Superoxide Dismutase (SOD) with Catalase – In our cells, we have our own SODs, but we can protect our skin by supplementing them with topically applied SOD. The size of the SOD used in skin care varies between 10,000 and 30,000 molecular weight, which is relatively small for an enzyme but large enough to be excluded from live cells. The fact that SOD is unlikely to enter live cells is not a problem. Lipid peroxidation occurs everywhere in the skin, not just in the live cells. The role of SOD is to eliminate the free radicals resulting from lipid peroxidation and to prevent the chain reactions that would eventually reach deeply into the skin, and topical application of SOD will certainly help to achieve this aim.