However, other factors can increase sensitivity, especially protein deficiency.
I strongly recommend using only vitamin supplements that contain P-5-P or one of the vitamers. A much lower dose can be effective if P-5-P replaces pyridoxine.
There are many features of amino acid metabolism in cirrhosis that suggest that activation of dietary pyridoxine to P-5-P by liver has become inadequate, and/or that the breakdown of P-5-P is excessive.
After administration of pyridoxine there was a significant increase in the plasma PLP level over a 2- to 12-hr period, after which the concentration returned gradually toward the initial value. The area under the concentration/time curve was from 2 to 8 times smaller (P less than 0.002) in the patients with liver disease. To assess possible mechanisms of this change, 5 mg of PLP were intravenously administered to the various patient groups and the pharmacokinetics of the disposition were assessed. The initial and steady state volumes of distribution of PLP were comparable in cirrhotics and controls (P greater than 0.05), but the clearance of plasma PLP in cirrhotics was much faster (63.0 +/- 7.4 versus 31.7 +/- 2.7 ml per min, P less than 0.004). Similar findings were obtained in the other liver disease subjects
From personal experience, I can testify that years of overuse of pyridoxine, especially by someone who is not eating regularly, can result in long-lasting sensory problems even if the doses taken are those normally prescribed or recommended on line. This is not an exclusive problem of the supplement industry, as most of the pyridoxine I have used has been a prescription medication.
Maybe, like DVT, it is caused by a diet too dependent on processed meat and refined carbohydrate.