Health Guide

The Cancer Council South Australia recognises that people with cancer, their families and friends will seek out information about alternative and complementary therapies. These methods may also be referred to as “unproven”, “non-toxic”, “unorthodox” or “unconventional” therapies and represent methods which are not scientifically proven by random clinical trials. The following information is intended to help with making decisions about the use of such treatments.
We also recommend you read “Making an informed choice”.

Rationale / Background / Claims

• The terms Laetrile and amygdalin are often used interchangeably, although they are not chemically identical. Both belong to a family of compounds called the cyanogenic glycosides. What is actually used in Laetrile therapy is amygdalin.
• According to the supporters of Laetrile, amygdalin is split by the enzyme beta-glucosidase, releasing glucose (sugar), benzaldehyde (a mild anaesthetic) and cyanide (a poison), which is lethal to cells. Cancer cells supposedly contain more of this enzyme than normal cells and therefore receive more cyanide. “Normal” cells are said to contain another enzyme, rhodanese, which detoxifies cyanide, thus preventing unwanted destruction of healthy cells.
• Another theory as to how Laetrile works relies on the belief that cancer is a vitamin deficiency disease, and Laetrile is the “missing vitamin” (vitamin B17).
• Laetrile is found naturally in the kernels and pits of apricots, peaches, cherries, apples, plums and nectarines. In the time of the pharoahs, peach kernel extract was used for performing executions.

What does the therapy involve?

• Laetrile is most commonly given intravenously for two to three weeks, followed by oral doses for maintenance therapy.
• Dietary therapy may accompany Laetrile treatment, and usually has the following characteristics:

Here are some cautions for a person with cancer using Laetrile/amygdalin

• Low doses of cyanide, the “active” breakdown product of amygdalin, causes headache, dizziness, nausea, vomiting, diarrhoea, fever, lethargy, abdominal tenderness and cramps, rash, neuro-muscular weakness of the arms and legs, gradual progressive loss of hearing and vision and other deteriorative nerve damage. Cyanide poisoning can lead to death.
• Cyanide toxicity is a risk when Laetrile is taken orally. Beta-glucosidase made by bacteria in the intestine breaks down amygdalin to cyanide; with intravenous Laetrile - the usual method - most is excreted in the urine without releasing cyanide. Thus intravenous Laetrile can have no therapeutic effect. Laetrile is 40-times more toxic when taken orally rather than by injection.
• Combining doses of Laetrile with foods containing beta-glucosidase, such as vegetables or apricot kernels, will generally poison the patient, and may lead to death. Megadoses of vitamin C in conjunction with Laetrile administration also increases the possibility of poisoning, as there is laboratory evidence vitamin C helps release cyanide from amygdalin.

Evaluation

• The theories underlying the mechanism of action of Laetrile are unfounded. The claim that beta-glucosidase, the enzyme responsible for breaking down amygdalin, is abundant in cancerous cells is misleading. Analysis shows that only traces of this enzyme are present in animal tissues. In addition, the enzyme responsible for protecting normal cells from cyanide toxicity, rhodanese, is present in equal amounts in both normal and cancerous tissues.
• A vitamin is classified as an organic substance which is required to promote one or more specific and essential biochemical reactions within the living cell. Disease will occur if deficiency is present, and reversal of the disease is achievable through administration of the missing vitamin. Laetrile does not meet these criteria, and therefore is not a vitamin.
• Laetrile has been proposed as a cancer remedy since 1845, but never has been found to be of value against cancer. Scientific studies commencing in the mid-1950’s were conducted for over 20 years, and no evidence for any benefit against tumours in animals was found. Despite this, a human trial was conducted in 1981. It did not show any anti-cancer effect of Laetrile.

Costs and Commitment

• Laetrile is usually given as part of a larger treatment program which can cost between US$2,000 and $5,000 per week.
• The Richardson Centre in Reno, Nevada, charges US$2,500 to $3,000 for the first four months. This does not include travel or room costs.

In Summary . . .

The available research does not support the claim that Laetrile is an effective anti-cancer agent. The risks of cyanide poisoning which accompany this therapy are clearly a cause for concern.