Vietnamese Coriander (Polygonum odoratum syn. Persicaria odorata, Polygonaceae) is a herb whose leaves are commonly used in Southeast Asian cooking. Other English names for the herb include Vietnamese mint, Vietnamese cilantro, Cambodian mint and hot mint. The Vietnamese name is Rau răm. In Malaysia and Singapore it is called daun kesom or daun laksa. It is not related to the mints, but the general appearance and odor are reminiscent.

Above all, the leaf is identified with Vietnamese cuisine, where it is commonly eaten fresh in salads and in raw spring rolls (goi cuon). Bowls of pho (beef noodles) are also typically garnished with Vietnamese mint. It is also popularly eaten with hột vịt lộn, (known as balut in the Philippines).

In Singapore and Malaysia, the shredded leaf is an essential ingredient of laksa soup, so much so that the Malay name daun laksa means "laksa leaf".

In Australia the plant is being investigated for a source of essential oil (kesom oil).

Characteristics

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The Vietnamese coriander is a perennial plant that grows best in tropical and subtropical zones in warm and damp conditions. It can not live above the 32° parallel or in places with too much water. In advantageous conditions, it can grow up to 15 to 30 cm. In the winter or when the temperature is too high, it can wither.

The top of its leaf is dark green, with chestnut-colored spots while the leaf's bottom is burgundy red. Its stem has sections. In Vietnam it can be cultivated or grown in the wild.

Components

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Its oil contains aldehydes such as decanal (28%) and dodecanal (44%), as well as the alcohol decanol (11%). Sesquiterpenes such as α-humulene and β-caryophyllene comprise about 15% of its oil.

Medicinal uses

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According to Vietnamese experts, Vietnamese coriander has a bitter and spicy taste, is nontoxic and can detoxify food. They claim that it can be used to treat swellings, acne, indigestion, flatulence, and stomachaches.

Effects on health

Studies performed at the University of Natural Sciences in Hanoi showed that the Vietnamese coriander reduce the sperm count in mice. It might have a similar effect on humans. In many Vietnamese herbal remedies, it is used to repress sexual urges. There is a saying in Vietnamese, "rau răm, giá sống" (Vietnamese coriander, live bean sprouts) meaning that Vietnamese coriander has the ability to reduce fertility, while live bean sprouts have the opposite effect. There is also a saying "rău răm diệt dục" (Vietnamese coriander kills sexual urges). Many Buddhist monks grow it in their private gardens and eat it frequently.

External links

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• Vietnamese Coriander (Polygonum odoratum Lour.) page from Gernot Katzer's Spice Pages
• Kesom Oil – a New Essential Oil for the International Flavour and Fragrance Industry in First Australian New Crops Conference 1996 – Volume 2

Herbs | Polygonaceae | Vietnamese cuisine

Rau răm