The claim that apricot seeds or their derivatives can cure cancer has persisted for decades, circulating widely among alternative health advocates. This belief centers on a compound naturally present in the seeds of apricots and other stone fruits. This article will examine the chemical basis of the purported therapy, the biological theory behind its proposed mechanism, the evidence from clinical research, and the serious safety hazards involved in consuming these substances.
Amygdalin, Laetrile, and the “Vitamin B17” Myth
The primary substance in apricot kernels linked to anti-cancer claims is amygdalin, a naturally occurring cyanogenic glycoside. Amygdalin is a molecule containing a cyanide group, which is released when the compound is broken down. This substance is the precursor to Laetrile, a semi-synthetic derivative promoted as a cancer treatment.
Promoters began marketing amygdalin under the misleading name “Vitamin B17” in the 1950s. Neither amygdalin nor Laetrile is recognized as a vitamin by any major health organization, as they do not meet the criteria for a nutrient required for normal body function. The designation “Vitamin B17” is pseudoscientific, created to lend credibility to the substance.
The Flawed Theory of Selective Toxicity
The theory proposed by proponents of Laetrile and amygdalin is known as selective toxicity. It suggests the compound specifically targets and kills cancer cells while leaving healthy cells unharmed. This mechanism relies on the idea that cancer cells contain high concentrations of the enzyme beta-glucosidase, which breaks down amygdalin to release hydrogen cyanide.
Healthy cells are theorized to be protected by the enzyme rhodanese, which detoxifies the released cyanide by converting it into a harmless thiocyanate. However, this theory is not supported by biological evidence. Beta-glucosidase is found in many healthy tissues, particularly in the gut, and its presence in tumors is inconsistent. Furthermore, while rhodanese is present in normal cells, it cannot always cope with the massive cyanide load released from ingested amygdalin.
Clinical Evidence: Does the Research Support the Claim?
Claims that amygdalin or Laetrile can cure cancer are not supported by sound clinical data, despite decades of promotion. Major health organizations, including the National Cancer Institute (NCI) and the Food and Drug Administration (FDA), have consistently found that Laetrile shows little to no anti-cancer activity in human trials. For example, one phase II study on 175 cancer patients found that amygdalin provided no meaningful tumor response.
The medical consensus is that the risk-benefit balance of using amygdalin or Laetrile as a cancer treatment is negative. Due to the lack of efficacy and clear safety concerns, the FDA banned the interstate shipment of Laetrile in 1980. While some laboratory studies have explored potential anti-cancer properties, these effects have not translated into objective proof of clinical benefit in people with cancer.
Cyanide Poisoning Risk
The most serious hazard associated with consuming apricot seeds or amygdalin is the risk of acute cyanide poisoning. When amygdalin is ingested, enzymes in the gut, including those from intestinal bacteria, break it down. This process releases toxic hydrogen cyanide, which interferes with the body’s ability to use oxygen and rapidly leads to cellular damage.
Symptoms of acute cyanide toxicity can appear quickly, often within minutes to hours of consumption. These symptoms include nausea, headache, dizziness, and difficulty breathing. In severe cases, the poisoning can lead to seizures, coma, cardiovascular collapse, and fatal respiratory failure.
The amount of amygdalin in apricot kernels varies widely. Consuming as few as three small kernels can exceed safe exposure levels for adults, and less than one kernel can be dangerous for toddlers. The risk of toxicity is significantly increased when amygdalin is consumed alongside high doses of Vitamin C, because this vitamin can increase the conversion of amygdalin into cyanide.