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

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

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

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: GalerinaImage: 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
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
Image : Porcupine

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