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Lecture 17

HNSC 1200 Lecture 17: Unit 3.5

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Human Nutritional Sciences
HNSC 1200
Snehil Dua

Natural Toxins in Foods Learning Objective: Define toxin and discuss examples of natural toxins Course Notes: Toxin: a chemical substance that can cause damage to a biological system Some foods, usually of plant origin, contain toxins Plantsproducetoxinchemicalsasaformofnaturaldefenseagainstanimalsand microbes Otherfoodshavenaturallyoccurringtoxinsthatareproducedbyorganismsthat contaminate the food Toxicants can be found in numerous foods that we eat on a regular basis, however we only typically consume a small amount of toxins Therefore, there is no need to eliminate these foods from our diet, as the small amounts of toxins do not present a serious health hazard cSD Examples of natural toxins Solanine Found in potatoes Has narcotic-like properties Lethal levels can be reached when potatoes are diseased, bruised or exposed to sunlight during storage Levels are controlled through breeding, handling and storage Cooking does not destroy solanine, however, because it is present in the green layer that develops under the skin it can be peeled off making the potato safe to eat Cyanogens Compounds that contain cyanide During processing or inadequate storage the compounds can be hydrolyzed to release free hydrocyanic acid (HCN) molecules HCN is a potent respiratory inhibitor Found in lima beans, fruit seeds such as apricot and peach seeds, and tubers such as cassava Long-term consumption can lead to ataxic neuropathy – a group of nervous disorders Goitrogens Compounds that inhibit proper utilization of iodine in the body, causing enlargement and atrophy of the thyroid gland (a condition called goiter) Found in cabbage and cruciferous vegetables (broccoli, cauliflower, Brussels sprouts) Marine toxins The toxins found in some fish and shell fish are not produced by the fish, but rather are caused by dinoflagellates (part of the algae family), which the fish and shellfish eat Paralytic shellfish poisoning Caused by consuming mussels, clams and oysters that contain a  toxin which produces saxitoxins Symptoms typically develop with 30 minutes of consumption and include tingling and numbness of the fingers and lips, aphasia (incoherent speech), and inability to understand  speech, because the saxitoxins bind to nerve cellsand prevent the brain from transmitting signals to the muscles  hours of the onset of symptomsry paralysis can occur within a few The saxitoxins are heat stable, so cooking does not prevent  paralytic shellfish poisoning Ciguatera grouper and red snapper), as well as larger fish who prey on,  these fish It is heat stable, so cooking the fish does not prevent ciguatera cSD Symptoms develop approximately 3-5 hours after consumption an include diarrhea, nausea, vomiting  and abdominal pain Neurological symptoms typically follow, including hot/cold inversion (i.e., think that foods are the opposite temperature than they are) muscle aches, tingling and numbness of the lips, itching, metallic taste, dryness of the mouth, dizziness,  chills, sweating, blurred vision, and temporary blindness. These symptoms can reoccur in an individual up to 25 years after  the original poisoning Neurotoxic shellfish poisoning Caused by consumption of clams and oysters that contain  several toxins called brevitoxins Red tid (sea water appears red) show the presence of these  organisms  Symptoms include tingling muscleaches, vomiting, and diarrhea, which disappear after a couple of days Diarrhetic shellfish poisoning Caused by consumption of clams and mussels that contain  toxins tha resemble brevitoxins (the most common one is okadaic acid).  The symptom is diarhea, which typically presents a few minutes after consumption Amnesic shellfish poisoning  Causedbyconsumingmusselsharvestefromtheeasternshore
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