"
Laetrile" is used interchangeably with "
amygdalin" to designate natural substances, derived primarily from apricots and almonds, that can release
cyanide, which is lethal to living organisms. In the 1920s, Dr. Ernst T. Krebs, Sr., formulated a theory that
amygdalin could kill
cancer cells. His theory was inconsistent with biochemical facts and has since been modified at least twice by his son, Ernst T. Krebs, Jr. Extensive work has been done by
cancer scientists to test the claim that
Laetrile fights
cancer. Many animal experiments in the 1970s showed a complete lack of
tumor killing by
Laetrile. Reviews of the medical records of patients whose
cancers were claimed to be reduced or cured after
Laetrile treatment found insufficient medical evidence to judge
Laetrile's efficacy. Finally, in a clinical trial in
cancer patients reported in 1982,
Laetrile neither caused shrinkage of
tumors, nor increased survival time, nor alleviated
cancer symptoms, nor enhanced well-being. Several reports in the medical literature document instances in which
Laetrile has caused serious, life-threatening toxicity when taken in large doses in the manner prescribed by
Laetrile advocates. In light of the lack of efficacy of
Laetrile and its demonstrated ability to cause harm,
Laetrile should not be used to treat
cancer.