Bok choy is October's vegetable of the month — and has 3 times more calcium than napa cabbage

Bok choy, a staple in shabu-shabu hot pot, is October's seasonal vegetable — and this is the best time of year to eat it. Though similar in appearance to napa cabbage, it contains far more calcium and vitamin K, both of which support bone health.

The vegetable originated in China and is one of the oldest cultivated crops among Asian cabbages, with records of its cultivation dating back to around the fifth century.

According to data from the Rural Development Administration's Agricultural Technology Institute, bok choy belongs to the Cruciferae family, the same as napa cabbage and broccoli.

Calcium is the nutrient in which bok choy most clearly outpaces napa cabbage. A study published in the Journal of the Korean Society of Food Science and Nutrition comparing the nutritional content of domestic napa cabbage and Chinese-origin bok choy found that bok choy contains three to four times more calcium than napa cabbage. According to nutritional data from the Ministry of Food and Drug Safety, 100 grams of blanched bok choy contains 82 milligrams of calcium.

Beyond calcium, bok choy is also rich in vitamin K, a nutrient essential for bone formation that also supports normal blood clotting. A deficiency in vitamin K can lead to easy bruising or bleeding problems.

Bok choy contains 189 micrograms of vitamin K per 100 grams — about 2.5 times the adequate daily intake for adult men. According to the Dietary Reference Intakes for Koreans published by the Ministry of Health and Welfare and the Korean Nutrition Society, the adequate daily intake is 75 micrograms for adult men and 65 micrograms for adult women.

Bok choy pairs well with high-protein foods such as chicken and tofu. Because it is low in calories, it is a good choice for diet-conscious meals when combined with protein-rich ingredients.

One easy dish to make at home is stir-fried bok choy with oyster sauce, which can be ready in about 10 minutes. Garlic and oyster sauce give it a savory depth of flavor.

To make it, trim the base of the bok choy and cut each head in half lengthwise. Heat a pan and stir-fry the bok choy over high heat. Add a sauce made from one tablespoon of oyster sauce, one tablespoon of soy sauce, half a tablespoon of sugar, and small amounts of ginger powder, salt and pepper, then stir-fry over medium heat for about two minutes. Remove from heat and finish with chopped peanuts and a drizzle of sesame oil. For a crunchier texture, keep the total cooking time within two to three minutes.

Tofu, mushrooms or chicken can be added for a heartier dish. When using mushrooms, stir-fry them separately over high heat first to cook off the excess moisture before combining them with the other ingredients.

For a different take, try charring the bok choy lightly and serving it as a salad. Heat a pan over medium heat for two minutes, then add one tablespoon of oil. Place the bok choy in the pan, season with salt and pepper, and leave it undisturbed for two to three minutes to char. Toss and cook for another three to four minutes. Finish with a dressing of your choice for a new way to enjoy bok choy.