In Barretts, tissue is the issue
NAC itself is a supplement form, but you can get the amino acid cysteine from high-protein foods like poultry, eggs, garlic, and onions

The concentration of the polynucleotides of the present invention may be at least 0.001 mg, at least 0.005 mg, at least 0.01 mg, at least 0.05 mg, at least 0.1 mg, at least 0.5 mg, at least 1 mg, at least 5 mg, at least 7 mg, at least 10 mg, at least 12, at least 15 mg, at least 17 mg, at least 20 mg, at least 22 mg, at least 25 mg, at least 27 mg, at least 30 mg, at least 32 mg, at least 35 mg, at least 40 mg, at least 45 mg, at least 50 mg, at least 55 mg, at least 60 mg, at least 65 mg, at least 70 mg, at least 75 mg, at least 80 mg, at least 85 mg, at least 90 mg, at least 95 mg, at least 100 mg, at least 105 mg, at least 110 mg, at least 115 mg, at least 120 mg, at least 125 mg, at least 130 mg, at least 135 mg, at least 140 mg, at least 145 mg or at least 150 mg in at least 0.1 ml, at least 0.2 ml, at least 0.3 ml, at least 0.4 ml, at least 0.5 ml, at least 0.6 ml, at least 0.7 ml, at least 0.8 ml, at least 0.9 ml, at least 1 ml, at least 2 ml, at least 3 ml, at least 4 ml, at least 5 ml, at least 6 ml, at least 7 ml, at least 8 ml, at least 9 ml, at least 10 ml, at least 11 ml, at least 12 ml, at least 13 ml, at least 14 ml, at least 15 ml, at least 16 ml, at least 17 ml, at least 18 ml, at least 19 ml, at least 20 ml, at least 21 ml, at least 22 ml, at least 23 ml, at least 24 ml, at least 25 ml, at least 26 ml, at least 27 ml, at least 28 ml, at least 29 ml or at least 30 ml of the surgical sealant, gel or hydrogel

Upregulation of SOD2 and antagonism of NMDA receptors can manipulate this vicious cycle (80)