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