Plant-based toxins pose danger to health

By Donna Eastlake

- Last updated on GMT

Plant-based toxins pose danger to health. GettyImages/Tara Moore
Plant-based toxins pose danger to health. GettyImages/Tara Moore

Related tags Plant-based toxins Plant toxins Food safety

Plant toxins have always existed in plant foods but their potential health implications remain relatively unknown to consumers. Why?

Recent consumer, media and industry attention has been placed on the potential dangers of PFAS, better known as forever chemicals​, in food and beverages. However, much less attention has been paid to the potential dangers of the naturally occurring chemicals in plants. In fact, a recent representative survey, by the German Federal Institute for Risk Assessment (BfR)​, found that just under half of the study respondents (47%) were even aware of the existence of plant toxins. Furthermore, just 27% of respondents to the survey claimed to be concerned about naturally occurring plant toxins.

“The survey results make it clear that risks of natural origin tend to be underestimated, while risks of synthetic origin tend to be overestimated,” says Professor Andreas Hensel, BfR President.

This is quite possibly a result of the fact that they are naturally occurring, rather than an unnatural substance, such as a chemical pesticide, which has been added during the growing process.

Salad - GettyImages-gbh007
Plant toxins exist in a wide range of foods, including vegetables such as tomatoes and lettuces. GettyImages/gbh007

Should consumers and food manufacturers be concerned about plant toxins?

Though naturally occurring, plant toxins could potentially be detrimental to human health. According to the World Health Organization (WHO), natural toxins can cause a variety of adverse health effects and pose a serious health threat to both humans and livestock.

“Adverse health effects can be acute poisoning, ranging from allergic reactions to severe stomach ache and diarrhoea, and even death,” said a spokesperson for the WHO. “Long-term health consequences include effects on the immune, reproductive or nervous systems, and also cancer.”

With the potential dangers, posed by plant toxins, it’s surprising to find public awareness to be so low. However, more than half of the respondents (53%) say that they feel poorly informed about plant toxins in food. This implies a desire to know and understand the potential dangers, more.

The study also shed light on the related topic of mould on food. Here, too, there was found to be a lack of understanding, with regards to the potential dangers.

While some foods, such as hard cheeses and dry-cured meats, are safe to eat once mould has been cut out, there are many more foods which should be avoided if mould is found to be growing on them. Foods, such as soft cheeses, yoghurts, breads and baked goods, nuts, seeds and uncured meats.

Even small amounts of mould toxins can be harmful to the health of humans and animals, with the United States Department of Agriculture Food Safety and Inspection Service (USDA) stating that, “some moulds cause allergic reactions and respiratory problems, and a few moulds, in the right conditions, produce ‘mycotoxins’, poisonous substances that can make people sick.”

Despite this, 25% of respondents stated that they only remove the mouldy part, which is visible to them.

What are plant toxins?

Plant toxins are naturally occurring phytochemicals or secondary metabolites formed by plants to protect themselves against threats, such as bacteria, fungi and insects. Toxins can be present in commonly consumed human foods, including fruits and vegetables.

The most common natural toxins, according to the World Health Organization, are listed below:

  • Algal toxins​ - Algal toxins are formed by algae in the ocean and fresh water. Shellfish such as mussels, scallops and oysters are likely to contain these toxins, but they can also be found in fish. 
  • Cyanogenic glycosides​ - Cyanogenic glycosides are phytotoxins (toxic chemicals produced by plants), which occur in at least 2000 plant species. Cassava, stone fruits and almonds all contain cyanogenic glycosides.
  • Furocoumarins​ - Furocoumarins are stress toxins, released as part of a plant's stress response, such as physical damage to the plant. These toxins are present in many plants, including parsnips, celery roots and citrus plants. 
  • Lectins​ - Lectins are carbohydrate binding proteins, present in most plants, especially seeds and tubers like cereals, potatoes, and beans.
  • Mycotoxins​ - Mycotoxins are naturally occurring toxic compounds produced by certain types of moulds. Moulds that can produce mycotoxins grow on numerous foodstuffs, including cereals, dried fruits, nuts and spices.
  • Solanines and chaconine​ - Solanacea plants contain natural toxins called solanines and chaconine. These plants produce toxins in response to stresses, such as bruising, UV light, and attacks from insects. Foods containing Solanines include tomatoes, potatoes, and aubergine.
  • Poisonous mushrooms​ - Wild mushrooms can contain several toxins, including muscimol and muscarine. Mushrooms such as Amanita muscaria and Amanita pantherina, are known to contain these toxins.
  • Pyrrolizidine alkaloids​ - Pyrrolizidine Alkaloids (PAs) are toxins produced by an estimated 600 plant species. The main plant sources are the families Boraginaceae, Asteraceae and Fabaceae, many of which are weeds growing in fields close to food crops.  They have been detected in herbal teas, honey and cereals. The Food and Agriculture Organization, and World Health Organization, are currently developing guidelines to prevent PA-containing plants from entering the food chain.
Mussels - GettyImages-fcafotodigital
Plant toxins formed by algae in the ocean and fresh water are called algal toxins. Shellfish, including mussels (pictured), scallops and oysters, are likely to contain these toxins. GettyImages/fcafotodigital

Consumers concerned about residues and contaminants

While evidence supporting the potential health implications of plant toxins is clear, consumers remain more concerned about the implications of consuming chemicals, which have been added to foods during the production process.

In fact, 63% remain more concerned about residues, such as pesticides used on plants, and 62% remain more concerned about contaminants, such as heavy metals and plastics, leeching into foods.

Related topics Ingredients

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