Until recently, manioc (cassava) has been in the lime light as a food with anti-cancerous properties due to the availability of ‘vitamin B17’.
We inquired about this from the World Health Organisation (WHO) headquarters, Geneva. The WHO Joint Secretary to JECFA and JMPR replied that the Joint FAO/WHO expert committee on Food Additives (JECFA) had recently assessed the toxic nature of cyanogenic glycosides. They confirmed that ‘vitamin B17’ is not in fact a vitamin.
The following information on manioc is provided for three reasons:
1. Cyanogenic glycoside
Manioc contains a cyanogenic glycoside called linamarin, a compound related to amygdalin. ‘Vitamin B17’ falls under the compound called amygdalin, which occurs naturally in plants. However, amygdalin belongs to the group of compounds known as ‘cyanogenic glycosides’, which contains cyanide (toxic compound which can have a negative effect on the central nervous system) that can be released upon digestion in the human body, which can even be a source of intoxication.
2. High glycemic index (GI)
Studies have shown that manioc has a very high GI of around 94, compared with white bread (reference food). High GI food rapidly raises blood glucose, which leads to you being hungry faster. Comparatively, low GI food releases glucose more slowly and steadily, which is more favourable as you feel full for longer.
3. Low protein
Manioc has a minimum amount of protein available, so consuming a meal with only manioc can lead to “protein-calorie malnutrition”. This is where inadequate amount of protein in the diet can lead to malnutrition. This form of malnutrition can eventually lead to kwashiorkor and marasmus in children.
However, it is ok to consume manioc as a curry as a part of your main meal on occasion.
Below is the letter sent by WHO for your information:
"The so-called 'vitamin B17' is in fact no vitamin, it is a compound called amygdalin that occurs naturally in certain plants. I understand that this has been promoted as cancer treatment, however this is totally non-scientific and there seems to be no evidence of effectiveness. To the contrary, amygdalin belongs to the group on compounds called 'cyanogenic glycosides' which contain cyanide that can be liberated when digested in the human body, and can even be a source of intoxication.
Cassava also contains a cyanogenic glycoside called linamarin, a compound related to amygdalin.
The Joint FAO/WHO Expert Committee on Food Additives (JECFA) has just recently evaluated the toxicity of cyanogenic glycosides, and the summary report is accessible on the web: http://www.who.int/foodsafety/chem/jecfa/summaries/Summary74.pdf . The full report and detailed monographs are in preparation and will be published by the end of this year."
Cassava also contains a cyanogenic glycoside called linamarin, a compound related to amygdalin.
The Joint FAO/WHO Expert Committee on Food Additives (JECFA) has just recently evaluated the toxicity of cyanogenic glycosides, and the summary report is accessible on the web: http://www.who.int/foodsafety/chem/jecfa/summaries/Summary74.pdf . The full report and detailed monographs are in preparation and will be published by the end of this year."
