Uncommon Food Uncommon Food PoisoningPoisoning

Dr LAU Fei-lungCOS (AED) UCH

(Natural) toxins in food (plants)

1. Cyanogenic glycoside

2. Beans

3. Potatoes

4. Fresh Jin Zhen

5. Star fruit

6. Aflatoxin

7. Ackee fruit

1) Cyanogenic glycoside

• Phytotoxin in 2000 plants• 25 cyanogenic glycosides• From 4 amino acids or nicotinic acid• Cyanogenic glucose Aldehyde or

ketoneglycoside + +

cyanohydria HCN

ß-glycosidase spontaneous or hydroxynitrile lipase

1) Cyanogenic glycoside

• Acute HCN toxicity: Headache, dizzy, mental confusion, stupor, twitching , convulsion, coma.

Lethal dose :0.5-3.5 mg /kg

• Chronic HCN toxicity : Goitre and cretinism: HCN converted to

thiocyanate interfere with thyriod Iodine uptake Tropical toxic neuropathy

Fruit seeds or stone

• Seeds of apple, apricots, plum,

prunes, cherries, peaches• Flesh of fruit not toxic• Kernals in pits chewed• Release hydrogen cyanide from Amygdalin• Lethal dose 0.5-3mg/kg• Bitter almond 南杏 poisoning commonest

Fruit seeds or stone

• ~ 6 mg HCN/ bitter almond• 5-10 raw almonds fatal for

young children• Mis-belief Amygdalin can prevent & cure cancer• Lady with cancer on 4 amp of laetrile (3g

amygdalin) daily, die with 24 hrs after ingestion of 3.5 ampoules.

Cassava poisoning ?in Philippine

• 9/3/05 after taking friedcassava ball

• 500 pupils sick , 30 died• ?cyanide poisoning ( ill prepared cassava)• Use white (bitter) cassava flour• Later prove to be organophosphate poisoning • Diarrhoea, salivation , frothing , convulsion ,

small pupils• Pesticide bottle to contain cooking oil .

Cassava ( 木薯 )

• Grow in tropical climate

• (important root crop in Pacific island, Latin America, Africa & some Asian countries)

• Tuber root (30% starch) + leaves

Cassava ( 木薯 )Poisoning also seen in China:

• under/uncooked cassava• Contain linamarin glucose, Acetone & HCN

Cyanide Content Processing

Sweet cassava 15 – 50 mg/kg Peeling & full cooking

Better cassava 50 – 400 mg/kg Heap fermentation

1 月 11 日，海南省儋州市发生食物中毒事件， 19 名学生食用了没煮熟透的油豆角（当地称青豆）而出现头晕、恶心、腹部隐痛等症状，经住院治疗后，中毒的学生已经全部痊愈出院。　　　　去年已经发生多起进食该种豆角引发的食物中毒，国内北京、天津、宁夏等地也出现多起此类中毒事件。

Bamboo Shoots

• 1200 bamboos, limited edible• Contain Taxiphyllin glucose, HCN & hydroxybenzaldehyde• 1000 mg/kg in apical part & • 8000 mg/kg in immature shoot tip• Reduced markedly after harvesting• Cooking for 2 hrs HCN to 3%

Cycas Seed ( 台灣鐵樹種子 )

• Contain Cycasin & Neocycasin• Reported in PCC Taiwan• 21 cases: 1990-2001• 70% mistaken as edible food,

others health promotion,

cancer prevention, cosmetic use• Washed & cooked

Cycas Seed

• Onset of symptom 30 min

to 7 hours• Ingested 1 to 30 seeds• Nearly all develop G.I. Symptom (vomiting)• All recovered in 24 hours• Blood cyanide & thiocyanate elevated but not

toxic

2) Beans

• Green bean 四季豆• Phytohaemagglutin

destroyed by soaking & cooking

• Onset 1-3 hours

• Symptoms: nausea, vomiting & diarrhoea

• Partial cooking to 80oC even more toxic

Castor Bean ( 萞麻毒素）蓖麻籽

• Contain ricin – in ‘mash’ after

bean processed to caster oil• Potent cytotoxin – inhibit ribosomal protein

synthesis• Weak haemagglutinin• Lethal dose: 1mg (oral); 0.5mg (injection)

Castor Bean

• 1 seed can kill a child (not toxic if swallow unchewed)

• Bulgarian writer in 1978, killed by KGB with ricin pellet

• S/S depend on route of exposure

Ricin

Ingestion:– Vomiting, bloody diarrhoea, abd pain– Within 6 hours– Progress to dehydration & shock– Followed by brain, liver, kidney failure– Death within 36-72 hours

• Inhalation:– Delay of 8-18 hours– Cough, SOB, weakness, fever, ARDS

• dermal:– dermatitis

3) Potatoes

• Contain glycoalkaloid

– solanine ( 龍葵碱 )• Usually low level & non-toxic• Greening, sprouting, rotting toxin• Bitter taste• Solanine cannot destroyed by cooking

3) Potatoes

• Cause oral burning sensation, severe abdominal pain vomiting

• Can cause respiratory depression, cerebral edema & haemolysis

4) Fresh Jian Zhen ( 鮮金針 )

• Bud of some lily harested

before blossoming• Flower & roots contain colchicine• Inadequate soaking & cooking• Cause abdo pain, vomiting & diarrhoea• Commercial & dry Jin Zhen colchicine destroyed

during processing

5) Star Fruit

• Averrhoa carambola• Tropical fruit popular in Asia• In uraemic patient• Cause hiccup, confusion,

convulsion , agitation• Treatable by intensified dialysis

5) Star Fruit

• Postulated related to oxalate• Healthy patient develop acute oxalate nephropathy

(ARF) ingesting large amount sour star fruit juice• Star fruit high oxalate content precipitate in brain

causing neurological symptom

6) Aflatoxins( 黃曲霉毒素 )

• Toxin produced by Fungi

• Aspergillus Flavus & A. parasiticus: green mould

• Grow an mouldy hay, grain & peanuts

• Aflatoxin:heat resistant no taste/smell/color

6) Aflatoxins ( 黃曲霉毒素 )

• Acute poisoning: vomiting, abdominal pain, pulmonary edema, convulsions coma, & death with cerebral edema & fatty liver, heart & kidney

• Chronic: chronic liver disease & CA liver

6) Aflatoxins ( 黃曲霉毒素 )

Accepted limited in HK – 20 mg/kg peanut oil – 15 mg/kg other food

• FEHD survey (1998-2000):– 526 food samples– 23% peanut & peanut oil +ve (1.6 – 20.0

mg/kg)

Jamaican Vomiting Sickness-Ackee friut

• Endemic in Jamaica

and Africa (+/- USA)• Acute illness with intractable

vomiting ,convulsion and coma associating with hypoglycaemia and acidaemia

Jamaican Vomiting Sickness

• 2-6 hours after eating

Ackee Fruit

• Unriped ackee fruit contains hypoglycins A and B

• Cause hypoglycaemia by binding carnitine and Coenzyme A