Tuesday, May 6, 2025

Toxins in Plant-Based Foods?

 I received a video claim in the link bellow from my nephew Vincent Lee saying that bean sprouts contains an alkaloid called N - propyl disulphide that can cause haemolytic anaemia, sprout garlic containing toxic sulphur compounds and sprout potato containing chaconine glycoalkaloids like solanine. 



He requested my opinion on these. Another doctor asked me wouldn't cooking denture all these alkaloids making vegetable food safe for consumption

Thank you Vincent and Dr Lingam for this very important  question. Let me give my opinion as a former postgraduate student at the University of Reading in England where I did my MSc dissertation in toxicology and as a former Research Food and Medical Toxicologist at the Massachusetts Institute of Technology (MIT).

I shall only very briefly list this down into several parts by verifying the claims about bean sprouts, sprouted garlic, and sprouted potatoes, followed by whether cooking destroys these toxins, and finally a comprehensive list of common natural food toxins in vegetables, legumes, fruits, and cereals.

1. On  Bean Sprouts and N-Propyl Disulfide

Claim by this lady in the video that bean sprouts contain N-propyl disulfide, an alkaloid causing haemolytic anaemia. 

First of all, N-propyl disulfide is not an alkaloid; it is a sulphur-containing compound found primarily in onions and garlic, and it's known to cause oxidative damage to red blood cells in cats and dogs, potentially leading to haemolytic anaemia. There is no strong evidence that bean sprouts (mung bean or soybean sprouts) contain significant levels of this compound.

 Bean sprouts do not typically pose a haemolytic risk in humans unless one has a rare condition like G6PD deficiency, in which even certain legumes or fava beans can trigger issues. In medicine, where medical doctors specialize in toxicology we know this very well. But I am unsure about  other medical doctors because nutritional toxicology is a very specialized field not meant for everyone. We don't except them to know so much. 

But to the best of my trained knowledge this claim is misleading. Bean sprouts are generally safe unless contaminated or consumed raw with certain vulnerabilities.


2. Sprouted Garlic and Toxic Sulphur Compounds

Garlic naturally contains organo sulphur  compounds, such as allicin, diallyl disulfide, and ajoene, which have antimicrobial and medicinal effects in small amounts. In fact, sulphur  compounds, especially ajoene in garlic are very beneficial for health and these compounds have never shown to be harmful. 

Sprouted garlic may have slightly altered composition (with higher antioxidant levels in some studies), but no credible evidence shows that sprouted garlic is toxic to humans.

Toxicity only occurs at very high, concentrated doses, often in extract or oil form. Thus, sprouted garlic is not toxic under normal dietary consumption.


3. Sprouted Potatoes and Glycoalkaloids (Solanine & Chaconine)

This concern is valid and serious. Potatoes naturally produce glycoalkaloids, especially solanine and chaconine, as a defense against pests. When potatoes sprout or turn green, these compounds increase significantly. Solanine and chaconine are neurotoxic and can cause nausea, vomiting, diarrhea, dizziness, hallucinations, and in rare severe cases, death. Levels above 200 mg / kg are considered hazardous. Even cooking (boiling, microwaving) does not reliably destroy glycoalkaloids. They are heat-stable. My advice is to avoid eating sprouted or green potatoes. Peel deeply or discard.

4. Does Cooking Destroy These Toxins? This depends on the compound. Glycoalkaloids (solanine, chaconine) are heat-stable. They are not destroyed by normal cooking. However, lectins (e.g., in red kidney beans) are destroyed by soaking and boiling. Cyanogenic glycosides (cassava, almonds) are partially destroyed by boiling and fermentation.

Goitrogens (in cruciferous vegetables like cabbage) are reduced by steaming or boiling, and oxalates in spinach, rhubarb are reduced by boiling and discarding water.

Mycotoxins (in mouldy grains, especially in mouldy nuts) are heat stable and cannot be destroyed by heat.

Thus,  cooking helps in many cases but not all toxins like aflatoxins  are neutralized by heat.

Since only a few foods  contain naturally-occurring toxins are mentioned in the video, let me give a more comprehensive list of common natural food toxins. Here is a categorized list very briefly in point forms:

A. Legumes

Toxin Food Risk Neutralized by

Lectins Raw kidney beans Gastroenteritis Boiling 10–30 min

Cyanogenic glycosides in Lima beans causes cyanide poisoning. Boiling may remove some of them


B. Tubers

Toxin Food Risk Neutralized by Cooking? 

Solanine, Chaconine Sprouted / green potatoes have neurotoxicity and are not reliably neutralized  by cooking


C. Nuts and Seeds

Toxin Food Risk also Not  Neutralized by cooking are:  

Aflatoxins (mycotoxins found in mouldy peanuts, and corn. These cancer-causing carcinogens  are not destroyed by cooking. Amygdalin (cyanogenic) Bitter almonds, apricot kernels cause cyanide poisoning.  Cooking may reduce, but not completely eliminate them. 


D. Fruits and Vegetables

Toxin Food Risk Neutralized by

Oxalates Spinach, rhubarb Kidney stones Boiling (partially)

Goitrogens in cabbage and broccoli. They are thyroid suppression, and can cause thyroid enlargement (goiter).  Cooking may destroy them 


E. Root Crops

Toxin Food Risk Neutralized by

Linamarin (cyanogenic) Cassava (tapioca).  Cyanide toxicity.  Boiling, fermentation may remove them 


F. Grains and Cereals

Toxin Food Risk Neutralized by

Ergot alkaloids Rye (infected with Claviceps) Hallucinations, vasoconstriction.  Milling may remove contaminated cereals.  Ergot alkaloids are cancer-causing carcinogenic, and are also nephrotoxic (damages the kidneys). They are  heat-resistant


Just to sum up on food toxins,  here is my final opinion. The video my nephew sent to me has mixed valid and invalid claims.

Sprouted garlic and bean sprouts are safe when properly prepared.

Sprouted potatoes are a genuine risk due to glycoalkaloids. There are actually many more naturally occurring toxins in foods, not just the few  simple examples I mention here. They are extremely lengthy and highly technical  to describe here 

Cooking helps reduce many toxins but not all, particularly heat-stable compounds like solanine and mycotoxins.

It's important to store, prepare, and cook food properly, and to avoid visibly spoiled or sprouted items (especially potatoes and moldy grains/nuts).

The video may appear alarming. But in truth, all or most plant-based foods are very health-protective due to their abundance of phytochemicals, I wrote in this link below.  

1 comment:

Vincent Lee said...

Thank you Uncle JB for enlightening us on the benefits of fruits and vegetables. You are really a God send genius to write up all these facts on fruits toxin and benefits. I'm especially grateful on your write up about green patches in potatoes and sprouts. Never knew the toxin are heat stable. I've always enjoyed KFC mashed potatoes and chips. Tasted good but deadly! Guess it's better to abstain from these unhealthy and toxic food.
Once again, thank you so much Uncle JB.

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