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Gardening and growing vegetables and plants at home has seen a boom during lockdown but home-grown produce isn’t always as innocent as it appears, or at least that is the case when it comes to rare ‘toxic courgettes’. An amateur gardener from East Yorkshire reported having ‘the worst illness he’s ever had’ as a result of accidentally poisoning himself from eating home-grown courgettes. Michael Andrews, 67, suffered sickness and diarrhoea after having just a bite of a courgette grown in his own back garden He explained: ‘I can’t describe what it was like, the taste was instantly horrific… I was desperately ill, shaking and sweating. I slept solidly for two days and two nights and I was having mad, hallucinogenic dreams. I lost 4.5kg.’
So what causes potentially poisonous, toxic courgettes and how can amateur gardeners like Michael avoid falling victim to the veg in the future? What is toxic squash syndrome? Toxic squash syndrome occurs when a person eats something from the gourd fruit and vegetable family that contains unusually high levels of cucurbitacins. Plants in the gourd family include courgette, melon, pumpkin, squash, and cucumber.

Cucurbitacins are bitter-tasting compounds that can be poisonous to humans. Courgette, melon, pumpkin, squash, and cucumber are all part of the cucurbits or gourd family Cucurbitacins are rare because farmers tend to cultivate plants carefully so that they produce little to none of the compounds that can be toxic to humans. However, if there is an accidental cross-pollination of crops or a rogue batch of seeds used by amateur gardeners, then produce can grow that has the potential to cause illnesses when eaten. Vegetables like courgette and squash that have high levels of cucurbitacins won’t necessarily look poisonous – making them more dangerous as you only know they could be toxic after eating them and then tasting bitterness. Symptoms of toxic squash poisoning can include: Nausea Diarrhea Abdominal pain Vomiting Dizziness Hair loss, in rare instances If you eat produce that tastes bitter and then experience any of the above symptoms, you should seek medical advice.

Guy Barter, chief horticulturalist of the Royal Horticultural Society, explained to ‘Toxic squash syndrome can happen with home saved garden seed or volunteer plants that have seeded themselves and if bitterness detected the fruits should be immediately discarded, and medical attention sought if required.  ‘This is very, very rare in the commercial seed industry as seed raisers take precautions to avoid cross-pollination with gourds and other cucumber family plants that contain potentially harmful compounds. ‘Supermarket courgettes, squash etc are usually raised from hybrid seed with very little possibility for cross-pollination in the seed raising company, so commercial produce is very safe indeed.’ How to safely grow courgettes at home The Royal Horticultural Society advise that cucurbitacins are caused by a mutation within the plant and therefore anyone considering growing courgette or summer squash should be careful with what seeds they use to cultivate the plant. ‘The problem is more likely when plants are grown from saved seeds, where inadvertent cross-pollination may have occurred.’ To safely grow courgettes at home, avoid using saved seeds or plants grown from clippings of other plants. Buying seeds from a reputable brand or garden centre should be safe. The RHS advise that any plants likely affected by cucurbitacins are completely removed from your garden: ‘Affected fruit should not be eaten as it causes stomach upsets and affected plants should be removed.’