4 years seems a significant time based on the literature & research this forum goes by. Do you know what else your friend has or hasn't been supplementing with these 4 years? And I don't necessarily mean this in just the conventional sense, but have they been supplementing (or perhaps "eating/drinking" is a better term) a steady supply of unfriendly halogens - breads and or bread stuffs, products containing BVOs, fluouridated water and or meds... and the like? Have they been routinely taking in Vitamin C in any form natural or otherwise? It sticks in my mind that even a conservative routine will have upwards to 90% of people saturated within 3 years or so.... perhaps your friend is among the 10%, and possibly worse, perhaps they are among the 10% and otherwise are not aware of this...?