The Body's Own Antioxidant Defenses: Enzymes, Glutathione and the Nutrients They Need

The three lines of defense

A 2024 review describes a three-line system. [3]

What each enzyme does

• Superoxide dismutase (SOD). Converts superoxide radicals to hydrogen peroxide. [3]
• Catalase and glutathione peroxidase. Remove hydrogen peroxide. [3]
• Glutathione. A small molecule the review counts in the first line because it acts as a helper (cofactor) for antioxidant enzymes. [3] Glutathione supplements are covered on the glutathione page.

Which nutrients the enzymes need

MedlinePlus says selenium helps the body make special proteins called antioxidant enzymes, which play a role in preventing cell damage. [4] NCI adds that selenium's antioxidant effects are most likely due to selenium-containing proteins, not selenium itself. [5] The NHS says manganese helps make and activate some enzymes, and zinc helps with making new cells and enzymes. [6] For each mineral's food sources, official intake levels and upper limits, read its own page: selenium, zinc, copper and manganese. We do not repeat intake figures here. NIH Office of Dietary Supplements pages could not be read this session, so no figures from that source are quoted.

Switching on the body's defenses

The 2020 review notes that enzymatic defenses are controlled by stress-response transcription factors such as NRF2 and NF-kB. [7] The authors of a small exercise trial proposed that exercise-induced oxidative stress prompts an adaptive response that builds endogenous defense capacity. [8] In that trial, supplementation with vitamins C and E blocked an exercise-induced rise in SOD and glutathione peroxidase. [8] That is one small study in 39 healthy young men, not a general rule.