selenium deficiency is a common factor in heart disease in low-selenium areas, selenium is essential for glutathione peroxidase which oxidises reduced glutathione enzymatically while neutralising lipid peroxides. so it is possible that a higher ratio of GSH to GSSG might exist in some areas due to selenium deficiency.
Just because the protein makes more reduced glutathione (GSH) it does not mean that this stays reduced; it is the GSH-GSSG ratio that matters. estimates of the ratio in healthy cells vary from 99-1 to 500-1. Such a high ratio of reduced to oxidised glutathione, normally, makes it hard to accept reductive stress as a realistic concept. It could exist in plasma, where an oxidising environment is needed to sustain S-S bonds, but GSH in plasma is sparse, and the main effect would probably be related to low insulin if reductive stress could exist. The fact is that humans who try to elevate levels of reduced glutathione by various means do not tend to suffer heart disease as a result; if anything, the opposite is true. But selenium is essential to utilise GSH properly, and selenium levels in food from over-farmed soil have declined significantly since the 1960s.