Please remember that although GSH is present in some food, it is easily broken down in the digestive tract and eliminated. GSH has to be produced by our cells (intra-cellularly) and the most effective and natural way of increasing our GSH levels is to give our body the raw materials or precursors to make GSH.
Immunocal®, which contains bioactive precursors of GSH, is both natural and effective and guarantees the rise in intra-cellular GSH levels.