The cell wall of the algae is deliberately broken in processing to liberate the nutrients. But these indigestible cell walls have a special affinity for heavy metals, such as mercury. Research into the health effects of Chlorella began in the 1950s. There were reports on its successful use in Hansen's disease and in preventing the development of liver necrosis in mice. Most algae research has been done in Japan, where Chlorella is the top-selling supplement.
Chlorella also counteracts well-known carcinogens.
At Japan's Kanazawa Medical College, scientists gave Chlorella to mice, either before or after the implantation of breast, ascites, or leukemic cancer cells. While all the control mice died within 20 days of the implantation, animals receiving Chlorella lived three times as long. Surviving mice were then injected with implants of either the same tumor cells they have previously received, or a different type. They resisted the re-implantation of the same type of tumor, but not the new types. These patients were advanced and had conventionally incurable disease.