|rsID Number||Major Allele||Minor Allele||Minor Allele Frequency (%)||Major Amino Acid||Minor Amino Acid|
Both the ‘C’ and ‘T’ alleles of T660C in the GPX4 gene carry an increased risk of various cancers, which is thought to be controlled by the their varying ability to incorporate selenium 4,5. It is not known if overall antioxidant capacity is altered by these changes, or if there is an observable difference between the two alleles.
Glutathione is an important antioxidant in its own right, but is also used by GPX4 as a cofactor. In those carrying either the ‘T’ or ‘C’ allele of T660C which is associated with impaired antioxidant capacity supplementation with glutathione may improve outcomes.
As the mechanism of impairment associated with T660 remains unknown it is not clear exactly how glutathione will benefit.
Two copies of the ‘C’ allele of T660C are associated with increased DNA damage when levels of selenium are low. However, when selenium levels are increased the rate of DNA damage decreases significantly 4,5.
Therefore those carrying two copies of the ‘C’ allele of T660C may benefit from selenium supplementation.
Those carrying the ‘T’ (including those carrying one C and one T) allele of T660C display reduced levels of DNA damage, which may correlate with cancer risk, compared to those carrying two copies of the ‘C’ allele when selenium levels are low.
Therefore, those carrying the ‘T’ allele may wish to avoid additional selenium supplementation.
Discuss this information with your doctor before taking any course of action.