

The aim of this study was to follow up whether the modification of pro-antioxidant status by oral thiol administration such as N-acetylcysteine and alpha-lipoic acid affects the haematological response. Twenty eight healthy men participated in two independent experiments. Subjects were randomly assigned to one of four groups: controls (C(NAC) and C(ALA)), N-acetylcysteine (NAC) and alpha-lipoic acid (ALA). 1200 mg of N-acetylcysteine, 600 mg of alpha-lipoic acid or placebo were administered for 8 days in two doses. NAC or ALA administration significantly elevated plasma total antioxidant status (TAS) and reduced protein carbonylation (PC) and lipid peroxidation (TBARS) by more than 30 %. The reduced glutathione (GSH) and haematological parameters changed only in response to NAC administration. NAC significantly elevated the level of GSH (+33 %), EPO (+26 %), Hb (+9 %) and Hct (+9 %) compared with C(NAC). The mean corpuscular volume (MCV) and the mean corpuscular haemoglobin (MCH) also increased by more than 12 % after NAC. The numerous negative or positive correlations between the measures of TAS, PC, TBARS and haematological parameters were found, which suggest the NAC-induced interaction between pro-antioxidant and haematological values. Our study has shown that both N-acetylcysteine and alpha-lipoic acid intake reveal an antioxidant action but only N-acetylcysteine improves the haematological response.
http://www.ncbi.nlm....pubmed/19093729

Endothelial activation and monocyte adhesion are initiating steps in atherogenesis thought to be caused in part by oxidative stress. The metabolic thiol antioxidant alpha-lipoic acid has been suggested to be of therapeutic value in pathologies associated with redox imbalances. We investigated the role of ®-alpha-lipoic acid (LA) vs. glutathione and ascorbic acid in tumor necrosis factor alpha (TNF-alpha) -induced adhesion molecule expression and nuclear factor kappaB (NF-kappaB) signaling in human aortic endothelial cells (HAEC). Preincubation of HAEC for 48 h with LA (0.05-1 mmol/l) dose-dependently inhibited TNF-alpha (10 U/ml) -induced adhesion of human monocytic THP-1 cells, as well as mRNA and protein expression of E-selectin, vascular cell adhesion molecule 1 and intercellular adhesion molecule 1. LA also strongly inhibited TNF-alpha-induced mRNA expression of monocyte chemoattractant protein-1 but did not affect expression of TNF-alpha receptor 1. Furthermore, LA dose-dependently inhibited TNF-alpha-induced IkappaB kinase activation, subsequent degradation of IkappaB, the cytoplasmic NF-kappaB inhibitor, and nuclear translocation of NF-kappaB. In contrast, TNF-alpha-induced NF-kappaB activation and adhesion molecule expression were not affected by ascorbic acid or by manipulating cellular glutathione status with l-2-oxo-4-thiazolidinecarboxylic acid, N-acetyl-l-cysteine, or d,l-buthionine-S,R-sulfoximine. Our data show that clinically relevant concentrations of LA, but neither vitamin C nor glutathione, inhibit adhesion molecule expression in HAEC and monocyte adhesion by inhibiting the IkappaB/NF-kappaB signaling pathway at the level, or upstream, of IkappaB kinase.
http://www.ncbi.nlm....pubmed/11689467

#40 ensun

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Posted 26 October 2009 - 12:45 AM

All the test tube experiments showing different effects may not be that interesting since in the body ALA is rapidly eliminated unlike in test tubes. The good effects may be due to something done during its brief existence before elimination. Furthermore, since we do not know exactly how ALA is causing its effects it may well be that SALA is actually more effective for that effect. Only animal or human studies with the different isomers really count.



There is no data in vitro or in vivo showing that S-ALA is more effective than R-ALA. There are many studies, however, showing no or negative effects. On the other hand, non-bioenhanced R-ALA has plenty of studies showing positive outcomes, even with its poor bioavailability. Racemic ALA will usually be more effective than non-bioehanced R-ALA in many cases as you noted most likely due to bioavailability.

You know your stuff, but still the point should be made that S-ALA in high doses could be responsible for these or other negative effects.

Edited by ensun, 26 October 2009 - 01:11 AM.


#41 niner

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Posted 26 October 2009 - 02:50 AM

There is no data in vitro or in vivo showing that S-ALA is more effective than R-ALA. There are many studies, however, showing no or negative effects. On the other hand, non-bioenhanced R-ALA has plenty of studies showing positive outcomes, even with its poor bioavailability. Racemic ALA will usually be more effective than non-bioehanced R-ALA in many cases as you noted most likely due to bioavailability.

You know your stuff, but still the point should be made that S-ALA in high doses could be responsible for these or other negative effects.

What studies show negative effects with S-ALA? I'm not aware of anything convincing. To be fair, it should really show that racemic ALA is inferior to R-ALA, since that's the true question at hand. Outside of special laboratory situations, there's no such thing as pure S-ALA; it's either racemic or pure R. IMO, the insistence on R-ALA over ALA is driven more by marketing than evidence.

#42 ensun

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Posted 26 October 2009 - 03:37 AM

Blue quoted the cataract study (in vivo):

While also the animal studies show greater effect from RALA than SALA unfortunately the racemic mixture is seldom tested against them. Here is one where it seems better than RALA alone:

This study revealed a marked stereospecificity in the prevention of buthionine sulfoximine-induced cataract, and in the protection of lens antioxidants, in newborn rats by alpha-lipoate, R- and racemic alpha-lipoate decreased cataract formation from 100% (buthionine sulfoximine only) to 55% (buthionine sulfoximine + R-alpha-lipoic acid) and 40% (buthionine sulfoximine + rac-alpha-lipoic acid) (p<0.05 compared to buthionine sulfoximine only). S-alpha-lipoic acid had no effect on cataract formation induced by buthionine sulfoximine. The lens antioxidants glutathione, ascorbate, and vitamin E were depleted to 45, 62, and 23% of control levels, respectively, by buthionine sulfoximine treatment, but were maintained at 84-97% of control levels when R-alpha-lipoic acid or rac-alpha-lipoic acid were administered with buthionine sulfoximine; S-alpha-lipoic acid administration had no protective effect on lens antioxidants. When enantiomers of alpha-lipoic acid were administered to animals, R-alpha-lipoic acid was taken up by lens and reached concentrations 2- to 7-fold greater than those of S-alpha-lipoic acid, with rac-alpha-lipoic acid reaching levels midway between the R-isomer and racemic form. Reduced lipoic acid, dihydrolipoic acid, reached the highest levels in lens of the rac-alpha-lipoic acid-treated animals and the lowest levels in S-alpha-lipoic acid-treated animals. These results indicate that the protective effects of alpha-lipoic acid against buthionine sulfoximine-induced cataract are probably due to its protective effects on lens antioxidants, and that the stereospecificity exhibited is due to selective uptake and reduction of R-alpha-lipoic acid by lens cells.
http://www.sciencedi...af2d60160f94f21


And here is more (in vivo):

In a group of 14 immunosuppressed NMRI-mice (nu/nu) raised and kept under germ-reduced conditions, SLA, even at 75 mg/kg body weight per day, increased the 50% survival rate, but did not expand "the total life span of its group"R.

"An intact organ, the isolated perfused rat heart, reduced R-lipoate six to eight times more rapidly than S-lipoate ... R.


So we know that SLA and RLA act differently in vivo.

The in vitro studies I posted previously. I don't currently know of a study in vivo that shows outright negative effects with SLA. But the vitro studies I posted show negative effects. The question is whether the body rapidly excretes SLA or whether it lingers enough to cause damage on its way out. I don't think there's conclusive evidence either way.

Edited by ensun, 26 October 2009 - 03:39 AM.


#43 niner

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Posted 26 October 2009 - 04:37 AM

Blue quoted the cataract study (in vivo)

While also the animal studies show greater effect from RALA than SALA unfortunately the racemic mixture is seldom tested against them. Here is one where it seems better than RALA alone:

This study revealed a marked stereospecificity in the prevention of buthionine sulfoximine-induced cataract, and in the protection of lens antioxidants, in newborn rats by alpha-lipoate, R- and racemic alpha-lipoate decreased cataract formation from 100% (buthionine sulfoximine only) to 55% (buthionine sulfoximine + R-alpha-lipoic acid) and 40% (buthionine sulfoximine + rac-alpha-lipoic acid) (p<0.05 compared to buthionine sulfoximine only). S-alpha-lipoic acid had no effect on cataract formation induced by buthionine sulfoximine. The lens antioxidants glutathione, ascorbate, and vitamin E were depleted to 45, 62, and 23% of control levels, respectively, by buthionine sulfoximine treatment, but were maintained at 84-97% of control levels when R-alpha-lipoic acid or rac-alpha-lipoic acid were administered with buthionine sulfoximine; S-alpha-lipoic acid administration had no protective effect on lens antioxidants. When enantiomers of alpha-lipoic acid were administered to animals, R-alpha-lipoic acid was taken up by lens and reached concentrations 2- to 7-fold greater than those of S-alpha-lipoic acid, with rac-alpha-lipoic acid reaching levels midway between the R-isomer and racemic form. Reduced lipoic acid, dihydrolipoic acid, reached the highest levels in lens of the rac-alpha-lipoic acid-treated animals and the lowest levels in S-alpha-lipoic acid-treated animals. These results indicate that the protective effects of alpha-lipoic acid against buthionine sulfoximine-induced cataract are probably due to its protective effects on lens antioxidants, and that the stereospecificity exhibited is due to selective uptake and reduction of R-alpha-lipoic acid by lens cells.
http://www.sciencedi...af2d60160f94f21

This study makes my point. The racemic ALA (equal parts R and S) is better than R-ALA at protecting the lens. The fact that the S isomer is inactive in some ways doesn't matter; we are interested in the best outcome.

So we know that SLA and RLA act differently in vivo.

The in vitro studies I posted previously. I don't currently know of a study in vivo that shows outright negative effects with SLA. But the vitro studies I posted show negative effects. The question is whether the body rapidly excretes SLA or whether it lingers enough to cause damage on its way out. I don't think there's conclusive evidence either way.

SLA is essentially a straw man. The only compounds people can actually buy are R-ALA or rac-ALA. The evidence says rac-ALA is about as good as, or in some cases better than R-ALA. I'm not aware of any evidence that rac-ALA is substantially worse than R-ALA. If rac-ALA is harmful, where's the evidence? I'm not taking either of them, for various reasons, but if I did decide to take one, I would want to base my decision on evidence rather than marketing. Why take a compound with bioavailability problems when you can take one that works better, costs less, and has a much longer history as a drug used in humans?

#44 ensun

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Posted 26 October 2009 - 04:46 AM

Would you please read my full posts? I have already commented on this.

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#45 How.I.Met.Me

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Posted 01 April 2010 - 04:58 AM

http://cat.inist.fr/...&cpsidt=1610136

ALA may indeed act as a low-level stressor.




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