Despite being treated as a mere side vegetable, coriander has long had a place in Thailand's culinary culture. A member of the parsley family, coriander -- or phak chee in Thai -- is a significant flavour enhancer and a commonly-used garnish. Thais even have the proverb phak chee roi na, which means window dressing.
However, in the past few years, coriander has become more than just a garnish for a specific group of consumers who believe that drinking a big glass of coriander juice can do wonders for the kidneys -- cleansing it and providing energy. This health hype, which has been circulating on social networks for years, was eventually debunked and officially labelled as false recently by Thailand's Anti-Fake News Centre after a clarification was sought from the Department of Thai Traditional and Alternative Medicine under the Ministry of Public Health.
A lecturer at the Institute of Nutrition, Mahidol University, Assoc Prof Aikkarach Kettawan said coriander has no negative health impact if used or consumed only as a food garnish or as a side vegetable.
"A pinch of coriander added to a dish will do no harm just like how it's been done in Thai kitchens since the old days. However, excessive consumption, especially in the form of extracted juice, can be detrimental especially if consumed over a long period of time," said Assoc Prof Aikkarach whose research expertise lies in the health benefits of vegetables, herbs, spices and traditional Thai food, among others.
In recent years, the popularity of phak chee has also hit Japan where the herb has gained significant popularity probably due to its unique strong flavour and scent. Called pakuchii by the Japanese, coriander has been made available in various forms in the Land of the Rising Sun including coriander drinks, coriander-flavoured noodles, coriander tea, coriander dipping sauce, coriander snacks and crisps, and coriander-infused chocolate, to name only a few.
In Thai kitchens, three phak chee varieties are widely used -- phak chee Thai (coriander or Chinese coriander), phak chee farang (parsley) and phak chee lao (dill). The three varieties are from the Apiaceae family which, according to Assoc Prof Aikkarach, has over 3,000 plant species in its family, including gotu kola, carrot and celery.
Nutritionally speaking, phak chee is low in calories but high in vitamin C, folic acid, beta carotene and vitamin K. In terms of fibre volume, phak chee is considered average as it contains only 2-3g of fibre per 100g of fresh coriander while the total dietary fibre intake should be 25-30g per day.
"Dill is also very rich in calcium," added Assoc Prof Aikkarach. "100g of dill gives up to 21% of the daily calcium requirement."
Though commonly known and used as a food ingredient, coriander can also be regarded as a herb with various medicinal properties, continued the nutrition expert. Medical research papers have backed coriander as being able to relieve coughing, thirst, cold, nausea, vomiting and dizziness. Moreover, coriander leaves are scientifically proven to lower blood sugar while the seeds can boost appetite, alleviate tooth pain, bloating, stomachache and reduce phlegm.
"All parts of coriander can be used as medicine," he explained. "The root can treat chickenpox while the stem can enhance perspiration and heal haemorrhoids. Coriander as food can render medicinal properties but extracted coriander oil will give more effective results given the higher concentration."
Despite the aforementioned medicinal wonders of phak chee, Assoc Prof Aikkarach stressed that there is no scientific data to prove that coriander juice can act as a kidney cleanser. Worse yet, excessive consumption of the green drink can do more harm than good.
All phak chee varieties are high in potassium, too much of which can be hazardous to the kidneys and the heart. While more than 270mg of potassium per 100g of food is considered too high, 100g of coriander, parsley and dill contains 520mg, 550mg and 700mg of potassium respectively. "People with kidney and heart diseases should be aware of the consequences of excessive consumption of phak chee," Assoc Prof Aikkarach warned. "The herb also comes with a medicinal property that stimulates diuresis [increased urination] which can be a significant health threat for kidney patients. Too much consumption of phak chee can mean too much workload on the kidneys, which is likely to eventually bring about kidney illnesses."
"Regular consumption of coriander juice even among generally healthy people can cause kidney damage," he added.
Parsley
Parsley also contains a high amount of oxalic acid which is associated with an increased risk of kidney stones. Other downsides of excessive coriander consumption also include dizziness and body odour. There are also reports of people being allergic to the plant, the nutritionist added.
"The safety threshold of phak chee consumption is 10g per day," said Assoc Prof Aikkarach, citing research that studied adverse effects of the herb on kidneys. "Eating 30g of coriander every day can be harmful to the kidneys."
"There was also a toxicology study of coriander oil extracted from the seeds," he added. "It was found that the daily consumption of over 250mg per kilogramme of body weight could be toxic to the kidney cells."
As with anything, Assoc Prof Aikkarach said too much of something is definitely not good. For fans of phak chee who usually treat it as more than just a garnish, he recommends eating a wide variety of fruits and veggies and alternatives to phak chee for adequate nutritional intake.
"Thailand is a country where fruits and vegetables are abundant. So, eating a wide variety would be a good way to go. There are two sides to every story and phak chee is no exception."
Watch what you eat
People falling prey to kidney disease are advised to avoid fruits and vegetables high in oxalic acid because it can lead to the formation of kidney stones. Here is a list of fruits and vegetables that contain more than 300mg of oxalic acid per 100g and should be avoided.
♦ Parsley 1,700 (mg of oxalic acid per 100g)
♦ Cassava 1,260
♦ Spinach 1,090
♦ Star fruit 820
♦ Wild betel leaf 690
♦ Carrot 500
♦ Chinese radish 480
♦ Garlic 360
Fruits and vegetables high in potassium can also be a threat to the kidneys. Here is a list of items people, especially kidney patients, should be aware of. According to Assoc Prof Aikkarach, over 270mg of potassium per 100g of fruit or vegetable can be dangerous.
♦ Spinach 846 (mg of potassium per 100g)
♦ Dill 700
♦ Durian (kan yao) 680
♦ Parsley 550
♦ Bamboo shoot 533
♦ Coriander 520
♦ Durian (chanee) 406
♦ Basil 398
♦ Carrot 367
♦ Cavendish banana 347
♦ Chinese kale 345
♦ Lady finger banana 310
♦ Pumpkin 310
♦ Broccoli 295
♦ Durian (mon thong) 292
♦ Cauliflower 285
♦ Chinese cabbage 284
♦ Dragon fruit 271
Information from the Faculty of Pharmacy, Mahidol University.
