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Food Safety Focus (124th Issue, November 2016) – Food Incident Highlight

Calcium Oxalate in Taro-like Plants

In September 2016, the Centre for Health Protection of the Department of Health reported a cluster of five people with calcium oxalate raphide (needle-shaped crystal) poisoning. They developed burning sensation of the mouth and tongue, numbness of the tongue and swelling of lips shortly after the consumption of the starchy corm part of some taro-like plants obtained from a friend from a farm.

Oxalates are found naturally in some fruits and vegetables, such as starfruit, rhubarb, beetroot, spinach and amaranth. Oxalates are in many forms of which calcium oxalates in needle shape can penetrate the skin and mucous membranes more readily and cause irritation. Some plants look like taro, e.g. a wild plant elephant ear ( Giant Alocasia ), may contain calcium oxalates in needle shape.

To prevent calcium oxalate food poisoning, consumers are reminded: 1) to purchase vegetables from reliable suppliers; 2) to remove any unidentified plants/objects mixed with edible vegetables; 3) to wash vegetables thoroughly before cooking and consumption; and 4) not to pick and consume wild plants.