Oral Glutathione Supplementation on the Levels of Blood Glutathione

This is a randomized double-blind, placebo-controlled study in which the treatment
allocations will be kept sealed until the final statistical evaluation. The design will
include the recruitment of 60 healthy subjects (30-79 yr of age) randomized into 3 groups. A
total of 48 subjects, 16 per group will be required based upon power calculations and results
from a previous clinical trial with selenium. An additional 4 subjects per group will be
placed on trial to account for possible attrition or non-compliance. Blood, urine and
exfoliated buccal mucosal samples will be obtained from all subjects at baseline.
Questionnaire data on usual dietary intake will also be obtained at baseline. Eligible
subjects will be required to have not have taken any high dose antioxidant supplements for at
least 1 month prior to the study. Subjects will then begin supplementation according to the
following schedule:

Group A, GSH (500 mg, 2 times daily); Group B, GSH (125 mg, 2 times daily); Group C, placebo
(2 times daily). Eligible participants who sign the informed consent will be randomly
assigned to either placebo or high or low dose Glutathione groups. Participants will be asked
not to consume any other high-dose vitamin, multi-vitamin, or mineral supplements containing
glutathione throughout the study in order to prevent variation in dose of supplemental GSH
between subjects. Supplementation will continue for 6 months with biological samples
collected at 1, 3 and 6 months after baseline. At 6 months, supplementation will be
discontinued. A final collection of biological samples will occur 1 month afterwards.
Compliance will be monitored by pill count.

Levels of glutathione will be measured in plasma, lymphocytes, and red blood cells as well as
in exfoliated buccal mucosal cells. Biomarkers of oxidative stress will include blood levels
of glutathionylated proteins and 8-isoprostanes and urine levels of 8-hydroxydeoxyguanosine.
Glutamylcystine ligase and GST activities, and C-reactive protein will be determined in
blood. Immune function biomarkers will be analyzed including t-natural killer cell
cytotoxicity, lymphoproliferation, neutrophils phagocytosis, neutrophil respiratory burst
assays.

Inclusion Criteria:

- Healthy male and females between the ages of 30 and 79 years of age

- Not taking glutathione as a dietary supplement

- Not taking high dose antioxidant supplement prior to 1 month

- Baseline blood glutathione level of < 1 mmol/L

Exclusion Criteria:

- History or evidence of disease including cancer, diabetes, heart disease

- Subjects who smoke