Bok Choy

 

Bok Choy is Our Food of the Week

If you are not familiar with bok choy (Chinese cabbage), I encourage you to try it as part of your Healthiest Way of Eating this week. Like other members of the cruciferous family of vegetables including broccoli, cauliflower, cabbage, and kale, it contains health-promoting nutrients (glucosinolates) that help rid your body of potential toxins and energize you.

What's New and Beneficial About Bok Choy

• Baby bok choy has become more widely available all over the world, and this wider availability is a good thing in terms of nutrition. A recent study has shown some unique characteristics of Baby Shanghai bok choy in terms of its phytonutrient contents. Specifically, among 17 different cruciferous vegetables analyzed in the study, Baby Shanghai bok choy was the only vegetable to contain high amounts of what the researchers called "Principle 1" and "Principle 2" phenols. "Principle 1" components were primarily flavonoids (and especially flavonoids related to kaempferol and quercetin). "Principle 2" components were non-flavonoid phenols, including molecules like malic acid and hydroxycinnamic acid.

• Phenols and other phytonutrients in bok choy represent what is now known to be a full spectrum of over 70 antioxidants in this cruciferous vegetable. The antioxidant richness of bok choy partly explains ongoing investigation of bok choy in relationship to cancer prevention since prevention and reduction of oxidative stress has often been linked to decreased cancer risk. In most research studies, increased intake of antioxidant nutrients from vegetables like bok choy has been associated with decreased oxidative stress, and this connection is one way that researchers explain the ability of certain vegetables to lower cancer risk. (Too much oxidative stress can leave our cells too susceptible to damage from free radicals and too much at risk for potential transformation into pre-cancerous cells.)

• Bok choy also contains glucosinolates, sulfur-containing compounds associated with reduced cancer risk. While all cruciferous vegetable contain beneficial amounts of glucosinolates, a recent study on the total glucosinolate content of bok choy shoots has caught our attention. This study looked at very early developmental forms of cruciferous vegetables including their seeds (pre-planting); their sprouts (an early germination form representing about 1 week of growth), and their shoots (still an early growth stage, but involving more development of plant structure including a well-defined stem and some leaves and representing about 1-2 weeks of growth). What the researchers found was a greater concentration of total glucosinolates in the shoots of the bok choy plants than in the shoots of most other cruciferous vegetables, including broccoli, cabbage, cauliflower, and kale. Only mustard green shoots contained more total glucosinolates than the bok choy shoots.

• Because of its strong beta-carotene content, bok choy ranks as our 11th richest food in vitamin A. This vitamin A richness places bok choy ahead of some of its fellow cruciferous vegetables, including cauliflower, cabbage, Brussels sprouts, and broccoli. Significant amounts of other carotenoids—for example, lutein—are also provided by bok choy.

 

 

 

Our Recommendations

You'll want to include bok choy as one of the cruciferous vegetables you eat on a regular basis if you want to receive the fantastic health benefits provided by the cruciferous vegetable family. We recommend a cruciferous vegetable serving of at least 3/4 cups per day. Even more outstanding would be an intake level of 1-1/2 cups per day. We've found bok choy to be a delightful alternative among the cruciferous vegetables for its quick preparation, enjoyable and easy-to-chew texture, milder and somewhat sweet taste, and versatility in recipes.

Enjoy the mild flavor of bok choy by using our Healthy Sauté method of cooking. Our 3-Minute Healthy Sautéed Bok Choy recipe will give you great tasting bok choy in a matter of minutes! 

 

 

 

Health Benefits

 

Antioxidant Benefits of Bok Choy

As an excellent source of vitamin C, vitamin A (in the form of carotenoids), and manganese, and a good source of zinc, bok choy provides us with a concentration of these core conventional antioxidants. Yet, its antioxidant support extends beyond these conventional antioxidants to a wide range of other phytonutrient antioxidants. These phytonutrients include flavonoids like quercetin, kaempferol, and isorhamnetin, as well as numerous phenolic acids (including significant amounts of hydroxycinnamic acids). It's important to understand the unique benefits provided by this diverse array of antioxidants. Different types of antioxidants function in different ways. While all types are helpful in preventing unwanted oxygen damage to our cells and body systems, different types of antioxidants go about this task in different ways, and it is the combination of these types in cruciferous vegetables—including bok choy—that make them so valuable in terms of their antioxidant support. (It is also a key reason why whole, natural foods like fresh bok choy provide you with benefits that antioxidant supplements cannot.) At least one study on bok choy has shown higher total phenol content in organically grown versus bok choy that was not organically grown. This study seems in keeping with research showing overall greater nutrient contents in organic versus non-organic food. Still, we would like to see some follow-up studies in this area, since there are many reasons why phenol content in bok choy might vary widely.

One interesting option for consumers of bok choy who are particularly interested in its antioxidant benefits is the commercial availability of purple bok choy. Sometimes called "Purple Choy" or "Pak Choi Rubi," purple cultivars of this cruciferous vegetable have been shown to contain anthocyanidins—the red-purple pigments that belong to the flavonoid category of antioxidants.

 

 

 

Anti-Inflammatory Benefits of Bok Choy

Many of the antioxidant nutrients listed above also provide anti-inflammatory benefits. They not only lower the risk of oxygen-based damage to your cells and body systems, but they also lower your risk of unwanted chronic inflammation. While it is a good thing for your body's inflammatory system to respond promptly to dangers or actual damage, it is not a good thing for it to continuously trigger inflammatory responses when there is not danger or actual damage. Anti-inflammatory phytonutrients in bok choy help prevent this type of continuous and unwanted inflammation from occurring. Yet in addition to these phytonutrients, bok choy also provides you with two additional anti-inflammatory nutrients. The first of these nutrients are omega-3s. Bok choy ranks as a good source of omega-3s in food rating system due to its significant amount of alpha-linolenic acid (ALA). About 70 milligrams of ALA are found in one cup of cooked bok choy. While this amount does not put bok choy anywhere close to the top of our omega-3 plant vegetable list, it does qualify bok choy as being about one-half as concentrated in omega-3s as walnuts on a calorie-for-calorie basis. We have yet to see research on bok choy's omega-3 content and inflammation, but we would expect this kind of research to show bok choy omega-3s as being helpful in lowering risk of unwanted inflammation.

Another anti-inflammatory nutrient provided by bok choy is vitamin K. Bok choy ranks in world wide Top 15 vitamin K-rich foods and is an excellent source of this fat-soluble vitamin. While best know for its role in bone health and blood clotting, vitamin K has also been shown to help regulate our body's inflammatory responses, especially in relationship to our cardiovascular system.

 

 

 

Other Health Benefits of Bok Choy

Bok choy has been included in human studies of cruciferous vegetables that have shown decreasing risk of certain cancers when these vegetables were consumed on a frequent basis, usually involving one or more daily servings. At least part of this protection has been associated with the glucosinolate content of the cruciferous vegetables, including bok choy. (Glucosinolates are unique sulfur-containing compounds that have been shown to have cancer-protective properties.) However, we have yet to see a study exclusively focused on bok choy in comparison to its fellow cruciferous vegetables, and we suspect that it would rank on the lower end in terms of its glucosinolate-related benefits since it contains a significantly lower amount of these sulfur-containing compounds than other vegetables in the cruciferous family like Brussels sprouts or mustard greens.

 

 

 

Description

All cruciferous vegetables provide integrated nourishment across a wide variety of nutritional categories and provide broad support across a wide variety of body systems as well.

Bok choy is a cruciferous vegetable that can go by many different names. Some of these different names for bok choy include white cabbage, mustard cabbage, celery cabbage, Chinese white cabbage, Chinese mustard, and white celery mustard. The English spelling of bok choy can also take several different forms. You might see the first word in this food name being spelled as "buk," "pok," or "pak." You might see the second word being spelled as "choi." And sometimes you might find these two words being combined into a single word like "pakchoi." Helping to make sense of many of the names above is the literal translation of "bok choy" in Chinese; the words "bok choy" come from "bai cai" where "bai" means "white" and "cai" means "cabbage."

Many of the cruciferous vegetables commonly eaten in the U.S. are known for the "heads" that they form in their more mature plant stages. Cauliflower, broccoli, cabbage, and Brussels sprouts can all fall into this category of "head-forming" cruciferous vegetables. By contrast, bok choy is a non-head-forming cruciferous vegetable, and in fact is sometimes referred to as "non-heading Chinese cabbage." While the leaves of the bok choy plant can cluster together in a noticeable way, they do not form a head and at times can be only loosely clustered together.

In many U.S. grocery stores, you are most likely to find bok choy that features green spoon-shaped leaves and slightly flattened white stalks. Varieties of bok choy that fall into this category include Mibuna Early, Canton, and Ching Chang. However, there are numerous varieties of bok choy and they can vary in their stalk color. While white and beige stalks are widely enjoyed, so are green stalks with many varying shades, including Shanghai Green and Green Boy. Also becoming more available in over groceries are varieties of bok choy with purple leaves. Purple varieties of bok choy include Rubi and Purple Hybrid.

Just as you can find more than one recognizable form of bok choy, you can also find more than one scientific name for this cruciferous vegetable. The most common name is Brassica rapa L. subsp. chinensis. But you may also find bok choy being scientifically referred to as Brassica chinensis (where "chinensis" is used as a species name rather than a subspecies name). Also, you may occasionally see bok choy being identified as Brassica campestris L. subsp. chinensis.

 

 

 

History

Bok choy has been enjoyed in China and other parts of Asia for over 1,500 years. And bok choy is by no means a total newcomer to North America either, having been cultivated on the continent for over 100 years. About 95 million pounds of Asian vegetables—the produce trading category that includes bok choy—are brought into the U.S. each year (primarily from Mexico). However, another 35 million pounds are produced in the U.S. The state of California dominates this domestic production, with smaller amounts being produced in Arizona and Texas. Some marketplace statistics on bok choy combine production of this vegetable together with overall cabbage production. If this approach is used, the numbers go up dramatically, since more than 2 billion pounds of cabbage are produced in the U.S. each year.

 

 

 

How to Select and Store

Look for bok choy with firm, bright green colored leaves (or purple, if you are purchasing a purple variety) and moist hardy stems. Bok choy should be displayed in a cool environment since warm temperatures will cause it to wilt and will negatively affect its flavor. The leaves should look fresh, be unwilted, and be free from signs of browning, yellowing, and small holes. Bok choy is available throughout the year, although it is more widely available, and at its peak, from the middle of winter through the beginning of spring.

We encourage the purchase of certified organically grown foods, and bok choy is no exception. Repeated research studies show that your likelihood of exposure to contaminants such as pesticides and heavy metals can be greatly reduced through the purchase of certified organic bok choy. In many cases, you may be able to find a local organic grower who sells bok choy but has not applied for formal organic certification either through the respected or through a state agency. However, if you are shopping in a large supermarket, your most reliable source of organically grown bok choy is very likely to be bok choy that displays the respected organic logo.

To store, place bok choy in a plastic storage bag, removing as much of the air from the bag as possible, and place it in the crisper of your refrigerator..Bok choy will keep for about 1 week if properly stored.

Here is some background on why we recommend refrigerating bok choy. Whenever food is stored, four basic factors affect its nutrient composition: exposure to air, exposure to light, exposure to heat, and length of time in storage. Vitamin C, vitamin B6, and carotenoids are good examples of nutrients highly susceptible to heat, and for this reason, their loss from food is very likely to be slowed down through refrigeration.

 

 

 

Tips for Preparing and Cooking

 

Tips for Preparing Bok Choy

Unlike some of the other cruciferous vegetables, you can consume virtually all parts of bok choy without much trimming or worrying about problematic textures or cooking times.

Chop leaf portion into 1/8" slices and the stems into 1/2" lengths for quick and even cooking.

 

 

 

The Nutrient-Rich Way of Cooking Bok Choy

From all of the cooking methods we tried when cooking bok choy, our favorite is Healthy sauté. We think that it provides the greatest flavor.

Healthy Sauté—similar to Quick Steaming and Quick Boiling, our other recommended cooking methods—follows three basic cooking guidelines that are generally associated in food science research with improved nutrient retention. These three guidelines are: (1) minimal necessary heat exposure; (2) minimal necessary cooking duration; (3) minimal necessary food surface contact with cooking liquid.

To Healthy Sautébok choy, heat 5 TBS of vegetable or chicken broth, or water, in a stainless steel skillet. Once bubbles begin to form add bok choy stems on the bottom of the pan and the leaves on top, cover, and Healthy Sautéfor 3 minutes. (See our recipe for details on how to prepare this dish.)

 

 

 

How to Enjoy

 

A Few Quick Serving Ideas

 

• Healthy Sautébok choy with snow peas and mushrooms.
• Add a few drops of tamari soy sauce to bok choy recipe.
• Combine Healthy Sautéed bok choy with tofu or chicken for a complete meal.

 

 

 

Individual Concerns

 

Bok Choy and Goitrogens

You may sometimes hear bok choy being described as a food that contains "goitrogens," or as a food that is "goitrogenic.".

 

 

 

Nutritional Profile

Bok choy is an excellent source of vitamin K, vitamin C, vitamin A (in the form of carotenoids), potassium, folate, vitamin B6, calcium and manganese. It is a very good source of iron, vitamin B2, phosphorus, fiber and protein as well as a good source of choline, magnesium, niacin, vitamin B1, copper, omega-3 fatty acids, zinc and pantothenic acid. Boy choy also provides flavonoids including quercetin, kaempferol and isorhamnetin, as well as numerous antioxidant phenolic acids, including hydroxycinnamic and malic acid.