Supplementation with glutathione doesn't raise blood levels of this antioxidant and cooking and storage destroys it. In some studies, Vitamin C and NAC can raise levels. But, without a doubt, eating raw fruits and vegetables is the ideal way to get this into your body--any way you can.
Dr. Murray has a good chart which displays the difference between glutathione in cooked and raw food:
Table 1. Comparison of Glutathione in Fresh vs. Cooked Foods
Glutathione amount (dry weight) (in milligrams per 31/2 oz (100 g) serving)
Food Uncooked Cooked
Apples 21 0.0
Carrots 74.6 0.0
Grapefruit 70.6 0.0
Spinach 166 27.1
Tomatoes 169 0.0
Asparagus, avocado, and walnuts are also good sources of glutathione.
WHAT TO FEED YOUR KIDS: Serve a raw fruit or vegetables with every meal and snack or buy a juicer and make fresh squeezed juice a daily habit. We all know that fruits and vegetables are the key to a healthy diet, but with so many environmental toxins (plastic is everywhere, there are prescription meds in our water, and countless chemicals in the food we eat!) everyone should be eating more raw fruits and vegetables so we can detoxify from the modern world.