In a field not too far from the famous Batu caves outside of Kuala Lumpur Malaysia, a group of us inspect a verdant and fragrant crop of kesum, a popular herb used in traditional Malaysian, Thai and Vietnamese cookery, sometimes as a curry seasoning, and sometimes as an ulam, a green salad vegetable. We are observing about 6 acres of the herb, growing like paddy in shallow water, right up against some of Malaysia’s remarkable 60 million-year-old rainforest. Our group includes a woman who plants and harvests kesum, a field biologist, a couple of other agricultural specialists, and two men from a botanical extraction company. Rumbling clouds portending a heavy rain warn us of soaking wet weather in minutes.
Kesum, which alternately goes by the botanical names Polygonum Minus or Persicaria minor, grows from seed to maturity in 90 days, and has the fresh flavor of basil and oregano together, with its own unique aroma. The farm we are visiting harvests and bundles a ton of kesum every day for the local fresh markets. In homes and local restaurants, kesum, also known as laksa leaf, finds a way into many regional dishes. Notable among them is a famous Malaysian salad called kerabu, which also contains shrimp, hot chiles, peanuts and lime.
In the United States, kesum has appeared in Thai and Vietnamese cuisine for decades, and you’d probably recognize its distinctive fresh aroma. Now, scientific inquiry into kesum has opened a new area of use as a cognitive enhancer, a mental sharpening agent that works without apparent negative effects. The herb is loaded with beneficial antioxidants — from carotenes, and vitamins C and E, to a host of flavonoids, catechins and more.
The plant has been used as a traditional remedy…