Superoxide Dismutase, Catalase and Antioxidant Enzyme Supplements: Claims Checked

What the enzymes do inside the body

• SOD. MedlinePlus Genetics says the gene SOD1 provides instructions for an enzyme called superoxide dismutase, abundant in cells throughout the body, which attaches to copper and zinc to break down toxic charged oxygen molecules called superoxide radicals. [1]
• Catalase. The CAT gene provides instructions for catalase, an enzyme active in cells and tissues throughout the body that breaks down hydrogen peroxide into oxygen and water. [2]

These are jobs done inside cells. For where these enzymes fit among the body's defenses see The Body's Own Antioxidant Defenses. The minerals the enzymes depend on are covered on Selenium, Zinc, Copper and Manganese.

Why swallowing an enzyme is a different question

MedlinePlus Genetics describes the SOD enzyme as built from amino acids (protein building blocks). [1] NIDDK explains that the digestive system breaks proteins into amino acids, and that stomach acid and digestive enzymes act on proteins. [3] Putting those two facts together, a swallowed enzyme would be expected to be digested like other protein. This is our reasoning from two general sources, not a result from a study of a particular supplement, and we did not find a source that tested it. A supplement might be made to survive digestion; we found no source we could read that shows this for SOD or catalase.

Also, the level of an enzyme in food or in a capsule is not the same as enzyme activity in your cells. A change in a blood marker would not show a health benefit either.

What we did find: injected SOD, a different thing

Older trials tested SOD (called orgotein) as an injected drug, not as a supplement:

1. 1989 trial in knee osteoarthritis

   The authors report symptom reduction for up to three months [4]

   What was done: 139 people; weekly injections into the joint for three weeks versus placebo [4]

2. 1987 study in bladder cancer radiation

   No protective effect detected, and allergic reactions to the drug itself occurred in some patients [5]

   What was done: 30 patients; orgotein injected after daily radiation [5]

These results do not apply to capsules or powders. The radiation study found that an SOD injection caused local allergic reactions in some patients. [5]

Questions to ask about any enzyme supplement

• What does the label say it contains, and is the claim about the body's own enzyme activity? A claim like "boosts your SOD" is a marketing claim unless a human trial shows a health outcome.
• Is it tested by an independent group? See Quality Testing and Certifications.
• Does it interact with your medicines, or is it safe in pregnancy, childhood, kidney or liver disease? Proper evidence not found in the sources we read; ask a clinician or pharmacist. See Medication Interactions.

Digestive enzymes sold for food are a separate category: Digestive Enzyme Supplements. For the wider topic, see Antioxidants Explained.