Toxins lurking in your Food

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Toxins lurking in your Food

You are what you eat, and we all try to eat healthily but how aware are of you of Food Toxins.


We all know at least some of the basics in food safety and hygiene…. ‘wash your hands’, ‘rinse your vegetables’, ‘don’t eat green potatoes or raw kidney beans’… and more recently advice to soak nuts.  BUT do we know why we do these things and are there other things we should know about naturally occurring  food toxins?

This blog introduces five toxins that  we may encounter in our foods, so is by no means an exhaustive list… and spoiler alert!! – watch out for upcoming blogs looking at different aspects of food safety.  My aim here is to give you some basics to be aware of and to tell you where you can go if you want to find out more.  For general food safety tips see

Also, bear in mind that we are all individuals, some of us will have higher sensitivities to food toxins than others… and this could be down to your genetics or just the exposure you have had to different toxins in your food or environment.

Paralytic Shellfish Poisoning (PSP)

What is it?  PSP is actually a common type of shellfish poisoning in New Zealand.  It is caused when we eat shellfish that have eaten a certain species of algae.

What does it do?  Within 10 minutes to three hours of eating contaminated shellfish a variety of symptoms can occur:

  • Numbness and a tingling around the mouth, face, and extremities
  • Difficulty swallowing or breathing
  • Dizziness
  • Headache
  • Nausea, vomiting, diarrhoea
  • Paralysis and respiratory failure and in severe cases, death.


What can I do? Well firstly rest assured that the shellfish you buy in supermarkets and shops has to meet food safety standards and this is monitored.  However, if you like to go fishing to catch your own shellfish, just make sure you look out for safety notices on the beach and check the Ministry for Primary Industries website for details of areas that are not safe (

PSP is not prevented by cooking shellfish, but crab and crayfish are safe as long as you carefully remove the gut before cooking.  Also, fish caught in the area are safe to eat; only shellfish are affected by this toxin.


What are they?  A family of chemical compounds, some of which are toxic.  Solanine is a type of toxic glycoalkaloid found in vegetables belonging to the nightshade family (e.g. eggplant, apples, bell peppers, cherries, sugar beets and tomatoes).  Chaconine is another type of toxic glycoalkaloid found in potatoes.

What do they do?  Solanine and chaconine can cause symptoms such as drowsiness, itchiness in the neck area, increased sensitivity, laboured breathing, abdominal pain, nausea, vomiting and diarrhea.

What can I do?  The greatest concentration of glycoalkaloids are found in the sprouts, peels and sun-greened areas of potatoes.  So peeling your potatoes and chopping off any green areas and sprouts will reduce your intake of this toxin.  Secondly, watch how you store your potatoes, as exposure to light, aging and injury can enhance the glycoalkaloid content and cause potatoes to green.  Unfortunately cooking does not reduce the toxicity.  If a potato tastes bitter after cooking then don’t eat it. For further information please see


What are they? A compound found in high levels in legumes (e.g. black beans, soybeans, lima beans, kidney beans and lentils) and grain products.

What do they do? Lectins can cause severe nausea, vomiting or diarrhea within three hours of ingestion.  Recovery generally occurs 4-5 hours after symptoms are experienced.

What can I do?  The good news is that lectin concentrations are significantly reduced by cooking legumes and grain products properly.  If you are eating canned beans or lentils, these are already cooked.  If you are cooking your own beans, make sure you soak them for at least 5 hours before steaming or boiling them.  Boiling for at least ten minutes of the cooking time has been shown to significantly reduce toxicity.  The minimum temperature to destroy lectins is 176*F (80*c) and slow cooking is therefore not recommended.

For further information please see


What are they? Phytic acid, or phytates, are found in the bran and germ of many plant seeds and in grains, legumes, tofu, bean curd and nuts.

What do they do?

Phytates can reduce the nutrients your body can use from the food you eat by:

  • Binding to certain minerals – zinc, copper, iron, magnesium and calcium – in the intestinal tract, reducing their absorption and availability in the body.
  • Inhibiting certain digestive enzymes which help your body break down protein, starch and sugars in your food for use in the body.

What can I do?  Well this is why you may have heard of people soaking their nuts before eating them.  Phytates are not removed by cooking, but can be removed through soaking or fermentation.  They only affect the meal that they are eaten with, so if you are taking a mineral supplement, take it away from meal times where you may be eating phytates.  For more information see


What are they? Oxalates, or oxalic acid, are found in lots of healthy foods such as rhubarb, tea, spinach, parsley and purslane. Also asparagus, broccoli, brussel sprouts, collards, lettuce, celery, cabbage, turnips, beets, peas, coffee, cocoa, beans, potatoes, berries and carrots.

What do they do?

Oxalates can reduce the nutrients your body can use from the food you eat by binding to calcium and other minerals in the intestinal tract, reducing their absorption and availability in the body.

High consumption of oxalates can cause decreased bone growth, kidney stones, renal toxicity, vomiting, diarrhea, convulsions, coma and impaired blood clotting.

What can I do?  Generally if you eat a varied diet and are in good health, oxalates shouldn’t be an issue for you.  However, oxalates are difficult to remove by cooking and, in those sensitive to mineral deficiencies or those at risk of developing kidney stones, a low oxalate diet and/or supplementation may be the way to go. For further information see and

Hopefully this blog has been interesting and helpful to you.  As usual, please seek advice from your health practitioner if you need any further information.

Brought to you by Suzy Walsh. Naturopathic and Herbal Medicine Student at Wellpark College.


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