Natural toxic substances in food

Poisonous matter produced within living cells or organisms

1. Food-borne infections and intoxications (VPH- 606) BY: DR. CHANDRANI GOSWAMI Regn no: 2015-VMK-72 NATURAL TOXIC SUBSTANCES IN FOOD PRESENTATION ON :

2. Natural Toxic substance Poisonous matter produced within living cells or organisms

3. Natural toxins Either plant or animal origin Plant origin get stored in vegetables, fruits Animal origin in meat, marine food Harmful when consumed in large quantities Long term ingestion  pose a public health risk Adverse effects only after chronic ingestion or by allergic reactions

4. Natural Toxins Present in Food of Plant Origin Of over 300,000 different plant species in the world, at least 2000 species are considered poisonous Amount and the distribution of the toxins present vary according to the species, geographical conditions where it is grown. Poisoning reported when wild species of mushrooms, berries or other plants are ingested

5. 1. Glycoalkaloid Produced by potato family ( Solanaceae ) Active as pesticides and fungicides Produced by the plants as a natural defense against animals, insects and fungi Toxic glycosides in potato are α- solanine and α- chaconine

6. Public Health Significance Mild gastrointestinal effects Generally begin within 8-12 hours of ingestion and are resolved within one or two days Symptoms : nausea and vomiting, diarrhoea , stomach cramps and headache Serious cases : Neurological problems (hallucinations and paralysis) could be fatal too

7. Unlikely that humans would consume fatal glycoalkaloid doses Glycoalkaloid concentrations above 200 mg/kg are associated with : bitter taste burning sensation in throat and mouth

8. Increase of Glycoalkaloids during Storage Prolonged exposure of potato tubers to light on the store shelf or at home stimulate  formation of green colour and glycoalkaloids “Greening” is considered to be an indication for an increase in the level of glycoalkaloids .

9. Image: Greenish appearance indicate Solanine

10. Image: Glycoalkaloids concentration high in tubers, peel, sprouts

11. 2. Toxic phenolic substances 2.1 Flavonoids Plant pigments that are widely present in human food Examples are nobiletin , tangeretin (in citrus fruits) Located in the oil vesicles of the fruit peel Found in the juice after pressing the peel Extensively investigated for mutagenicity Quercetin is the only flavonoid shown to be carcinogenic in mammals after oral administration

12. Image: Citrus fruit peel

13. 2.2 Tannins Two types : hydrolyzable tannins and condensed tannins Reported to cause acute liver injury, i.e., liver necrosis and fatty liver. Tannins occur in many tropical fruits, including mango and dates Tea has the highest tannin content

14. 2.3 Safrole , coumarin , myristicin Coumarin widely occurs in a number of natural flavorings used in sweets and liquors Safrole has been shown to cause liver tumors in rats Myristicin is found in spices and herbs such as nutmeg, mace, black pepper, carrot, parsley and celery Nutmeg abuse : tachycardia, salivation, CNS excitation Nutmeg has been abused as a narcotic

15. 3. Cyanogenic glycosides Widely distributed in the plant kingdom including many that are commonly consumed by humans Cyanogenic glycosides serve as important chemical weapons in the defence of the plant against herbivores because of the potential to generate toxic hydrogen cyanide Amygdalin is the most common of the cyanogenic glycosides Present in abundance in the seeds and kernels of fruits such as apricot, almond, apple, cherry, plum, peach and nectarine Peeling, washing in running water and cooking or fermenting can remove and volatilize the cyanide

16. Toxicity occur in humans at doses between 0.5-3.5 mg kg-1 body weight When cyanogenic plants are ingested by humans, enzymes produced by the intestinal microflora are able to hydrolyse intact cyanogenic glycoside to produce hydrogen cyanide in vivo. Symptoms : Headache, nausea, vomiting, abdominal pain, dizziness, weakness, mental confusion, convulsions, cardiac arrest, circulatory and respiratory failure, coma and in extreme cases death.

17. Image: Fruits containing Cyanogenic glycosides

18. 4. Goitrogens ( Glucosinolates ) Antinutritives Occurrs in cruciferous plants, such as cabbage and turnips Inhibit the uptake of iodine by the thyroid  iodine deficiency. Image : Illustrating Goitre

19. 5. Biogenic amines Sources: fermented foods, vegetables, meats Mainly caused by the enzymatic decarboxylation of amino acids by microorganism High concentration in fish and cheese 1000 mg/kg amine (based on histamine intoxication & amine concentration in food) is dangerous for human health.

20. 6. Mushroom Toxins Caused by the high content of amatoxins in mushrooms. Mushrooms identified as containing amatoxin toxins are the species Amanita bisporigera , A. temifolia , A. ocreata , A. suballiacea , Galerina autumnalis , and Lipiota brunneolilacea . Image: Galerina autumnalis Image: Amanita bisporigera

21. 7. Antivitamins Biotin-binding protein, avidin , in raw egg white Avidin is inactivated when heated. Image: Half boiled egg

22. 8. Lectins Are proteins capable of damaging the intestinal mucosa. Enhances the shedding of brush-border membranes  decreases villus length  reduces surface area for absorption SI Overall effect  reduced nutrient absorption Immune function may also be impaired. Image: Soybean Image: Jack bean

23. 9. Gossypol Pigment occurs in cottonseed in free and bound forms. Free gossypol is the toxic entity and causes organ damage, cardiac failure and death Cottonseed meal fed to bulls  induce increased sperm abnormalities + decreased sperm production

24. 10. Mycotoxin Cereals, oilseeds, spices and three nuts, moldy fruits and vegetables - can be contaminated with  mycotoxins  ( aflatoxin , ochratoxin A, patulin , fusarium ) Cause serious damage to the liver, kidneys and nervous system, they are often carcinogenic and mutagenic Not biodegradable  penetrate the food chain (meat, dairy) through infected feed crops Not destroyed by cooking or freezing

25. One of the most potent mycotoxins - aflatoxin - can be a hidden toxic contaminant in some foods of tropical origin, especially peanuts The only way to reduce your exposure to mycotoxins is to avoid foods that are not, or don't appear fresh Currently, a few hundred mycotoxins are known, often produced by the genera Aspergillus , Penicillium , and Fusarium Because of their chemical stability, several mycotoxins persist during food processing, while the molds are killed

26. Aflatoxins Produced by certain species of Aspergillus (A. flavus and A. parasiticus ) Indicative of Carcinogenic properties Cause cancer, cirrhosis of the liver Most common commodities contaminated are tree nuts, peanuts, and corn and cottonseed oil.

27. The major aflatoxins of concern are B1, B2, G1, and G2  usually found together in various proportions A major metabolic product of aflatoxin B1 is aflatoxin M (usually excreted in the milk of dairy cattle that have consumed aflatoxin -contaminated feed).LD50 ranges from 0.5 to 10 mg/kg body weight (any species of animals)

28. Natural Toxins Present in Food of Animal Origin 1200 species of poisonous and venomous animals in the world May be a product of metabolism or a chemical that is passed along the food chain Poisoning after eating terrestrial animals is relatively uncommon Poisoning due to marine toxins occurs in many parts of the world

29. While most of them are not used as food, care must be taken to avoid the poisonous glands or tissue containing the toxins when these animals are used as food Glands of some animals that are not considered poisonous or venomous when ingested can also cause food poisoning Eg . gall-bladder of grass carp which contains the cyprinol related chemicals

30. Natural Marine Toxins Around the world, cases of seafood poisoning occur from time to time due to the presence of naturally occurring substances. .

31. Phycotoxins Produced by algae in both temperate and tropical climate, such as dinoflagellates and diatoms Not all algae or mircoalgae are toxic Over 5 000 species of marine algae, only about 70 or more species are known to produce toxins When toxic algae are involved in a red tide, seafood contamination is possible.

32. Ciguatoxin and Shellfish Toxins Upon ingestion by human in significant amounts, these toxins may cause poisoning with various gastrointestinal and neurological effects. No antidotes against these phycotoxins and medical treatment is mainly supportive. 385 cases of ciguatoxin poisoning affecting 1 356 people, and 69 cases of shellfish poisoning affecting 145 people were reported in Hong Kong from 1997 to 2006 [Centre for Health Protection] Certain coral reef fish are of high risk for ciguatera fish poisoning. Larger the fish, the higher is the level of toxin. Fish liver, guts, head and skin are parts of the fish where ciguatoxins are concentrated

33. Tetrodotoxin Poisoning Potent neurotoxin found in fish of the family  Tetraodontidae Concentrated in the ovaries (eggs), liver, guts and the skin Fish include puffer fish and porcupine fish although not all the species contain the toxin Symptoms: Paraesthesia in the face and extremities, dizziness and numbness Death may occur in severe cases. Image : Porcupine fish

34. Scombroid Poisoning/Histamine Poisoning Occurs after the ingestion of scombroid fish species (e.g. tuna, mackerel, sardines, anchovy) containing histamine Histamine is formed during spoilage and improper storage by conversion of the free amino acid histidine in muscles of dead fish with the presence of certain bacteria Clinical symptoms: facial flushing, rashes, and palpitations. Image : Tuna fish

35. Does Cooking Reduce the Risk? Ciguatoxin , shellfish toxins, tetrodotoxin and histamine are heat-stable These natural toxic substances are tasteless and odourless , and contaminated seafood cannot be distinguished by their appearance.

36. Prevention Coral reef fish: Eat only small amounts in any one meal Avoid consuming the roe, liver, guts, head and skin Avoid nut products together with fish These substances are known to increase the severity of symptoms.

37. Shellfish: Remove the viscera and gonads before cooking avoid consuming the cooking liquid since some of the shellfish toxins are water soluble Puffer fish : Avoid dressing and cooking puffer fish on your own Scombroid fish: Properly refrigerate fish that may contain histamine such as tuna, mackerel, sardine and anchovy at 4°C or below. Image : Mackerel Image : Shell fish Image: Puffer fish