In the body, dangerous naturally occurring substances called free radicals pose a risk of harm to many tissues. The body deploys an “antioxidant defense system” to hold them in check. Superoxide dismutase (SOD) is one of the most important elements of this system. It controls levels of a chemical named “superoxide.” The body manufactures superoxide to kill bacteria and for other uses, but excess levels of superoxide can injure healthy cells. SOD converts superoxide to hydrogen peroxide. Then another enzyme, catalase, neutralizes hydrogen peroxide.
Nutrients such as
also help neutralize free radicals. In the 1990s, such
were widely promoted for preventing a variety of diseases, including cancer and heart disease. During this period, oral SOD became popular as a supplemental antioxidant supplement. Unfortunately, the results of several large studies tended to dash these hopes. Compared to ordinary antioxidants, SOD suffers from the additional disadvantages of being expensive and poorly absorbed when taken by mouth.
SOD is not an essential nutrient, and it is not obtained through food.
When taken orally, little to no SOD is absorbed.
Some manufacturers advertise a sublingual (under the tongue) form of SOD to get around this problem. However, there does not appear to be any meaningful evidence that SOD can be absorbed any better this way.
Weak evidence hints that a form of SOD in which the substance is encapsulated in structures called liposomes may be absorbable.
The optimum dose, if any, is not known.
Various websites promote SOD for a wide variety of health problems, from preventing aging to enhancing sports performance. However, as noted above, oral SOD supplements may be ineffective due to poor absorption.
SOD applied directly to wounds may enhance wound healing, according to experiments in animals.
, genetic manipulation has been used to increase SOD levels, in hopes of finding anti-aging effects, but the results have been mixed.
Inhaled SOD appears to be useful for premature infants, helping to prevent a condition called respiratory distress syndrome.
However, the only evidence for benefits with any oral form of SOD is a study in animals involving the special liposome form of the supplement mentioned above. It found possible anti-inflammatory effects.
Oral SOD is presumably quite safe, since it is apparently not absorbable. The safety of other forms of SOD (including the possibly absorbable encapsulated form) has not been established.
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