In one 2020 study published in Diagnostics , researchers measured levels of various antioxidants, including glutathione, in high-risk prostate cancer participants
doi: 10.1038/s41419-018-0739-y 91 KanoskiSEZhangYZhengWDavidsonTL
Here are some other ways to help increase levels of glutathione, along with taking care to optimize vitamin D: limit alcohol consumption decrease exposure to POPs increase intake of other antioxidants to decrease overall oxidative stress increase intake of nutrients that promote glutathione production, such as NAC (N-acetylcysteine), 1000 mg/day, whey, or SAMe get enough magnesium and selenium in the diet, as both are necessary for glutathione production foods such as almonds, cruciferous vegetables, and even alcohol-free beer have been shown to raise glutathione levels, as has meditation
Shen L, Zhang T, Yang Y, Lu D, Xu A, Li K