Introduction:
Toxic substances in food items can lead to the progression of different brain diseases. They are termed neurotoxins. These toxins are of external origin. The food items become a medium to transmit into the human body. Ingesting such food items may cause damage to the nerves in the brain and lead to adverse neurological symptoms. Neurotoxins have been found in fruits, meats, and dietary supplements. Some substances termed neurotoxic are essential for the normal functioning of the body, but their consumption in excess amounts may lead to toxicity. The World Health Organisation (WHO) has declared a variety of fruits and vegetables and even animal meats as neurotoxic, which will be discussed below.
What Are Potentially Neurotoxic Food Substances?
Not all natural foods are good for health. The different naturally-occurring neurotoxic food substances include -
Fruits:
Some fruits contain toxic substances in minute quantities, and cause harmful effects after consuming large quantities of such fruits. The following fruits are considered neurotoxic -
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Lychee Fruit - This sweet fruit can be toxic and fatal. It contains a naturally occurring toxin known as hypoglycin that blocks sugar production in the body. When unripe lychee is consumed on an empty stomach, it can further drop blood sugar levels and cause hypoglycemia. It can cause symptoms such as fever, convulsions, and seizure episodes.
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Ackee Fruit - The ackee fruit plant is found in Jamaica and West Africa. This fruit contains a toxic substance, hypoglycin, similar to lychee fruit. Ackee is not supposed to be consumed unripe, as the unripe ackee fruit consists of high amounts of toxins. Malnourished children are commonly affected as the body has limited glucose reserves to overcome the deficit.
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Star Fruit - This fruit is found in Asia. The star fruit contains toxins that affect the brain. The healthy kidneys normally eliminate the toxin present in this fruit. Still, in individuals with unhealthy kidneys (chronic kidney disease), this toxin cannot be eliminated from the body and may pose serious side effects such as convulsions and seizures. This fruit may also cause hiccups in an individual. It may even cause kidney failure if consumed for a prolonged period.
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Apple Seeds and Stone Fruit Pits - Stone fruits have a stone-like seed within them. For example, apricots, peaches, cherries, and plums. The flesh of the fruit is not toxic, but the kernels present in the pits of these stone fruits contain a toxic substance called cyanogenic glycoside. When ingested, the seeds are not harmful, but when chewed and swallowed, the toxin cyanogenic glycoside gets converted into hydrogen cyanide, which can be fatal. Even one piece of a kernel may pose dangerous threats to small children.
Vegetables:
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Cycad Plants - They are considered one of the most toxic plants. Sago grains are a product of these plants. These plants require extensive processing to be fit for consumption, as processing will eliminate most of the toxins. If the plant is consumed unprocessed, it may lead to neurological disorders.
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Potatoes and Eggplants - They contain glycoalkaloids, a substance that imparts flavor to the potatoes. When consumed in excess, the increased levels of glycoalkaloids cause a burning sensation in the stomach and bitterness in the mouth. It is not recommended to consume potatoes that have turned green and have sprouts on them because they contain the toxin solanine, which is associated with neurological symptoms such as hallucinations and even paralysis.
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Cassava - This is a well-known vegetable found in Africa, South America, and some parts of Asia. It is a calorie-rich nutrient-dense vegetable. The cassava plant contains naturally occurring hydrogen cyanide. If the vegetables from this plant are not processed adequately, this vegetable is not fit for consumption. If this vegetable is consumed unprocessed and raw, the cyanide from it gets metabolized in the body and affects different organs, such as the thyroid gland and the brain. In the brain, it can damage the nerve cells and cause impairment in motor function (movement disorder or paralysis).
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Poisonous Mushrooms - Species of mushrooms that are poisonous contain several toxins that produce adverse neurological symptoms such as visual disturbances, mental confusion, and hallucinations (false perceptions of events created by the mind which are not real).
Aquatic Biotoxins:
These are formed by the algae that grow in the ocean. When the fish consume these algae, the toxin gets inside them. Shellfish such as oysters, mussels, and scallops have high concentrations of this toxin. These toxins are not eliminated even by washing and cooking. They cause gastric disturbances when ingested and even severe neurological symptoms such as tingling in the hands and feet and paralysis (inability to move).
Mercury Poisoning in Fishes:
Mercury leakage into the seas and oceans from industries causes great havoc on flora and fauna in the water. The fishes consume this contaminated water, and the mercury gets deposited in their bodies. When we consume these fishes, we also ingest the mercury in the fish. Mercury has various health hazards, including neurological disturbances. Mackerel fish has a high content of mercury in it, and it poses a great health risk to those who consume it in large quantities.
Artificially Processed Neurotoxic Foods:
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Artificial sweeteners (present in sugar-free drinks and used by people with diabetes).
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Artificial flavorings and colors (present in packaged food and drinks).
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High fructose corn syrup (a common ingredient of various kinds of cereal, canned foods, and juices).
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Monosodium glutamate or MSG (artificial food flavor-enhancing substance).
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Trans fats and hydrogenated oils (present in chips and snacks).
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Preservatives (present in all packaged foods to increase the shelf life of products).
Which Neurological Diseases Are Associated With Neurotoxins?
Neurotoxins play a critical role in the progression of neurological disorders such as:
Botulism:
It is a serious life-threatening condition caused by the bacteria Clostridium botulinum which harbors processed canned food and preserved food items. This bacteria grows without oxygen and produces a toxin known as the botulinum toxin. This toxin causes serious neurological problems. Food-borne botulism is when this bacteria enters the body through contaminated food.
The symptoms of food-borne botulism appear 12 to 36 hours after ingesting the toxin. The severity of the symptoms depends upon how much toxin has been consumed by the patient. Some of the symptoms include -
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Drooping eyelids and blurred or double vision.
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Nausea, vomiting, and stomach cramps.
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Paralysis (inability to move) and facial weakness.
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Difficulty in breathing.
The botulinum toxin targets the nerves in the brain that are responsible for the movement of the muscles. Damage to these nerves causes muscle weakness and even paralysis of the associated muscles.
Guam Parkinsonism-Dementia Complex:
This disease is a common neurodegenerative disease seen in the region of the Pacific island of Guam. It is caused due to the toxin present in the cycad seeds. The disease is characterized by facial paralysis, speech, swallowing, and breathing difficulty due to paralysis of the associated muscles of the respiratory tract and esophagus and progressive dementia (memory loss).
Konzo Disease:
Konzo is a condition associated with motor neuron damage (damage to the nerves responsible for the movement of the limbs). It is caused due to consumption of unprocessed cassava vegetables. Cassava needs to be adequately processed before consumption. The cassava plant contains hydrogen cyanide which is a potent neurotoxin. This disease is characterized by irreversible paralysis of the limbs.
What Precautions Must Be Taken to Prevent Toxicity Caused by Food Stuffs?
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Abstain from eating raw uncooked vegetables and meat. All food items should be properly washed and cooked at high temperatures before consumption.
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Sago grains should be eaten only if they are properly processed and all the toxins are eliminated. After that, they should be adequately washed and cooked before consumption.
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Processed canned food should be avoided at all times to reduce the risk of botulism. If used at all, the expiry date should be checked before purchasing, and after opening, the contents must also be carefully seen before consumption.
How to Treat Neurotoxicity?
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Supportive Care - Treating the symptoms is the first step in managing neurotoxicity. Physical therapy may be required to maintain muscle function and strength.
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Neurological Monitoring - A detailed physical examination is carried out, and the physician assesses all the motor and sensory functions of the patient. All the symptoms are carefully noted down.
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Neuroimaging - Brain imaging scans such as MRI (magnetic resonance imaging) and CT scan (computed tomography) help examine the brain tissue for abnormalities.
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Preventive Measures - Individuals should be aware of what they are eating. Proper hygienic practices must be followed while handling the food, and ensure that the food items are properly cleaned and treated before consumption. Food preparation must be done carefully, and food should be cooked well before consumption.
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Medications - The physician will prescribe medications to reverse the toxicity and treat the neurological symptoms.
Conclusion:
Neurotoxicity can be a serious life-threatening condition, and if not treated in time, it may cause permanent neurological damage. Consumption of potentially neurotoxic substances should be avoided at all times. All should adopt proper practices of clean and hygienic cooking. Neurotoxicity can be treated if the diagnosis is prompt and the treatment is started as early as possible.
