Although the amygdalin in apricot seeds is believed to kill cancer cells, the amygdalin converts into cyanide in the stomach, not in the tumor, according to WebMD. The cyanide can potentially spread to the entire body from the stomach, putting patients at severe risk of death.
The apricot kernel is administered orally or intravenously, explains WebMD. As of 2012, the FDA has not cleared apricot kernels or Laetrile, a modified form of amygdalin, as a medical treatment. There is no scientific evidence supporting apricot kernels as a form of cancer-fighting agent, while several cases of cyanide poisoning in the United States are linked to Laetrile.
Despite this, Laetrile is known as "the perfect chemotherapeutic agent," reports the American Cancer Society. Proponents state that Laetrile affects only cancer cells while leaving normal cells untouched. Others state that Laetrile contains "the missing vitamin B17" that can cure cancer or keep it in remission. Laetrile does not fit the requirements of a vitamin, nor is it an essential chemical for good health.
The belief in Laetrile, and by extension, apricot seeds, is traced back to a theory proposed by Dr. Ernst T. Krebs, Sr. during the 1920s, notes the American Cancer Society. However, in 1957, clinical trials debunked his claims that amygdalin had anti-tumor properties.