General Description
Glutathione is a tripeptide protein composed of the amino acids
cysteine, glycine, and glutamic acid. One of nature's premier antioxidants
and free-radical scavengers, glutathione is found in a wide variety
of plant and animal tissues, where it serves as an oxygen carrier
in respiration and as a coenzyme in certain metabolic processes.
While there are many food sources of glutathione, including fruits,
vegetables, meat, and fish, most circulating glutathione in humans
is manufactured in the body from amino acid components rather than
obtained directly through the diet. Glutathione is marketed as a
dietary supplement, usually in tablet or capsule form.
Health Applications
- Antioxidant protection
- Immune system support
Primary Uses
Although glutathione supplements are often promoted as natural
antioxidants and immune-system boosters,1
there is little scientific evidence to support such claims; as
research indicates that oral glutathione is poorly absorbed in
humans.2 While studies conducted on mice and
rats found oral glutathione supplements to be well-absorbed and
effective in raising plasma glutathione levels,3-5
these animals lack an enzyme found in the human digestive tract
(gamma-glutamyltransferase) that breaks down glutathione, preventing
it from being absorbed intact. Researchers in one study concluded
that dietary glutathione has little influence on circulating glutathione
levels in humans, after three grams of glutathione failed to significantly
increase plasma glutathione in seven healthy human subjects.2
Nevertheless, supplemental glutathione may serve as a significant
source of amino acids.
Dosage/Toxicity
There is no known therapeutic dosage for supplemental glutathione.
Label recommendations range from 50 to 250 mg per day. There are
no known side effects associated with supplemental glutathione
at this dosage range. Glutathione is a common nutritional component
of many foods and has no known toxicity. |
