Hi IMark,
The fact that theses researchers had to convert NAC into the amide, to get it past the BBB suggests that NAC can't pass the BBB.
Indeed a search confirmed that.
See
http://www.fasebj.org/cgi/content/full/15/1/243
where it says,
"N-acetylcysteine does not cross the blood–brain barrier"

I have little medical knowledge, I am a chemist, and had better leave the interpretation of the paper you quote, to somone better medically quailified.

Sorry my forulae came out jumbled in my other message,
Best wishes
Ron

Hello Ron,
I have been taking NAC for some time hoping some of it at least may cross the BBB but now I have second thoughts.
By the way the paper posted by Zflower above states :"Systemic administration of NAC can deliver cysteine to the brain and raise GSH levels in the CNS (Pocernich et al., 2000). "??

Perhapse you have further comment.

Thank you so much for you offering your knowledge generously to the forum

Hello IMark,
N-acetylcysteine can be turned into cysteine by removal of the N-acetyl group. Cysteine is a smaller molecule and can presumably cross the BBB. Cysteine and N-acetylcysteine are different chemicals.
Don't ask me why they use NAC rather than cysteine itself, there must be a reason!! Found it, the acetyl group is used in NAC to speed absorbtion by the body, once quickly absorbed, the NAC is quickly hydrolysed to cysteine. So you are doing the right thing taking NAC, it boosts the level of glutathione a powerful natural antioxidant.

If you want to see the formulae of the 2 compounds, go to
http://www.benbest.com/nutrceut/NAC.html

Ron

..You are a treasure ..

Another source for cystein : the Whey ! and it is natural. Pls see following link which I partially quote. It claims it gets through BBB ...
FEEDBACK GREATLY APPRECIATED

http://64.233.169.104/search?q=cache...lnk&cd=5&gl=jo
"WHEY PROTEIN & GLUTATHIONE Whey Protein contains essential amino acids which are noted to provide overall health benefits. More specifically, whey protein is very beneficial because whey protein drinks increase Glutathione (GSH) concentration in a number of tissues. Whey-based peptide studies have shown that whey protein may reduce hypertension which contributes to cardiovascular diseases. In fact, one of whey protein’s major benefits is to assist in the building of collagen. Therefore, by supplementing whey protein to your diet, it helps to accelerate the healing of fractures as well as provide overall health benefits. Whey protein is also helpful in the prevention and treatment of Osteoporosis. American Journal of Clinical Nutrition, June 2000.Whey protein increases Glutathione levels. Glutathione (GSH) is a powerful antioxidant. It is a tripeptide protein (made within the body) from three key amino acids; Cysteine, Glutamic Acid, and Glycine. The benefits of Glutathione include detoxifying many toxic chemicals and heavy metals from the body such as lead, mercury, aluminum, arsenic and cadmium, as well as the effects of alcohol and tobacco smoke. In the Immune System, Glutathione inhibits the excessive production of Cytokines that are implicated in Autoimmune Disease. Glutathione combats Free Radicals that cause allergies and aids in Chronic Fatigue. In regards to aging and life extension, old cells contain 20% less Glutathione compared to young cells, indicating it may be beneficial. In the Cardiovascular System, Atherosclerosis patients generally exhibit reduced Glutathione, indicating it may be beneficial. Brink; Life Ext., 6(2), 2000"
--
"THE EFFECTS OF WHEY PROTEIN ON NEUROTRANSMITTER FUNCTION Essential Amino Acids, the building blocks that make up proteins, play a large part in every living cell in the body. Each group of amino acids is tailored for a specific need. It is actually the amino acids rather than the proteins that are the essential nutrients. Amino acids act as neurotransmitters to carry information from one nerve cell to another. The neurotransmitter dysfunction is caused by the lack of amino acids. The dysfunction of the neurotransmitters results in depression and obesity with further results in diabetes, heart diseases, hypertension (high blood pressure), and lack of emotional control. “Essential amino acids are primarily responsible for the amino acid stimulation of muscle protein anabolism in healthy elderly adults,” Elena Volpi, Hisamine Kobayaski, Melinda Sheffield-Moore, Bettina Mittendorfer, and Robert R. Wolfe, Am J Clin Nutr 2003;78:250-8. Amino acids also act as neurotransmitters to carry information from one nerve cell to another. Amino acids enable vitamins and minerals to do their jobs properly, but if there is a deficiency in amino acids, nerve cells can’t function. There are approximately 28 amino acids. The liver produces 19 amino acids while the other 9 must be obtained from the diet which is called the essential amino acids. Prescription for Nutritional Healing, James F. Balch, M.D., Phyllis A. Balch, CNC, 1997, Page 34-35.Plainly, the neurotransmitter dysfunction is caused by the lack of amino acids. The dysfunction of the neurotransmitters results in depression and obesity with further results in diabetes, heart diseases, hypertension (high blood pressure), and lack of emotional control. The neurotransmitters are fat soluble and cannot cross the blood/brain barrier. Therefore, the amino acids that made up the neurotransmitters must cross the blood/brain barrier and then the body makes the neurotransmitters out of the amino acids and the appropriate vitamins and minerals necessary. Neurotransmitter Testing and Amino AcidTherapy, Marty Hinz, MD, NeuroResearch, Morgan Park Clinic, Duluth, Minnesota, 2002, Pages 22-24.Nutritional deficiency is a major cause of neurotransmitter dysfunction, as well as drugs such as Zoloft and Prozac. These drugs inhibit the reuptake of serotonin and so cause a loss of serotonin. Neurotoxic effects are permanent. They are caused by heavy metals, chemicals and drugs. The main drug that causes neurotoxicity is amphetamines. Neurotoxic effects are in the post-synaptic neurons. The treatment is the same as deficiency of amino acids, but it takes more of these amino acids forming serotonin to be effective at the post-sympathic neuron. Neurotransmitter Testing and Amino Acid Therapy, Marty Hinz, MD, NeuroResearch, Morgan Park Clinic, Duluth, Minnesota, 2002, Pages 22-24"

I drink whey protein. It's my favorite protein drink. I'd read that whey helps diabetics stabilize blood sugar, even when ingested with a high carb meal. I posted the study on the old board. My friend is diabetic, and the whey protein definitely helps her.

I don't understand that. I thought those AD's increased serotonin which is a good thing for depression.

I'm sure there are other reasons!

: Anticancer Res. 2003 Mar-Apr;23(2B):1411-5.
The antioxidant system.
Bounous G, Molson JH.



The glutathione (GSH) antioxidant system is the principal protective mechanism of the cell and is a crucial factor in the development of the immune response by the immune cells. Experimental data demonstrate that a cysteine-rich whey protein concentrate represents an effective cysteine delivery system for GSH replenishment during the immune response.

Animal experiments showed that the concentrates of whey protein also exhibit anticancer activity. They do this via the GSH pathway, the induction of p53 protein in transformed cells and inhibition of neoangiogenesis.

PMID: 12820403 [PubMed - indexed for MEDLINE]

***************

Elevated glutathione as a therapeutic strategy in Alzheimer's disease -
DA Butterfield, CB Pocernich, J Drake - Drug Development Research, 2002

GSH levels are increased with strict adherence to a diet rich in whey proteins. ....whether they're increased in the brain is probable but needs demonstration.

....The bioavailability of NAC given orally is less than 20%.

Lots of good info here:

http://www3.interscience.wiley.com/c...17480/PDFSTART

Wow. Nice to see such an avid discussion about this. I have MS and posted about this on an MS forum (not the board here) -- not one response!

I look forward to reading all the back and forth more carefully -- hope you don't mind that I poked my head in here.

Hi,

I recently found an article at the Journal of Animal Science that dealt specifically with this issue of NAC bioavailability that I think might be insightful.

Oral N-acetyl-L-cysteine is a safe and effective precursor of cysteine
R. N. Dilger and D. H. Baker

"It is apparent that considerable confusion exists with regard to the meaning of the term "NAC bioavailability." Previous pharmacokinetic studies (Borgström et al., 1986Go; Olsson et al., 1988Go; De Caro et al., 1989Go) have focused on the amount of an oral NAC dose that reaches the bloodstream as NAC itself. Little emphasis has been placed on the chemical modification of NAC (i.e., deacetylation) within the gut lumen and enterocyte during absorption. Therefore, pharmacokinetic studies suggesting that less than 10% of oral NAC is absorbed into portal blood as NAC per se are misleading. Our approach, however, was based on the assumption that beneficial effects of NAC do not result from NAC itself, but rather from NAC delivering Cys for in vivo functions (e.g., glutathione synthesis). Thus, the ability of NAC (the test precursor) to provide Cys relative to Cys itself (the standard nutrient) was assessed in assay 2. The results of this study (Table 3Go) clearly showed that oral NAC was 100% effective as a Cys precursor."

*to read more please go to http://jas.fass.org/cgi/content/full/85/7/1712

Thank you for a great discussion!

In health,

Paul